| 1. |
- Kampmann, Christian, 1975-
(författare)
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Go with your gut : The human intestinal microbiota, international travel, Campylobacter and ESBL-producing Enterobacteriaceae
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Up to 100 million people travel annually from industrialized countries to resource-limited ones. Each traveller contains an internal ecosystem composed of tens of trillions of microbes, known as the intestinal microbiota, which has a large effect on health. The microbiota seems to be highly individual and mostly stable but can be significantly affected by several factors. Many international travellers are at high risk of getting infected by Campylobacter, the most common cause of bacterial enteritis worldwide. Campylobacter infection can cause a wide range of symptoms, with varying severity, for reasons largely unknown. Travel also radically increases the risk of colonization by antibiotic-resistant intestinal bacteria, notably Extended spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae (EPE). To date, there are no therapies available for EPE-decolonization. In this thesis, it was investigated whether the bacterial intestinal microbiota affected susceptibility to Campylobacter and if international travel as such had an impact on the microbiota. In a prospective, observational study, 67 healthy Swedes, travelling in groups to countries with a high risk of Campylobacter infection, were followed. The travellers answered questionnaires and delivered two faecal samples before and three samples after the trip. These samples were cultured for enteropathogens and analysed for the microbiota composition. Low diversity of microbiota seemed to increase the risk of Campylobacter jejuni infection, whereas a high relative abundance of Lachnospiraceae might decrease the risk (Paper I). Furthermore, the overall bacterial diversity did not seem to change in connection with travelling. However, the bacterial family Enterobacteriaceae (otherwise connected with inflammation, infection and antibiotic-resistance) was shown to be dramatically increased in abundance immediately after travel, and the family Christensenellaceae (otherwise connected with beneficial health conditions) simultaneously decreased (Paper II). Eight travellers, from two different destinations, were infected with closely related C. jejuni isolates (ST353CC). The bacterial analysis of genomic and phenotypic characteristics revealed that the C. jejuni isolates of the travellers returning from one of the destinations and with more severe symptoms actually showed less pathogenic potential, compared to the isolates of travellers from the other destination and with milder symptoms. However, the travellers with more severe symptoms had much higher relative abundances of Bacteroidetes in their intestinal microbiota and, in contrast to the other travellers, excluded meat from their diet. (Paper III) Finally, we investigated in a randomized, placebo-controlled clinical trial of 80 established intestinal carriers of EPE, whether the oral probiotic product Vivomixx® could eradicate EPE. Vivomixx® was not superior to placebo (Paper IV).
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| 2. |
- Anderberg, Eva, et al.
(författare)
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Prevalence of impaired glucose tolerance and diabetes after gestational diabetes mellitus comparing different cut-off criteria for abnormal glucose tolerance during pregnancy.
- 2011
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Ingår i: Acta Obstetricia et Gynecologica Scandinavica. - : Wiley. - 1600-0412 .- 0001-6349. ; 90, s. 1252-1258
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Tidskriftsartikel (refereegranskat)abstract
- Objective. To determine the prevalence of diabetes and impaired glucose tolerance after gestational diabetes mellitus in relation to different categories of glucose tolerance during pregnancy. Design. Prospective study. Setting. Four delivery departments and three hospitals in southern Sweden took part in recruitment and follow-up. Population. Women undergoing a 75 g oral glucose tolerance test during pregnancy delivering in 2003-2005. Methods. At first follow-up, 1-2 years after delivery, 29% of eligible women with abnormal glucose tolerance during pregnancy had an oral glucose tolerance test; 160 with gestational diabetes, 309 with gestational impaired glucose tolerance, in addition to 167 control women. Cut-off levels defining gestational diabetes and impaired glucose tolerance were 2-hour capillary blood glucose levels 9.0 and 7.8 mmol/l or plasma glucose 10.0 and 8.6 mmol/l, respectively. Main outcome measures. Frequency of abnormal test results at follow-up. Results: Diabetes was diagnosed in 11% and impaired glucose tolerance in 24% of women with gestational diabetes vs. 4% and 23% in those with gestational impaired glucose tolerance. Combining women with abnormal test results during pregnancy revealed diabetes or impaired glucose tolerance in 29% as compared to 10% among controls; the odds ratio (95% confidence interval) for having abnormal test results was 3.3 (1.8-5.9) in a multivariate logistic regression analysis. Conclusions: Lowering the cut-off level for gestational diabetes to also include the category of impaired glucose tolerance would identify a high percentage of women with diabetes and impaired glucose tolerance postpartum, they constitute target groups for intervention and/or diabetes prevention.
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| 3. |
- Dahal, Prabin, et al.
(författare)
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Competing risk events in antimalarial drug trials in uncomplicated Plasmodium falciparum malaria : a WorldWide Antimalarial Resistance Network individual participant data meta-analysis
- 2019
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Ingår i: Malaria Journal. - : BMC. - 1475-2875. ; 18
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Tidskriftsartikel (refereegranskat)abstract
- Background: Therapeutic efficacy studies in uncomplicated Plasmodium falciparum malaria are confounded by new infections, which constitute competing risk events since they can potentially preclude/pre-empt the detection of subsequent recrudescence of persistent, sub-microscopic primary infections.Methods: Antimalarial studies typically report the risk of recrudescence derived using the Kaplan-Meier (K-M) method, which considers new infections acquired during the follow-up period as censored. Cumulative Incidence Function (CIF) provides an alternative approach for handling new infections, which accounts for them as a competing risk event. The complement of the estimate derived using the K-M method (1 minus K-M), and the CIF were used to derive the risk of recrudescence at the end of the follow-up period using data from studies collated in the WorldWide Antimalarial Resistance Network data repository. Absolute differences in the failure estimates derived using these two methods were quantified. In comparative studies, the equality of two K-M curves was assessed using the log-rank test, and the equality of CIFs using Gray's k-sample test (both at 5% level of significance). Two different regression modelling strategies for recrudescence were considered: cause-specific Cox model and Fine and Gray's sub-distributional hazard model.Results: Data were available from 92 studies (233 treatment arms, 31,379 patients) conducted between 1996 and 2014. At the end of follow-up, the median absolute overestimation in the estimated risk of cumulative recrudescence by using 1 minus K-M approach was 0.04% (interquartile range (IQR): 0.00-0.27%, Range: 0.00-3.60%). The overestimation was correlated positively with the proportion of patients with recrudescence [Pearson's correlation coefficient (rho): 0.38, 95% Confidence Interval (CI) 0.30-0.46] or new infection [rho: 0.43; 95% CI 0.35-0.54]. In three study arms, the point estimates of failure were greater than 10% (the WHO threshold for withdrawing antimalarials) when the K-M method was used, but remained below 10% when using the CIF approach, but the 95% confidence interval included this threshold.Conclusions: The 1 minus K-M method resulted in a marginal overestimation of recrudescence that became increasingly pronounced as antimalarial efficacy declined, particularly when the observed proportion of new infection was high. The CIF approach provides an alternative approach for derivation of failure estimates in antimalarial trials, particularly in high transmission settings.
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| 4. |
- Dahal, Prabin, et al.
