Inverted CD4+/CD8+ T cell ratio in Boran (Bos indicus) cattle.

The CD4+/CD8+ ratio is used as a marker of the immune regulation of T cell balance. When the ratio in peripheral blood is less than 1, this is considered an indication of immune suppression in an individual. Previous work on bovine Peripheral Blood Mononuclear Cells (PBMC) has consistently reported a ratio ≥1 as seen in other mammalian hosts, i.e. higher circulating CD4+ cell numbers than CD8+ cell numbers. However, a consistent inverted CD4+/CD8+ ratio (<1) was observed in Boran cattle, an African Bos indicus breed. The T cell populations were characterized in Boran cattle (n = 52), revealing higher percentages of circulating CD8+ cells (31.9 % average) than CD4+ cells (19.1 % average), thus resulting in the inversion of the expected T cell homeostasis in these animals. The results show that this inversion is not an effect of age or relatedness of the cattle, rather, it was shared by almost all Boran cattle used in this study. Despite this inversion being a feature shared by both males and females, the female cattle had significantly higher CD4+/CD8+ ratios than the male Boran. This paper describes the characteristics of the T cell fractions in the study animals and compares the findings to those of other Boran cattle in Kenya, and four other cattle breeds representing African indicine, African taurine, Brazilian indicine and European taurine cattle. We demonstrate that the consistent observation of inverted CD4+/CD8+ cell ratio was restricted to the Boran.

Environment and farm factors associated with exposure to Theileria parva infection in cattle under traditional mixed farming system in Mbeere District, Kenya.

The objective of this study was to investigate the relationship between seroprevalence to Theileria parva infection in cattle and potential environmental and farm-level effects in 80 farms under traditional crop-livestock system in Mbeere District, Kenya. A standardized questionnaire was used to collect the effects characteristics as related to T. parva infection epidemiology. Serum samples were collected from 440 cattle of all ages for detection of T. parva antibodies by the enzyme-linked immunosorbent assay technique. The association between the variables was assessed using a generalized estimation equation logistic regression model. The overall T. parva seroprevalence, accounting for correlation of responses, was 19.3% (95% confidence interval (CI) 14%, 25%). Two variables, "administrative division" and "presence of the vector tick on the farm", were significantly associated with the T. parva seroresponse. Respectively, cattle from farms in Gachoka, Evurore, and Mwea divisions were (and their 95% CI) 1.3 (0.36, 4.8), 4.4 (1.2, 15.9), and 15.2 (4.9, 47.1) times more likely to be seropositive relative to those from Siakago Division (P = 0.000). Cattle from farms in which the vector tick was present were 2.9 (1.2, 6.7) times more likely to be seropositive (P = 0.011). Results of this study suggested that both environmental and farm factors may be associated with T. parva infection epidemiology in Mbeere District. Under such circumstances, characterization of environmental suitability for the vector tick and corresponding environment-specific farm management practices in the district is required both for improved understanding of the disease and in planning disease control programs.

A survey of bovine cysticercosis/human taeniosis in Northern Turkana District, Kenya.

Bovine cysticercosis is a zoonosis that is mainly of socioeconomic and public health importance. A survey of this disease was carried out in Northern Turkana District, Kenya to estimate the prevalence through both serology and meat inspection, to determine the prevalence of the adult tapeworm in the human definitive host, and to determine risk factors for cattle seropositivity. This information is of public health importance and will be of use in assessing economic losses due to downgrading, refrigeration or condemnation of infested carcasses. The study area was stratified into the three livestock grazing regions of Oropoi to the south, Lokichoggio-Mogilla centrally and Kibish in the north for the purposes of the serological and questionnaire (n = 53 herd owners) data. Five adakaars (grazing units) were selected and 34, 63, 49, 75 and 571 cattle serum samples obtained from these. The slaughter slabs of Lokichoggio and Kakuma were visited and 188 serum samples were obtained from slaughter cattle and compared to results of meat inspection. Human stool samples were collected in each of the three grazing areas and 66, 97 and 78 samples were obtained. The seroprevalence of cysticercosis in cattle was estimated at 16.7% (95% CI 13-20.9%) using a secretory-excretory antigen detection ELISA. There was poor agreement between meat inspection and serology (k = 0.025; p = 0.2797). The prevalence of taeniosis was estimated as 2.5% (95% CI 0.8-5.6%) by microscopy. A backwards elimination logistic regression analysis indicated that the grazing unit (Adakaar), the deworming history of household members and the distance (>2 km) of grazing fields from the homestead were significant explanatory variables for cattle being found to be positive on serology. An intra-cluster correlation coefficient (ICC) of 0.07 (0.02-0.12); p < 0.0001 was calculated for bovine cysticercosis in this area.