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Serological assays for diagnosis of Venezuelan equine encephalitis virus (VEEV) currently require bio-safety level 3 facilities and select agent certification to produce antigens, reference sera, or viral stocks. Rapid identification of VEEV infection is required to respond to human and equine outbreaks of encephalitis caused by that virus and can be useful for epidemiologic surveillance. Alphavirus (Sindbis)-based recombinant viruses that express VEEV structural proteins are attenuated in animal models, thus representing an alternative to the handling of virulent infectious virus. Virus and viral antigens from recombinant Sindbis/VEE constructs engineered to express structural proteins from multiple VEEV subtypes were evaluated as diagnostic reagents in VEEV-specific serological assays, e.g., plaque reduction neutralization test (PRNT), hemagglutination inhibition (HI) assay, and complement fixation (CF) test. Chimeric viruses were produced efficiently in cell culture and were as effective as the parental virus for identifying infection of humans, horses, and rodents in these serological assays.

Here in is described the clinical and laboratorial findings of a laboratory-acquired infection caused by the virus SP H 114202 (Arenavirus, family Arenaviridae) a recently discovered agent responsible for a viral hemorrhagic fever. The patient was sick for 13 days. The disease had an abrupt onset characterized by high fever (39 degree C.), headache, chills and myalgias for 8 days. In addition, on the 3rd day, the patient developed nausea and vomiting, and in the 10th, epigastralgia, diarrhea and gengivorrhagia. Leucopenia was seen within the 1st week of onset, with counts as low as 2,500 white cells per mm3. Counts performed after the 23rd day of the onset were within normal limits. With the exception of moderate lymphocytosis, no changes were observed in differential counts. An increase in the titer of antibodies by complement fixation, neutralization and ELISA (IgM) was detected. Suckling mice and baby hamsters were inoculated intracerebrally with 0.02 ml of blood samples collected in the 2nd and 7th days of disease. Attempts to isolate the virus were also made in Vero cells. No virus was isolated. This virus was isolated before in a single occasion in São Paulo State, in 1990, from the blood of a patient with hemorrhagic fever with a fatal outcome. The manipulation of the virus under study, must be done carefully, since the transmission can occur through aerosols.

We report the first outbreak of dengue fever caused by dengue 2 (DEN 2) in Araguaina, Tocantins State. Four hundred people of 74 families, living at S. João, Araguaina Sul and Neblina districts were questioned and then bled, in order to obtain sera to test for anti-dengue antibodies. If a person was sick, a small quantity of blood was collected for virus isolation. The main clinical picture of disease was characterized by fever, headache, myalgias, arthralgias and skin rash. Were obtained 1,105 (56 females and 45 males of Culex quinquefasciatus and 567 females and 437 males of Aedes aegypti) mosquitoes from larvae collected in Araguaina. The females of Aedes aegypti obtained from larvae were allowed to feed on 8 febrile patients. The diagnosis of infection was made by both virus isolation into Aedes albopictus (C6/36) cells, and serology, by Hemagglutination-inhibition (HI) and IgM capture ELISA (MAC ELISA). No virus was isolated from mosquitoes. Although five strains of DEN 2 were obtained from humans, and another 111 infections were diagnosed serologically (IgM positive). The positivity rate of the samples was 27.75% (111 of 400), while that of the families was 66.2% (45 of 72), where at least one member of the each family was infected. It was also detected 26.1% of asymptomatic infections. All age groups were affected. Therefore, the infection was more frequent in females (33.5%) than males (23.8%).(ABSTRACT TRUNCATED AT 250 WORDS)

The conditions of maintenance of YF virus in brazilian Amazonia are not yet elucidated. Generally, the presence of the virus is attested by human cases of sylvatic origin. During a survey done at the exact place where a man have probably been contaminated, it was possible for the first time in South America, to estimate the mean parity rate of a population of the potential vector Haemagogus janthinomys, from which the YF virus was actually isolated. The survival rate (Ts = 0.96), the biting rate (0.60 mosquitoes/man x hour), and the infection rate (1.71%) were also determinated for the same mosquitoes and have values compatible with the probable conditions of the human contamination. However, more data are needed, in particular in relation with other possible human contaminations and/or circulation of the YF virus in the monkey population (extension and duration of the epizootic episode), in order to know what maintenance cycle is prevalent in this region: a low level transmission, with the mosquito being a "vector-reservoir", or a "constantly moving epizootic wave".

Thirteen (8.0%) of 162 blood donors from Uberaba-Minas Gerais State showed neutralizing antibodies to the vesiculovirus Piry. The previous residence in rural area (p less than 0.0001) and in the cities of the São Paulo State (p less than 0.05) were statistically more frequent in the Piry seropositive group.

