Serological evidence of antibodies to certain arboviruses in desert rodent sera in Egypt

Small rodents inhabiting the wadis close to St Katherine in the mountains of the Sinai Peninsula, Egypt, were trapped and antibodies to Sindbis [SIN], West Nile [WN] and Quaranfil [QRF] viruses in their sera were studied. One mouse had Haemagglutination-inhibition [HI] antibodies against SIN antigen in his serum, 3 mice had HI antibodies against WN antigen in their sera. The titers is low to be of any significance. It seems that natural cycle of transmission of SIN and WN viruses involving rodents does not exist. Seven mice had Complement-fixation [CF] antibodies in their sera against Quaranfil antigen. Conclusion, the CF test results suggest the existence of another mammal vector cycle

The Acre Project: the epidemiology of malaria and arthropod-borne virus infections in a rural Amazonian population

The authors describe the baseline malaria prevalence and arbovirus seroprevalence among 467 subjects in an ongoing cohort study in rural Amazonia. Most subjects (72.2 percent) reported one or more previous episodes of malaria, and 15.6 percent had been hospitalized for malaria, but only 3.6 percent of individuals five years or older had malaria parasites detected by microscopy (10 with Plasmodium vivax and 4 with P. falciparum). Antibodies to Alphavirus, Orthobunyavirus, and/or Flavivirus were detected by hemagglutination inhibition (HI) in 42.6 percent of subjects aged five years or older, with a higher seropositivity rate among males (49.2 percent) than females (36.2 percent). Since 98.9 percent of subjects had been immunized for yellow fever, the presence of cross-reactive antibodies to dengue and other Flaviviruses cannot be ruled out, but at least 12 subjects (3.3 percent) with IgM antibodies to dengue virus detected by ELISA had a putative recent exposure to this virus.

Establishment and characterization of a new continuous cell line from Lutzomyia longipalpis (Diptera: Psychodidae) and its susceptibility to infections with arboviruses and Leishmania chagasi

Embryonic tissue explants of the sand fly Lutzomyia longipalpis (Lutz & Neiva 1912) the main vector of Leishmania chagasi (Cunha and Chagas), were used to obtain a continuous cell line (Lulo). The tissues were seeded in MM/VP12 medium and these were incubated at 28ºC. The first subculture was obtained 45 days after explanting and 96 passages have been made to date. Lulo is composed of epithelioid cells, showed a 0.04 generations/hour exponential growth rate and population doubling time at 24.7 h. The cell line isoenzymatic profiles were determined by using PGI, PGM, MPI and 6-PGDH systems, coinciding with patterns obtained from the same species and colony's pupae and adults. The species karyotype characteristics were recognized (2n = 8), in which pair 1 is subtelocentric and pairs 2, 3 and 4 are metacentric. Lulo was free from bacterial, fungal, mycoplasmic and viral infection. Susceptibility to five arbovirus was determined, the same as Lulo interaction with Leishmania promastigotes.

Historical, Epidemiological and Ecological Aspects of Arboviruses in Argentina: Flaviviridae, Bunyaviridae and Rhabdoviridae

This is a review of the arboviruses in Argentina belonging to families Flaviviridae, Bunyaviridae and Rhabdoviridae. Of the many viruses beloging to these families, the flavivirus St. Louis encephalitis (SLE), has been most intensively studies. SLE virus strains have been recovered from three sources: 2 strains from humans with an undifferentiated, febrile disease; 6 from mosquitoes; and 2 from rodents. The viruses recovered from rodents are attenuated and those from mosquitoes are virulent based on a neuroinvasiveness test in mice; the degree of virulence of the mosquito strains remain to be analyzed. Serological surveys indicate a wide distribution and endemicity of SLE virus in the temperate and subtropical areas (central and northern Argentina), but no data are available from the Andean region or from the South. The virulent SLE virus strains appear to be transmitted between Culex (Cx.) spp., from which they were isolated, and wild birds, based on antibody prevalence. A urban cycle may involve Cx. quinquefasciatus (source of a viral isolate and a competent experimental vector) and abundant birds (house sparrows, doves, and/or chickens), chickens are experimentally competent host species. Despite similarities in the ecology of SLE between Argentina and North America, urban outbreaks of SLE have not recognized. Possible explanations for this discrepancy include virus strain differences in virulence, ecologic factors determining the rate os virus transmission, and the lack of disease recognition and specific laboratory diagnosisof human meningoencephalitis. The transmission cycle of attenuated SLE virus strains isolated from rodents has not been studied. Ilheus virus has been isolated only once from a human being. The available serological data are difficult to interpret due to cross-reactivity with other flaviviruses, and the ecology and medical importance of this agent remain uncertain. Dengue has not been recognized in Argentina since 1916, although its vector, Aedes aegypti, was not eradicated until 1963. Dengue was previously present in coastal localities of Chaco, Corrientes and Misiones Provinces. Within the last few years, Argentina was reinfested by Ae. aegypti. Although no human cases have yet been reported, outbreaks of dengue in bordering countries (Brazil, Paraguay, Bolovia) since 1986, clearly signal that the country in once again at risk of importation and spread of the viruse

