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The prevalence and numbers of coccidian oocysts in faecal samples from young (less than 6 months old), immature (6-12 months old) and adult (over 12 months old) sheep on 15 farms in Nyandarua district were studied during the dry and wet seasons. The species of Eimeria occurring in these sheep were also identified. The proportion of animals shedding coccidian oocysts did not vary significantly with season. The prevalence of the oocysts was significantly higher (p < 0.05) in young sheep (mean 85.3%) compared to immature (mean 40.2%) and adult sheep (mean 32.15%). OPG counts (oocysts per gram of faeces) were significantly higher (p < 0.01) in the young sheep compared to immature and adult sheep during both seasons. Prevalence and OPG did not differ between immature and adult sheep. There was no significant difference in OPG during the wet season (mean 328 +/- 997) compared to the dry season (mean 219 +/- 773). The sex of the sheep had no significant effect on prevalence or OPG. Eight species of Eimeria were recognized. They (and their prevalence) were E. bakuensis (ovina) (43.6%), E. ovinoidalis (23.6%), E. ahsata (15.2%), E. intricata (8.27%), E. granulosa (4.8%), E. faurei (2.8%), E. parva (1.06%) and E. pallida (0.67%).

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A survey of gastrointestinal parasite infections of young (< 6 months old), immature (6-12 months old) and adult (> 12 months old) dairy cattle on 16 farms in Kiambu District, Kenya was conducted during a dry season (September 1991 to January 1992) and during a wet season (March to July 1992). The survey was based on monthly coproparasitological examination of cohorts and worm counts in tracer calves. The effects of age, sex, farm and season on the prevalence and intensity of helminth and coccidial infections were determined. Faecal egg and oocyst counts revealed that the overall prevalences were: strongyles (including trichostrongyles) (85.5%), liver flukes (Fasciola gigantica) (34.0%), coccidia (30.9%) and tapeworms (9.6%). Eight species of the protozoan Eimeria were identified, the most prevalent species being E. bovis and E. zuernii. The most prevalent nematode genera were Haemonchus, Cooperia, Oesophagostomum and Trichostrongylus. Season, farm and age of the animals had a significant (p<0.05) influence on the intensity of infection with strongyles, liver flukes and coccidia, whereas the sex of the animals had no significant (p>0.05) effect on the prevalence or intensity of infections. A higher intensity of infection with strongyles and coccidia was found in the wet season than in the dry season (p<0.05). The age-specific intensity was in the following order: for strongyles, immature animals of 6-12 months of age had the highest egg counts, followed by young calves and adults. Calves had significantly (p<0.05) higher oocyst counts than immatures or adults. Liver fluke egg counts did not differ significant (p>0.05) between immatures and adult cattle.