Absence of focal neurological involvement in tick-borne relapsing fever in northern Tanzania

The aim of the study was to chart incidence and clinical features of tick-borne relapsing fever in Tanzania. Consecutive patients with fever and spirochetes demonstrated in a thick blood smear at Haydom Lutheran Hospital from 1 January to 31 December 2003 underwent clinical and cerebrospinal fluid (CSF) examination. Forty-four patients were included, making an estimated minimum annual incidence of 11 per 100 000 population in this region. The mortality rate was 2.3% (95% CI = 0-12). The most frequent complaints were generalized malaise (93%), headache (86%), nausea and vomiting (52%). None of the patients [0% (95% CI = 0-8)] had focal neurological symptoms. Cell count in CSF was normal in 22 and slightly elevated (6-12 leukocytes/mm(3)) in 20 patients. Two of three pregnancies had a poor outcome. Jarisch-Herxheimer reactions, bleeding complications and ocular manifestations were infrequent. In conclusion, tick-borne relapsing fever is a common disease in the Northern highland of Tanzania, but in contrast to other parts of the world, neurological involvement is uncommon in this area.