Rickettsia africae is a parasitic species of bacteria that causes African tick-bite fever, or ATBF. It is found in sub-Saharan Africa and in some islands of the French West Indies. ATBF, also called tick typhus, is transmitted to humans by ticks of the genus Amblyomma that are often found on ungulates, or hooved animals. The majority of cases of ATBF are in clusters of travelers that are exposed to ticks during safaris or game hunting expeditions. A report in the journal "Clinical Infectious Diseases" estimates that the incidence of ATBF in safari travelers is between 4 and 5.3 percent.
Symptoms
ATBF is characterized by acute flu-like symptoms, such as fever, headache and muscle pain. The study in, "Clinical Infectious Diseases" reported that in travelers that were infected with Rickettsia africae, 80 percent exhibited flu-like symptoms and less than 50 percent displayed lymph node enlargement, skin rashes, canker sores and/or eschars, which are lesions at the site of the tick bite that contain dead, blackened tissue. Symptoms emerge one to two weeks after being bitten by an infected tick. The Florida Health Department noted that complications are rare, and no ATBF deaths have ever been reported.
Risk Factors
The risk factors for ATBF are travel to southern Africa, especially in the countries of South Africa, Botswana and Zimbabwe during November through April. The majority of case reports of ATBF are found in clusters of travelers who have been involved in hunting, backpacking or ecotourism activities.
Detection
The U.S. Centers for Disease Control and Prevention, or CDC, reports that no commercially available test for ATBF exists, but kits that utilize antibodies to detect the Rickettsia tick, which causes spotted fever, also will detect Rickettsia africae.
Treatment
The CDC says treatment with broad-spectrum antibiotics tetracyclines or fluoroquinolones have been effective in reducing symptoms in infected travelers.
Prevention
The CDC says topical repellants are not effective in preventing exposure to Rickettsia africae because ticks often bite portions of the body that have not been treated. The CDC recommends treating clothing with synthetic pyrethroid insecticide in addition to using a topical repellant. No vaccines are available to prevent ATBF.
