| 1. |
|
|
| 2. |
- Silverlås, Charlotte
(author)
-
Cryptosporidium infection in dairy cattle : prevalence, species distribution and associated management factors
- 2010
-
Doctoral thesis (other academic/artistic)abstract
- For almost 25 years, it has been known that Cryptosporidium parasites infect Swedish calves. This thesis explores how common these parasites are at herd level and at individual level in preweaned calves, young stock and periparturient cows. Species distribution and association with diarrhoeal problems are also highlighted. Two field studies were performed and in addition, existing clinical or cohort studies on the cryptosporidiostatic substance halofuginone were examined. Cryptosporidium oocyst shedders were detected in 68 of 69 investigated herds. Calves had the highest prevalences followed by young stock and cows. The four common species in cattle, C. parvum, C. bovis, C. ryanae and C. andersoni, were all detected. Cryptosporidium bovis was most common in all age groups with an overall 77% prevalence, and the prepatent period was shown to be at least three days shorter than previously described. Overall, Cryptosporidium infection was not associated with disease in calves, but a higher percentage of calves infected with C. parvum had diarrhoea compared to calves infected with C. bovis. Nine different C. parvum subtypes were identified, of which three were novel. All subtypes belonged to the zoonotic subtype families iia and iid. Several management factors were associated with shedding of oocysts. One management factor, 'disinfection of single pens', was associated with diarrhoeal problems at herd level, but several more management differences were indicated although they could not be shown statistically. Halofuginone had some beneficial effects on infection and diarrhoeal prevalences when used for prophylaxis, but mortality was not affected. Cryptosporidium parasites were widely spread in the Swedish dairy cattle population, but because most animals were not infected with the zoonotic C. parvum, the potential for zoonotic transfer is fairly low. Management routines are important to decrease infection pressure and prevent infected calves from clinical disease. Halofuginone should be used with great care in a transition period when management routines are changed to improve calf health.
|
|
| 3. |
- Silverlås, Charlotte, et al.
(author)
-
Cryptosporidium infection in herds with and without calf diarrhoeal problems
- 2010
-
In: Parasitology Research. - : Springer Science and Business Media LLC. - 0932-0113 .- 1432-1955. ; 107, s. 1435-1444
-
Journal article (peer-reviewed)abstract
- A case-control study was designed to investigate the role of different Cryptosporidium spp. in Swedish dairy herds with and without calf diarrhoeal problems. Faecal samples were collected from preweaned calves, young stock and cows. Cryptosporidium oocysts were detected by sodium chloride flotation and epifluorescence microscopy. Molecular diagnostics were used to identify Cryptosporidium species. Samples containing C. parvum were further analysed to determine subtypes. Calf faecal samples were also analysed for rotavirus, coronavirus and Escherichia coli F5+. Total protein was assessed in 1- to 8-day-old calves. A questionnaire was used to identify differences in management routines. Cryptosporidium infection was diagnosed in all herds, with equal prevalence in case and control herds in all three age groups. Cryptosporidium parvum, Cryptosporidium bovis, Cryptosporidium ryanae and Cryptosporidium andersoni were all identified, as were rotavirus, coronavirus and E. coli F5+. C. ryanae and C. andersoni were only detected in non-diarrhoeal samples, whereas the other pathogens were detected in both diarrhoeal and non-diarrhoeal samples. Diarrhoea was more common in case herd calves. Disinfection of single pens was more common in case herds and several other management routines seemed to differ although results were not significant.
|
|
| 4. |
- Silverlås, Charlotte, et al.
