Emergence of new insect-restrictive viruses in the Amazon region.

The complete genome was determined for 12 viruses isolated from 8 different pools of mosquitoes (Culex sp. and Psorophora ferox) collected at Brejeira farm, Canaan dos Carajas, Para state in northern Brazil. Eight of the viruses were distantly related to Piura virus, hereafter designated as Brejeira virus; the other 4 were similar to Wallerfield virus.

Yellow fever virus in Haemagogus leucocelaenus and Aedes serratus mosquitoes, southern Brazil, 2008.

Yellow fever virus (YFV) was isolated from Haemagogus leucocelaenus mosquitoes during an epizootic in 2001 in the Rio Grande do Sul State in southern Brazil. In October 2008, a yellow fever outbreak was reported there, with nonhuman primate deaths and human cases. This latter outbreak led to intensification of surveillance measures for early detection of YFV and support for vaccination programs. We report entomologic surveillance in 2 municipalities that recorded nonhuman primate deaths. Mosquitoes were collected at ground level, identified, and processed for virus isolation and molecular analyses. Eight YFV strains were isolated (7 from pools of Hg. leucocelaenus mosquitoes and another from Aedes serratus mosquitoes); 6 were sequenced, and they grouped in the YFV South American genotype I. The results confirmed the role of Hg. leucocelaenus mosquitoes as the main YFV vector in southern Brazil and suggest that Ae. serratus mosquitoes may have a potential role as a secondary vector.

Oropouche fever epidemic in Northern Brazil: epidemiology and molecular characterization of isolates.

BACKGROUND: Oropouche fever virus is an important arbovirus associated with febrile disease that re-emerged in 2006 in several municipalities of Pará State, Bragantina region, Amazon, Brazil, 26 years after the last epidemic. OBJECTIVE: To investigate an Oropouche fever outbreak in this region. STUDY DESIGN: A serologic survey and prospective study of acute febrile cases were performed in Magalhães Barata (urban and rural areas) and Maracanã (rural area) municipalities. Serology (IgM-ELISA and hemagglutination-inhibition [HI]), virus isolation, RT-PCR and real-time-PCR were used to confirm Oropouche virus (OROV) as responsible for the febrile outbreaks. RESULTS: Real-time-PCR showed high titers of OROV in acute-phase serum samples from febrile patients. From 113 of 119 acutely febrile patients with paired serum samples, OROV infections was confirmed by serologic conversion (n=76) or high titers (n=37) for both HI and IgM-ELISA. Patients had a febrile disease characterized by headache, chills, dizziness, photophobia, myalgia, nausea, and vomiting. Females and children under 15 years of age were most affected. Nucleotide sequencing of six OROV isolates identified that genotype II was associated with the human disease epidemic. CONCLUSIONS: Oropouche fever, which has re-emerged in the Bragantina region in eastern Amazon 26 years after the last epidemic, is caused by genotype II, a lineage previously found only in Peru and western Brazil.

Characterization of Minaçu virus (Reoviridae: Orbivirus) and pathological changes in experimentally infected newborn mice.

Minaçu virus was isolated from Ochlerotatus scapularis (Diptera: Culicidae) in Minaçu, Goiás State, Brazil, in 1996. In attempting characterization of virus serological (hemagluttination inhibition, HI; indirect immunofluorescence assay, IFA), physicochemical [test for deoxycholate acid (DCA) sensitivity; polyacrylamide gel electrophoresis (PAGE)] tests and ultrastructural studies were made. Virus was also assayed in suckling mice after intracerebral inoculation of 0.02 ml and in VERO and C6/36 cells with 0.1 ml of viral suspension containing 10(5) LD50/ml. Inoculated and control systems were observed daily. Every 24 h, one control and two inoculated animals were killed for tissue testing, including histopathological changes by haematoxylin and eosin (HE)-stained sections, which were semi-quantified. Research into viral antigen in the tissues of mice [central nervous system (CNS), liver, heart, lungs, spleen and kidneys] was carried out by the immunohistochemical technique using the peroxidase system. The virus only replicated in VERO cells, with antigen positive by IFA. Positive complement fixation tests were only obtained using antiserum of Minaçu virus. Minaçu virus is DCA resistant; haemagglutinating activity was negative. By electronic microscopy non-enveloped virus particles were 75 nm in diameter. PAGE analysis showed Minaçu virus genome profile with 10 RNA segments. Infected, non-killed animals died 7 days after inoculation. Tissue lesions were observed in all organs, except the lungs. Intense lesions were observed in the CNS and the heart, where neurone and cardiocyte necroses, respectively, were noted. The liver, spleen and kidneys had moderate tissue changes. Viral antigens were more abundant in the CNS and the heart, and absent in the lungs. In conclusion, Minaçu virus belongs to the family Reoviridae, genus Orbivirus.

Isolations of yellow fever virus from Haemagogus leucocelaenus in Rio Grande do Sul State, Brazil.

Following howling monkey (Alouatta caraya) deaths and yellow fever (YF) antigen detection by immunohistochemistry in the liver sample of a dead monkey in April and May 2001 in the municipalities of Garruchos and Santo Antônio das Missões, Rio Grande do Sul State, Brazil, epidemiological field investigations were initiated. Two strains of YF virus were isolated in suckling mice from 23 Haemagogus (Conopostegus) leucocelaenus Dyar & Shannon mosquitoes collected from the study sites. The YF virus was isolated from this species in the 1930s in Brazil and in the 1940s in Colombia. No human cases were reported during the current epizootic outbreak. The YF virus isolation and the absence of Hg. (Haemagogus) janthinomys Dyar from the area suggest that Hg. leucocelaenus may be a secondary YF vector and play an important role in the epidemiology of this disease in the Southern Cone.

Entomological studies on Dengue fever vectors in Brazil: the epidemics of Boa Vista, Roraima, 1982, Niteroi, Rio de Janeiro, 1986, and Ceara State, 1986, 1994

No Brasil, o virus deo dengue é transmitido pelo mosquito urbano Aedes Aegypti. Foi na ocasiäo dos primeiros isolamentos realizados a partir de casos humanos em Boa Vstas (RR) que o virus foi também isolado - sorotipos DEN 1 (1 amostra) e DEN 4 (2 amostras) - a partir de mosquitos naturalmente infectados. Durante o segundo episódio epidêmico, em Niterói (RJ) , foram isoladas 3 amostras de DEN 1 a partir de mosquitosfêmeas coletadas com isca humana ou em repouso. Durante essa epidemia, nos locais nâo tratados por inseticidas, o índice de Breteau era de 102. A dissecaçäo de uma amostragen dos mosquitos mostrou que (1) as fêmeas agressivas eram mais velhas que as coletadas em repouso, (2) a proporçäo de repastos interrompidos ou múltiplos era elevada. Inquéritos entomológicos foram realizados durante as epidemias de 1986 e 1994 no Ceará. Tres amostras de DEN 1 e 16 amostras de DEN 2 foram isoladas a partir de AE. aegypti coletados em Cascavel e Caucaia, respectivamente. A suscetibilidade à infecçäo oral dos mosquitos sobre os pacientes com viremia pelo virus DEN 2 foi testada. Positividade dos mosquitos apareceu a partir do terceiro dia após repasto. 44 por cento dos mosquitos form infectados após ter sido alimentados com sangue contendo um título de virus ( Log TCD 50) igual a 3,5 . Tentativas de isolamento a partir de mosquitos machos, imaturos ou outras espécies foram negativas