NOTA RESEARCH NOTE 1531 Common vampire bat attacks on humans in a village of the Amazon region of Brazil Agressões de morcegos hematófagos a pessoas em um povoado da região amazônica do Brasil Maria Cristina Schneider 1 Joan Aron 2 Carlos Santos-Burgoa 3 Wilson Uieda 4 Sílvia Ruiz-Velazco 5 1 Pan American Health Abstract Many people in Amazonian communities have reported bat bites in the last decade. Organization. Bites by vampire bats can potentially transmit rabies to humans. The objective of this study was 525 23rd Street NW, Washington, DC to analyze factors associated with bat biting in one of these communities. A cross-sectional sur- 20037-2895, U.S.A. vey was conducted in a village of gold miners in the Amazonian region of Brazil (160 inhabi- 2 Science Communication tants). Bats were captured near people’s houses and sent to a lab. Of 129 people interviewed, 41% Studies. 5457 Marsh Hawk Way, Columbia, had been attacked by a bat at least once, with 92% of the bites located on the lower limbs. A lo- MD 21045, U.S.A. gistic regression found that adults were bitten around four times more often than children (OR = 3 Instituto de Salud 3.75, CI 95%: 1.46-9.62, p = 0.036). Males were bitten more frequently than females (OR = 2.08, CI Ambiente y Trabajo. Cerrada del Convento 48-A, 95%: 0.90-4.76, p = 0.067). Nine Desmodus rotundus and three frugivorous bats were captured Tlalpan, DF 14420, México. and tested negative for rabies. The study suggests that, in an area of gold miners, common vam- 4 Departamento de Zoologia, pire bats are more likely to attack adults and males. The control strategy for human rabies devel- Instituto de Biociências, Universidade Estadual oped in this region should therefore place special emphasis on adult males. There should also be Paulista. Botucatu, SP more research on how the search for gold in the Amazonian region places people and the envi- 18618-000, Brasil. 5 Universidad Nacional ronment at risk. Autonóma de México. Key words Agression; Chiroptera; Desmodus rotundus Edificio del IIMAS, Ciudad Universitaria, México, DF 045190, México. Resumo Agressões de morcegos a pessoas vêm sendo notificadas em várias comunidades ama- zônicas nesta última década. Isto constitui um risco potencial para a raiva humana transmitida por morcegos. O objetivo deste estudo foi de analisar fatores associados a estas agressões em uma destas comunidades. Foi realizado um estudo transversal em um povoado de garimpeiros na Região Amazônica brasileira (160 habitantes). Foi realizada a captura de morcegos junto às casas e foram enviadas amostras para o laboratório. Das 129 pessoas entrevistas, 41% foram agredidas por morcegos pelo menos uma vez, com 92% das mordidas localizadas nos dedos dos pés. Por meio de regressão logística, encontrou-se que adultos eram agredidos ao redor de quatro vezes mais do que crianças (OR = 3,75, IC: 1,46-9,62, p = 0,036). Homens foram agredidos com maior freqüência do que mulheres (OR = 2,08, IC: 0,90-4,76, p = 0,067). Nove Desmodus rotun- dus e três morcegos frugívoros foram capturados e resultaram negativos para a raiva. O estudo sugere que, em áreas de garimpo, adultos do sexo masculino têm maior probabilidade de serem agredidos por morcegos. As ações de controle para a raiva humana a serem desenvolvidas nestes lugares devem dar ênfase especial a adultos homens. Recomendam-se mais investigações sobre o modo como o garimpo na Região Amazônica está colocando em risco as pessoas e o ambiente. Palavras-chave Agressão; Quirópteros; Desmodus rotundus Cad. Saúde Pública, Rio de Janeiro, 17(6):1531-1536, nov-dez, 2001 1532 SCHNEIDER, M. C. et al. Introduction the area had been slaughtered (MacCarthy, 1989). Gold prospectors in Roraima, Brazil, are The very first settlers of the Americas reported frequently attacked by bats (Uieda et al., 1996). incidents of bats attacking people and cases of A series of attacks in a village in a rural area of human rabies transmitted by these animals in Brazil was ascribed to both local environmen- the early 16th century (Baer, 1982). Hemato- tal changes and a topical pesticide applied to phagous bats inhabit a territory ranging from cattle (Costa et al., 1993). Although there are re- the North of Mexico to the North of Argentina ports of bats attacking people in various coun- (Lord et al., 1975). There are three species of tries, the extent of the problem and its associ- bats that feed on blood: Diphylla ecaudata, Di- ated risk factors are not known. aemus youngi, and Desmodus rotundus (Uieda, This paper examines factors associated 1989). The latter species, also known as the with high incidence of vampire bat attacks on common vampire, specializes in bleeding mam- humans, identifying a potentially high risk for mals and is probably responsible for attacks on human rabies. people (Greenhall, 1988). Bats can