Prevalence of parasites of the local scavenging chickens in a selected semi-arid zone of Eastern Kenya.

A study to identify and estimate the prevalence of parasites of local chickens in a semi arid area of Kenya was conducted between March 2005 and August 2006. Three hundred and sixty (360) local chickens purchased from Yathui division of Machakos were examined. Of those, 93.3% had helminths. Nematodes were recovered in 268 (74.4%) chickens whereas 245 (68.1%) had cestodes. Tetrameres americana (37.7%), Ascaridia galli (33.3%) and Heterakis gallinarum (22.8%) were the most important nematode species identified. Raillietina echinobothrida (33.3%) and Davainea proglottina (19.4%) were the two most important cestode species identified. Two coccidia species, namely Eimeria necatrix (6.7%) and E. tenella (16.7%) were isolated and identified as per location in the digestive system. Important ectoparasites identified included Echidnophaga gallinacea (76.7%), Menacanthus stramineus (79.4%) and Dermanyssus gallinae (60.0%). Endo-parasites (helminths and coccidia) occurred in significantly (p<0.05) higher frequencies during the wet season than during the dry season. On the contrary, ecto-parasites were significantly (p<0.05) more fequent during the dry season. Male chickens generally exhibited increased odds for the occurrence of parasites than female birds. Further investigations are required to establish a plausible explanation for this. Overall, parasitism was a big constraint to chicken productivity in the study area. Urgent integrated parasite control approaches should be initiated to address parasitism in chickens in the Yathui cluster.

The prevalence and economic significance of Fasciola gigantica and Stilesia hepatica in slaughtered animals in the semi-arid coastal Kenya.

Fasciola gigantica and Stilesia hepatica constrain ruminant productivity. The prevalence and economic losses caused by F. gigantica and S. hepatica in the ruminant production systems of Taveta division of Kenya were estimated in a retrospective appraisal of the slaughter records on the total number of animals slaughtered and livers condemned over the period 1989 to 2004. Only liver condemnations based on infestation by F. gigantica and S. hepatica were considered for purposes of this study. Liver condemnation rates differed significantly between bovines, caprines and ovines (p < or = 0.05) for F. gigantica (26%, 6.6% and 5.2%, respectively) and for S. hepatica (0.4%, 22% and 28%, respectively). The total loss through condemnation of both F. gigantica and S. hepatica infested livers was 4,408,272 KES (Kenyan shillings) (US dollars 72,272). The proportion of loss in bovines, caprines and ovines, was 76%, 17% and 7%, respectively. Fasciolosis contributed 3505410 KES (79.5%) and S. hepatica infestation 903,210 KES (20.5%) to the total losses due to liver condemnations. The authors feel strongly that there is a need for more work on the two parasites using live animals to determine the prevalence in animals of various ages, species and breeds and the economics of disease control at farm level.

Ag-ELISA and PCR for monitoring the vaccination of cattle against Taenia saginata cysticercosis using an oncospheral adhesion protein (HP6) with surface and secreted localization.

A Taenia saginata oncosphere-derived adhesion protein (HP6) with surface and secreted localization was used to successfully vaccinate calves against oral challenge with T. saginata eggs. In contrast, vaccination using a combination of T. saginata oncosphere-derived peptides, selected on the basis of their antigenic index, and including three derived from the HP6 molecule (HP6-1, HP6-2 and HP6-3), was unsuccessful. This either indicated that the wrong peptides were selected or, in the case of the HP6 protein, that the protective epitope is conformational in nature. The protection experiments were monitored using a parasite antigen detection ELISA (HP10 Ag-ELISA), which allowed the early determination of the success of the vaccination protocol, subsequently confirmed at autopsy. PCR assays were used for the first time to confirm the presence of T. saginata DNA in lesions recovered at autopsy and thus verify the parasite origin of the lesions.

Taenia saginata derived synthetic peptides with potential for the diagnosis of bovine cysticercosis.

Immunity in Taeniids is predominantly antibody mediated and thus many serological immuno-determinants will have potential in both protection and diagnosis. The antigenicity of six peptides derived from four potentially protective molecules cloned from a Taenia saginata oncospheres cDNA library have been evaluated as targets for the specific diagnosis of bovine cysticercosis. The six peptides consist of: two peptides (HP6-2 and HP6-3) derived from the sequence of the 18 kDa surface/secreted oncospheral adhesion antigen identified by McAb-HP6, two peptides (Ts45W-1 and Ts45W-5) derived from the sequence of the T. saginata homologue of the T. ovis 45W protective gene family, one peptide (TS45S-10) derived from a T. saginata sequence with significant similarity to the T. ovis 45S protective antigen, and one peptide (TEG-1) derived from the sequence of the T. saginata homologue of Echinococcus spp. main surface protein. Longitudinal studies indicate that T. saginata infected cattle respond to all six peptides by 3-4 weeks post-infection and that the antibody levels remain high for at least 12 weeks post-infection. As protection against Taeniid parasites is predominantly antibody mediated, some of these six peptides may be of value as immuno-prophylactic tools and hence also in assays to determine resistance to infection with the parasite. For diagnosis, on the other hand, only three peptides (HP6-2, TEG-1 and Ts45S-10) performed with the necessary sensitivity and specificity to determine exposure to infection with T. saginata, and now merit an exhaustive evaluation prior to employment as routine diagnostic tools.

Comparison of production losses caused by chronic Fasciola gigantica infection in yearling Friesian and Boran cattle.

Yearling Friesian and Boran cattle were given a standard dose of Fasciola gigantica metacercariae designed to produce chronic infection. Their liveweights were then monitored for 23 weeks post-infection. Following standard meat inspection procedures, all the livers from the infected cattle were condemned. At 22 kg per animal, the mean reduction in liveweight gain in infected Borans was significantly greater than in infected Friesians. Compared to the control cattle and based on current sale prices in Kenya, the production losses from the combination of liver condemnations and reduction in liveweight gain constituted a loss in value of US$$12.11 (4.92%) and US$23.41 (10.34%) for Friesians and Borans respectively. These data indicate that productivity losses and the economic consequencies of fasciolosis in yearling Boran cattle are much more severe than in Friesians. These findings have implications for assessing the likely benefits of control measures against this parasite.