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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.

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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%.

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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.

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A Leishmania sp.-like organism was found in the skin of a naturally infected 8-mo-old Red Dane female calf (Bos taurus) from Zimbabwe. There were multiple alopecic nodules, particularly on the face and udder. The nodules were up to 5 cm in diameter and larger ones were ulcerated and hemorrhagic. Numerous Leishmania-like amastigotes were seen in the skin lesions. Ultrastructurally, the organisms were oval to elongated (2-2.5 microm long), had a nucleus, a kinetoplast, and a flagellum. To our knowledge, this is the first report of Leishmania-like organisms found in an animal from Zimbabwe.

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An epidemiological study of gastrointestinal nematode infections of cattle was conducted on the highveld of Zimbabwe from June 1993 to May 1995. The study was carried out in two communal areas, two conventional beef farms and two commercial beef farms with irrigated pastures. On all farms/areas, faecal egg counts were low (< 500 eggs per g faeces) during the dry season. During the rainy season faecal egg counts were highest in communal areas and lowest in conventional beef farms. Those of irrigated farms had intermediate values. During the dry season pasture larval counts were low in irrigated pastures and conventional beef farms and virtually zero in communal areas. They increased and peaked during the rainy season, coinciding with the egg count peaks. Worm burdens of necropsied cattle indicated that 100% of the animals were infected with nematodes. The important species were Cooperia pectinata, C. punctata, Haemonchus placei, Trichostrongylus axei and Oesophagostomum radiatum in all farms/areas and Ostertagia ostertagi in a beef farm with irrigated pastures. Haemonchus survived the dry season as inhibited early fourth stage larvae whereas Cooperia and Trichostrongylus survived as adults.

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The susceptibility of 14 stocks of Trypanosoma congolense, recently isolated from cattle, to therapeutic doses of diminazene aceturate and to isometamidium chloride was assessed in laboratory mice. Eight isolates were readily susceptible to the normal therapeutic dose of diminazene, two were resistant to the drug at 14 mg kg-1, and four were totally resistant at 28 mg kg-1. All the isolates were susceptible to isometamidium chloride at 0.5 mg kg-1. These observations highlight the need for regular evaluation of drugs used in the control of trypanosomosis.

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Comparative transmission electron microscopy on Besnoitia besnoiti and on a strain of Besnoitia derived from goats in Kenya revealed that the two organisms differ in their pellicle, micropore, microtubules, nucleus, wall-forming body 1 (W1), amount of lipids and amylopectin. Thus the caprine besnoitia is probably a different organism and the term Besnoitia caprae should continue to be used.

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Hepatozoon canis-like schizonts were found in the hearts of 2 lionesses (Panthera leo) from Kenya. The parasite, initially described as a new genus and new species Microbesnoitia leoni Bwangamoi, 1989, is determined to be a junior synonym of Hapatozoon canis (James, 1905) Wenyon, 1926.

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Three of six wild dogs (Lycaon pictus) which died of rabies, and one Alsatian dog which died of adenocarcinoma, were found to harbour sarcocysts in their cardiac and/or skeletal muscles. The bradyzoites and metrocytes of the cysts were smaller than those seen in a lion infected with Microbesnoitia leoni and the common Sarcocystis spp. found in ruminants. It is proposed that Lycaon pictus is the natural intermediate host of the unidentified Sarcocystis-like species.

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An adult female rabbit was submitted for necropsy after sudden death. Pneumonia and nephritis were diagnosed by gross examination. On histological examination. Besnoitia cysts were seen in the pulmonary interalveolar tissue. The Besnoitia cysts were morphologically normal in appearance, measured 127 to 185 microns in diameter and provoked mild mononuclear inflammatory reaction. To the best of our knowledge there has been no previous report of natural besnoitiosis in rabbits.

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Inoculation of cystozoites obtained from natural, chronic cases of caprine besnoitiosis produced clinical disease in goats but not in rabbits, mice, guinea pigs, hamsters, rats or cattle. Histological examination of tissue sections from the experimental animals showed Besnoitia cysts only in goats. This, together with field observations that cattle reared together with goats having besnoitiosis do not contract the disease, suggests that the Besnoitia species that infects goats in Kenya is host-specific and is not Besnoitia besnoiti. We suggest that the name Besnoitia caprae be adopted for the caprine pathogen.

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