Common vampire bat attacks on humans in a village of the Amazon region of Brazil

NOTA RESEARCH NOTE 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 Organization. 525 23 rd Street NW, Washington, DC 20037-2895, U.S.A. 2 Science Communication Studies. 5457 Marsh Hawk Way, Columbia, MD 21045, U.S.A. 3 Instituto de Salud Ambiente y Trabajo. Cerrada del Convento 48-A, Tlalpan, DF 14420, México. 4 Departamento de Zoologia, Instituto de Biociências, Universidade Estadual Paulista. Botucatu, SP 18618-000, Brasil. 5 Universidad Nacional Autonóma de México. Edificio del IIMAS, Ciudad Universitaria, México, DF 045190, México. Abstract Many people in Amazonian communities have reported bat bites in the last decade. Bites by vampire bats can potentially transmit rabies to humans. The objective of this study was to analyze factors associated with bat biting in one of these communities. A cross-sectional survey was conducted in a village of gold miners in the Amazonian region of Brazil (160 inhabitants). Bats were captured near people’s houses and sent to a lab. Of 129 people interviewed, 41% had been attacked by a bat at least once, with 92% of the bites located on the lower limbs. A logistic regression found that adults were bitten around four times more often than children (OR = 3.75, CI 95%: 1.46-9.62, p = 0.036). Males were bitten more frequently than females (OR = 2.08, CI 95%: 0.90-4.76, p = 0.067). Nine Desmodus rotundus and three frugivorous bats were captured and tested negative for rabies. The study suggests that, in an area of gold miners, common vampire bats are more likely to attack adults and males. The control strategy for human rabies developed in this region should therefore place special emphasis on adult males. There should also be more research on how the search for gold in the Amazonian region places people and the environment at risk. Key words Agression; Chiroptera; Desmodus rotundus Resumo Agressões de morcegos a pessoas vêm sendo notificadas em várias comunidades amazônicas 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 rotundus 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 1531 1532 SCHNEIDER, M. C. et al. Introduction The very first settlers of the Americas reported incidents of bats attacking people and cases of human rabies transmitted by these animals in the early 16th century (Baer, 1982). Hematophagous bats inhabit a territory ranging from the North of Mexico to the North of Argentina (Lord et al., 1975). There are three species of bats that feed on blood: Diphylla ecaudata, Diaemus youngi, and Desmodus rotundus (Uieda, 1989). The latter species, also known as the common vampire, specializes in bleeding mammals and is probably responsible for attacks on people (Greenhall, 1988). Bats can transmit various diseases to humans, such as arbovirus diseases ( Tamsitt & Valdivieso, 1970), histoplasmosis and trypanosomiasis (Constantine, 1988), leptospirosis, rickettsiosis, and cryptococcosis (Tamsitt & Valdivieso, 1970), and brucellosis, salmonellosis, and candidiasis (Constantine, 1988). However, the most serious disease that can be transmitted by bats is rabies. This disease has caused numerous deaths in Latin America over the last several decades, where the bat has been identified as the second most important animal species in the transmission of rabies to humans (INPPAZ, 1997). The first outbreak of human rabies transmitted by hematophagous bats reported in the scientific literature took place in Trinidad in the 1930s, when 55 people died ( Verteuil & Urich, 1935). From the 1930s until the present approximately one thousand deaths attributed to vampire-transmitted rabies have been reported, and this number is probably an underestimate (Alvarez, 1997). The countries that reported the most cases between 1990 and 1995 were Peru (78) and Brazil (43) (Alvarez, 1997). Cases of rabies transmitted by vampire bats occurred mostly in areas with difficult access in the Amazon region of these countries (Schneider & Santos-Burgoa, 1995). There are various reports of vampire bats attacking humans without the attack being followed by rabies. This obviously depends on how widespread the virus is in the area. Some of these attacks have taken place among indigenous populations, such as the Yanomami in Venezuela in 1979 (Almansa & Garcia, 1980). Note that in the latter case deforestation had taken place in the area as a result of lumbering and gold prospecting; it was also reported that the poultry being raised in those communities had been rapidly exterminated before the attacks started. In 1975, a series of attacks on people was reported in Belize after the swine in Cad. Saúde Pública, Rio de Janeiro, 17(6):1531-1536, nov-dez, 2001 the area had been slaughtered (MacCarthy, 1989). Gold prospectors in Roraima, Brazil, are frequently attacked by bats (Uieda et al., 1996). A series of attacks in a village in a rural area of Brazil was ascribed to both local environmental changes and a topical pesticide applied to cattle (Costa et al., 1993). Although there are reports of bats attacking people in various countries, the extent of the problem and its associated risk factors are not known. This paper examines factors associated with high incidence of vampire bat attacks on humans, identifying a potentially high risk for human rabies. Methods and materials A cross-sectional study was conducted in the village of Mina Nova on the island of Aurizona, in the county of Godofredo Viana, located in the extreme northern region of Mara (...truncated)