(författare)
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Temporal distribution of Plasmodium falciparum recrudescence following artemisinin-based combination therapy : an individual participant data meta-analysis
- 2022
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Ingår i: Malaria Journal. - : Springer Nature. - 1475-2875. ; 21
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Tidskriftsartikel (refereegranskat)abstract
- Background: The duration of trial follow-up affects the ability to detect recrudescent infections following anti-malarial treatment. The aim of this study was to explore the proportions of recrudescent parasitaemia as ascribed by genotyping captured at various follow-up time-points in treatment efficacy trials for uncomplicated Plasmodium falciparum malaria.Methods: Individual patient data from 83 anti-malarial efficacy studies collated in the WorldWide Antimalarial Resistance Network (WWARN) repository with at least 28 days follow-up were available. The temporal and cumulative distributions of recrudescence were characterized using a Cox regression model with shared frailty on study-sites. Fractional polynomials were used to capture non-linear instantaneous hazard. The area under the density curve (AUC) of the constructed distribution was used to estimate the optimal follow-up period for capturing a P. falciparum malaria recrudescence. Simulation studies were conducted based on the constructed distributions to quantify the absolute overestimation in efficacy due to sub-optimal follow-up.Results: Overall, 3703 recurrent infections were detected in 60 studies conducted in Africa (15,512 children aged < 5 years) and 23 studies conducted in Asia and South America (5272 patients of all ages). Using molecular genotyping, 519 (14.0%) recurrences were ascribed as recrudescent infections. A 28 day artemether-lumefantrine (AL) efficacy trial would not have detected 58% [95% confidence interval (CI) 47-74%] of recrudescences in African children and 32% [95% CI 15-45%] in patients of all ages in Asia/South America. The corresponding estimate following a 42 day dihydroartemisinin-piperaquine (DP) efficacy trial in Africa was 47% [95% CI 19-90%] in children under 5 years old treated with > 48 mg/kg total piperaquine (PIP) dose and 9% [95% CI 0-22%] in those treated with <= 48 mg/kg PIP dose. In absolute terms, the simulation study found that trials limited to 28 days follow-up following AL underestimated the risk of recrudescence by a median of 2.8 percentage points compared to day 63 estimates and those limited to 42 days following DP underestimated the risk of recrudescence by a median of 2.0 percentage points compared to day 42 estimates. The analysis was limited by few clinical trials following patients for longer than 42 days (9 out of 83 trials) and the imprecision of PCR genotyping which overcalls recrudescence in areas of higher transmission biasing the later distribution.Conclusions: Restricting follow-up of clinical efficacy trials to day 28 for AL and day 42 for DP will miss a proportion of late recrudescent treatment failures but will have a modest impact in derived efficacy. The results highlight that as genotyping methods improve consideration should be given for trials with longer duration of follow-up to detect early indications of emerging drug resistance.
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| 5. |
- Henriksson, Jens, et al.
(författare)
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Out-of-Distribution Detection as Support for Autonomous Driving Safety Lifecycle
- 2023
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Ingår i: <em>Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatic. )</em>Volume 13975 LNCS, Pages 233 - 242. - : Springer Science and Business Media Deutschland GmbH. - 9783031297854 ; , s. 233-242
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Konferensbidrag (refereegranskat)abstract
- The automotive industry is moving towards increased automation, where features such as automated driving systems typically include machine learning (ML), e.g. in the perception system. [Question/Problem] Ensuring safety for systems partly relying on ML is challenging. Different approaches and frameworks have been proposed, typically where the developer must define quantitative and/or qualitative acceptance criteria, and ensure the criteria are fulfilled using different methods to improve e.g., design, robustness and error detection. However, there is still a knowledge gap between quality methods and metrics employed in the ML domain and how such methods can contribute to satisfying the vehicle level safety requirements. In this paper, we argue the need for connecting available ML quality methods and metrics to the safety lifecycle and explicitly show their contribution to safety. In particular, we analyse Out-of-Distribution (OoD) detection, e.g., the frequency of novelty detection, and show its potential for multiple safety-related purposes. I.e., as (a) an acceptance criterion contributing to the decision if the software fulfills the safety requirements and hence is ready-for-release, (b) in operational design domain selection and expansion by including novelty samples into the training/development loop, and (c) as a run-time measure, e.g., if there is a sequence of novel samples, the vehicle should consider reaching a minimal risk condition. [Contribution] This paper describes the possibility to use OoD detection as a safety measure, and the potential contributions in different stages of the safety lifecycle. © 2023, The Author(s)
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| 6. |
- Jovel, Irina Tatiana, et al.
(författare)
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Temporal and Seasonal Changes of Genetic Polymorphisms Associated with Altered Drug Susceptibility to Chloroquine, Lumefantrine, and Quinine in Guinea-Bissau between 2003 and 2012.
- 2015
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Ingår i: Antimicrobial Agents and Chemotherapy. - 0066-4804 .- 1098-6596. ; 59:2, s. 872-9
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Tidskriftsartikel (refereegranskat)abstract
- In 2008, artemether-lumefantrine was introduced in Guinea-Bissau, West Africa, but quinine has also been commonly prescribed for the treatment of uncomplicated Plasmodium falciparum malaria. An efficacious high-dose chloroquine treatment regimen was used previously. Temporal and seasonal changes of genetic polymorphisms associated with altered drug susceptibility to chloroquine, lumefantrine, and quinine have been described. P. falciparum chloroquine resistance transporter (pfcrt) K76T, pfmdr1 gene copy numbers, pfmdr1 polymorphisms N86Y and Y184F, and pfmdr1 sequences 1034 to 1246 were determined using PCR-based methods. Blood samples came from virtually all (n = 1,806) children <15 years of age who had uncomplicated P. falciparum monoinfection and presented at a health center in suburban Bissau (from 2003 to 2012). The pfcrt K76T and pfmdr1 N86Y frequencies were stable, and seasonal changes were not seen from 2003 to 2007. Since 2007, the mean annual frequencies increased (P < 0.001) for pfcrt 76T (24% to 57%), pfmdr1 N86 (72% to 83%), and pfcrt 76 + pfmdr1 86 TN (10% to 27%), and pfcrt 76T accumulated during the high transmission season (P = 0.001). The pfmdr1 86 + 184 NF frequency increased from 39% to 66% (from 2003 to 2011; P = 0.004). One sample had two pfmdr1 gene copies. pfcrt 76T was associated with a lower parasite density (P < 0.001). Following the discontinuation of an effective chloroquine regimen, probably highly artemether-lumefantrine-susceptible P. falciparum (with pfcrt 76T) accumulated, possibly due to suboptimal use of quinine and despite a fitness cost linked to pfcrt 76T. (The studies reported here were registered at ClinicalTrials.gov under registration no. NCT00137514 [PSB-2001-chl-amo], NCT00137566 [PSB-2004-paracetamol], NCT00426439 [PSB-2006-coartem], NCT01157689 [AL-eff 2010], and NCT01704508 [Eurartesim 2012].).
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| 7. |
- Jovel, Irina T., et al.
