Age-related seroprevalence study for St. Louis encephalitis in a population from Cordoba, Argentina

A serological screening was performed in 615 individuals aged 0-87 years, living in the city of Cordoba, Argentina to study the relationship between antibody prevalence for the SLE virus and age. A 13.98% prevalence of neutralizing antibodies was obtained and its relation to age was significantly high (p = 0.045). The highest seroprevalence was noted on individuals over 60 years old (>20%), whereas no subject under 10 was seropositive for this virus. Our results confirm that the agent is endemic in this area and neurological pathology studies should be performed on those individuals aged 60 since they represent the most susceptible group to SLE virus.

St. Louis encephalitis vírus: first isolation from a human in São Paulo state, Brasil

This paper reports the isolation of St. Louis encephalitis virus (SLEV) from a febrile human case suspected to be dengue, in São Pedro, São Paulo State. A MAC-ELISA done on the patient's acute and convalescent sera was inconclusive and hemagglutination inhibition test detected IgG antibody for flaviviruses. An indirect immunofluorescent assay done on the C6/36 cell culture inoculated with the acute serum was positive for flaviviruses but negative when tested with dengue monoclonal antibodies. RNA extracted from the infected cell culture supernatant was amplified by RT-PCR in the presence of NS5 universal flavivirus primers and directly sequenced. Results of BLAST search indicated that this sequence shares 93% nucleotide similarity with the sequence of SLEV (strain-MSI.7), confirmed by RT-PCR performed with SLEV specific primers. Since SLEV was identified as the cause of human disease, it is necessary to improve surveillance in order to achieve early detection of this agent in the state of São Paulo and in Brazil. This finding is also an alert to health professionals about the need for more complete clinical and epidemiological investigations of febrile illnesses as in the reported case. SLEV infections can be unrecognized or confused with other ones caused by an arbovirus, such as dengue.

SAINT LOUIS ENCEPHALITIS VIRUS IN MATO GROSSO, CENTRAL-WESTERN BRAZIL

The dengue virus (DENV), which is frequently involved in large epidemics, and the yellow fever virus (YFV), which is responsible for sporadic sylvatic outbreaks, are considered the most important flaviviruses circulating in Brazil. Because of that, laboratorial diagnosis of acute undifferentiated febrile illness during epidemic periods is frequently directed towards these viruses, which may eventually hinder the detection of other circulating flaviviruses, including the Saint Louis encephalitis virus (SLEV), which is widely dispersed across the Americas. The aim of this study was to conduct a molecular investigation of 11 flaviviruses using 604 serum samples obtained from patients during a large dengue fever outbreak in the state of Mato Grosso (MT) between 2011 and 2012. Simultaneously, 3,433 female Culex spp. collected with Nasci aspirators in the city of Cuiabá, MT, in 2013, and allocated to 409 pools containing 1-10 mosquitoes, were also tested by multiplex semi-nested reverse transcription PCR for the same flaviviruses. SLEV was detected in three patients co-infected with DENV-4 from the cities of Cuiabá and Várzea Grande. One of them was a triple co-infection with DENV-1. None of them mentioned recent travel or access to sylvatic/rural regions, indicating that transmission might have occurred within the metropolitan area. Regarding mosquito samples, one pool containing one Culex quinquefasciatus female was positive for SLEV, with a minimum infection rate (MIR) of 0.29 per 1000 specimens of this species. Phylogenetic analysis indicates both human and mosquito SLEV cluster, with isolates from genotype V-A obtained from animals in the Amazon region, in the state of Pará. This is the first report of SLEV molecular identification in MT.