(author)
-
Cryptosporidium spp. in calves and cows from organic and conventional dairy herds
- 2013
-
In: Epidemiology and Infection. - 0950-2688 .- 1469-4409. ; 141, s. 529-539
-
Journal article (peer-reviewed)abstract
- A cohort study was performed to investigate cryptosporidial prevalence and species distribution in 13 organic and 13 conventional dairy herds. Faecal samples were collected from 221 calves and 259 cows. Management routines were recorded at farm inspection and through a questionnaire. Samples were concentrated using sodium chloride flotation and cryptosporidial oocysts were detected by epifluorescence microscopy. Molecular analysis was used to determine species and subtypes. A multivariable model for factors associated with calves being Cryptosporidium spp. positive was built. Cryptosporidium spp.-positive animals were identified in all herds. Prevalences were similar in organic and conventional calves (44.7% vs. 52.3%), as well as in cows (3.1% vs. 3.8%), P>0.05. Cryptosporidium bovis, C. ryanae and C. parvum were identified. C. ryanae was identified in a calf younger than the described prepatent period. The multivariable model included four significant variables; calf age, cleanliness of bedding, cleaning routines for group pens and farmers' attitudes towards biosecurity.
|
|
| 5. |
- Silverlås, Charlotte, et al.
(author)
-
Is there a need for improved Cryptosporidium diagnostics in Swedish calves?
- 2013
-
In: International Journal for Parasitology. - : Elsevier BV. - 0020-7519 .- 1879-0135. ; 43, s. 155-161
-
Journal article (peer-reviewed)abstract
- Cryptosporidium parvum is a common pathogen in preweaned calves but in Sweden Cryptosporidium bovis, which is considered apathogenic, is the most common species in this age group and it has been identified in diarrhoeal samples, indicating that it could be a cause of diarrhoea. In routine diagnostic procedures, infection is determined by microscopy, which is not sufficient to differentiate these species. We investigated whether routine Cryptosporidium diagnostic procedures need improvement to include species determination. The relation of Cryptosporidium spp. and subtype with the clinical picture and other pathogens was also investigated. A total of 782 diarrhoeal calf samples were analysed and Cryptosporidium infection was diagnosed in 198 samples. Cryptosporidium parvum was identified in 178, C bovis in six and mixed C bovis/C. parvum in seven samples. Twenty-seven C. parvum subtypes were identified, of which 16 were newly described. Except for three herds, only one subtype per herd was identified. Cryptosporidium parvum-positive calves were younger than C. bovis-positive calves and most C parvum infections were seen at 1-3 weeks of age. Oocyst counts were higher in C parvum samples. Yellow faecal colour was associated with C. parvum infection. Watery faeces had no greater association with C parvum infection. but C parvum subtype family IIa was more common than subtype family IId in watery faecal samples. No other pathogens were detected in the six C. bovis-infected calves, indicating a pathogenic potential. Our results show that species determination does not need to be included in routine Cryptosporidium diagnostic procedures in order to estimate the clinical relevance of infection in diarrhoeal calves. The maximum age when analysis for clinical cryptosporidiosis is performed can be lowered to 6 weeks of age. However, the indicated pathogenic potential of C. bovis warrants further attention. (C) 2012 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.
|
|
| 6. |
- Silverlås, Charlotte, et al.
(author)
-
Molecular characterisation of Cryptosporidium isolates from Swedish dairy cattle in relation to age, diarrhoea and region
- 2010
-
In: Veterinary Parasitology. - : Elsevier BV. - 0304-4017 .- 1873-2550. ; 169, s. 289-295
-
Journal article (peer-reviewed)abstract
- Cryptosporidium positive samples from 176 preweaned calves, young stock and cows of 48 herds were subjected to molecular characterisation of the 185 rRNA gene to determine which species are present in Swedish dairy cattle. In addition, samples characterised as Cryptosporidium parvum were further analysed at the GP60 gene to investigate distribution and zoonotic potential of subtypes. The 18S rRNA gene was successfully sequenced in 110 samples, with Cryptosporidium bovis in 83, C parvum in 15, Cryptosporidium ryanae in 10, and Cryptosporidium andersoni in two samples. C. bovis was the most common species, being identified in 74% of calf samples, in 77% of young stock samples and in 100% of cow samples. The youngest calves infected with C. bovis were 7 days old, showing that the prepatent period is shorter than the previously stated 10 days. C. parvum was detected in 15 calves from nine farms, and samples were clustered in the southern parts of Sweden. Diarrhoeic calf samples contained C parvum, C. bovis or C. ryanae. Sequencing of the GP60 gene was successful in 13 of the C parvum samples. Eight subtypes, including three novel ones, were detected. Four of the subtypes have previously been identified in humans. This indicates that there is a zoonotic potential in C. parvum infected Swedish dairy calves. (C) 2010 Elsevier B.V. All rights reserved.
|
|
| 7. |
- Silverlås, Charlotte, et al.