(författare)
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Unexpected selections of Plasmodium falciparum polymorphisms in previously treatment-naive areas after monthly presumptive administration of three different anti-malarial drugs in Liberia 1976-78
- 2017
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Ingår i: Malaria Journal. - : Springer Science and Business Media LLC. - 1475-2875. ; 16
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Tidskriftsartikel (refereegranskat)abstract
- Background: To assess the effect on malaria prevalence, village specific monthly administrations of pyrimethamine, chlorproguanil, chloroquine or placebo were given to children in four previously treatment-naive Liberian villages, 1976-78. Plasmodium falciparum in vivo resistance developed to pyrimethamine only. Selection of molecular markers of P.falciparum resistance after 2 years of treatment are reported. Methods: Blood samples were collected from 191 study children in a survey in 1978. Polymorphisms in pfcrt, pfmdr1, pfdhfr, pfdhps, pfmrp1 and pfnhe1 genes were determined using PCR-based methods. Results: Pfcrt 72-76 CVIET was found in one chloroquine village sample, all remaining samples had pfcrt CVMNK. Pfmdr1 N86 prevalence was 100%. A pfmdr1 T1069(ACT -> ACG) synonymous polymorphism was found in 30% of chloroquine village samples and 3% of other samples (P = 0.008). Variations in pfnhe1 block I were found in all except the chloroquine treated village (P < 0.001). Resistance associated pfdhfr 108N prevalence was 2% in the pyrimethamine village compared to 45-65% elsewhere, including the placebo village (P = 0.001). Conclusions: Chloroquine treatment possibly resulted in the development of pfcrt 72-76 CVIET. Selection of pfmdr1 T1069(ACG) and a pfnhe1 block 1 genotypes indicates that chloroquine treatment exerted a selective pressure on P. falciparum. Pyrimethamine resistance associated pfdhfr 108N was present prior to the introduction of any drug. Decreased pfdhfr 108N frequency concurrent with development of pyrimethamine resistance suggests a non-pfdhfr polymorphisms mediated resistance mechanism.
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| 8. |
- Kofoed, Poul-Erik, et al.
(författare)
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Paracetamol versus placebo in treatment of non-severe malaria in children in Guinea-Bissau : a randomized controlled trial
- 2011
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Ingår i: Malaria Journal. - : Springer Science and Business Media LLC. - 1475-2875. ; 10, s. 148-
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND:The current guidelines for treatment of malaria include paracetamol to children with fever. No convincing evidence for the beneficial effects of this practice exists. Studies show that time to parasite clearance is significantly longer in children treated with paracetamol, which questions the policy. Whether this is of clinical importance has not been investigated.METHODS:Children with Plasmodium falciparum monoinfection and ≥20 parasites per 200 leucocytes at the Bandim Health Centre, Guinea-Bissau were randomized to receive paracetamol or placebo together with chloroquine for three days in a double blind randomized study. Temperature and symptoms were recorded twice daily during treatment and on day 3. The participants were interviewed and a malaria film taken once weekly until day 35. The data is in the form of grouped failure-times, the outcome of interest being time until parasitaemia during follow-up. Mantel-Haenszel weighted odds ratios are given. Other differences between and within the two groups have been tested using the Chi-square test and Mann-Whitney U test.RESULTS:In the evening of the day of inclusion, the temperature was slightly, but statistically insignificant, higher in the placebo group and significantly more children complained of headache. At no other time was a significant difference in temperature or symptoms detected. However, 6 children from the placebo-group as compared to two children from the paracetamol-group were admitted to hospital with high fever and convulsions by day 3. No differences in the cumulative percentages of children with adequate clinical and parasitological response were found in the intention-to-treat analysis or in the per-protocol analysis.CONCLUSION:Fewer children had early treatment failure and the mean temperature was slightly lower in the afternoon on day 0 in the paracetamol group. However, the cumulative adequate clinical and parasitological cure rates were not significantly different during the period of study. It is doubtful whether adding paracetamol to the treatment of uncomplicated malaria in children is beneficial.TRIAL REGISTRATION:NCT00137566
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| 9. |
- Mansoor, Rashid, et al.
(författare)
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Haematological consequences of acute uncomplicated falciparum malaria : a WorldWide Antimalarial Resistance Network pooled analysis of individual patient data
- 2022
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Ingår i: BMC Medicine. - : Springer Nature. - 1741-7015. ; 20:1
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundPlasmodium falciparum malaria is associated with anaemia-related morbidity, attributable to host, parasite and drug factors. We quantified the haematological response following treatment of uncomplicated P. falciparum malaria to identify the factors associated with malarial anaemia.MethodsIndividual patient data from eligible antimalarial efficacy studies of uncomplicated P. falciparum malaria, available through the WorldWide Antimalarial Resistance Network data repository prior to August 2015, were pooled using standardised methodology. The haematological response over time was quantified using a multivariable linear mixed effects model with nonlinear terms for time, and the model was then used to estimate the mean haemoglobin at day of nadir and day 7. Multivariable logistic regression quantified risk factors for moderately severe anaemia (haemoglobin < 7 g/dL) at day 0, day 3 and day 7 as well as a fractional fall >= 25% at day 3 and day 7.ResultsA total of 70,226 patients, recruited into 200 studies between 1991 and 2013, were included in the analysis: 50,859 (72.4%) enrolled in Africa, 18,451 (26.3%) in Asia and 916 (1.3%) in South America. The median haemoglobin concentration at presentation was 9.9 g/dL (range 5.0-19.7 g/dL) in Africa, 11.6 g/dL (range 5.0-20.0 g/dL) in Asia and 12.3 g/dL (range 6.9-17.9 g/dL) in South America. Moderately severe anaemia (Hb < 7g/dl) was present in 8.4% (4284/50,859) of patients from Africa, 3.3% (606/18,451) from Asia and 0.1% (1/916) from South America. The nadir haemoglobin occurred on day 2 post treatment with a mean fall from baseline of 0.57 g/dL in Africa and 1.13 g/dL in Asia. Independent risk factors for moderately severe anaemia on day 7, in both Africa and Asia, included moderately severe anaemia at baseline (adjusted odds ratio (AOR) = 16.10 and AOR = 23.00, respectively), young age (age < 1 compared to >= 12 years AOR = 12.81 and AOR = 6.79, respectively), high parasitaemia (AOR = 1.78 and AOR = 1.58, respectively) and delayed parasite clearance (AOR = 2.44 and AOR = 2.59, respectively). In Asia, patients treated with an artemisinin-based regimen were at significantly greater risk of moderately severe anaemia on day 7 compared to those treated with a non-artemisinin-based regimen (AOR = 2.06 [95%CI 1.39-3.05], p < 0.001).ConclusionsIn patients with uncomplicated P. falciparum malaria, the nadir haemoglobin occurs 2 days after starting treatment. Although artemisinin-based treatments increase the rate of parasite clearance, in Asia they are associated with a greater risk of anaemia during recovery.
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| 10. |
- Mero, Sointu, et al.
(författare)
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Multiplex PCR detection of Cryptosporidium sp, Giardia lamblia and Entamoeba histolytica directly from dried stool samples from Guinea-Bissauan children with diarrhoea
- 2017
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Ingår i: Infectious Diseases. - : Taylor & Francis. - 2374-4235 .- 2374-4243. ; 49:9, s. 655-663
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Tidskriftsartikel (refereegranskat)abstract
- Background: In developing countries, diarrhoea is the most common cause of death for children under five years of age, with Giardia lamblia, Cryptosporidium and Entamoeba histolytica as the most frequent pathogenic parasites. Traditional microscopy for stool parasites has poor sensitivity and specificity, while new molecular methods may provide more accurate diagnostics. In poor regions with sample storage hampered by uncertain electricity supply, research would benefit from a method capable of analysing dried stools. Methods: A real-time multiplex PCR method with internal inhibition control was developed for detecting Giardia lamblia, Cryptosporidium hominis/parvum and Entamoeba histolytica directly from stool specimens. Applicability to dried samples was checked by comparing with fresh ones in a small test material. Finally, the assay was applied to dried specimens collected from Guinea-Bissauan children with diarrhoea. Results: The PCR's analytical sensitivity limit was 0.1 ng/ml for G. lamblia DNA, 0.01 ng/ml for E. histolytica DNA and 0.1 ng/ml for Cryptosporidium sp. In the test material, the assay performed similarly with fresh and dried stools. Of the 52 Guinea-Bissauan samples, local microscopy revealed a parasite in 15%, while PCR detected 62% positive for at least one parasite: 44% of the dried samples had Giardia, 23% Cryptosporidium and 0% E. histolytica. Conclusions: Our new multiplex real-time PCR for protozoa presents a sensitive method applicable to dried samples. As proof of concept, it worked well on stools collected from Guinea-Bissauan children with diarrhoea. It provides an epidemiological tool for analysing dried specimens from regions poor in resources.
