Serum anti-Toxoplasma gondii antibodies in Passer domesticus (Linnaeus, 1758) (Passeriformes: Passeridae), in the municipality of Pelotas, RS, Brazil / Anticorpos séricos anti-Toxoplasma gondii em pardais, Passer domesticus (Linnaeus, 1758) (Passeriformes: Passeridae), do município de Pelotas, RS, Brasil

The objective of this study was to detect the presence of anti-Toxoplasma gondii antibodies in serum samples from 100 house sparrows (Passer domesticus Linnaeus, 1758) that were caught in the municipality of Pelotas, Rio Grande do Sul, Brazil. The modified agglutination test (MAT) was used to investigate anti-T. gondii antibodies and samples with a cut-off dilution > 5 were considered positive. Among the 100 serum samples analyzed, 80 (80%) were reactive. These results demonstrate that P. domesticus may play an important role in the epidemiological chain of T. gondii, since it is widely distributed throughout Brazil, and may act as a source of infection to domestic and wild felids.(AU)

O objetivo deste estudo foi detectar a presença de anticorpos anti-Toxoplasma gondii em amostras de soro de 100 pardais (Passer domesticus Linnaeus, 1758) capturados na área urbana do município de Pelotas, Rio Grande do Sul, Brasil. Para a pesquisa de anticorpos anti-T. gondii foi utilizado o teste de aglutinação modificado (MAT) e foram consideradas positivas as amostras que apresentaram título > 5. Das 100 amostras de soro analisadas, 80 (80%) foram reagentes. Esses resultados demonstram que P. domesticus, por ser amplamente distribuído em todo país, pode desempenhar um papel importante na cadeia epidemiológica de T. gondii, podendo atuar como fonte de infecção para felinos domésticos e silvestres.(AU)

Serum anti-Toxoplasma gondii antibodies in Passer domesticus (Linnaeus, 1758) (Passeriformes: Passeridae), in the municipality of Pelotas, RS, Brazil / Anticorpos séricos anti-Toxoplasma gondii em pardais, Passer domesticus (Linnaeus, 1758) (Passeriformes: Passeridae), do município de Pelotas, RS, Brasil

The objective of this study was to detect the presence of anti-Toxoplasma gondii antibodies in serum samples from 100 house sparrows (Passer domesticus Linnaeus, 1758) that were caught in the municipality of Pelotas, Rio Grande do Sul, Brazil. The modified agglutination test (MAT) was used to investigate anti-T. gondii antibodies and samples with a cut-off dilution > 5 were considered positive. Among the 100 serum samples analyzed, 80 (80%) were reactive. These results demonstrate that P. domesticus may play an important role in the epidemiological chain of T. gondii, since it is widely distributed throughout Brazil, and may act as a source of infection to domestic and wild felids.(AU)

O objetivo deste estudo foi detectar a presença de anticorpos anti-Toxoplasma gondii em amostras de soro de 100 pardais (Passer domesticus Linnaeus, 1758) capturados na área urbana do município de Pelotas, Rio Grande do Sul, Brasil. Para a pesquisa de anticorpos anti-T. gondii foi utilizado o teste de aglutinação modificado (MAT) e foram consideradas positivas as amostras que apresentaram título > 5. Das 100 amostras de soro analisadas, 80 (80%) foram reagentes. Esses resultados demonstram que P. domesticus, por ser amplamente distribuído em todo país, pode desempenhar um papel importante na cadeia epidemiológica de T. gondii, podendo atuar como fonte de infecção para felinos domésticos e silvestres.(AU)

Evaluation of Argentinean Bird Species as Amplifying Hosts for St. Louis Encephalitis Virus (Flavivirus, Flaviviridae).

St.Louis encephalitis virus (SLEV) is an emerging human pathogen flavivirus in Argentina. Recently, it has reemerged in the United States. We evaluated the role as amplifying host of six resident bird species and analyzed their capacity as host during the 2005 encephalitis outbreak of SLEV in Córdoba. Eared Dove, Picui Ground Dove, and House Sparrow were the three species with highest host competence index. At a city level, Eared Dove and Picui Ground Dove were the most important amplifying hosts during the 2005 SLEV human outbreak in Córdoba city. This finding highlighted important differences in the SLEV ecology between Argentina and the United States. Characterizing and evaluating the SLEV hosts contribute to our knowledge about its ecology and could help us to understand the causes that promote its emergence as a human pathogen in South America.

Reduced West Nile Virus Transmission Around Communal Roosts of Great-Tailed Grackle (Quiscalus mexicanus).

