RESUMO
To examine the prevalence of human pathogens carried by rats in urban areas in Hanoi and Hai Phong, Vietnam, we live-trapped 100 rats in January 2011 and screened them for a panel of bacteria and viruses. Antibodies against Leptospira interrogans (22·0%), Seoul virus (14·0%) and rat hepatitis E virus (23·0%) were detected in rats, but antibodies against Yersinia pestis were not detected. Antibodies against L. interrogans and Seoul virus were found only in adult rats. In contrast, antibodies to rat hepatitis E virus were also found in juvenile and sub-adult rats, indicating that the transmission mode of rat hepatitis E virus is different from that of L. interrogans and Seoul virus. Moreover, phylogenetic analyses of the S and M segments of Seoul viruses found in Rattus norvegicus showed that Seoul viruses from Hai Phong and Hanoi formed different clades. Human exposure to these pathogens has become a significant public health concern.
Assuntos
Anticorpos Antibacterianos/sangue , Anticorpos Antivirais/sangue , Doenças dos Roedores/epidemiologia , Doenças dos Roedores/etiologia , Zoonoses/epidemiologia , Zoonoses/etiologia , Animais , Análise por Conglomerados , Feminino , Variação Genética , Masculino , Dados de Sequência Molecular , Filogenia , RNA Viral/genética , Ratos , Vírus Seoul/classificação , Vírus Seoul/genética , Vírus Seoul/isolamento & purificação , Análise de Sequência de DNA , Estudos Soroepidemiológicos , Vietnã/epidemiologiaRESUMO
A new method was developed to determine HT deposition velocity and to investigate how environmental factors affect the deposition processes including the diffusion into soil and the biochemical conversion by microorganisms to HTO in soil. This method, using a chamber and two tritium samplers, enables determination of the HT deposition velocity in situ without a large scale experiment and an additional tritium source. The main problem concerning the use of a flow-through method is the possible effect of flow rate on flux measurement. Since the tritium sampler used in this study has many collecting columns, the flow rate is limited. Experimental results showed no significant effect of flow rate over a low range from 0.48 to 0.95 l.min-1. From the increase of HT deposition velocity with increase of water content, it was indicated that biochemical oxidation rather than physical diffusion dominantly affects the HT deposition velocity under examined site conditions. No clear relationship between the HT deposition velocity and atmospheric temperature, relative humidity or soil temperature was observed. The soil temperature was only of secondary importance as a factor controlling the HT deposition velocity.