transmit various diseases to hu- mans, such as arbovirus diseases (Tamsitt & Methods and materials Valdivieso, 1970), histoplasmosis and try- panosomiasis (Constantine, 1988), leptospiro- A cross-sectional study was conducted in the sis, rickettsiosis, and cryptococcosis (Tamsitt & village of Mina Nova on the island of Aurizona, Valdivieso, 1970), and brucellosis, salmonello- in the county of Godofredo Viana, located in sis, and candidiasis (Constantine, 1988). How- the extreme northern region of Maranhão State, ever, the most serious disease that can be part of the Amazon region of Brazil (01o16’ 18” transmitted by bats is rabies. This disease has S and 45o 46’ 0” W). On this 225km2 island caused numerous deaths in Latin America over there are some 20 garimpos de barranco (exten- the last several decades, where the bat has sive areas with labor-intensive surface mining been identified as the second most important of gold) as well as hundreds of individual gold animal species in the transmission of rabies to prospectors. Aurizona has extensive gold de- humans (INPPAZ, 1997). posits that have been exploited for several The first outbreak of human rabies trans- decades. The vegetation consists of mangrove mitted by hematophagous bats reported in the thickets interrupted by extended barren areas scientific literature took place in Trinidad in where the vegetation has been destroyed by the the 1930s, when 55 people died (Verteuil & search for gold. Most inhabitants of Mina Nova Urich, 1935). From the 1930s until the present were gold prospectors and their wives and chil- approximately one thousand deaths attributed dren. In the period leading up to the study, the to vampire-transmitted rabies have been re- village had experienced attacks by vampire ported, and this number is probably an under- bats but no case of human rabies had been re- estimate (Alvarez, 1997). The countries that re- ported. Visits were conducted to all houses oc- ported the most cases between 1990 and 1995 cupied by people at the time of the interviews were Peru (78) and Brazil (43) (Alvarez, 1997). (87.5% of the total). One hundred twenty-nine Cases of rabies transmitted by vampire bats oc- people (total population = 160) were inter- curred mostly in areas with difficult access in viewed, either directly or by proxy in the case the Amazon region of these countries (Schnei- of children or absent family members (35%). der & Santos-Burgoa, 1995). The survey requested information about the There are various reports of vampire bats dwelling and the individuals in the household. attacking humans without the attack being fol- Data included type of construction, number of lowed by rabies. This obviously depends on individuals per house, presence of domestic how widespread the virus is in the area. Some animals, and whether these animals had been of these attacks have taken place among in- bitten by bats (as reported by the respondent). digenous populations, such as the Yanomami Individual data included gender, age, profes- in Venezuela in 1979 (Almansa & Garcia, 1980). sion, time of residence in the village, sleeping Note that in the latter case deforestation had quarters, time and frequency of bat attacks, lo- taken place in the area as a result of lumbering cation of the last bite, type of protection used, and gold prospecting; it was also reported that immunization status, treatment preference, the poultry being raised in those communities and knowledge concerning rabies. Bats were had been rapidly exterminated before the at- also captured at night to determine whether tacks started. In 1975, a series of attacks on the rabies virus was circulating in the area people was reported in Belize after the swine in (Schneider et al., 1996). Cad. Saúde Pública, Rio de Janeiro, 17(6):1531-1536, nov-dez, 2001 COMMON VAMPIRE BAT ATTACKS ON HUMANS 1533 For the bivariate analysis, the fact of ever and the average residence time in Mina Nova having been attacked by bats in Mina Nova was was 2.7 years. Forty percent of the households considered a yes/no factor, where “yes” and raised pigs and several of them also raised oth- “no” are analogous to cases and controls in a er animals such as poultry and goats. These an- case-control study. This variable was cross-tab- imals are a common feeding source for D. ro- ulated one by one with possible explanatory tundus (Greenhall, 1988). It was reported that (or “exposure”) variables in order to estimate 66.7% of these animals had been attacked by an odds ratio (OR) (ratio of exposure odds bats. Seventy-one percent of the question- among cases to exposure odds among controls) naires obtained were from adults (over 14 years and to apply Fisher’s one-tailed exact test. For of age) and 65.9% were men, most of whom each possible explanatory variable, these two were gold prospectors (98%).