(author)
-
Prevalence and associated management factors of Cryptosporidium shedding in 50 Swedish dairy herds
- 2009
-
In: Preventive Veterinary Medicine. - : Elsevier BV. - 0167-5877 .- 1873-1716. ; 90, s. 242-253
-
Journal article (peer-reviewed)abstract
- Cryptosporidium parvum is a protozoan parasite causing diarrhoea in young calves. This cross-sectional study was performed to estimate the prevalence of Cryptosporidium infected herds in a sample of Swedish dairy herds and to identify potential risk factors associated with shedding of oocysts. Fifty dairy herds, selected by stratified random sampling, were included. The herds were visited once during the indoor seasons of 2005-2006 and 2006-2007. Faecal samples were collected from 10 calves, 10 young stock and 5 cows in each herd. Clinical observations of sampled animals and environmental status were recorded, and farmers were interviewed about management procedures. Faecal samples were cleaned by sodium chloride flotation and detection of oocysts was made by epifluorescence microscopy. Cryptosporidium parvum-like oocysts were found in 96% of the herds. Prevalence was 52% in calves, 29% in young stock and 5.6% in cows. Three two-day-old calves shed oocysts. Cryptosporidium andersoni was found in seven animals from four different herds. Factors associated with prevalence of shedders among sampled animals in a herd were age at weaning, cleaning of single calf pens, placing of young stock, system for moving young stock, and year of sampling. Factors associated with shedding in calves were age, placing of young stock, routines for moving young stock and time calf stays with the cow. The only significant factor in young stock was age. In cows, number of calves in the herd and type of farming (organic vs. conventional) affected shedding. (C) 2009 Elsevier B.V. All rights reserved.
|
|
| 8. |
- Silverlås, Charlotte, et al.
(author)
-
Systematic review and meta-analyses of the effects of halofuginone against calf cryptosporidiosis
- 2009
-
In: Preventive Veterinary Medicine. - : Elsevier BV. - 0167-5877 .- 1873-1716. ; 91, s. 73-84
-
Research review (peer-reviewed)abstract
- Halofuginone seems to reduce diarrhoea and oocyst shedding in calves with cryptosporidiosis, but provides no complete cure. To develop more precise estimates of the effects of halofuginone on calf cryptosporidosis, meta-analyses were performed, including studies on prophylactic and therapeutic treatment. Meta-analysis increases statistical power because several trials are evaluated together, increasing the effective sample size and possibility of detecting true effects. In total, 20 cohort or clinical studies (in 16 publications) investigating halofuginone treatment in calves were identified. One study was excluded because treated calves and control calves were not investigated in parallel. Four studies (three publications) were excluded because only abstracts were available. Thus, 15 studies from 12 publications, with 10-311 calves were included for data extraction. Of these, five studies from three publications could not be used for meta-analysis because they did not report the data needed.Effects on infection prevalence, diarrhoeal prevalence and mortality were investigated. For prophylactic treatment, halofuginone had an effect on infection and diarrhoeal prevalence on study days 4 and 7, but the control group had significantly lower infection prevalence than the halofuginone treated group on study day 21. Heterogeneity was detected on study days 14 and 21 and publication bias was detected on study days 7 and 14. Mortality was not affected. For therapeutic treatment, a shortage of studies in combination with heterogeneity made interpretations uncertain, and we could not determine if halofuginone treatment benefits calves. (C) 2009 Elsevier B.V. All rights reserved.
|
|