An epidemic of human febrile illness caused by Oropouche virus was studied in the village of Mojui dos Campos, Pará State, in February 1975. The major clinical symptoms, fever, chills, headache, myalgia, arthralgia and dizziness persisted for 2 to 7 days. Leukopenia was commonly observed. Some patients were severely ill but no deaths were attributed to the disease. Recurrence of symptoms was reported in several people. 55 cases of recent infection were diagnosed in Mojuí dos Campos between February and April. In the same period 26 cases were recorded from the Palhal area, near to Mojuí. Two additional cases were observed, one in the small settlement of Terra Preta and the other in the town of Santarém, which are 12 and 20 km from Mojuí, respectively. Of the 83 infections, 65 were proven by virus isolation from the blood of patients and 18 by the demonstration of an increasing antibody level to the agent. Both sexes of the population were infected in equal proportions. Most patients were below 20 years of age. In the village of Mojuí dos Campos with a population of about 2,900, 45 (40,1%) out of 112 students aged 4 to 18, had HI antibodies to the virus when examined late in February. The epidemic, however, only declined after the middle of March. Two isolations of Oropouche virus were obtained from some 15,000 Culicoides inoculated into mice. About 4,000 Culicoides and all the 9,420 mosquitoes captured during the outbreak remain to be inoculated. Over 95% of the Culicoides were C. paraensis. Only 1 rodent of the genus Proechimys had HI antibodies to Oropouche virus out of the 602 wild and domestic mammals captured in the area. All 5 reptiles examined were negative. 34 (4.9%) out of the 681 wild birds and 12 (5.8%) out of the 206 domestic birds examined were positive for the presence of HI antibodies to the agent.

The authors describe the occurrence of outbreaks caused by Oropouche virus (ORO) in the states of Maranhão and Goiás, Brazil in 1988. 36 strains of the virus were obtained from the intracerebral inoculation of the blood of 120 patients into 2-3 day-old infant mice. The illness was characterized by headache, fever, pain in the muscles, joints and back, photophobia, retrobulbar pain, nausea and dizziness. 128 of 197 people examined in Porto Franco, MA, had hemagglutination-inhibiting antibodies to the agent, while 106 of them had IgM antibodies by MAC ELISA test. All age groups were infected, although the incidence was higher among who had 10 to 19 years old. There was no difference, in relation to sex infections. Recurrence of symptoms was reported in 56% of sick people. Mice inoculated with 3624 Culicoides paraensis (Ceratopogonidae) and 1970 Culex (Cux.) quinquefasciatus (Culicidae) collected in Porto Franco resulted in one single isolation of ORO virus, from the Culicoides. These are the first confirmed cases of ORO infection in Maranhão and Goiás states.

Five new phlebotomus fever virus serotypes (Bunyaviridae: Phlebovirus) are described. These viruses, designated Ambe, Ixcanal, Mariquita, Armero, and Durania, were isolated from sand flies (Diptera: Psychodidae) collected in Brazil, Colombia, and Guatemala. Two of the agents were recovered from pools of male sand flies. The new viruses are antigenically related to other members of the phlebotomus fever serogroup by immunofluorescence, but are distinct from the other 39 members of this serogroup by plaque reduction neutralization test.

The presence of IgM antibodies to Rocio in sera of two children from rural area of Ribeira Valley, Brazil, was detected by MAC-ELISA. This new arbovirus of the Flaviviridae family was responsible for an extensive encephalitis epidemic that occurred in the region in 1975-1977. Since 1980 no human disease caused by this virus has been diagnosed. An improvement on surveillance of Rocio infections and on the researches for virus identification in suspected vectors and reservoirs is necessary.

The antigenic, biological, and chemical properties of 24 selected Changuinola serogroup viruses were examined. The viruses tested were chloroform-resistant, and they were lethal to newborn hamsters after intracerebral inoculation. The prototype Changuinola virus strain (BT-436) replicated in mosquito and sandfly cell cultures. In complement-fixation tests, the viruses were broadly cross-reacting and indistinguishable; but by neutralization test at least 12 distinct serotypes were identified, and by PAGE of double-stranded RNA 22 distinct profiles were found. These data suggest that the Changuinola serogroup may be comprised of a large number of genetically different viruses. A brief review of the natural history of Changuinola serogroup viruses is also given.

An epidemic of Oropouche fever occurred in Santarém, Pará, Brazil in 1975. In the first survey for Oropouche antibodies involving a random sample of an entire city, infection rates varied from 0-44%, depending on the specific area within the city. Women had higher infection rates than men, but this difference was statistically significant only for persons older than 10 years of age. An analysis of school data showed that pupils in the evening classes had a greater increase in absenteeism during the epidemic period than those attending morning or afternoon classes. These data are compatible with the concept that Culicoides paraensis rather than Culex pipiens quinquefasciatus is the main vector of Oropouche virus in Brazil.

A serological survey for research on antibodies to arbovirus was carried out on 288 residents of the rural zone of the village of Corte de Pedra, Valença, Bahia. It was observed that 3.8% of the sample population presented HI and N antibodies against Flaviviruses (Ilhéus 6, St. Louis 2, Yellow fever 3 and Rocio 1). One person, who had previously lived in the Amazon region, had antibodies to Mayaro. The authors were unable to detect either N antibodies for Piry virus in a random sample of 75 persons or CF antibodies against viruses of the Changuinola and Phlebotomus groups and ungrouped BE AR 408005 and BE AR 421710 in another random sample of 28 individuals. Complementary studies should be conducted in order to define the transmission of the different viruses in the area.