| 1. |
- Vielot, Nadja A., et al.
(författare)
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First Episodes of Norovirus and Sapovirus Gastroenteritis Protect Against Subsequent Episodes in a Nicaraguan Birth Cohort
- 2022
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Ingår i: Epidemiology. - 1044-3983 .- 1531-5487. ; 33:5, s. 650-653
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Tidskriftsartikel (refereegranskat)abstract
- Background: Norovirus and sapovirus cause a large burden of acute gastroenteritis (AGE) in young children. We assessed protection conferred by norovirus and sapovirus AGE episodes against future episodes.Methods: Between June 2017 and July 2018, we recruited 444 newborns in León, Nicaragua. Weekly household surveys identified AGE episodes over 36 months, and AGE stools were tested by reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR) for norovirus genogroup (G)I/GII and sapovirus. We used recurrent-event Cox models and negative control methods to estimate protection conferred by first episodes, controlling for observed and unobserved risk factors, respectively.Results: Sapovirus episodes conferred a 69% reduced hazard of subsequent episodes using the negative control method. Norovirus GI (hazard ratio [HR] = 0.67; 95% confidence interval [CI] = 0.31, 1.3) and GII (HR = 0.20; 95% CI = 0.04, 0.44) episodes also appeared highly protective. Protection against norovirus GII was enhanced following two episodes.Conclusions: Evidence of natural immunity in early childhood provides optimism for the future success of pediatric norovirus and sapovirus vaccines.
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| 2. |
- Becker-Dreps, Sylvia, et al.
(författare)
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Etiology of Childhood Diarrhea After Rotavirus Vaccine Introduction A Prospective, Population-based Study in Nicaragua
- 2014
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Ingår i: The Pediatric Infectious Disease Journal. - : Lippincott, Williams andamp; Wilkins. - 0891-3668 .- 1532-0987. ; 33:11, s. 1156-1163
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Tidskriftsartikel (refereegranskat)abstract
- Background: Nicaragua was the first developing nation to implement routine immunization with the pentavalent rotavirus vaccine (RV5). In this RV5-immunized population, understanding infectious etiologies of childhood diarrhea is necessary to direct diarrhea treatment and prevention efforts. Methods: We followed a population-based sample of children less than5 years in Leon, Nicaragua for diarrhea episodes through household visits. Information was obtained on RV5 history and sociodemographics. Stool samples collected during diarrhea episodes and among healthy children underwent laboratory analysis for viral, bacterial and parasitic enteropathogens. Detection frequency and incidence of each enteropathogen was calculated. Results: The 826 children in the cohort experienced 677 diarrhea episodes during 607.5 child-years of exposure time (1.1 episodes per child-year). At least 1 enteropathogen was detected among 61.1% of the 337 diarrheal stools collected. The most common enteropathogens among diarrheal stools were: norovirus (20.4%), sapovirus (16.6%), enteropathogenic Escherichia coli (11.3%), Entamoeba histolytica/dispar (8.3%), Giardia lamblia (8.0%) and enterotoxigenic E. coli (7.7%), with rotavirus detected among 5.3% of diarrheal stools. Enteropathogenic Escherichia coli and enterotoxigenic E. coli were frequently detected among stools from healthy children. Among children with diarrhea, norovirus was more commonly detected among younger children (less than2 years) and G. lamblia was more commonly detected among older children (2-4 years). The mean age of rotavirus detection was 34.6 months. Conclusions: In this Central American community after RV5 introduction, rotavirus was not commonly detected among children with diarrhea. Prevention and appropriate management of norovirus and sapovirus should be considered to further reduce the burden of diarrheal disease.
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| 3. |
- Bucardo, Filemon, et al.
(författare)
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Susceptibility of Children to Sapovirus Infections, Nicaragua, 2005–2006
- 2012
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Ingår i: Emerging Infectious Diseases. - Atlanta, GA, USA : U.S. Department of Health and Human Services * Centers for Disease Control and Prevention. - 1080-6040 .- 1080-6059. ; 18:11, s. 1875-1878
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Tidskriftsartikel (refereegranskat)abstract
- We describe the genetic diversity of sapovirus (SaV) in children in Nicaragua and investigate the role of host genetic factors and susceptibility to SaV infections. Our results indicate that neither ABO blood group, Lewis phenotype, nor secretor status affects susceptibility to SaV infection in Nicaragua.
