Seroprevalence of Anaplasma marginale and Babesia bigemina infections and associated risk factors in Machakos County, Kenya.

Anaplasma marginale and Babesia bigemina are important tick-borne pathogens of cattle. A cross-sectional survey was undertaken to determine the seroprevalence of A. marginale and B. bigemina infections and identify associated risk factors on traditional smallholder farms in Machakos County, Kenya. A total of 421 cattle from 127 farms from four divisions in the county were sampled and visited between September and November 2007. The farms were selected by a proportional allocation approach based on the number of farms in the four divisions previously selected by stratified random sampling method. Information on animal and individual farm management variables was obtained using standardized questionnaires. Prevalence of serum antibodies due to A. marginale and B. bigemina pathogens was determined using the enzyme-linked immunosorbent assay (ELISA) technique. The relationship between the seropositivity and associated risk factors was assessed by multivariable analyses using standard logistic regression models. The overall estimation (and their 95% confidence intervals) of A. marginale and B. bigemina seropositivity at the animal level was 53.4% (48.5%, 58.2%) and 40.6% (35.8%, 45.4%), respectively. Two variables, "animal age" and "administrative division," were significantly associated with the A. marginale seroresponse. Three variables, "animal age" "grazing system" and "administrative division" were significantly associated with the B. bigemina seroresponse. These findings suggest possible indicators of existence of endemic instability for the two infections. The study identifies characterization of environmental suitability for the vectors and how they interact with grazing systems to cause the infections as an area for further studies, for improved understanding of the infections and in designing disease control programs.

Atypical dermatophilosis of sheep in Kenya.

An outbreak of an atypical form of ovine dermatophilosis affecting the lips and muzzle with a very high morbidity in weaners and hoggets in Kenya is reported. Clinical diagnosis of ovine dermatophilosis was made and confirmed by direct microscopic examination as well as isolation and identification of Dermatophilus congolensis from scab material from the affected sheep. The morbidity rate within the flock was 31.8% (237/745) with 98.3% (233/237) of the affected sheep being weaners and hoggets. No fatalities were recorded. The lesions, confined in the lips and the muzzle, were swelling of both the upper and lower lips, circumscribed lumps in the skin of both the upper and lower lips, oedema of the head and the submandibular area and scabs and crusts on the lips and muzzle. Within 1 week following treatment with long acting oxytetracycline (20%) at a rate of 20 mg/kg body weight, intramuscularly and a topical application of oxytetracycline spray, lumps regressed in size and were covered by dark-brown scabs. Removal of the dark-brown scabs revealed erythematous areas covered with purulent material and horny erythematous projections (papillae) projecting from the surfaces. Within the 2nd week, the horny erythematous projections formed greyish scabs, which later peeled off leaving alopaecic areas around the lips. The paper highlights atypical dermatophilosis of sheep and we believe that this is the first published report of an outbreak of ovine dermatophilosis in Kenya.

Semen characteristics of goats with subacute, acute and chronic besnoitiosis.

A study on the semen obtained from breeding goats suffering from mild to severe chronic besnoitiosis revealed marked changes in semen volume, colour, density, concentration, mass and individual motility and percentage live. There were also many neutrophils and spermatozoa with primary and secondary defects, including missing tails and deformed heads and tails. The observed changes were considered to be severe enough to account for the infertility observed in the flock. Sections of testes obtained for histopathology were characterised by massive blockage of the pampiniform plexus, degeneration of the germinal epithelium, tubular necrosis with an inflammatory infiltrate and, in some cases, accumulation of haemosiderin-like material in the tunica vaginalis.

Prevalence of besnoitiosis in domestic ruminants in Kenya: a preliminary survey.

A preliminary survey on the prevalence of besnoitiosis in domestic ruminants in Kenya based on field and farm visits, clinical and post mortem examinations and histopathological examination of tissues and biopsies, showed that goats are the most affected, followed by cattle, while sheep were unaffected. Caprine besnoitiosis occurred in a continuous belt in 5 of the 8 provinces in Kenya stretching from the Coast, Eastern, North Eastern, Nairobi and the Rift Valley Provinces. Mandera, in the North Eastern Province, had the highest prevalence rate of 36%, followed by Kwale (35%), Isiolo (35%), Marsabit (33%), Wajir (28%), Nairobi (26%), Meru (24%), Garissa (21%), Taita Taveta (18%), Embu (17%), Kitui (9%), Machakos (7%), Laikipia (3%), Kajiado (2%) and Turkana and Elgeyo-Marakwet (1% each). In all flocks where the prevalence rates were over 6%, kids were observed to be affected. There were no significant differences (P < 0.05) between the prevalence rates in bucks and does (18% and 18.4, respectively), but kids were less (4%) affected. Bovine besnoitiosis was found only in the Tana River District, with an infection rate of 11%.

Experimental transmission of Besnoitia caprae in goats.

Experimental transmission of Besnoitia caprae from naturally chronically-infected goats to susceptible ones was achieved by intra-nasal instillation and intra-conjunctival inoculation of cystozoite-containing suspensions, subcutaneous implantation of fascia containing cysts and alternate needle pricking between the infected and non-infected goats. Typical chronic symptoms developed in the fascia-infected does. Cystozoite inoculation into the eyes and mouth did not result in infection. Kids born of dams with acute and chronic besnoitiosis did not contract the infection in utero, suggesting that intra-uterine transmission may not occur. In contrast to does with acute besnoitiosis, which occasionally aborted, the does with chronic besnoitiosis gave birth to healthy kids. Kids below the age of 4 months (pre-weaned period) born of both infected and non-infected does were susceptible to besnoitiosis but appeared to be more resistant than adult goats.