Arthropod-Borne viral Diseases in Peru

Arthropode-Borne viral diseases have been a significant cause of morbidity and mortality for several decades in Peru. Epidemics and epizootics of Venezuelan equine encephalitis (VEE), subtype IAB virus occurred among humans and equine at intermittent intervals from 1925 through 1973 along the Pacific coastal plains, extending southward from the most northern Departament of Tumbes to the Departament of Ica. While the VEE IAB virus has not been detected since 1973, several isolates of VEE ID and an isolate VEE IIIC were obtained during 1971 and 1975 from mosquitoes and/or sentinel hamster in Quistococha, northeastern Amazon region. In 1994, the first human cases, associated with VEE virus ID were diagnosed among Peruvian soldiers near Pantoja, northern Amazon region, and during 1995, primarily among students and military personnel in Iquitos, northastern Amazon region. As early as 1913 , a disease resembling yellow fever was recognized in the Amazon region Peru. Outbreaks of this disease have continued to occur, apparently at annual interval, with the most recent and the largest sylvan outbreak ever recorded in Peru being documented during 1995 along the eastern foothills of the Andes Mountains. In 1990, dengue (DEN) 1 and DEN4 were first isolated in Peru during an outbreak of DEN fever among residents of the city of Iquitos, northeastern Amazon basin region. Seroepidemiological and case surveillance studies conducted 1992 through 1995 documented that DEN 1 continued to cause cases of DEN fever in Iquitos, and in 1995, an outbreak was associated with the introduction of DEN 2 into the community. Outbreaks of DEN fever, associated with DEN 1 occurred during 1994 and 1995 in the northern coastal cities of Tumbes and Piura, and in Pucallpa, Amazon basin region. In 1995, the first isolations of DEN 2 were obtained from febriles cases in Tumbes, Piura and Pucallpa. Although 2 serotypes of DEN were associated with human infection, none of the cases presented with hemorragic manifestations. The first isolations of Oropouche (ORO) fever virus were obtained during 1992 from febrile patients in Iquitos. The virus was isolated during 1994 from febrile cases and serological results revealed that ORO was the cause of an outbreak in the southeastern Amazon region. A single isolate of ORO virus was obtained during 1995 from a febrile patient in Iquitos

Evidências sorológicas da circulação do arbovírus Rocio (Flaviviridae) na Bahia / Serological evidence of the circulation of the Rocio arbovirus (Flaviviridae) in Bahia

Oito casos com anticorpos anti-Rocio são descritos, de quatro cidades do Estado da Bahia, sendo seis portadores de anticorpos IgG (IH e TN) e dois IgM (ELISA e TN). Os autores comentam sobre a circulação deste arbovírus no Estado, e as possibilidades de reações cruzadas com outros vírus antigenicamente relacionados.

Eight antibody anti-Rocio cases, from four distinct cities in the state of Bahia, are described; six of them being carriers of the antibody IgG (HI and NT) and two IgM (ELISA and NT). The authors comment on the circulation of these arboviruses in the state of Bahia and on the possibility of cross reactions with other antigenically related viruses.

Estudos sorológicos para pesquisa de anticorpos de arbovirus em populacao humana da regiao do Vale do Ribeira. II Inquerito em pacientes do Hospital Regional de Pariquera-Acu, 1980. / Serological studies for the research of arbovirus antibodies in human population of the Ribeira Valley region. II - Survey in patients of Pariquera-Acu Regional Hospital, 1980

Foi realizado inquerito sorologico para pesquisa de anticorpos inibidores de hemaglutinacao de arbovirus em 516 moradores das zonas urbana e rural da regiao do Vale do Ribeira, Brasil, area extensamente coberta de florestas onde ocorreu recentemente uma epidemia de encefalite atribuida ao Flavivirus Rocio. Verificou-se que 24,2% destas pessoas tinham anticorpos IH para um ou mais arbovirus (11,2% para Alphavirus; 13,2% para Flavivirus 4,6% para Bunyavirus Caraparu e 0,8% para outros arbovirus). Alguns dos investigados, sem antecedente de vacinacao contra febre amarela apresentaram anticorpos neutralizantes para o virus da encefalite equina do Leste, St.Louis e da febre amarela, os dois ultimos ainda nao isolados na regiao. A analise das caracteristicas dos individuos com sorologia positiva sugeria que a transmissao de arboviroses nao era fato recente e estava se fazendo em pelo menos 9 municipios da area, nao so no ambiente silvestre como fora do mesmo. Os individuos do sexo masculino e entre estes os que trabalham em pesca, em geral no periodo vespertino e noturno, apresentaram maior risco a infeccoes arboviricas

Alphaviruses in Peninsular Malaysia: II. Serological evidence of human infection.

A serum survey of several characteristic groups of humans in urban, rural, and forested areas of Peninsular Malaysia for evidence of infection with three alphaviruses (Sindbis, getah, and chikungunya) was made on 4384 specimens collected between 1965 and 1969. Analysis of the serological results indicated that 1) persons residing in predominantly rural and forested areas have higher frequencies of specific alphavirus antibody of all three viruses than persons residing in urban areas, 2) human infection with chikungunya virus appears to be at a low level of activity but is widespread, although more common and recent in the northern part of the country, and 3) Sindbis and getah viruses probably do not represent a threat to the public health, but chikungunya virus remains a potential menance and may be responsible for future epidemics transmitted by A. aegypti and A. albopictus mosquitoes.