West Nile virus has caused several outbreaks among humans in the Phoenix metropolitan area (Arizona, southwest USA) within the last decade. Recent ecologic studies have implicated Culex quinquefasciatus and Culex tarsalis as the mosquito vectors and identified three abundant passerine birds-great-tailed grackle (Quiscalus mexicanus), house sparrow (Passer domesticus), and house finch (Haemorhous mexicanus)-as key amplifiers among vertebrates. Nocturnal congregations of certain species have been suggested as critical for late summer West Nile virus amplification. We evaluated the hypothesis that house sparrow (P. domesticus) and/or great-tailed grackle (Q. mexicanus) communal roost sites (n = 22 and n = 5, respectively) in a primarily suburban environment were spatially associated with West Nile virus transmission indices during the 2010 outbreak of human neurological disease in metropolitan Phoenix. Spatial associations between human case residences and communal roosts were non-significant for house sparrows, and were negative for great-tailed grackle. Several theories that explain these observations are discussed, including the possibility that grackle communal roosts are protective.

Envelope and pre-membrane protein structural amino acid mutations mediate diminished avian growth and virulence of a Mexican West Nile virus isolate.

The hallmark attribute of North American West Nile virus (WNV) strains has been high pathogenicity in certain bird species. Surprisingly, this avian virulent WNV phenotype has not been observed during its geographical expansion into the Caribbean, Central America and South America. One WNV variant (TM171-03-pp1) isolated in Mexico has demonstrated an attenuated phenotype in two widely distributed North American bird species, American crows (AMCRs) and house sparrows (HOSPs). In order to identify genetic determinants associated with attenuated avian replication of the TM171-03-pp1 variant, chimeric viruses between the NY99 and Mexican strains were generated, and their replicative capacity was assessed in cell culture and in AMCR, HOSP and house finch avian hosts. The results demonstrated that mutations in both the pre-membrane (prM-I141T) and envelope (E-S156P) genes mediated the attenuation phenotype of the WNV TM171-03-pp1 variant in a chicken macrophage cell line and in all three avian species assayed. Inclusion of the prM-I141T and E-S156P TM171-03-pp1 mutations in the NY99 backbone was necessary to achieve the avian attenuation level of the Mexican virus. Furthermore, reciprocal incorporation of both prM-T141I and E-P156S substitutions into the Mexican virus genome was necessary to generate a virus that exhibited avian virulence equivalent to the NY99 virus. These structural changes may indicate the presence of new evolutionary pressures exerted on WNV populations circulating in Latin America or may signify a genetic bottleneck that has constrained their epiornitic potential in alternative geographical locations.

Comparison of argentinean saint louis encephalitis virus non-epidemic and epidemic strain infections in an avian model.

St. Louis encephalitis virus (SLEV, Flavivirus, Flaviviridae) is an emerging mosquito-borne pathogen in South America, with human SLEV encephalitis cases reported in Argentina and Brazil. Genotype III strains of SLEV were isolated from Culex quinquefasciatus mosquitoes in Cordoba, Argentina in 2005, during the largest SLEV outbreak ever reported in South America. The present study tested the hypothesis that the recent, epidemic SLEV strain exhibits greater virulence in birds as compared with a non-epidemic genotype III strain isolated from mosquitoes in Santa Fe Province 27 years earlier. The observed differences in infection parameters between adult House sparrows (Passer domesticus) that were needle-inoculated with either the epidemic or historic SLEV strain were not statistically significant. However, only the House sparrows that were infected with the epidemic strain achieved infectious-level viremia titers sufficient to infect Cx. spp. mosquitoes vectors. Furthermore, the vertebrate reservoir competence index values indicated an approximately 3-fold increase in amplification potential of House sparrows infected with the epidemic strain when pre-existing flavivirus-reactive antibodies were present, suggesting the possibility that antibody-dependent enhancement may increase the risk of avian-amplified transmission of SLEV in South America.

Cotton rats and house sparrows as hosts for North and South American strains of eastern equine encephalitis virus.

Eastern equine encephalitis virus (EEEV; family Togaviridae, genus Alphavirus) is an arbovirus that causes severe disease in humans in North America and in equids throughout the Americas. The enzootic transmission cycle of EEEV in North America involves passerine birds and the ornithophilic mosquito vector, Culiseta melanura, in freshwater swamp habitats. However, the ecology of EEEV in South America is not well understood. Culex (Melanoconion) spp. mosquitoes are considered the principal vectors in Central and South America; however, a primary vertebrate host for EEEV in South America has not yet been identified. Therefore, to further assess the reservoir host potential of wild rodents and wild birds, we compared the infection dynamics of North American and South American EEEV in cotton rats (Sigmodon hispidus) and house sparrows (Passer domesticus). Our findings suggested that each species has the potential to serve as amplification hosts for North and South America EEEVs.