RESUMO
Madariaga virus (MADV) has recently been associated with severe human disease in Panama, where the closely related Venezuelan equine encephalitis virus (VEEV) also circulates. In June 2017, a fatal MADV infection was confirmed in a community of Darien Province. We conducted a cross-sectional outbreak investigation with human and mosquito collections in July 2017, where sera were tested for alphavirus antibodies and viral RNA. In addition, by applying a catalytic, force-of-infection (FOI) statistical model to two serosurveys from Darien Province in 2012 and 2017, we investigated whether endemic or epidemic alphavirus transmission occurred historically. In 2017, MADV and VEEV IgM seroprevalences were 1.6% and 4.4%, respectively; IgG antibody prevalences were MADV: 13.2%, VEEV: 16.8%, Una virus (UNAV): 16.0%, and Mayaro virus: 1.1%. Active viral circulation was not detected. Evidence of MADV and UNAV infection was found near households, raising questions about its vectors and enzootic transmission cycles. Insomnia was associated with MADV and VEEV infections, depression symptoms were associated with MADV, and dizziness with VEEV and UNAV. Force-of-infection analyses suggest endemic alphavirus transmission historically, with recent increased human exposure to MADV and VEEV in Aruza and Mercadeo, respectively. The lack of additional neurological cases suggests that severe MADV and VEEV infections occur only rarely. Our results indicate that over the past five decades, alphavirus infections have occurred at low levels in eastern Panama, but that MADV and VEEV infections have recently increased-potentially during the past decade. Endemic infections and outbreaks of MADV and VEEV appear to differ spatially in some locations of eastern Panama.
Assuntos
Encefalomielite Equina do Leste/epidemiologia , Encefalomielite Equina Venezuelana/epidemiologia , Fazendeiros/estatística & dados numéricos , Adolescente , Adulto , Distribuição por Idade , Idoso , Idoso de 80 Anos ou mais , Alphavirus/imunologia , Infecções por Alphavirus/epidemiologia , Infecções por Alphavirus/imunologia , Infecções por Alphavirus/fisiopatologia , Animais , Anticorpos Antivirais/imunologia , Febre de Chikungunya/epidemiologia , Febre de Chikungunya/imunologia , Febre de Chikungunya/fisiopatologia , Vírus Chikungunya/imunologia , Criança , Pré-Escolar , Estudos Transversais , Depressão/fisiopatologia , Tontura/fisiopatologia , Vírus da Encefalite Equina do Leste/imunologia , Vírus da Encefalite Equina Venezuelana/imunologia , Encefalomielite Equina do Leste/imunologia , Encefalomielite Equina do Leste/fisiopatologia , Encefalomielite Equina Venezuelana/imunologia , Encefalomielite Equina Venezuelana/fisiopatologia , Doenças Endêmicas , Epidemias , Fadiga/fisiopatologia , Feminino , Habitação/estatística & dados numéricos , Humanos , Imunoglobulina G , Imunoglobulina M , Masculino , Pessoa de Meia-Idade , Mosquitos Vetores/virologia , Panamá/epidemiologia , Vírus da Floresta de Semliki/imunologia , Estudos Soroepidemiológicos , Distúrbios do Início e da Manutenção do Sono/fisiopatologia , Adulto JovemRESUMO
Eastern equine encephalitis virus (EEEV) is an arthropod-borne virus associated with life-threatening encephalitis in humans, equines, birds and many other domestic animals. To investigate the suitability of the Aotus nancymaae New World owl monkey as a viable animal model for EEE candidate vaccine testing we used clinical presentation, serology, viral isolation and PCR to evaluate pathogenesis and immunity in infected animals. Monkeys were inoculated subcutaneously (SQ) or intranasally (IN) with 10(4)pfu of virulent EEEV and were initially followed for 45 days. While none of the animals displayed clinical signs of disease, all of the SC inoculated animals (n=6) manifested a viremia averaging 3.2 days (+/-0.8 days). Likewise, serologic responses (IgM, IgG and PRNT) were observed in all SC infected animals. Interestingly, none of the IN inoculated animals (n=6) became viremic or mounted an antibody response and no pathological abnormalities were observed in two animals that were necropsied on day 6 post-infection (p.i.) from each group. To determine if the antibodies produced by the SC inoculated animals were protective against homologous challenge, three animals from the SC group were serologically evaluated on day 253 p.i. and were administered an inoculum identical to initial challenge on day 270 p.i. A positive control group of four naïve animals was also infected as before. All of the naïve positive control animals manifested a similar viremia as observed initially, averaging 2.75 days (+/-0.5 days) while none of the previously challenged animals became viremic. On days 45 and 253 p.i. geometric mean PRNT titers in the SC group were 453 and 101, respectively. This study demonstrates that the Aotus nancymaae can be reproducibly infected with EEE virus and can serve as a suitable model for infection and immunogenicity for the evaluation of candidate vaccines against EEEV.
Assuntos
Aotidae/imunologia , Aotidae/virologia , Vírus da Encefalite Equina do Leste/imunologia , Vírus da Encefalite Equina do Leste/patogenicidade , Encefalomielite Equina do Leste/imunologia , Encefalomielite Equina do Leste/virologia , Administração Intranasal , Animais , Anticorpos Antivirais/análise , Anticorpos Antivirais/biossíntese , Modelos Animais de Doenças , Vírus da Encefalite Equina do Leste/isolamento & purificação , Ensaio de Imunoadsorção Enzimática , Cavalos , Imunoglobulina G/análise , Imunoglobulina G/biossíntese , Imunoglobulina M/análise , Imunoglobulina M/biossíntese , Injeções Subcutâneas , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Ensaio de Placa Viral , Viremia/virologiaRESUMO
Reptiles can harbor pathogenic microorganisms asymptomatically and serve as potential reservoirs of infection for humans, domestic animals, and other reptiles. Infectious diseases are also problematic for free-ranging reptile populations and are an important consideration in reptile reintroduction and translocation projects. There have been limited serologic studies of free-ranging reptiles for evidence of exposure to potential pathogens. In the present study, serum or plasma samples from five male and five female free-ranging Venezuelan anacondas (Eunectes murinus) were screened for antibodies to eastern, western, and Venezuelan equine encephalitis viruses, vesicular stomatitis virus, ophidian paramyxovirus, 19 Leptospira interrogans serovars, and Cryptosporidium serpentes. Antibodies to these agents were not detected, or antibody titers were low and possibly nonspecific. These results for the limited number of anacondas surveyed suggest that they do not serve as significant reservoirs for these infectious agents at this location.