Short Report: Dengue Virus in Bats from Southeastern Mexico

To identify the relationship between landscape use and dengue virus (DENV) occurrence in bats, we investigated the presence of DENV from anthropogenically changed and unaltered landscapes in two Biosphere Reserves: Calakmul (Campeche) and Montes Azules (Chiapas) in southern Mexico. Spleen samples of 146 bats, belonging to 16 species, were tested for four DENV serotypes with standard reverse transcriptase polymerase chain reaction (RT-PCR) protocols. Six bats (4.1%) tested positive for DENV-2: four bats in Calakmul (two Glossophaga soricina, one Artibeus jamaicensis, and one A. lituratus) and two bats in Montes Azules (both A. lituratus). No effect of anthropogenic disturbance on the occurrence of DENV was detected; however, all three RT-PCR–positive bat species are considered abundant species in the Neotropics and well-adapted to disturbed habitats. To our knowledge, this study is the first study conducted in southeastern Mexico to identify DENV-2 in bats by a widely accepted RT-PCR protocol. The role that bats play on DENV’s ecology remains undetermined. Dengue fever is an important public health concern in the tropics, and ecological and epidemiological studies are needed to assess the role of bats and other mammals in a possible sylvatic maintenance cycle. Dengue viruses (DENVs) comprise four antigenically distinct but genetically related serotypes of the Flavivirus genus (Flaviviridae family). DENVs are positive-sense single-stranded RNA viruses that cause one of the most common infectious diseases in humans in tropical regions. Their transmission includes an urban endemic/epidemic cycle between Aedes aegypti mosquitoes and humans as the reservoir host and a sylvatic enzootic cycle between non-human primates and arboreal mosquitoes of the genus Aedes. The urban cycle is well-documented in the Neotropics, with four serotypes reported in urban areas, whereas the sylvatic cycle has been shown in West Africa and peninsular Malaysia. Thus far, the sylvatic cycle has not been described in the Neotropics. However, in Bolivia, DENV seroconversions among the indigenous Ayoreo people were found in a remote area where Ae. aegypti, the primary vector, was absent. This finding suggests a possible sylvatic cycle involving a different mosquito species or cross-reaction with antibodies to another flavivirus. In French Guiana, all four DENV serotypes have been identified by molecular methods in 92 wild mammals (bats, rodents, and marsupials) in all settings investigated: periurban, rural, and sparsely populated areas. This finding suggests that primarily urban DENV strains could infect wildlife in non-urban forested areas. The role of wildlife in DENV transmission remains unknown. Bats are important reservoirs of many viruses, such as rabies viruses, Nipah viruses, and coronaviruses. Flaviviridae are the second most frequently reported viral family in the order Chiroptera (13% frequency; second only to rhabdoviruses); however, their role in the dynamics of DENVs remains poorly understood. DENV have been reported in large frugivorous bats (Pteropus genus) in Australia. More recently, polymerase chain reaction (PCR) and antigen detection (direct immunofluorescent assay) of DENV were described in bats from DENV-endemic islands in China. Seroconversion in bats (DENV-1, -2, and -3) has been reported in urban areas in Costa Rica and Ecuador. Bats captured during a dengue fever outbreak along the Gulf and Pacific Coasts of Mexico were found to beDENV-seropositive (enzyme-linked immunosorbent assay [ELISA]), have DENV NS1 protein, and be positive on reverse transcriptase (RT) -PCR for DENV-2. Molecular evidence of DENV-1, -2, and -3 in bats from French Guiana was reported, including a phylogenetic sequence from a Carollia perspicillata bat consistent with DENV-1. Qualitative detection of the NS1 antigen of DENVs in bat serum samples and plaque reduction neutralization tests has been reported in bats from southeasternMexico from disturbed sites near human settlements in Campeche (S. Cabrera-Romo and others, unpublished data) and Mérida, which is the largest city in the Yucatan Peninsula. In this study, samples were collected from bats trapped in two biosphere reserves located in southeastern Mexico. High bat diversity and large tracts of continuous forest characterize these areas. Additionally, DENV-1, -2, and -4 have been reported in human populations. The aim of this study was to show the presence of DENV serotypes in bats within the biosphere reserves and adjacent areas with anthropogenic changes using RT-PCR. Bats were collected in Montes Azules Biosphere Reserve (Chiapas; 16 °9¢462 N, 90 °41¢182 W) and Calakmul Biosphere Reserve (Campeche; 18°26¢12 N, 89°36¢612 W) from two landscape types categorized as undisturbed forest (UD), comprised of primary forest with no human disturbance, and disturbed forest (D), defined as a transitional zone between primary forest and agricultural/ livestock areas or human settlements. In both regions, the sites were located at least 20 km from significant human populations where dengue has been reported (Xpujil in Campeche State and Benemérito de la Américas in Chiapas State). Bats were *Address correspondence to Jesús Sotomayor-Bonilla, Universidad 3000, Colonia Ciudad Universitaria, México, Distrito Federal, Mexico 03310. E-mail: [email protected]