Long-acting oxytetracycline prophylaxis to protect susceptible cattle introduced into an area of Kenya with endemic East Coast fever.

Two field trials were carried out in successive years at the Ngong Veterinary Farm, Kenya, in which young cattle, previously unexposed to tick-borne diseases, were introduced into an area with endemic East Coast fever while protected by a series of injections of a long-acting oxytetracycline. In 1984, 12 animals which received injections of 20 mg/kg of the drug on days 0, 7, 14 and 21 after introduction, together with 12 untreated controls, were exposed without tick control until clinical disease occurred. All 12 control animals contracted East Coast fever by day 24 and 10 of them died. Five of the 12 injected animals had detectable parasites, and one of them required antitheilerial treatment. In 1985, four groups of 10 calves were introduced. One group received injections of 20 mg/kg of oxytetracycline on days 7 and 14, one group received injections on days 7, 14 and 21, and a third group received injections on days 7, 12 and 17; the fourth group (controls) had no treatment until clinical disease occurred. By day 35 all the control animals had contracted the disease and one had died despite antitheilerial treatment. Three injections of oxytetracycline suppressed the disease so that mild reactions occurred in only four animals in each group, but two injections failed to prevent severe reactions in two animals and mild reactions in four others.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical trial of halofuginone lactate for the treatment of East Coast fever in Kenya.

A field trial was undertaken to test the efficacy of halofuginone lactate in the treatment of East Coast fever under farming conditions in Kenya. The drug was administered orally at a dose of 1.2 mg/kg bodyweight and treatment was repeated after 48 hours. Of 293 cases treated 236 (80.5 per cent) recovered and 49 (16.7 per cent) died. Five animals were disposed of by the owners and three became chronically infected. No differences were recorded in recovery rate between uncomplicated cases and cases with concurrent anaplasmosis or babesiosis, nor were there any significant differences in recovery rates between animals of different types. However, zebu cattle (Bos indicus) tended to respond more rapidly to treatment than exotic cattle (Bos taurus). Younger animals had a poorer recovery rate than adults. Early treatments were more successful than those administered late. It was concluded that with early detection and treatment, coupled with efficient tick control, halofuginone lactate is effective in the treatment of clinical East Coast fever under field conditions.

Indirect fluorescent antibody test for experimental and epizootiological studies on East coast fever (Theileria parva infection in cattle). Evaluation of a cell culture schizont antigen fixed and stored in suspension.

A schizont antigen for the indirect fluorescent antibody test against Theileria parva was prepared from a T parva-infected bovine lymphoblastoid cell line by fixing the cells in suspension with a mixture of acetone and formaldehyde. The antigen was stored in suspension in phosphate buffered saline for one and a half years at -60 degrees C without loss of activity; the antigen could also be lyophilised. The fluorescence of the intracellular schizonts was bright and specific with T parva positive bovine control serum and absent with negative bovine control serum and Theileria mutans positive bovine control serum. Fluorescence of the lymphoblastoid cell itself was observed with Trypanosoma brucei positive control serum and some bovine test sera: this fluorescence, which masked the intracellular schizonts, was eliminated by absorbing the sera in the supernatant of sonicated lymphocytes obtained from bovine lymph nodes. The antigen was evaluated with sera from cattle experimentally infected with T parva. In an epizootiological study on East Coast fever in the Coast Province of Kenya, there was good correlation between the serological responses of cattle to T parva schizont antigen and the distribution of Rhipicephalus appendiculatus ticks.