An epidemiological survey of bovine fascioliasis in selected districts of Kenya
MetadataShow full item record
Fascioliasis is a global parasitic disease caused by trematodes of the genus Fasciola. These causative agents belong to two species of Fasciola, namely Fasciola gigantica and Fasciola hepatica. In Kenya both species are known to cause the disease. although Fasciola gigantica is regarded as the most important species. The mode of transmission of fascioliasis is well established, and practical tactics exist on how to arrest the biological cycle to prevent further transmission. However application of these tactics either singly or in an integrated form has not been effective in ridding off the cattle industry of this health problem. While abattoir data acts as an indicator of the existence of bovine fascioliasis in the field. it does not probably give an accurate estimation of prevalence of the condition. In addition. only a few surveys carried out by the V.I.L.s examined the factors inffuenctng the -occurrence and distribution of bovine fascioliasis. These factors have always been studied singly and therefore their combined influence on the prevalence and distribution of, the condition has not been determined. In order to improve on these deficiencies, the present study was initiated with the following objectives: a) To update and improve on the approach of estimating prevalences of bovine fascioliasis in Kenya using abattoir data. b) To investigate the factors influencing the distributions of bovine fascioliasis with particular reference to environment, animal husbandry systems, disease control practices and cattle demographics. Abattoir data on condemnation of bovine livers due to bovine fascioliasis were compiled for the 1985 to 1990 period from 24 districts covered by the meat inspectorate section of the Veterinary Department. In addition data based on diagnostic records of the Veterinary Investigation Laboratories (V.I.Ls) were also compiled for the same period. These data helped in estimating trends of bovine fascioliasis as well as assessing the prevalence estimates of the various geographical regions. Livestock population figures were obtained from the Kenya Rangeland Ecological Monitoring Unit and Ministry of Livestock Development. Climatological data were obtained from Kenya Meteorological Department. From the abattoir data for the five year period (1985-1990) the results indicated that districts could broadly be divided into high risk districts with prevalence of over 40%, medium prevalence districts with prevalences of between 10-39% and low risk districts with prevalences of less than 100/0. The V.I.Ls data showed variations in prevalences depending on the region served by a particular laboratory. A major peak of mean monthly prevalences occurred in March-May with a minor peak occurring in September-November. The field survey data was collected from six randomly selected districts based on the Agricultural Research Foundation Report of 1986. These were Nakuru, Kericho, Nyandarua Machakos, Kwale and Kilifi. The farm data were used to better improve the estimation of prevalences of bovine fascioliasis. A total of 256 farms were sampled from the six districts surveyed. A questionnaire covering all aspects of farm management, animal husbandry practices, disease control practices and cattle demographics was administered in each of the selected farms. Faecal and serum samples from a total of 2434 bovines were' . sampled. The faecal samples were analysed for Fasciola eggs using the Faecal Sedimentation test, while the serum samples were analysed using the ELISA test for antibodies against Fasciola antigens. From the results of these analyses, ,it was observed that farm prevalences of bovine fascioliasis varied from district to district in the following descending order, Kwale 32.6%, Kilifi 28.4%, Machakos 14.3%, Nyandarua 12.5%, Kericho 3.4% and Nakuru 2.1%. The results of logistic regression analysis showed that farm prevalences were significantly influenced by various risk factors, ' for example grazing management, nutrition, availability of housing, breed type and source of water. An important objective of this study was to improve prevalence estimates of bovine fascioliasis using farm data. The results showed that areas previously reported to have had low abattoir based prevalences of bovine fascioliasis particularly Kwale (8.5%) and Kilifi (6.3%) showed relatively high farmbased prevalences, whereas districts that had earlier been reported to have high abattoir based prevalences e.g. Nakuru (22.3%) and Kericho (40.7%) showed relatively low farm based prevalences (less than 1o%). The results of this study therefore, contradict those of the Agricultural Research Foundation Report of 1986. A possible explanation for the changes in prevalences is probably due to success in control measures directed against the disease or a decline of the same. The conclusions drawn from this study are: a) Prevalence estimates based on abattoir and V.I.Ls data act only as indicators of the existence of fascioliasis problem in the country but not the true picture of the problem within specific districts. b) Risk factors namely. animal husbandry practices and meteorologic factors are the most important factors affecting the prevalence and distribution of bovine fascioliasis. c) Design of control measures against bovine fascioliasis should be based on the combinations of the farm management factors and animal husbandry practices.