Prevalence of attibodies against influenza viru in non-vaccinated equines fromm the Brazilian pantaall / Prevalência de anticorpos contra o vírus da Influenza em equinos não vacinados do Pantanal Brasileiro

The prevalence of antibodies against Equine Influenza Virus (EIV) was determined in 529 equines living on ranches in the municipality of Poconé, Pantanal area of Brazil, by means of the hemagglutination inhibition test, using subtype H3N8 as antigen. The distribution and possible association among positive animal and ranches were evaluated by the chi-square test, spatial autoregressive and multiple linear regression models. The prevalence of antibodies against EIV was estimated at 45.2% (95% CI 30.2 - 61.1%) with titers ranging from 20 to 1,280 HAU. Seropositive equines were found on 92.0% of the surveyed ranches. Equine from non-flooded ranches (66.5%) and negativity in equine infectious anemia virus (EIAV) (61.7%) were associated with antibodies against EIV. No spatial correlation was found among the ranches, but the ones located in non-flooded areas were associated with antibodies against EIV. A negative correlation was found between the prevalence of antibodies against EIV and the presence of EIAV positive animals on the ranches. The high prevalence of antibodies against EIV detected in this study suggests that the virus is circulating among the animals, and this statistical analysis indicates that the movement and aggregation of animals are factors associated to the transmission of the virus in the region.

A prevalência de anticorpos para o vírus da Influenza Equina (VIE) no município de Poconé, MT. foi determinada em 529 equídeos pela técnica de Inibição da hemaglutinação utilizando como antígeno a variante H3N8 (SP/1/85). A distribuição da positividade e possíveis associações entre os animais e as propriedades foram avaliadas pelo teste do Qui-quadrado e pelos modelos espacial autoregressivo misto e de regressão linear múltipla. A prevalência de anticorpos para o VIE no município de Poconé foi estimada em 45,2% (IC 95% 30,2 - 61,1%) com títulos variando entre 20 e 1280UIH. Das fazendas analisadas 23 (92,0%) apresentaram animais soropositivos. Animais de fazendas não alagadas (66,5%) e negativos para Anemia Infecciosa Equina (AIE) (61,7%) foram associados a soropositividade. Não houve correlação espacial entre as fazendas estudadas, entretanto aquelas localizadas nas áreas não alagadas foram associadas à infecção. Observou-se correlação negativa entre a prevalência de anticorpos para o VIE e a presença de animais positivos para AIE nas propriedades. A elevada prevalência de anticorpos para o VIE detectada neste estudo sugere circulação viral ativa entre os animais, e as análises estatísticas indicam que o trânsito e aglomeração animal são fatores associados à transmissão do vírus na região.

Presence of resiiratory viruses in equines in Brazil / Presença de vírus respiratórios em equinos do Brasil

Equines are susceptible to respiratory viruses such as influenza and parainfluenza. Respiratory diseases have adversely impacted economies all over the world. This study was intended to determine the presence of influenza and parainfluenza viruses in unvaccinated horses from some regions of the state of São Paulo, Brazil. Blood serum collected from 72 equines of different towns in this state was tested by hemagglutination inhibition test to detect antibodies for both viruses using the corresponding antigens. About 98.6% (71) and 97.2% (70) of the equines responded with antibody protective titers (≥ 80 HIU/25µL) H7N7 and H3N8 subtypes of influenza A viruses, respectively. All horses (72) also responded with protective titers (≥ 80) HIU/25µL against the parainfluenza virus. The difference between mean antibody titers to H7N7 and H3N8 subtypes of influenza A viruses was not statistically significant (p > 0.05). The mean titers for influenza and parainfluenza viruses, on the other hand, showed a statistically significant difference (p < 0.001). These results indicate a better antibody response from equines to parainfluenza 3 virus than to the equine influenza viruses. No statistically significant differences in the responses against H7N7 and H3N8 subtypes of influenza A and parainfluenza 3 viruses were observed according to the gender (female, male) or the age (≤ 2 to 20 years-old) groups. This study provides evidence of the concomitant presence of two subtypes of the equine influenza A (H7N7 and H3N8) viruses and the parainfluenza 3 virus in equines in Brazil. Thus, it is advisable to vaccinate equines against these respiratory viruses.

