Rabies Virus in Bats, State of Pará, Brazil, 2005-2011.

Rabies is an acute, progressive zoonotic viral infection that in general produces a fatal outcome. This disease is responsible for deaths in humans and animals worldwide and, because it can affect all mammals, is considered one of the most important viral infections for public health. This study aimed to determine the prevalence of rabies in bats of different species found in municipalities of the state of Pará from 2005 to 2011. The rabies virus was detected in 12 (0.39%) bats in a total of 3100 analyzed, including hematophagous, frugivorous, and insectivorous bats. Of these, eleven were characterized as AgV3, which is characteristic of the hematophagous bat Desmodus rotundus (E. Geoffroy 1810); one insectivorous animal showed a different profile compatible with the Eptesicus pattern and may therefore be a new antigenic variant. This study identified the need for greater intensification of epidemiological surveillance in municipalities lacking rabies surveillance (silent areas); studies of rabies virus in bats with different alimentary habits, studies investigating the prevalence of AgV3, and prophylactic measures in areas where humans may be infected are also needed.

VIROLOGICAL AND SEROLOGICAL DIAGNOSIS OF RABIES IN BATS FROM AN URBAN AREA IN THE BRAZILIAN AMAZON / Diagnóstico virológico e sorológico de raiva em morcegos de uma área urbana na Amazônia Brasileira

The outbreaks of rabies in humans transmitted by Desmodus rotundus in 2004 and 2005, in the northeast of the Brazilian State of Para, eastern Amazon basin, made this a priority area for studies on this zoonosis. Given this, the present study provides data on this phenomenon in an urban context, in order to assess the possible circulation of the classic rabies virus (RABV) among bat species in Capanema, a town in the Amazon basin. Bats were collected, in 2011, with mist nets during the wet and dry seasons. Samples of brain tissue and blood were collected for virological and serological survey, respectively. None of the 153 brain tissue samples analyzed tested positive for RABV infection, but 50.34% (95% CI: 45.67-55.01%) of the serum samples analyzed were seropositive. Artibeus planirostris was the most common species, with a high percentage of seropositive individuals (52.46%, 95% CI: 52.31 52.60%). Statistically, equal proportions of seropositive results were obtained in the rainy and dry seasons (c2 = 0.057, d.f. = 1, p = 0.88). Significantly higher proportions of males (55.96%, 95% CI: 48.96-62.96%) and adults (52.37%, 95% CI: 47.35-57.39%) were seropositive. While none of the brain tissue samples tested positive for infection, the high proportion of seropositive specimens indicates that RABV may be widespread in this urban area.

Os surtos de raiva em humanos transmitida por Desmodus rotundus em 2004 e 2005 no nordeste do estado do Pará, Brasil, Amazônia Oriental, fizeram desta uma área prioritária para estudos sobre essa zoonose. Diante disso, o presente estudo fornece dados sobre esse fenômeno em contexto urbano, afim de avaliar uma possível circulação do vírus clássico da raiva (RABV) entre espécies de morcegos em Capanema, cidade localizada na bacia Amazônica. Os morcegos foram coletados em 2011, com auxílio de redes de espera durante as estações seca e chuvosa. Amostras de encéfalo e de sangue foram coletadas para o diagnóstico virológico e sorológico, respectivamente. Das 153 amostras de encéfalo analisadas, nenhuma encontrou-se positiva para infecção pelo RABV, porém, 50,34% (95% CI: 45,67-55,01) das amostras de soro analisadas estavam soropositivas. Artibeus planirostris foi a espécie mais comum, e seu percentual de indivíduos soropositivos foi bem elevado (52.46%, 95% CI: 52,31-52,60). Porções estatisticamente iguais de soropositivos foram registrados nas estações (c2 = 0,057, d.f. = 1, p = 0,88). Uma porção significativamente elevada de machos (55,96%, 95% CI: 48,96%-62,96%), e adultos (52,37%, 95% CI: 47,35%-57,39%) foram soropositivos. Apesar de nenhuma das amostras de encéfalo terem sido positivas para raiva, a alta proporção de espécimes soropositivos indica uma possível circulação do RABV nessa área urbana.

VIROLOGICAL AND SEROLOGICAL DIAGNOSIS OF RABIES IN BATS FROM AN URBAN AREA IN THE BRAZILIAN AMAZON.

The outbreaks of rabies in humans transmitted by Desmodus rotundus in 2004 and 2005, in the northeast of the Brazilian State of Para, eastern Amazon basin, made this a priority area for studies on this zoonosis. Given this, the present study provides data on this phenomenon in an urban context, in order to assess the possible circulation of the classic rabies virus (RABV) among bat species in Capanema, a town in the Amazon basin. Bats were collected, in 2011, with mist nets during the wet and dry seasons. Samples of brain tissue and blood were collected for virological and serological survey, respectively. None of the 153 brain tissue samples analyzed tested positive for RABV infection, but 50.34% (95% CI: 45.67-55.01%) of the serum samples analyzed were seropositive. Artibeus planirostris was the most common species, with a high percentage of seropositive individuals (52.46%, 95% CI: 52.31 52.60%). Statistically, equal proportions of seropositive results were obtained in the rainy and dry seasons (c2 = 0.057, d.f. = 1, p = 0.88). Significantly higher proportions of males (55.96%, 95% CI: 48.96-62.96%) and adults (52.37%, 95% CI: 47.35-57.39%) were seropositive. While none of the brain tissue samples tested positive for infection, the high proportion of seropositive specimens indicates that RABV may be widespread in this urban area.

Molecular epidemiology of rabies virus isolated from different sources during a bat-transmitted human outbreak occurring in Augusto Correa municipality, Brazilian Amazon.

We genetically characterize rabies virus (RABV) strains isolated from human cases, domestic and wild animals during a human outbreak of bat-transmitted rabies in Augusto Correa municipality, Pará state, Brazilian Amazon in 2005. Partial nucleotide sequences of the N gene (491 bp) were obtained for all strains, and phylogenetic analysis grouped these into two major clades (Pará and Central-Southeast) and identified them as bat-related viruses genotype I, Desmodus rotundus antigenic variant 3 (AgV3). A molecular clock was used to estimate the time of emergence for each RABV isolate. The molecular data from this study suggest the association of vampire bats with human and domestic animal cases reported in the outbreak, the circulation of at least two predominant lineages in the Pará state, and also a geographic association to lineages dispersion.