Persistence of Rabies Virus-Neutralizing Antibodies after Vaccination of Rural Population following Vampire Bat Rabies Outbreak in Brazil.

BACKGROUND: Animal control measures in Latin America have decreased the incidence of urban human rabies transmitted by dogs and cats; currently most cases of human rabies are transmitted by bats. In 2004-2005, rabies outbreaks in populations living in rural Brazil prompted widespread vaccination of exposed and at-risk populations. More than 3,500 inhabitants of Augusto Correa (Pará State) received either post-exposure (PEP) or pre-exposure (PrEP) prophylaxis. This study evaluated the persistence of rabies virus-neutralizing antibodies (RVNA) annually for 4 years post-vaccination. The aim was to evaluate the impact of rabies PrEP and PEP in a population at risk living in a rural setting to help improve management of vampire bat exposure and provide additional data on the need for booster vaccination against rabies. METHODOLOGY/PRINCIPAL FINDINGS: This prospective study was conducted in 2007 through 2009 in a population previously vaccinated in 2005; study participants were followed-up annually. An RVNA titer >0.5 International Units (IU)/mL was chosen as the threshold of seroconversion. Participants with titers ≤0.5 IU/mL or Equivalent Units (EU)/mL at enrollment or at subsequent annual visits received booster doses of purified Vero cell rabies vaccine (PVRV). Adherence of the participants from this Amazonian community to the study protocol was excellent, with 428 of the 509 (84%) who attended the first interview in 2007 returning for the final visit in 2009. The long-term RVNA persistence was good, with 85-88.0% of the non-boosted participants evaluated at each yearly follow-up visit remaining seroconverted. Similar RVNA persistence profiles were observed in participants originally given PEP or PrEP in 2005, and the GMT of the study population remained >1 IU/mL 4 years after vaccination. At the end of the study, 51 subjects (11.9% of the interviewed population) had received at least one dose of booster since their vaccination in 2005. CONCLUSIONS/SIGNIFICANCE: This study and the events preceding it underscore the need for the health authorities in rabies enzootic countries to decide on the best strategies and timing for the introduction of routine rabies PrEP vaccination in affected areas.

Spatial distribution of envenomation by scorpions in Pará state, Brazil

Scorpionism is recognized by the World Health Organization as a neglected disease and, in Pará State, Brazil, it is considered a public health hazard. The objective of this study was to describe the spatial distribution of envenomation caused by scorpions in Pará. The data related to envenomation were collected from 2007 to 2014 and used for both descriptive and transversal studies. For those studies records obtained from ongoing investigations from the database of the National Notifiable Diseases Information System at the Public Health Department of Pará State were used. Envenomation occurs year round, most often in the first half of the year, in males from the countryside, aged 20 to 59 years and taking up to 3 hours to reach medical care. The deaths occurred from ages 15 to 59. Regarding the severity of the cases, class I cases were the most frequent and class III cases were the least frequent, accounting for only 5.1% of all cases. Of the 144 municipalities of Pará State, in 126 the frequency of envenomation ranged from 1 to 1,208 cases per municipality. Thirteen municipalities located in the lower Amazon region and in the southwest of Pará State presented higher occurences, including the highest number of deaths. Scorpionism is present throughout Pará State. However, there were differences in severity and incidence in the various regions, with higher frequency in the southwest of the State and in the lower Amazon region, corresponding to the Tapajós and Guyana endemic areas in the Brazilian Amazon.

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.

Bat-transmitted human rabies outbreaks, Brazilian Amazon.

We describe 2 bat-transmitted outbreaks in remote, rural areas of Portel and Viseu Municipalities, Pará State, northern Brazil. Central nervous system specimens were taken after patients' deaths and underwent immunofluorescent assay and histopathologic examination for rabies antigens; also, specimens were injected intracerebrally into suckling mice in an attempt to isolate the virus. Strains obtained were antigenically and genetically characterized. Twenty-one persons died due to paralytic rabies in the 2 municipalities. Ten rabies virus strains were isolated from human specimens; 2 other cases were diagnosed by histopathologic examination. Isolates were antigenically characterized as Desmodus rotundus variant 3 (AgV3). DNA sequencing of 6 strains showed that they were genetically close to D. rotundus-related strains isolated in Brazil. The genetic results were similar to those obtained by using monoclonal antibodies and support the conclusion that the isolates studied belong to the same rabies cycle, the virus variants found in the vampire bat D. rotundus.

Epidemiologia molecular do vírus da raiva no estado do Pará no período de 2000 a 2005: emergência e transmissão por morcegos hematófagos (Desmodus rotundus) / Molecular epidemiology of rabies virus in Para state during 2000 to 2005: emergence and transmission by hematophagous bats (Desmodus rotundus)

A ocorrência recente de surtos de raiva humana transmitida por morcegos hematófagos Desmodus rotundus vem sendo registrada no Estado do Pará desde 2004. Neste artigo, é realizado um estudo retrospectivo de caracterização genética de 37 cepas do vírus rábico de diferentes mamíferos, incluindo o homem, isoladas de 2000 a 2005, de diferentes regiões paraenses. Foi obtido o sequenciamento nucleotídico parcial do gene N e construída árvore filogenética baseada no método Neighbor-joining. A análise filogenética determinou a formação de cinco clades principais e agrupou as cepas isoladas no Estado do Pará em três distintas clades: clade I, cepas da variante antigênica 3 (VAg3), comumente encontrada nos morcegos D. rotundus; clade II, cepa relacionada à VAg3, porém com topologia diferenciada isolada de morcego frugívoro Uroderma bilobatum; e clade IV, cepas da variante antigênica 2 (VAg2), comumente isoladas de cães domésticos. No Pará, no período estudado, circularam as variantes VAg2 e VAg3. A VAg3 da clade I se encontra subdividida em três linhagens virais (I-a, I-b, e I-c) associadas à distribuição geográfica: duas delas (I-a e I-b) circulam no continente nas regiões paraenses do Sudeste, Nordeste e Baixo Amazonas, enquanto a linhagem I-c restringe-se à ilha do Marajó. A associação dos dados genéticos com os ecológicos fornece uma melhor compreensão da epidemiologia molecular da raiva no Estado do Pará e sugere que duas distintas variantes antigênicas isoladas do vírus da raiva foram associadas com a transmissão da doença por morcegos hematófagos entre 2000 e 2005. Finalmente, foi demonstrado neste estudo a presença de pelo menos três distintas linhagens genéticas de VAg3 no estado, e a emergência de uma possível nova variante, que foi isolada de um morcego frugívoro U. bilobatum capturado na localidade de Ajará, município de Portel, durante o surto ocorrido em 2004.