Os equinos são susceptíveis aos vírus respiratórios, como o vírus influenza, e também tem sido citado o vírus parainfluenza. Doenças respiratórias têm impactado a economia em todo mundo. Este estudo intencionou determinar a presença dos vírus influenza e parainfluenza em equinos não vacinados de certas regiões do Estado de São Paulo, Brasil. Os soros coletados de 72 equinos, de diferentes cidades deste Estado, foram submetidos ao teste de Inibição da Hemaglutinação (IH) com objetivo de detectar anticorpos contra os referidos vírus, usando antígenos correspondentes. Cerca de 98,8% (72) e 97,2% (70) desses equinos responderam com títulos protetores (≥ 80 UIH/25µL) para os subtipos H7N7 e H3N8 de vírus influenza, respectivamente. Todos equinos (72) responderam com títulos protetores (≥ 80 UIH/25µL) contra o vírus parainfluenza 3. A diferença entre as médias de anticorpos contra o vírus influenza A não foi estatisticamente significante (p > 0,05). As médias de títulos dos vírus influenza e parainfluenza, por outro lado, demonstraram diferença estatisticamente significante (p < 0,001). Esses resultados indicam melhor resposta de anticorpos pelos equinos ao vírus parainfluenza 3 do que ao vírus da influenza equina. Nenhuma diferença estatística foi observada nas respostas contra os vírus da influenza equina A (H7N7 e H3N8) e parainfluenza 3, com relação ao gênero (fêmeas e machos) e grupo etário (≤ 2 até 20 anos) nos equinos avaliados. Este estudo fornece evidência da presença concomitante dos dois subtipos vírus influenza A (H7N7 e H3N8) e do parainfluenza 3 em cavalos no Brasil. Portanto, é aconselhável a vacinação dos cavalos contra esses vírus respiratórios.

Influenza A virus infection of healthy piglets in an abattoir in Brazil: animal-human interface and risk for interspecies transmission

Asymptomatic influenza virus infections in pigs are frequent and the lack of measures for controlling viral spread facilitates the circulation of different virus strains between pigs. The goal of this study was to demonstrate the circulation of influenza A virus strains among asymptomatic piglets in an abattoir in Brazil and discuss the potential public health impacts. Tracheal samples (n = 330) were collected from asymptomatic animals by a veterinarian that also performed visual lung tissue examinations. No slaughtered animals presented with any noticeable macroscopic signs of influenza infection following examination of lung tissues. Samples were then analysed by reverse transcription-polymerase chain reaction that resulted in the identification of 30 (9%) influenza A positive samples. The presence of asymptomatic pig infections suggested that these animals could facilitate virus dissemination and act as a source of infection for the herd, thereby enabling the emergence of influenza outbreaks associated with significant economic losses. Furthermore, the continuous exposure of the farm and abattoir workers to the virus increases the risk for interspecies transmission. Monitoring measures of swine influenza virus infections and vaccination and monitoring of employees for influenza infection should also be considered. In addition regulatory agencies should consider the public health ramifications regarding the potential zoonotic viral transmission between humans and pigs.

Influenza viruses in adult dogs raised in rural and urban areas in the state of São Paulo, Brazil / Incidência do vírus influenza em cães adultos criados em áreas rural e urbana do estado de São Paulo, Brasil

In 1970, searching for the interspecies transmission of influenza viruses led to the first study on influenza viruses in domestic animals. Birds and mammals, including human beings, are their natural hosts; however, other animals may also play a role in the virus epidemiology. The objective was to investigate the incidence of influenza viruses in adult dogs raised in rural (9, 19.56%) and urban (37, 80.43%) areas in the state of São Paulo, Brazil. Dog serum samples were examined for antibodies to influenza viruses by the hemagglutination inhibition (HI) test using the corresponding antigens from the circulating viruses in Brazil. Dogs from rural areas presented antibodies to influenza A H3N2, and influenza A H7N7 and H3N8. In rural areas, dog sera displayed mean titers as 94.37, 227.88, 168.14, 189.62 HIU/25 µL for subtypes H1N1, H3N2, H7N7, H3N8, respectively. About 84% and 92% of dogs from urban areas exhibited antibodies to human influenza A H1N1 and H3N2, respectively, with statistical difference at p < 0.05 between the mean titers of antibodies to H1N1 and H3N2. About 92% and 100% were positive for H7N7 and H3N8, respectively. In dogs from urban areas, the mean titers of antibodies against influenza A H1N1, H3N2, H7N7 and H3N8, were 213.96, 179.42, 231.76, 231.35 HIU/25 µL respectively. The difference among them was not statistically significant at p > 0.05. In conclusion, these dogs were positive for both human and equine influenza viruses. The present study suggests the first evidence that influenza viruses circulate among dogs in Brazil.

A transmissão interespecífica do vírus influenza é relatada em estudo sobre influenza com animais domésticos desde 1970. Pássaros e mamíferos, incluindo o homem, são seus hospedeiros naturais, porém outros animais podem participar da sua epidemiologia. Foi investigada a incidência do vírus influenza em cães adultos criados em zonas rural (9, 19,56%) e urbana (37, 80,43%), do Estado de São Paulo. Os soros dos cães foram examinados pelo teste de inibição da hemaglutinação (IH), usando antígeno dos vírus influenza circulantes no Brasil. Nos cães rurais foram detectados títulos médios de 94,37, 227,88, 168,14 e 189,62 UIH/25 mL (unidades inibidoras de hemaglutinação/25 mL) para os subtipos H1N1, H3N2, H7N7, H3N8 de vírus influenza A, respectivamente, com diferenças estatisticamente significativas (p<0,05) entre as médias de títulos de anticorpos contra H1N1 e H3N2. Cerca de 84% e 92% dos cães urbanos responderam aos vírus influenza A humano H1N1 e H3N2, respectivamente e destes 92% e 100% foram positivos para os vírus eqüinos H7N7 e H3N8, respectivamente. Para esses cães as médias de títulos de anticorpos para os vírus influenza A H1N1, H3N2, H7N7 e H3N8 foram 213,96, 179,42, 231,76 e 231,35UIH/25 mL, respectivamente. As diferenças entre as médias não foram estatisticamente significativas (p>0,05). Conclui-se que os cães apresentaram positividade para ambos vírus influenza humano e equino. O presente estudo sugere, pela primeira vez, evidências de que há circulação do vírus influenza em cães, no Brasil.

