Transient infections of goats with a novel spotted fever group rickettsia from Zimbabwe.

A novel spotted fever group rickettsia has recently been isolated from Amblyomma hebraeum ticks in Zimbabwe. In a survey of 172 goat sera collected throughout Zimbabwe the highest prevalence of antibodies reactive with this rickettsia was in the south of the country, the area where A hebraeum is most commonly found. Nine goats were infected using male and female A hebraeum taken from a tick line shown to be infected with the novel rickettsia. By week 3 after infection, seroconversion occurred in all nine goats but no clinical signs of disease could be detected. A leucocytosis due to a mature neutrophilia one to two weeks after infection was the only abnormality. Rickettsaemia was detected only on day 3 after exposure to infected ticks. Immunosuppression failed to induce recrudescence of the rickettsaemia.