Onchocerciasis in an expatriate living in Cameroon.
Travelers to West, central and eastern Africa as well as to selected areas of Latin America are at risk for infection with Onchocerca volvulus. Infection with this tissue nematode may cause chorioretinitis and keratitis, and it is responsible in endemic areas for blindness in millions.1 In addition to ocular manifestations, it can produce a distressing pruriginous dermatitis or subcutaneous nodules. Clinical manifestations vary according to the parasitic load, previous immunity, and duration of infection.1 Infection is initiated by inoculation with larvae during the bite of the Simulium black fly. Once in the connective tissue, larvae mature to filiform adults and may remain in tissues for years, with the clinical manifestations being produced by the inflammatory reaction to dying parasites. Female adults produce large amounts of microfilaria that migrate through skin and connective tissue; once an infected host is bitten, the infectious larvae develop again in the female Simulium black fly and the life cycle is completed. Transmission is from person to person, and may occur even after a relatively short exposure.2 Although infection of travelers with O. volvulus is rare, according to the Centers for Disease Control and Prevention, 46 new cases of onchocerciasis were diagnosed in the United States in 1994 (Dr. David Addis, personal communication, June 1996). We describe the case of an expatriate who became infected with O. volvulus and we review the treatment and recommendations for prevention of this parasitic infection.
Okhuysen
PC
The University of Texas-Houston, Health Science Center, Division of Infectious Diseases, Houston, Texas.