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| 11. |
- Mero, Sointu, et al.
(författare)
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Prevalence of diarrhoeal pathogens among children under five years of age with and without diarrhoea in Guinea-Bissau
- 2021
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Ingår i: PLoS Neglected Tropical Diseases. - : Public Library of Science (PLoS). - 1935-2727 .- 1935-2735. ; 15:9
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Tidskriftsartikel (refereegranskat)abstract
- Background Childhood diarrhoea, a major cause of morbidity and mortality in low-income regions, remains scarcely studied in many countries, such as Guinea-Bissau. Stool sample drying enables later qPCR analyses of pathogens without concern about electricity shortages. Methods Dried stool samples of children under five years treated at the Bandim Health Centre in Bissau, Guinea-Bissau were screened by qPCR for nine enteric bacteria, five viruses, and four parasites. The findings of children having and not having diarrhoea were compared in age groups 0-11 and 12-59 months. Results Of the 429 children- 228 with and 201 without diarrhoea- 96.9% and 93.5% had bacterial, 62.7% and 44.3% viral, and 52.6% and 48.3% parasitic pathogen findings, respectively. Enteroaggregarive Escherichia coli (EAEC; 60.5% versus 66.7%), enteropathogenic E. coli (EPEC; 61.4% versus 62.7%), Campylobacter (53.2% versus 51.8%), and enterotoxigenic E. coli (ETEC; 54.4% versus 44.3%) were the most common bacterial pathogens. Diarrhoea was associated with enteroinvasive E. coli (EIEC)/Shigella (63.3%), astrovirus (75.0%), norovirus GII (72.6%) and Cryptosporidium (71.2%). The only pathogen associated with severe diarrhoea was EIEC/Shigella (p<0.001). EAEC was found more frequent among the infants, and EIEC/Shigella, Giardia duodenalis and Dientamoeba fragilis among the older children. Conclusions Stool pathogens proved common among all the children regardless of them having diarrhoea or not. Author summary Diarrhoeal diseases rank second as cause of childhood mortality and morbidity in low-income countries, yet prospective cohort studies in children with and without diarrhea covering the large variety of diarrhoeal pathogens are limited. While some studies have been conducted among Guinea-Bissauan children, many of them were from the 1990s, when the coverage of the various pathogens was less extensive and the diagnostic methods less sensitive than the modern qPCR methods. We conducted an observational study with a large cohort and covered concomitantly the various bacterial, viral and parasitic agents, and analyzed their associations with the presence/absence of diarrhoeal symptoms and age groups. Importantly, the assay performed well with dried stool samples and, therefore, appears applicable for epidemiological studies in resource-poor regions. A pathogen finding was recorded for almost all (98%) children: bacteria in 97%, viruses in 59% and parasites in 51%. Ongoing diarrhoea was associated with findings of enteroninvasive Escherichia coli/Shigella, astrovirus, norovirus GII and Cryptosporidium. Differences were seen between age groups, infants and young children. The only pathogen associated with severe diarrhoea was enteroninvasive Escherichia coli/Shigella.
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| 12. |
- Mero, Sointu, et al.
(författare)
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Seasonal variation of diarrhoeal pathogens among Guinea-Bissauan children under five years of age
- 2023
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Ingår i: PLoS Neglected Tropical Diseases. - : Public Library of Science (PLoS). - 1935-2727 .- 1935-2735. ; 17:3
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Tidskriftsartikel (refereegranskat)abstract
- Background: Diarrhoea remains a major cause of childhood morbidity and mortality in low-income countries (LICs). The frequency of diarrhoeal episodes may vary by season, yet few prospective cohort studies have examined seasonal variation among various diarrhoeal pathogens using multiplex qPCR to analyse bacterial, viral and parasitic pathogens.Methods: We combined our recent qPCR data of diarrhoeal pathogens (nine bacterial, five viral and four parasitic) among Guinea-Bissauan children under five years old with individual background data, dividing by season. The associations of season (dry winter and rainy summer) and the various pathogens were explored among infants (0-11 months) and young children (12-59 months) and those with and without diarrhoea.Results: Many bacterial pathogens, especially EAEC, ETEC and Campylobacter, and parasitic Cryptosporidium, prevailed in the rainy season, whereas many viruses, particularly the adenovirus, astrovirus and rotavirus proved common in the dry season. Noroviruses were found constantly throughout the year. Seasonal variation was observed in both age groups.Conclusion: In childhood diarrhoea in a West African LIC, seasonal variation appears to favour EAEC, ETEC, and Cryptosporidium in the rainy and viral pathogens in the dry season.
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| 13. |
- Montelin, Hanna, 1984-
(författare)
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Antibiotic-Induced Damage on the Intestinal Microbiota and Treatment of Urinary Tract Infections Caused by ESBL- and Non-ESBL-Producing Bacteria
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Therapeutic options for urinary tract infection (UTI) caused by Escherichia coli and Klebsiella pneumoniae are limited due to resistance against cephalosporins and carbapenems, which is typically mediated by the production of extended-spectrum β-lactamases (ESBLs) and carbapenemases. ESBL-producing bacteria are frequently co-resistant to other antibiotic classes, resulting in a shortage of treatment options. While all systemic antibiotic treatments are likely to disturb the microbiota and increase selection of resistance, evidence on the extent and persistence of such effects for different antibiotics is limited. The primary objective of this thesis was to investigate the therapeutic effect of carbapenem-sparing and narrow-spectrum oral antibiotics in the treatment of UTI, and to evaluate the impact of commonly used antibiotics on the intestinal microbiota. The first study investigated the efficacy of nitrofurantoin and pivmecillinam for lower UTI in men (n=171), with trimethoprim as a comparator. We concluded that nitrofurantoin and pivmecillinam are suitable for empirical treatment of lower UTIs in men, considering their high activity against Eschericha coli and limited impact on the microbiota. In a prospective multi-center study conducted at 15 infectious diseases hospital departments, patients (n=235) with UTI caused by ESBL-producing Enterobacterales were recruited. We aimed to evaluate clinical and microbiological treatment outcomes and relapse rates. The results indicate that carbapenem-sparing antibiotics were effective for UTI caused by ESBL-producing Enterobacterales and can be recommended for non-critically ill patients. Moreover, we noted that certain bacterial genetic features (e.g., ST131 in Eschericha coli and haemolysin) were associated with microbiological failure and relapse.In a randomized, controlled trial with healthy adults (n=86), we investigated the impact on the microbiota of five antibiotics (ceftibuten, ciprofloxacin, nitrofurantoin, pivmecillinam, trimethoprim-sulfamethoxazole) that are commonly used for UTI. Fecal samples were collected before and up to one year after five days of antibiotic treatment. Ciprofloxacin demonstrated significant immediate and long-term disruption of the intestinal microbiota in terms of diversity and taxonomy and stands out in comparison with the other antibiotics included in the study.In a prospective study, we investigated the intestinal microbiota in patients with hematological diseases undergoing hematopoietic stem cell transplantation (HSCT, n=88). Changes over time and during antibiotic treatment and potential associations between the intestinal microbiota at baseline and patient outcomes were explored. Oral ciprofloxacin demonstrated a significant impact on the intestinal microbiota, which was greater than the impact of intravenous broad-spectrum antibiotics. A low microbiome diversity at baseline was associated with neutropenic fever and antibiotic treatment following HSCT.
