Review Article: Relapsing Fever Borreliae in Africa

The study of relapsing fever borreliae in Africa has long suffered from the use of non-specific laboratory tools for the direct detection of these spirochetes in clinical and vector specimens. Accordingly, Borrelia hispanica, Borrelia crocidurae, Borrelia duttonii, and Borrelia recurrentis have traditionally been distinguished on the basis of geography and vector and the unproven hypothesis that each species was exclusive to one vector. The recent sequencing of three relapsing fever Borrelia genomes in our laboratory prompted the development of more specific tools and a reappraisal of the epidemiology in Africa. Five additional potential species still need to be cultured from clinical and vector sources in East Africa to further assess their uniqueness. Here, we review the molecular evidence of relapsing fever borreliae in hosts and ectoparasites in Africa and explore the diversity, geographical distribution, and vector association of these pathogens for Africans and travelers to Africa. periods. For the louse-borne B. recurrentis, fever is accompa- nied in more than 90% of patients by tachycardia, headache, myalgia, and arthralgia and is less frequently accompanied by hepatosplenomegaly, epistaxis, petechial rash, and jaundice. For the tick-borne B. crocidurae, the disease is characterized by a fever, asthenia, and vomiting in some patients. Most infected patients experience 1 to 2 relapses; however, up to eight relapses have been observed. The clinical signs and den- sity of Borrelia are not affected by the age or sex of the patient. Immunity after infection is not permanent and patients may be newly infected as soon as 6 months after recovery. However, no deaths from borreliae were recorded in Senegal over a period of 14 years. 20 In this country, 0.9% of 1,340 children were smear positive, 21 and real-time PCR for the 16S rRNA Borrelia gene detected borreliae in 27 (13%) of 206 samples from febrile patients in rural Senegal. 22 The clinical features of B. duttonii infection have been well studied in Tanzania, in which the total mortality rate of the disease is ~2.3%. 23 Symptoms of this path- ogen include fever, which is accompanied in more than 90% of cases by tachycardia, headache, myalgia, arthralgia, conjunctivi- tis, hepatomegaly, and splenomegaly, along with orange urine in a few cases. 24 In Tanzania, investigators found a perinatal mortality caused by B. duttonii of 436/1,000 births. 25 In North Africa, B. hispanica causes 20.5% of unexplained fever cases in Northwestern Morocco. 26