The prevalence of Cryptopsoridium Parvum infections in cattle, sheep and goats in Zambia

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Date
2012-09-17
Authors
Goma, Fusya Yvonne
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Abstract
Cryptosporidium parvum has become increasingly important in ruminants in recent years as an etiological agent of neonatal diarrhoea complex causing significant economic losses. Cryptosporidium parvum "bovine genotype" found in ruminants is also zoonotic causing life threatening diarrhoea in immunocompromised individuals and children below 5 years. In developing countries like Zambia, infections with C. parvum are prevalent in humans due to high prevalence of HIV/AIDS, poor sanitation and use of contaminated drinking water. Reported prevalence of C. parvum in humans ranges from 18 to 30%. However, it is not known if the parasite occurs in Zambian livestock and whether the genotypes found are of public health significance. Therefore the objectives of this study were; to determine the prevalence of C parvum in calves in 3 cattle husbandry systems, determine prevalence in small ruminants and find out the genotypes involved. The association between management factors and infection were also investigated in the dairy sector. Furthermore the conventional microscopic method of oocyst detection was compared to that of coproantigen ELISA (Techlab).During the period August 2003 to July 2004, faecal samples were collected per-rectum from lambs, kids and calves (dairy, beef and traditional) aged 3 months and below. The study area included 4 of the 9 provinces of Zambia. For each faecal sample the consistency was recorded and all samples were analysed using the coproantigen ELISA (Techlab) commercial kit. A total of 744 calves were sampled, out of these 250 were from dairy, 238 from ranch beef and 256 from the traditional husbandry systems. A total of 37, 26 and 91 farms were sampled from the dairy, beef and traditional husbandry systems, respectively. After coproantigen ELISA examination an overall prevalence 19.2% was obtained and specific prevalence in dairy, beef and traditional husbandry systems were 42.8%, 8.0% and 6.2%, respectively. The farm prevalence was 75.7% dairy, 42.3% beef and 15.4% traditional husbandry systems. Comparison of prevalence in the 3 husbandry systems revealed that the dairy sector (intensive management) had a significantly higher prevalence than the beef and traditional (extensive management) sector (x2, P< 0.001). When farms were grouped according to animal population, the prevalence was found to be increasing from the small-scale to the medium-scale and large-scale farms. There was significant difference in prevalence among the 3 farm sizes in the dairy (x2, P<0.001) and traditional {x2, P<0.001) husbandry systems. Infection with C. parvum was significantly associated with liquid faeces only in the dairy sector (x2, P= 0.02). A questionnaire survey was conducted on 27 dairy farms to determine the association of infection with 3 risk factors namely, general management, maternity management and calf housing and hygiene. Only 1 of the management risk factor (intensive or semi-intensive) was found to be significantly associated with infection (x2 P= 0.004).In lambs and kids the prevalence on coproantigen ELISA was 18.4% (n=152) and 5.7% (n=I05), respectively. Both the sheep and goat farms were under semi - extensive management. Of the 16 sheep farms sampled, 37.5% had one or more lambs shedding C. parvum oocysts, while of the 12 goat farms sampled, 41.7% had one or more kids shedding oocysts. In sheep, infections were significantly associated with faecal consistency, with prevalence of 40%, 34.8% and 14.5% for liquid soft and solid faeces (x2, P=0.03), respectively. In goats there was no association between infection and faecal consistency (x2, P=O.4). A total of 432 calf faecal samples were also analysed using the modified Ziehl Neelsen staining technique to evaluate this test against the coproantigen ELISA (Techlab). The sensitivity and specificity were determined to be 58% and 84.3%, respectively with a kappa value of 0.41. The oocyst detection level of the 2 tests was significantly different (x2, P<0.0001). A total of 55 samples comprising 5 sheep, 5 goat and 45 cattle which were positive on the coproantigen ELISA (Techlab), were examined by Polymerase Chain Reaction (PCR) for amplification of the Heat Shock (HSP-70) gene of Cryptosporidium. Amplification products were obtained for 45 isolates, whereas 9 isolates failed to amplify. Sequence analysis was performed on a sub sample of 10 isolates from cattle and sheep. Analysis revealed C. parvum "bovine genotype" and a novel Cervid genotype.It can be concluded from the present study that C. parvum infections are prevalent in cattle, sheep and goats in Zambia with high levels in dairy calves and lambs. The study has also observed that prevalence in calves is higher in the intensive (dairy) than extensive husbandry systems (ranch beef and traditional). In view of the lack of effective treatment against cryptosporidiosis, control measures targeting management practices and hygiene measures are recommended in the dairy sector. Furthermore, the "bovine genotype" of C. parvum found in the samples that were analysed is of public health significance. Therefore, it is suggested that farm owners and animal handlers/workers be educated on the risk of infection with the parasite. It is suggested that further studies be conducted to elucidate on the risk that dairy cattle and sheep pose in transmitting the infection to humans, especially those living in close proximity to these animals. Although there was good agreement between the microscopic method and the coproantigen ELISA, the latter is preferable as it is fast, easy to read and a number of samples can be done simultaneously.
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Keywords
Cryptosporidium -- Zambia , Cryptosporidiosis
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