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| 14. |
- Mårtensson, Andreas, et al.
(författare)
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Influence of consecutive-day blood sampling on polymerase chain reaction-adjusted parasitological cure rates in an antimalarial-drug trial conducted in Tanzania
- 2007
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Ingår i: Journal of Infectious Diseases. - Chicago : University of Chicago Press. - 0022-1899 .- 1537-6613. ; 195:4, s. 597-601
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Tidskriftsartikel (refereegranskat)abstract
- We assessed the influence that consecutive-day blood sampling, compared with single-day blood sampling, had on polymerase chain reaction (PCR)-adjusted parasitological cure after stepwise genotyping of merozoite surface proteins 2 (msp2) and 1 (msp1) in 106 children in Tanzania who had uncomplicated falciparum malaria treated with either sulfadoxine-pyrimethamine or artemether-lumefantrine; 78 of these children developed recurrent parasitemia during the 42-day follow-up period. Initial msp2 genotyping identified 27 and 33 recrudescences by use of single- and consecutive-day sampling, respectively; in subsequent msp1 genotyping, 17 and 21 of these episodes, respectively, were still classified as recrudescences; these results indicate a similar sensitivity of the standard single-day PCR protocol--that is, 82% (27/33) and 81% (17/21), in both genotyping steps. Interpretation of PCR-adjusted results will significantly depend on methodology.
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| 15. |
- Pathak, Ashish, 1973-, et al.
(författare)
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Characterization of drug resistance associated genetic polymorphisms among Plasmodium falciparum field isolates in Ujjain, Madhya Pradesh, India.
- 2014
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Ingår i: Malaria Journal. - : Springer Science and Business Media LLC. - 1475-2875. ; 13, s. 182-
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Since 2011, artesunate + sulphadoxine-pyrimethamine (ASP), instead of chloroquine, has been recommended for treatment of uncomplicated malaria in India. In Ujjain, central India, with an annual parasite index <0.1, the prevalence of drug-resistant Plasmodium falciparum is unknown. In other parts of India chloroquine and sulphadoxine-pyrimethamine-resistant P. falciparum is prevalent. The aim of this study was to determine the prevalence of anti-malarial drug resistance-associated genetic polymorphisms in P. falciparum collected in Ujjain in 2009 and 2010, prior to the introduction of ASP.METHODS: Blood samples from 87 patients with P. falciparum mono-infection verified by microscopy were collected on filter-paper at all nine major pathology laboratories in Ujjain city. Codons Pfcrt 72-76, pfmdr1 1034-1246, pfdhfr 16-185, pfdhps 436-632 and pfnhe1 ms4760 haplotypes were identified by sequencing. Pfcrt K76T and pfmdr1 N86Y were identified by restriction fragment length polymorphism, and pfmdr1 gene copy number by real-time PCR.RESULTS: Sulphadoxine-pyrimethamine resistance-associated pfdhfr 108 N and 59R alleles were found in 75/78 (96%) and 70/78 (90%) samples, respectively, and pfdhps 437G was found in 7/77 (9%) samples. Double mutant pfdhfr 59R + 108 N were found in 62/76 (82%) samples. Triple mutant pfdhfr 59R + 108 N and pfdhps 437G were found in 6/76 (8%) samples. Chloroquine-resistance-associated pfcrt 76 T was found in 82/87 (94%). The pfcrt 72-76 haplotypes found were: 80/84 (95%) SVMNT, 3/84 (4%) CVMNK and 1/84 (1%) CVMNT. Pfmdr1 N86 and 86Y were identified in 70/83 (84%) and 13/83 (16%) samples, respectively. Pfmdr1 S1034 + N1042 + D1246 were identified together in 70/72 (97%) of successfully sequenced samples. One pfmdr1 gene copy was found in 74/75 (99%) successfully amplified samples.CONCLUSION: This is the first characterization of key anti-malarial drug resistance-associated genetic markers among P. falciparum collected in Ujjain, Madhya Pradesh, India. The results indicate that the efficacy of standard dose chloroquine at the time of the study was likely to be poor, whereas ASP was likely to be efficacious, supporting the changed drug treatment policy. However, P. falciparum with reduced susceptibility to sulphadoxine-pyrimethamine is highly prevalent, highlighting the need for continuous surveillance of ASP efficacy in the study area.
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| 16. |
- Pathak, Ashish, 1973-, et al.
(författare)
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Stable high frequencies of sulfadoxine-pyrimethamine resistance associated mutations and absence of K13 mutations inPlasmodium falciparum3 and 4 years after the introduction of artesunate plus sulfadoxine-pyrimethamine in Ujjain, Madhya Pradesh, India
- 2020
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Ingår i: Malaria Journal. - : BMC. - 1475-2875. ; 19:1
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Tidskriftsartikel (refereegranskat)abstract
- Background Artesunate plus sulfadoxine-pyrimethamine (ASP) is first-line treatment for uncomplicatedPlasmodium falciparummalaria in most of India, except for six North-eastern provinces where treatment failure rates were high. In Ujjain, central India, the frequency of mutations associated with increased drug tolerance, but not overt resistance to sulfadoxine and pyrimethamine were 9% and > 80%, respectively, in 2009 and 2010, just prior to the introduction of ASP. The frequency of drug resistance associated mutations in Ujjain in 2015-2016 after 3-4 years of ASP use, are reported. Methods Blood samples from patients withP. falciparummono-infection verified by microscopy were collected on filter-paper at all nine major pathology laboratories in Ujjain city. Codonspfdhfr16-185,pfdhps436-632 and K13 407-689 were identified by sequencing.PfcrtK76T andpfmdr1N86Y were identified by restriction fragment length polymorphism. Results Sulfadoxine-pyrimethamine resistance-associatedpfdhfr108 N and 59R alleles were found in 100/104 (96%) and 87/91 (96%) samples, respectively.Pfdhps437G was found in 10/105 (10%) samples. Double mutantpfdhfr59R + 108 N were found in 75/81 (93%) samples. Triple mutantpfdhfr59R + 108 N andpfdhps437G were found in 6/78 (8%) samples. Chloroquine-resistance-associatedpfcrt76T was found in 102/102 (100%).Pfmdr1N86 and 86Y were identified in 83/115 (72%) and 32/115 (28%) samples, respectively. Conclusion The frequency ofP. falciparumwith reduced susceptibility to sulfadoxine-pyrimethamine remained high, but did not appear to have increased significantly since the introduction of ASP. No polymorphisms in K13 associated with decreased artemisinin susceptibility were found. ASP probably remained effective, supporting continued ASP use.
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| 17. |
- Rombo, Lars, et al.
(författare)
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Antimalarial Prophylaxis-Efficacy or Effectiveness?