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| 4. |
- Vielot, Nadja Alexandra, et al.
(författare)
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Association between breastfeeding, host genetic factors, and calicivirus gastroenteritis in a Nicaraguan birth cohort
- 2022
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Ingår i: PLOS ONE. - : PUBLIC LIBRARY SCIENCE. - 1932-6203. ; 17:10
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Tidskriftsartikel (refereegranskat)abstract
- Background Norovirus and sapovirus are important causes of childhood acute gastroenteritis (AGE). Breastfeeding prevents AGE generally; however, it is unknown if breastfeeding prevents AGE caused specifically by norovirus and sapovirus. Methods We investigated the association between breastfeeding and norovirus or sapovirus AGE episodes in a birth cohort. Weekly data on breastfeeding and AGE episodes were captured during the first year of life. Stools were collected from children with AGE and tested by RT-qPCR for norovirus and sapovirus. Time-dependent Cox models estimated associations between weekly breastfeeding and time to first norovirus or sapovirus AGE. Findings From June 2017 to July 2018, 444 newborns were enrolled in the study. In the first year of life, 69 and 34 children experienced a norovirus and a sapovirus episode, respectively. Exclusive breastfeeding lasted a median of 2 weeks, and any breastfeeding lasted a median of 43 weeks. Breastfeeding in the last week did not prevent norovirus (HR: 1.09, 95% CI: 0.62, 1.92) or sapovirus (HR: 1.00, 95% CI: 0.82, 1.21) AGE in a given week, adjusting for household sanitation, consumption of high-risk foods, and mothers and childs histo-blood group phenotypes. Maternal secretor-positive phenotype was protective against norovirus AGE, whereas childs secretor-positive phenotype was a risk factor for norovirus AGE. Interpretation Exclusive breastfeeding in this population was short-lived, and no conclusions could be drawn about its potential to prevent norovirus or sapovirus AGE. Non-exclusive breastfeeding did not prevent norovirus or sapovirus AGE in the first year of life. However, maternal secretor-positive phenotype was associated with a reduced hazard of norovirus AGE.
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| 5. |
- Vilchez, Samuel, et al.
(författare)
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Prevalence of diarrhoeagenic Escherichia coli in children from Leon, Nicaragua
- 2009
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Ingår i: JOURNAL OF MEDICAL MICROBIOLOGY. - : Microbiology Society. - 0022-2615 .- 1473-5644. ; 58:5, s. 630-637
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Tidskriftsartikel (refereegranskat)abstract
- Diarrhoeal disease is a public health problem worldwide, mostly affecting children in developing countries. In Nicaragua, diarrhoea is the second greatest cause of infant mortality. During the period March 2005 to September 2006, a total of 526 faecal samples from children aged 0-60 months (381 with and 145 without diarrhoea) from Leon, Nicaragua, were studied. In order to detect five different diarrhoeagenic Escherichia coli pathotypes simultaneously [enterotoxigenic E. coli (ETEC), enteroaggregative E. coli (EAEC), enteropathogenic E. coli (EPEC), enterohaemorrhagic E. coli (EHEC) and enteroinvasive E. coli (EIEC)], a mixture of eight primer pairs was used in a single PCR. At least one diarrhoeagenic E. coli pathotype was detected in 205 samples (53.8%) of the diarrhoea group and in 77 samples (53.1 %) in the non-diarrhoea group. ETEC was detected significantly more often in children with diarrhoea (20.5 %) than in children without diarrhoea (8.3%) (P=0.001). Atypical EPEC, EIEC and EAEC were detected with slightly lower frequencies in children with (16.0, 0.8 and 27.8%, respectively) than in children without (20.7, 1.4 and 33.1 %,respectively) diarrhoea. EHEC was only detected in children with diarrhoea (2.1%). In conclusion, ETEC continues to be an important agent associated with diarrhoea in children from Leon, Nicaragua. Although not very frequent, the only findings that were 100 % associated with diarrhoea were ETEC estA (4.7%) and EH EC (2.1%). Nevertheless, EAEC and EPEC were also frequent pathotypes in the population under study. In children with severe diarrhoea, more than half had EAEC, ETEC or EPEC, and EAEC was the most prevalent pathotype.
