. ~ Comparison of Black Fly Species (Diptera: Simuliidae) on an Amerindian Reservation with a High Prevalence of Fogo Selvagem to Neighboring Disease-Free Sites in the State of Mato Grossodo SuI, Brazil DONALD P. EATON! LUIS A. DIAZ,2GUNTER HANS-FILHO,3 VANDIR DOS SANTOS,4 VALERIAAOKI,5 HORACIO FRIEDMAN,5 EVANDRO A. RMTTI,4 SEBASTIAO A. P. SAMPAIO,5 MARK S. GOTTLIEB,7 GEORGE J. GIUDICE,2 ARGELIALOPEZ,2 EPDIE W. CUff,s AND THE COOPERATIVE GROUP ONFOGO SELVAGEM RESEARCH J. Med. Entomol. 35(2): 120-131 (1998) ABSTRACT Fogo selvagem is an autoimmune blistering skin disease that principally occurs among rural Brazilians living in geographically clumped disease foci. Exposure tohematopha- gous black Hies possibly is related to the cause of the disease. We compared the occurrence, proportions, andrichness of simuliid species immatures andthe biting activity of adult females within a recentlydiscovered, high prevalence focus of fogoselvagem, the LimaoVerde Terena Reservation, to that of neighboring regions with no reported cases of fogoselvagem. Nine black fly species were collectedfrom 12stream sitesduring 5 trips to the fogo selvagem focus. The species showed longitudinal (upstream-downstream) trends in occurrence, proportions, and richness, and the abundance of simuliid immatures was greater at downstream sites. The most prevalentspecies at the focus,Simulium nigrimanum (Macquart), dominated the stream sites with highly abundant simuliid assemblages, andwas the mostcommon blackHy in human bait collections. This species was absent or in very low numbers in neighboring valleys and villages that did not havecases of fogo selvagem. KEY WORDS Simulium nigrimanum,Simuliidae, fogo selvagem, Amerindians, Brazil ENDEMIC PEMPHIGUS FOlJACEUS, also known as fogo Of the many plausible environmental factors, the selvagem,is a potentially fatal autoimmune disease presence of anthropophagic black flies near disease with a unique epidemiology (Diaz et al. 1989a, b). foci has been discussed most often in the fogo sel- Most caseshave been reported from Brazil among vagemliterature (Aranha-Campos 1942; Vieira 1940, poor, outdoor laborers in geographically distinct 1948; Diaz et al. 1989a). During the historical peak regions or foci. The historical distribution of these of reported fogo selvagem casesin the state of Sao foci has shifted over the past 50 yrfrom southeastern Paulo, Lane (1950) collected black flies and showed to central and midwestern Brazil (Diaz et al.1989a). that Simulium nigrimanum (Macquart) was abun- This geographical clustering and temporal shifting dant near fogo selvagem foci, but absent from the of focal locations has led investigators to the hy- coastal region of the state where fogo selvagem pothesisthat an environmental factor(s) associated rarely had been reported. More recently, Lombardi with the foci is related to the cause(s) of fogo et al. (1992) showed that outdoor laborers exposed selvagem. to black fly bites were more likely to develop fogo selvagemthan those not exposed,with an odds ratio 1Program in Ecology, Evolution, and Conservation Biology, Uni- of 4.7. versity of Nevada-Reno, NV. Based on these observations and as part of the . Departments ofDermatology and Biochemistry and the Vet- .. .. fh .' I ff I erans AffairsMedical Center, Medical College of Wisconsin Mil- ongoIng Investigation 0 t e etio ogy 0 ogo se va- waukee, WI 53226. ' gem, the Cooperative Group on Fogo Selvagem Re- aDepartmento de Dermatologia, Universidade Federal de Mato search began a study of the black flies at fogo sel- Grosso do Sui,Brazil. vagem foci in regions of Brazil where the disease was . Secretaria de Estado de Saude do Mato Grosso do Sui, Brazil. h. . all ' I al h I 5 Departamento de Dermatologia Universidade de Sio Paulo Istonc y or IS current y most prevent. T e goa Brazil. ' , of the study was to examine the distribution and 6Departmentos de Patologia, Morfologia e Geneticas, Univer- biting activity of species near foci and in regions sidade de Brasilia, Brazil. without the disease and to determine whether par- 7Department of Family and Community Medicine and the . I . ' h .. f h r. HealthPolicy Institute,Medical College of Wisconsin, Milwaukee, ticu ar specIes were c aractenstic 0 t e rOCI. Here, WI. we present the results of a black fly survey from one 8Department of Entomology, AuburnUniversity, Auburn,AL. recently characterized focus of fogo selvagem with