- 2014
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Ingår i: Journal of Travel Medicine. - : Oxford University Press (OUP). - 1195-1982 .- 1708-8305. ; 21:2, s. 137-138
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 18. |
- Stefansson, Måns, et al.
(författare)
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Safety and tolerability of frozen, capsulized autologous faecal microbiota transplantation. A randomized double blinded phase I clinical trial
- 2023
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 18:9
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Tidskriftsartikel (refereegranskat)abstract
- Background: Faecal microbiota transplantation (FMT) is recommended treatment for recurrent Clostridioides difficile infection and is studied as a potential modifier of other gastrointestinal and systemic disorders. Autologous FMT limits the potential risks of donor transplant material and enables prophylactic treatment. Capsulized FMT is convenient and accessible, but safety data are lacking.Aims: To describe safety and tolerability of capsules containing autologous FMT, compared to placebo, in healthy volunteers treated with antibiotics.Method: Healthy volunteers without antibiotic exposure during the past three months, that had a negative Clostridioides difficile stool sample, were recruited. Study persons donated faeces for production of capsules containing autologous microbiota. They were then given Clindamycin for seven days to disrupt the intestinal microbiota, which was followed by a two-day washout. Study persons were then randomized (1:1) to unsupervised treatment with autologous faecal matter or placebo, with two capsules twice daily for five days. A standardized questionnaire about side effects and tolerability, daily until day 28, and on days 60 and 180, was completed.Results: Twenty-four study persons were included, all completed the treatment. One person from the placebo and FMT groups each, were lost to follow up from days 21 and 60, respectively. No study person experienced serious side effects, but severe fatigue was reported during the antibiotic period (n = 2). Reported side effects were mild to moderate and there were no significant differences between the groups. Reported general and intestinal health improved significantly and similarly in both groups after the antibiotic treatment. Time to normalized intestinal habits were 17 and 19 days from study start in the placebo group and the FMT group, respectively (p = 0.8).Conclusion: Capsulized frozen autologous faecal microbiota transplantation was safe and well tolerated but did not affect time to normalized intestinal habits compared to placebo.
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| 19. |
- Ursing, Johan, et al.
(författare)
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Artemether-Lumefantrine versus Dihydroartemisinin-Piperaquine for Treatment of Uncomplicated Plasmodium falciparum Malaria in Children Aged Less than 15 Years in Guinea-Bissau - An Open-Label Non-Inferiority Randomised Clinical Trial
- 2016
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 11:9
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Tidskriftsartikel (refereegranskat)abstract
- Background Artemether-lumefantrine (AL) was introduced for treatment of uncomplicated malaria in Guinea-Bissau in 2008. Malaria then resurged and recurrent malaria after treatment with AL and stock-outs of AL were common. This study therefore aimed to assess the efficacy of AL and identify an alternative second line antimalarial. Dihydroartemisinin-piperaquine (DP) was chosen as it has been shown to be safe and efficacious and to reduce the incidence of recurrent malaria. Methods and Findings In a multicentre randomised open-label non-inferiority clinical trial, AL or DP were given over 3 days to children aged 6 months-15 years with uncomplicated P. falciparummonoinfection. Intake was observed and AL was given with milk. Children were seen on days 0, 1, 2 and 3 and then weekly days 7-42. Recurring P. falciparumwere classified as recrudescence or new infections by genotyping. Between November 2012 and July 2015, 312 children were randomised to AL (n = 155) or DP (n = 157). The day 42 PCR adjusted per protocol adequate clinical and parasitological responses were 95% and 100% in the AL and DP groups respectively, Mantel-Haenszel weighted odds ratio (OR) 0.22 (95% CI 0-0.68), p = 0.022. In a modified intention to treat analysis in which treatment failures day 0 and reinfections were also considered as treatment failures adequate clinical and parasitological responses were 94% and 97% (OR 0.42 [95% CI, 0.13-1.38], p = 0.15). Parasite clearance and symptom resolution were similar with both treatments. Conclusions Both treatments achieved the WHO recommended efficacy for antimalarials about to be adopted as policy. DP was not inferior to AL for treatment of uncomplicated P. falciparum malaria in Guinea-Bissau.
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| 20. |
- Ursing, Johan, et al.
(författare)
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Chloroquine Is Grossly Overdosed and Overused but Well Tolerated in Guinea-Bissau
- 2009
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Ingår i: Antimicrobial Agents and Chemotherapy. - 0066-4804 .- 1098-6596. ; 53:1, s. 180-185
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Tidskriftsartikel (refereegranskat)abstract
- High chloroquine doses are commonly prescribed in Guinea-Bissau. Double-dose chloroquine has been shown to be more efficacious (92% efficacy) than the standard dose (80% efficacy). However, chloroquine is toxic when overdosed, and it was not known if the high doses prescribed in Guinea-Bissau were taken or whether they caused adverse effects. We aimed to determine the dosage of chloroquine commonly prescribed, the doses commonly taken, and whether concentration-dependent adverse events occurred in routine practice. Chloroquine prescriptions by eight physicians and chloroquine intake by 102 children were recorded. Chloroquine intake and adverse events were assessed by questioning. Chloroquine concentrations in whole blood were measured. The median total chloroquine dose prescribed and that reportedly taken were 81 and 77 mg kg(-1), respectively. The total dose was usually split into two to three daily doses of 6.6 mg kg(-1) each. These were taken unsupervised for a median of 5 days. Forty percent of the study children had chloroquine concentrations in the same range as those found in a previous study in which double the normal dose (50 mg kg(-1)) of chloroquine was taken. Only 3/102 children had Plasmodium falciparum in the blood at the time of diagnosis and treatment. No severe adverse events were reported. No adverse events were associated with higher chloroquine concentrations. High doses of chloroquine are commonly taken and well tolerated in Guinea-Bissau. Malaria diagnostics are poor, and chloroquine is commonly prescribed to children without parasitemia. Use of high-dose chloroquine is concurrent with an exceptionally low prevalence of chloroquine-resistant P. falciparum.
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| 21. |
- Ursing, Johan, et al.
(författare)
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Chloroquine is grossly under dosed in young children with malaria : implications for drug resistance
- 2014
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Plasmodium falciparum malaria is treated with 25 mg/kg of chloroquine (CQ) irrespective of age. Theoretically, CQ should be dosed according to body surface area (BSA). The effect of dosing CQ according to BSA has not been determined but doubling the dose per kg doubled the efficacy of CQ in children aged <15 years infected with P. falciparum carrying CQ resistance causing genes typical for Africa. The study aim was to determine the effect of age on CQ concentrations.Methods and Findings: Day 7 whole blood CQ concentrations were determined in 150 and 302 children treated with 25 and 50 mg/kg, respectively, in previously conducted clinical trials. CQ concentrations normalised for the dose taken in mg/kg of CQ decreased with decreasing age (p<0.001). CQ concentrations normalised for dose taken in mg/m(2) were unaffected by age. The median CQ concentration in children aged <2 years taking 50 mg/kg and in children aged 10-14 years taking 25 mg/kg were 825 (95% confidence interval [CI] 662-988) and 758 (95% CI 640-876) nmol/l, respectively (p = 0.67). The median CQ concentration in children aged 10-14 taking 50 mg/kg and children aged 0-2 taking 25 mg/kg were 1521 and 549 nmol/l. Adverse events were not age/concentration dependent.Conclusions: CQ is under-dosed in children and should ideally be dosed according to BSA. Children aged <2 years need approximately double the dose per kg to attain CQ concentrations found in children aged 10-14 years. Clinical trials assessing the efficacy of CQ in Africa are typically performed in children aged <5 years. Thus the efficacy of CQ is typically assessed in children in whom CQ is under dosed. Approximately 3 fold higher drug concentrations can probably be safely given to the youngest children. As CQ resistance is concentration dependent an alternative dosing of CQ may overcome resistance in Africa.