Prevalencia serológica del virus de influenza A en cerdos en Argentina durante la temporada 2002: evaluación mediante inhibición de la hemaglutinación y ELISA / Seroprevalence of the swine Influenza virus in fattening pigs in Argentina in the 2002 season: evaluation by hemagglutination-inhibition and ELISA tests

Se evaluó la prevalencia serológica del virus de influenza mediante las pruebas de inhibición de la hemaglutinación (IHA) y ELISA para los subtipos H1N1 y H3N2 en 13 granjas porcinas de Argentina. Se compararon los resultados obtenidos mediante ambas pruebas en términos individuales y de establecimientos. La prevalencia individual por la técnica de IHA fue de 38,46% a 100% para H1 y de 7,69% a 100% para H3. Por la técnica de ELISA, la prevalencia individual fue de 2,33% a 6,9% para H1 y de 9,65% a 48% para H3. No se observaron diferencias significativas entre ambas técnicas a escala de granja (H1: p=0,20; H3: p=0,11). La concordancia entre las pruebas fue nula al tomar como unidad de referencia el animal (H1: 0,005; H3: 0,070), mientras que en términos de establecimiento fue escasa (H1: 0,350; H3: 0,235). Considerando la alta prevalencia individual obtenida por la prueba de IHA y la alta sensibilidad de esta técnica, se podría sugerir que en las poblaciones porcinas de la Argentina circularon cepas virales humanas o cepas porcinas con gran proximidad filogenética a las utilizadas en este estudio desde el año 2002.

The seroprevalence of the Influenza virus against H1N1 and H3N2 was determined by the hemagglutination-inhibition test (HI) and a commercial swine influenza ELISA kit, in 13 Argentinean swine herds. The results of within-herd and between-herd prevalence obtained by both tests were statistically correlated. The within-herd prevalence observed by the HI test varied from 38.46 to 100% against H1 and 7.69 to 100% for H3. When the within-herd prevalence was measured with the ELISA test, it varied from 2.33 to 6.9% for H1 and 9.65 to 48% for H3. No statistical differences were observed at herd level between HI and ELISA (H1: p = 0. 20; H3: p=0.11). No agreement between HI and ELISA detected prevalence was observed when the within-herd prevalence was compared (H1: 0.005; H3: 0.070), while the agreement at herd level was considered poor (H1: 0,350; H3: 0,235). The high within-herd prevalence values observed with the HI test and the high sensibility of this test might show that human strains or swine strains phylogenetically closely related to the humans strains used in the HI test in this study have been affecting the swine population since 2002.

The spread of avian influenza H5N1 virus; a pandemic threat to mankind.

Influenza A H5N1 virus infection presents a major public health problem in Asian and Eurasian countries. The World Health organization has voiced their concerns about a potential pandemic with the imminent threat to humankind. In 1997, an outbreak of highly pathogenic H5N1 virus emerged and caused severe systemic disease among poultry and humans in Hong Kong. This article reviews the magnitude of the 2004-2006 outbreaks in various countries and highlights the highly pathogenic avian influenza (HPAI) subtype H5N1 virus as the cause of a major epidemic with potentially vast repercussions on economics, public health and society at large. Not only has this avian influenza (AI) virus infected poultry but has also proven highly pathogenic and fatal to mammalian species including humans and felines. The present review draws a comprehensive picture encompassing epidemiology, inter-species transmission and genetic characterization of this highly virulent virus. Moreover, laboratory diagnostic techniques, vaccination strategies and antiviral therapies aimed at outbreak control and management are also discussed.

ELISA indirecto para el diagnóstico rápido de Influenza Equina / Indirect ELISA for the rapid diagnosis of Equine Influenza

An indirect enzyme linked immunosorbent assay was developed. Infected and non infected allantoic fluids precipitated with polyetilenglycol 6000 were used as antigen and control antigen, respectively. Serum samples were diluted 1/20 and a commercial horse radish peroxidase-labelled rabbit anti-equine IgG was used as second antibody. The reaction was developed using azino-diethylbenzotyazol-sulfonate (ABTS). Cut-off was determined by ratio sample (Rs). The hemagglutination inhibition test was used as a reference test for the 391 samples analyzed. Of these, 301 sera were positive by hemagglutination inhibition test and indirect ELISA, 75 were negative by both techniques, and 15 were positive by indirect ELISA and negative by hemagglutination inhibition test. Using hemagglutination inhibition test as standard, the indirect ELISA showed a relative specificity and sensitivity of 83.3 and 100, respectively. This indirect ELISA is useful as screening test.