Serological evidence for Saint Louis encephalitis virus in free-ranging New World monkeys and horses within the upper Paraná River basin region, Southern Brazil

Introduction Saint Louis encephalitis virus (SLEV) primarily occurs in the Americas and produces disease predominantly in humans. This study investigated the serological presence of SLEV in nonhuman primates and horses from southern Brazil. Methods From June 2004 to December 2005, sera from 133 monkeys (Alouatta caraya, n=43; Sapajus nigritus, n=64; Sapajus cay, n=26) trap-captured at the Paraná River basin region and 23 blood samples from farm horses were obtained and used for the serological detection of a panel of 19 arboviruses. All samples were analyzed in a hemagglutination inhibition (HI) assay; positive monkey samples were confirmed in a mouse neutralization test (MNT). Additionally, all blood samples were inoculated into C6/36 cell culture for viral isolation. Results Positive seroreactivity was only observed for SLEV. A prevalence of SLEV antibodies in sera was detected in Alouatta caraya (11.6%; 5/43), Sapajus nigritus (12.5%; 8/64), and S. cay (30.8%; 8/26) monkeys with the HI assay. Of the monkeys, 2.3% (1/42) of A. caraya, 6.3% 94/64) of S. nigritus, and 15.4% (4/26) of S. cay were positive for SLEV in the MNT. Additionally, SLEV antibodies were detected by HI in 39.1% (9/23) of the horses evaluated in this study. Arboviruses were not isolated from any blood sample. Conclusions These results confirmed the presence of SLEV in nonhuman primates and horses from southern Brazil. These findings most likely represent the first detection of this virus in nonhuman primates beyond the Amazon region. The detection of SLEV in animals within a geographical region distant from the Amazon basin suggests that there may be widespread and undiagnosed dissemination of this disease in Brazil.

A Saint Louis encephalitis and Rocio virus serosurvey in Brazilian horses

Introduction Arboviruses are an important public health problem in Brazil, in especially flaviviruses, including the Saint Louis encephalitis virus (SLEV) and the Rocio virus (ROCV), are especially problematic. These viruses are transmitted to humans or other vertebrates through arthropod bites and may cause diseases with clinical manifestations that range from asymptomatic infection, viral hemorrhagic fever to encephalitis. Methods A serological survey of horses from various regions of Brazil using an enzyme-linked immunosorbent assay (ELISA) with recombinant SLEV domain III peptides and ROCV E protein as antigens. Results Overall, 415 (55.1%) of the 753 horses that were screened were seropositive for flavivirus and, among them, monotypic reactions were observed to SLEV in 93 (12.3%) and to ROCV in 46 (6.1%). These results suggested that these viruses, or other closely related viruses, are infecting horses in Brazil. However, none of the studied horses presented central nervous system infection symptoms. Conclusions Our results suggest that SLEV and ROCV previously circulated among horses in northeast, west-central and southeast Brazil.

Tendência da mortalidade por doenças do aparelho circulatório no Brasil: 1950 a 2000

FUNDAMENTO: As doenças do aparelho circulatório (DAC), um dos mais importantes problemas de saúde da atualidade, apesar de proporcionalmente ainda liderarem as estatísticas de morbi-mortalidade, começam a apresentar tendência declinante da mortalidade em diversos países. OBJETIVO: Analisar a tendência da mortalidade por DAC nas capitais brasileiras, no período de 1950 a 2000. MÉTODOS: Estudo de série temporal das razões de mortalidade padronizadas por DAC. Utilizamos dados secundários de óbitos dos anuários estatísticos do IBGE e do Sistema de Informação de Mortalidade. Realizamos análise de tendência linear das razões de mortalidade padronizadas por DAC nas capitais brasileiras que apresentaram séries completas de mortalidade, considerando os anos censitários do período do estudo (1950 a 2000). RESULTADOS: Apesar de proporcionalmente as DAC representarem a primeira causa de óbito na população brasileira, bem como apresentarem crescimento proporcional no período de análise deste estudo, o risco de óbito, representado pelas razões de mortalidade padronizadas, apresenta-se em decréscimo, particularmente a partir da década de 80. Destacam-se as cidades de Fortaleza, Salvador, Belo Horizonte, Rio de Janeiro e São Paulo, que apresentam razões de mortalidade padronizadas elevadas, porém em decréscimo (p < 0,05 e p < 0,10) desde o início do período analisado. CONCLUSÃO: O comportamento do risco de óbito por DAC sugere que esse grupo de enfermidades é o que primeiro se estabelece, acompanhando o aumento da industrialização no Brasil, verificado a partir da década de 1930 e após a Segunda Guerra Mundial, Como ocorreu em São Paulo e Rio de Janeiro, que historicamente experimentaram um processo de desenvolvimento e urbanização anterior e diferenciado em relação às outras capitais.