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| 22. |
- Ursing, Johan, et al.
(författare)
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Chloroquine-susceptible and -resistant Plasmodium falciparum strains survive high chloroquine concentrations by becoming dormant but are eliminated by prolonged exposure
- 2022
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Ingår i: Journal of Antimicrobial Chemotherapy. - : Oxford University Press (OUP). - 0305-7453 .- 1460-2091. ; 77:4, s. 1005-1011
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Tidskriftsartikel (refereegranskat)abstract
- Background: Plasmodium falciparum strains that are resistant to standard-dose chloroquine can be treated by higher chloroquine concentrations maintained for a longer time in vivo.Objectives: To determine the relative importance of chloroquine concentrations versus exposure time for elimination of chloroquine-susceptible and -resistant P. falciparum in vitro.Methods: Chloroquine-susceptible (3D7) and -resistant (FCR3) strains were exposed in vitro to 1, 2, 4, 8, 16 or 32 times their respective 90% inhibitory chloroquine concentrations for 3, 5, 7 or 14 days and then followed until recrudescence, or not, by 42 days after the end of exposure.Results: Exposure to chloroquine appeared to eliminate susceptible and resistant parasites, leaving small pyknotic apparently dead parasites. Chloroquine-susceptible and -resistant parasites recrudesced after 3 and 5 days of chloroquine exposure. Recrudescence occurred in one out of four 7 day exposure series but not after 14 days exposure. The median time to recrudescence was 13 to 28 days with a range of 8 to 41 days after the end of exposure. Time to recrudescence after the end of exposure increased with duration of exposure for susceptible and resistant strains (P < 0.001). Time to recrudescence did not correlate with concentrations greater than 1x IC90.Conclusions: Chloroquine-susceptible and -resistant P. falciparum probably become dormant. Elimination of dormant parasites is primarily dependent upon the duration of chloroquine exposure. Exposure to effective drug concentrations for 7 days eliminates most parasites in vitro. The results support in vivo data indicating that elimination of chloroquine-resistant P. falciparum correlates with Day 7 chloroquine concentrations.
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| 23. |
- Ursing, Johan, et al.
(författare)
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High-Dose Chloroquine for Treatment of Chloroquine-Resistant Plasmodium falciparum Malaria
- 2016
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Ingår i: Journal of Infectious Diseases. - : Oxford University Press (OUP). - 0022-1899 .- 1537-6613. ; 213:8, s. 1315-1321
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Tidskriftsartikel (refereegranskat)abstract
- Background. Due to development of multidrug-resistant Plasmodium falciparum new antimalarial therapies are needed. In Guinea-Bissau, routinely used triple standard-dose chloroquine remained effective for decades despite the existence of "chloroquine-resistant" P. falciparum. This study aimed to determine the in vivo efficacy of higher chloroquine concentrations against P. falciparum with resistance-conferring genotypes. Methods. Standard or double-dose chloroquine was given to 892 children aged < 15 years with uncomplicated malaria during 3 clinical trials (2001-2008) with >= 35 days follow-up. The P. falciparum resistance-conferring genotype (pfcrt 76T) and day 7 chloroquine concentrations were determined. Data were divided into age groups (< 5, 5-9, and 10-14 years) because concentrations increase with age when chloroquine is prescribed according to body weight. Results. Adequate clinical and parasitological responses were 14%, 38%, and 39% after standard-dose and 66%, 84%, and 91% after double-dose chloroquine in children aged < 5, 5-9, and 10-14 years, respectively, and infected with P. falciparum genotypes conferring chloroquine resistance (n = 195, P < .001). In parallel, median chloroquine concentrations were 471, 688, and 809 nmol/L for standard-dose and 1040, 1494, and 1585 nmol/L for double-dose chloroquine. Conclusions. Chloroquine resistance is dose dependent and can be overcome by higher, still well-tolerated doses.
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| 24. |
- Ursing, Johan, et al.
(författare)
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High-Dose Chloroquine for Uncomplicated Plasmodium falciparum Malaria Is Well Tolerated and Causes Similar QT Interval Prolongation as Standard-Dose Chloroquine in Children
- 2020
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Ingår i: Antimicrobial Agents and Chemotherapy. - : AMER SOC MICROBIOLOGY. - 0066-4804 .- 1098-6596. ; 64:3
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Tidskriftsartikel (refereegranskat)abstract
- Higher chloroquine doses can effectively treat up to 93 to 96% of malaria infections caused by Plasmodium falciparum carrying the resistance-conferring chloroquine resistance transporter (pfcrt) 76T allele. The tolerability of 50 (double the standard dose) and 70 mg/kg total chloroquine doses were assessed in this study. Fifteen 4- to 8-year-old children with uncomplicated malaria were given 10 mg/kg of chloroquine twice daily for 2 days and 5 mg/kg twice daily on the third day. Fifteen additional children were given 5 mg/kg twice daily for 2 more days. Chloroquine concentrations, blood pressure, electrocardiograms (ECGs), parasite density, and adverse events were assessed until day 28. Both dosages were well tolerated, and symptoms resolved by day 3 in parallel with increasing chloroquine concentrations. The median corrected QT (QTc) interval was 12 to 26 ms higher at expected peak concentrations than at day 0 (P < 0.001). Pfcrt 76T was associated with delayed parasite clearance. Day 28 clinical and parasitological responses against P. falciparum with pfcrt 76T were 57% (4/7) and 67% (4/6) after treatment with 50 and 70 mg/kg, respectively. Dosages were well tolerated, and no severe cardiac adverse events occurred. The QTc interval increase was similar to that found in adults taking 25 mg/kg of chloroquine.
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| 25. |
- Ursing, Johan, et al.
(författare)
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Malaria Transmission in Bissau, Guinea-Bissau between 1995 and 2012 : Malaria Resurgence Did Not Negatively Affect Mortality
- 2014
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:7, s. e101167-
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Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION: As Plasmodium falciparum prevalence decreases in many parts of Sub-Saharan Africa, so does immunity resulting in larger at risk populations and increased risk of malaria resurgence. In Bissau, malaria prevalence decreased from ?50% to 3% between 1995 and 2003. The epidemiological characteristics of P. falciparum malaria within Bandim health and demographic surveillance site (population similar to 100000) between 1995 and 2012 are described. METHODS AND FINDINGS: The population was determined by census. 3603 children aged <15 years that were enrolled in clinical trials at the Bandim health centre (1995-2012) were considered incident cases. The mean annual malaria incidence per thousand children in 1995-1997, 1999-2003, 2007, 2011, 2012 were as follows; age <5 years 22 -> 29 -> 4 -> 9 -> 3, age 5-9 years 15 -> 28 -> 4 -> 33 -> 12, age 10-14 years 9 -> 15 -> 1 -> 45 -> 19. There were 4 campaigns (2003-2010) to increase use of insecticide treated bed nets (ITN) amongst children <5 years. An efficacious high-dose chloroquine treatment regime was routinely used until artemisinin based combination therapy (ACT) was introduced in 2008. Long lasting insecticide treated bed nets (LLIN) were distributed in 2011. By 2012 there was 1 net per 2 people and 97% usage. All-cause mortality decreased from post-war peaks in 1999 until 2012 in all age groups and was not negatively affected by malaria resurgence. CONCLUSION: The cause of decreasing malaria incidence (1995-2007) was probably multifactorial and coincident with the use of an efficacious high-dose chloroquine treatment regime. Decreasing malaria prevalence created a susceptible group of older children in which malaria resurged, highlighting the need to include all age groups in malaria interventions. ACT did not hinder malaria resurgence. Mass distribution of LLINs probably curtailed malaria epidemics. All-cause mortality was not negatively affected by malaria resurgence.