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| 6. |
- Vilchez Rugama, Bayardo Samuel
(författare)
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Molecular and phenotypic characterization of diarrhoeagenic Escherichia coli from Nicaraguan children
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Diarrhoeal diseases continue to be a foremost public health problem worldwide, with over 1.5 million deaths occurring each year, mostly in children in developing countries. In Nicaragua, the mortality due to diarrhoea in children less than 5 years of age is 11 per 10,000 inhabitants. Additionally, this group of children account for more than 120,000 thousands consultations due to diarrhoea per year, most of them occurring during the winter season. However, in Nicaragua, information about the prevalence of many of the enteric pathogens such as diarrheoagenic Escherichia coli (DEC), is still lacking. Thus, the studies presented in this thesis focused on the identification, molecular and phenotypic characteristics of diarrhoeagenic E. coli pathotypes as enteric pathogens associated with diarrhoea in children from León, Nicaragua. The results from studies I to III are: Five DEC types have been identified in 526 faecal samples from children less than 5 years of age, using PCR based methods. Additionally, the majority of the E. coli positives for a DEC type occurred alongside with the winter season in Nicaragua. The ETEC pathotype was identified with significantly higher prevalence in children with 78/381 (20.5%) compared to children without 12/145 (8.3%) diarrhoea. The distribution of the identified ETEC was as follow: eltB 72/90 (80%), followed by eltB-estA 14/90 (15.6%) and finally estA 4/90 (4.4%) positives. Using the biochemical fingerprinting method PhP-RE, ETEC positive samples seem to belong to defined biochemical phenotypes (BPTs). In addition, facts that a limited number of BPTs grouped estA positives, and estA ETEC samples were only isolated from children with diarrhoea suggest the spread of a marked pathogenic clonal group. On the other hand, atypical EPEC (only eaeA+), was identified with similar frequencies in children with 61/381 (16%) and children without 30/145 (20.7%) diarrhoea. Additionally, clonal group analysis of atypical EPEC isolates showed no differences between children with and without diarrhoea. EIEC was identified at low, but similar frequency in both children with 3/381 (0.8%) and without 2/145 (1.4%) diarrhoea. Conversely, EIEC positive samples seem to be a clonal group, yet the number of samples was rather small. EAEC was the most prevalent pathotype of the identified E. coli. However, no differences were observed between the children with 106/382 (27.8%) and without 48/145 (33.1%) diarrhoea in terms of prevalence and phenotypic fingerprinting characteristics. Although, differences were appreciated between the herein tested EAEC isolates from children with 73/116 (62.9%) and without 28/68 (41.2%) diarrhoea, that showed aggregative adherence to Caco-2 cells. Additionally, a great variety of other putative virulence markers combination was detected, confirming the heterogeneity of this pathotype. EHEC was only identified in samples from children with 8/381 (2.1%) diarrhoea. The identified EHEC were distributed as follow: vt2 6/8 (75%), followed by vt2-eaeA 1/8 (12.5%) and vt1 1/8 (12.5%) positives, at similar frequencies. In addition, the low diversity (Di=0.829) obtained from PhPRE analysis of EHEC positive samples suggest the presence of pathogenic clonal groups. In addition, the majority of the group of children that required IRT 42/68 (61.8%) harboured EAEC, ETEC and EPEC either alone or in combination. Also, the diversity value (Di=0.937) of the isolates from these children suggest that these strains may represent virulent clones capable of causing a more severe case of diarrhoea. In summary, the ETEC pathotype play an important role in diarrhoea in children less than 5 years of age in León, Nicaragua. Nonetheless, EAEC, EPEC and EHEC pathotypes are to some extent important pathogens associated with diarrhoea in those children. In addition to all the above, the structure of the Oantigen polysaccharides (PS) from the EAEC strain 94/D4 and the international type strain from Escherichia coli O82 were determined in study IV. The O-antigen is composed of tetrasaccharide repeating units with the following structure: [--->4)-alpha-D-Glcp6-P-2-D-GroA-(1--->4)-beta-D-Galp-(1--->4)-beta-D-Glcp-(1--->3)-beta-D-GlcpNAc-(1--->]18
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