Expanded description of the female of Lernaeenicus longiventris Wilson, 1917, (Copepoda, Siphonostomatoida, Pennellidae) based on specimens from Mugil platanus Günter, 1880 (Perciformes, Mugilidae) of the state of Rio de Janeiro, Brazil

The description of Lernaeenicus longiventris is expanded and revised, based on specimens collected from the skin and fins of mullets, Mugil platanus Gunther, 1880, from 21 locations in coastal waters of the state of Rio de Janeiro, Brazil.

Maintenance and breeding of Thrichomys (Trouessart, 1880) (Rodentia: Echimyidae) in captivity

South American histricognath rodents Thrichomys apereoides laurentius and Thrichomys pachyurus are natural hosts of Trypanosoma cruzi, agent of Chagas disease. We established breeding colonies of these species to serve as experimental models in various parasitological studies. Both species of Thrichomys have all the requirements necessary to become excellent laboratory models: they can be easily maintained in the standard laboratory conditions and breed throughout the year and they do not have any special dietary demands and can be fed by standard food pellets designed for laboratory mice. Both species produce precocious offspring that have their eyes and ears open, teeth erupted, fur well developed, and can eat solid food in the first week of life. T. a. laurentius has larger litter sizes and lower body masses at birth and weaning than T. pachyurus. Moreover, females of T. a. laurentius reach puberty earlier and with lower body mass than T. pachyurus.

Genetic characterization of St. Louis encephalitis virus isolated from human in São Paulo, Brazil

The molecular characterization of SPH253157, a new strain of St. Louis encephalitis virus (SLEV), isolated in 2004 from the first case of human infection recognized in the state of São Paulo, Brazil, is reported. The patient, presenting a febrile illness without neurological involvement, was hospitalized as a probable case of dengue fever. Genomic RNA was isolated from the supernatant of C6/36 cells infected with acute phase-serum specimen of the patient and the envelope gene was amplified by reverse-transcription-polymerase chain reaction. The complete nucleotide sequence of the envelope gene of this isolate was directly sequenced from the amplified products and compared with other Brazilian and American SLEV strains. Phylogenetic analyses were carried out under maximum likelihood criterion with outgroups both included and excluded. Outgroups comprised four flavivirus of the Japanese encephalitis group. Phylogeny also included Bayesian analysis. The results indicated that the new SLEV isolate belongs to lineage III, being closely related to an Argentinean strain recovered from Culex sp. in 1979. It is concluded that there are at least 3 lineages of SLEV in Brazil.

Serologic evidence of the recent circulation of Saint Louis encephalitis virus and high prevalence of equine encephalitis viruses in horses in the Nhecolândia sub-region in South Pantanal, Central-West Brazil

As in humans, sub-clinical infection by arboviruses in domestic animals is common; however, its detection only occurs during epizootics and the silent circulation of some arboviruses may remain undetected. The objective of the present paper was to assess the current circulation of arboviruses in the Nhecolândia sub-region of South Pantanal, Brazil. Sera from a total of 135 horses, of which 75 were immunized with bivalent vaccine composed of inactive Eastern equine encephalitis virus (EEEV) and Western equine encephalitis virus(WEEV) and 60 were unvaccinated, were submitted to thorough viral isolation, reverse transcriptase polymerase chain reaction (RT-PCR) and neutralization tests for Saint Louis encephalitis virus (SLEV), EEEV, WEEV and Mayaro virus (MAYV). No virus was isolated and viral nucleic-acid detection by RT-PCR was also negative. Nevertheless, the prevalence of neutralizing antibodies in horses older than seven months was 43.7% for SLEV in equines regardless of vaccine status, and 36.4% for WEEV and 47.7% for EEEV in unvaccinated horses. There was no evidence of MAYV infections. The serologic evidence of circulation of arboviruses responsible for equine and human encephalitis, without recent official reports of clinical infections in the area, suggests that the Nhecolândia sub-region in South Pantanal is an important area for detection of silent activity of arboviruses in Brazil.