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| 26. |
- Ursing, Johan
(författare)
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Plasmodium falciparum response to chloroquine and artemisinin based combination therapy (ACT) in Guinea-Bissau
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Plasmodium falciparum causes the most severe form of malaria and is the most common malaria species in sub-Saharan Africa. Chloroquine used to be the most common drug for the treatment of malaria. Due to development of resistance, chloroquine is no longer efficacious in most of the world. The first line option for treatment of P. falciparum is now artemisinin based combination therapy, such as artemether-lumefantrine. In Guinea-Bissau, in contrast to the rest of Africa, chloroquine has been considered to be effective by practitioners in line with clinical trials by our group. Artemether-lumefantrine replaced chloroquine for the treatment of malaria in Guinea-Bissau in 2008. The main aim of this thesis has been to study if and why chloroquine has remained efficacious in Guinea-Bissau. We have shown that chloroquine resistance is associated with the CVIET haplotype at amino-acid positions 72-76 of the chloroquine resistance transporter (pfcrt). Genotyping and in vitro data presented in the thesis indicate that the proportion of resistant P. falciparum has been stable and low (~25%) since the early 90's. In line with that, P. falciparum with pfcrt 76T do not accumulate during the high transmission season, in Guinea-Bissau. Concurrently, approximately 3 times standard dose chloroquine has been routinely prescribed and taken without severe adverse events. In a randomized clinical trial, we show that the PCR corrected day 28 and day 42 efficacies of double standard dose chloroquine were 95 and 94% respectively. The corresponding artemether-lumefantrine efficacies were 97%. Both antimalarial treatment options were well tolerated. The PCR corrected day 28 efficacies of double standard dose and standard dose chloroquine against P. falciparum with pfcrt 76T were 78-87% and 38%, respectively. Chloroquine concentrations were lower in children with PCR adjusted treatment failure compared to children with PCR adjusted adequate clinical and parasitological response by day 42. Recrudescent P. falciparum following treatment with artemether-lumefantrine or chloroquine appeared to carry opposite alleles at pfcrt codon 76 and multidrug resistance gene codon 86. The dose and concentration dependent efficacy of chloroquine against P. falciparum with pfcrt 76T indicate that chloroquine resistance can be overcome by higher doses of chloroquine. High total chloroquine doses are well tolerated when split into repeated smaller daily doses. The lack of seasonal accumulation of pfcrt 76T indicates that the dosage schedule commonly used in Guinea-Bissau is efficacious and that pfcrt 76T is associated with a loss of fitness. Double standard dose chloroquine and artemetherlumefantrine fulfill the WHO efficacy requirements for antimalarials about to be adopted as treatment policy.
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| 27. |
- Ursing, Johan, et al.
(författare)
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Similar efficacy and tolerability of double-dose chloroquine and artemether-lumefantrine for treatment of Plasmodium falciparum infection in Guinea-Bissau : a randomized trial
- 2011
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Ingår i: Journal of Infectious Diseases. - : Oxford University Press (OUP). - 0022-1899 .- 1537-6613. ; 203:1, s. 109-116
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Tidskriftsartikel (refereegranskat)abstract
- Background. In 2008. Guinea-Bissau introduced artemether-lumefantrine for treatment of uncomplicated malaria. Previously, 3 times the standard dose of chloroquine, that was probably efficacious against Plasmodium falciparum with the resistance-associated chloroquine-resistance transporter (pfcrt) 76T allele, was routinely used. The present study compared the efficacy and tolerability of a double standard dose of chloroquine with the efficacy and tolerability of artemether-lumefantrine.Methods. In a randomized open-label clinical trial, artemether-lumefantrine or chloroquine (50 mg/kg) were given as 6 divided doses over 3 days to children aged 6 months - 15 years who had uncomplicated P. falciparum monoinfection. Drug concentrations were measured on day 7. P. falciparum multidrug resistance gene N86Y and pfcrt K76T alleles were identified.Results. The polymerase chain reaction adjusted day 28 and 42 treatment efficacies were 162 (97%) of 168 and 155 (97%) of 161, respectively, for artemether-lumefantrine and 150 (95%) of 158 and 138 (94%) of 148, respectively, for chloroquine. When parasites with resistance-associated pfcrt 76T were treated, the day 28 efficacy of chloroquine was 87%. No severe drug-related adverse events were detected. Symptom resolution was similar with both treatments.Conclusions. Both treatments achieved the World Health Organization recommended efficacy for antimalarials that will be adopted as policy. High-dose chloroquine treatment regimes should be further evaluated with the aim of assessing chloroquine as a potential partner drug to artemisinin derivatives.
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| 28. |
- Venkatesan, Meera, et al.
(författare)
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Polymorphisms in Plasmodium falciparum chloroquine resistance transporter and multidrug resistance 1 genes : parasite risk factors that affect treatment outcomes for P. falciparum malaria after artemether-lumefantrine and artesunate-amodiaquine.
- 2014
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Ingår i: The American journal of tropical medicine and hygiene. - : American Society of Tropical Medicine and Hygiene. - 1476-1645 .- 0002-9637. ; 91:4, s. 833-43
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Tidskriftsartikel (refereegranskat)abstract
- Adequate clinical and parasitologic cure by artemisinin combination therapies relies on the artemisinin component and the partner drug. Polymorphisms in the Plasmodium falciparum chloroquine resistance transporter (pfcrt) and P. falciparum multidrug resistance 1 (pfmdr1) genes are associated with decreased sensitivity to amodiaquine and lumefantrine, but effects of these polymorphisms on therapeutic responses to artesunate-amodiaquine (ASAQ) and artemether-lumefantrine (AL) have not been clearly defined. Individual patient data from 31 clinical trials were harmonized and pooled by using standardized methods from the WorldWide Antimalarial Resistance Network. Data for more than 7,000 patients were analyzed to assess relationships between parasite polymorphisms in pfcrt and pfmdr1 and clinically relevant outcomes after treatment with AL or ASAQ. Presence of the pfmdr1 gene N86 (adjusted hazards ratio = 4.74, 95% confidence interval = 2.29 - 9.78, P < 0.001) and increased pfmdr1 copy number (adjusted hazards ratio = 6.52, 95% confidence interval = 2.36-17.97, P < 0.001 : were significant independent risk factors for recrudescence in patients treated with AL. AL and ASAQ exerted opposing selective effects on single-nucleotide polymorphisms in pfcrt and pfmdr1. Monitoring selection and responding to emerging signs of drug resistance are critical tools for preserving efficacy of artemisinin combination therapies; determination of the prevalence of at least pfcrt K76T and pfmdr1 N86Y should now be routine.
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| 29. |
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| 30. |
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