Presence of antibodies against H5, H7 and H9 influenza A virus in wild birds in the State of São Paulo, Brazil

E De Sousa,T P Costa,Aa Pinto,Cs Ferreira,K Werther,J De Araujo,El Durigon

doi:10.1590/s1516-635x2013000300001

E De Sousa, T P Costa + Show 5 more

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https://doi.org/10.1590/s1516-635x2013000300001

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Abstract

Although the natural reservoirs of the avian influenza (AI) virus have been extensively studied in many countries, there is a clear lack of information on this subject in South America, particularly in Brazil. The objective of this study was to conduct a serological survey for H5, H7 and H9 antibodies to AI-subtype viruses in wild birds in the state of São Paulo , Brazil. Serum samples were tested using the hemagglutination-inhibition assay. Out of the 31 wild birds sampled between January and December of 2006, seven (22.58%), were seropositive for H5, H7 and H9; four (12.90%) were seropositive for H5 and H7; 13 (41.94%), were seropositive only for H7; three (9.7%), were seropositive only for H9; and four (12.90%) were negative for all three hemagglutinin subtypes. These results indicate that AI viruses belonging to H5, H7 and H9 subtypes circulate among wild birds in the state of São Paulo in the form of either concurrent or consecutive infections. This study contributes to the knowledge of AI epidemiology in Brazil, and stresses the need of further detailed and long-term epidemiological and ecological investigation to determine the current status of this virus.

Highlights

Influenza virus type A of bird origin, called avian influenza (AI) virus, has been implicated in endemic infections and outbreaks in poultry and wild birds and in human infection and fatalities, as well as in important economic losses (Martins, 2001; Mcleod, 2008; Moraes et al, 2009; Malik, 2009; Lupiani & Reddy, 2009; Kalthoff et al, 2010)
AI viruses are further classified into low pathogenic AI (LPAI) or highly pathogenic AI (HPAI) viruses according to their ability to cause illness and death of 4- to 6-week-old chickens infected intravenously and/or the presence of multiple basic amino acids at the cleavage site of the H molecule (World Organisation For Animal Health Avian Influenza, 2009)
Only H5 and H7 AI viruses have been identified as HPAI, and these viruses have been responsible for outbreaks in many countries, causing the death of many thousands of domestic poultry and wild birds (Capua & Alexander, 2004; Kalthoff et al, 2010)

Summary

Introduction

Influenza virus type A of bird origin, called avian influenza (AI) virus, has been implicated in endemic infections and outbreaks in poultry and wild birds and in human infection and fatalities, as well as in important economic losses (Martins, 2001; Mcleod, 2008; Moraes et al, 2009; Malik, 2009; Lupiani & Reddy, 2009; Kalthoff et al, 2010). Only H5 and H7 AI viruses have been identified as HPAI, and these viruses have been responsible for outbreaks in many countries, causing the death of many thousands of domestic poultry and wild birds (Capua & Alexander, 2004; Kalthoff et al, 2010). In 1999, an H9N2 AI virus was implicated in human infections in Asia, suggesting a pandemic threat related to this virus (Lin et al, 2000; Peiris et al, 1999)

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