Evidence of transmission and risk factors for influenza A virus in household dogs and their owners.

BACKGROUND: The possible transmission of influenza A virus between dogs and humans is important, as in Mexico City there are approximately 1·2 million dogs. We present the first evidence of influenza A virus infection in household dogs in Mexico. OBJECTIVES: The objective of this study was to identify the presence of antibodies against influenza A virus in dogs and their owners, as well as the presence of RNA of influenza A virus in nasal exudates of dogs and, thereby, assess the possible transmission of the virus between humans and dogs. METHODS: Serum samples from household dogs and their owners were analyzed to detect the presence of antibodies against three subtypes of human influenza virus (H1N1pdm09, H1N1, and H3N2), as well as subtype H3N8 of equine influenza. We analyzed dog nasal exudates to detect influenza viral RNA. The relationship between the seropositivity of dogs and various factors (age, sex, constantly at home, and seropositivity of owners) was statistically analyzed. RESULTS: Seroprevalence for human influenza in dogs was 0·9% (1 of 113), and it was 4% (5 of 113) for equine influenza. In humans, seroprevalence was 22% for subtype H1N1pdm09, 20% for subtype H1N1, and 11% for subtype H3N2. No significant association (P>0·05) was found between seropositivity and any of the assessed factors. Furthermore, no viral RNA was detected in the nasal exudate samples. CONCLUSIONS: Results revealed seroprevalence of the influenza virus in household dogs in Mexico City. It can be assumed that dogs are currently becoming infected with different subtypes of influenza viruses.

Retrospective serological survey of influenza viruses in backyard pigs from Mexico City.

BACKGROUND: In the present study, we analyzed the presence of antibodies to four different influenza viruses (pH1N1, hH1N1, swH1N1, and swH3N2) in the sera of 2094 backyard pigs from Mexico City. The sera were obtained between 2000 and 2009. OBJECTIVES: The aim of this study was to perform a retrospective analysis of the 2000-2009 period to determine the seroprevalence of antibodies against pH1N1, hH1N1, swH1N1, and swH3N2 viruses in sera obtained from backyard pigs in Mexico City. METHODS: Antibody detection was conducted with hemagglutination inhibition assay (HI) using four influenza viruses. We used linear regression to analyze the tendency of antibody serum titers throughout the aforementioned span. RESULTS: We observed that the antibody titers for the pH1N1, swH1N1, and swH3N2 viruses tended to diminish over the study period, whereas the antibodies to hH1N1 remained at low prevalence for the duration of the years analyzed in this study. A non-significant correlation (P > 0.05) between antibody titers for pH1N1 and swH1N1 viruses was observed (0.04). It contrasts with the significance of the correlation (0.43) observed between the swH1N1 and swH3N2 viruses (P < 0.01). CONCLUSIONS: Our findings showed no cross-antigenicity in the antibody response against the same subtype. Antibodies against pH1N1 virus were observed throughout the 10-year study span, implying that annual strains shared some common features with the pH1N1 virus since 2000, which would then be capable of supporting the ongoing presence of these antibodies.

Adenoviruses C in non-hospitalized Mexican children older than five years of age with acute respiratory infection.

Adenoviruses (AdV) are commonly involved in acute respiratory infections (ARI), which cause high morbidity and mortality in children. AdV are grouped in six species (A-F), which are associated with a wide range of diseases. The aim of this study was to identify the AdV species infecting non-hospitalized Mexican children with ARI symptoms, attending to the same school. For that, a PCR/RFLP assay was designed for a region of the hexon gene, which was chosen, based on the bioinformatical analysis of AdV genomes obtained from GenBank. A total of 100 children's nasopharyngeal samples were collected from January to June, 2005, and used for viral isolation in A549 cells and PCR/RFLP analysis. Only 15 samples produced cytopathic effect, and in all of them AdV C was identified. AdV C was also identified in eight additional nasopharyngeal samples which were negative for viral isolation. In summary, this outpatient population showed a rate of AdV infection of 23%, and only AdV C was detected.

Adenoviruses C in non-hospitalized Mexican children older than five years of age with acute respiratory infection

Adenoviruses (AdV) are commonly involved in acute respiratory infections (ARI), which cause high morbidity and mortality in children. AdV are grouped in six species (A-F), which are associated with a wide range of diseases. The aim of this study was to identify the AdV species infecting non-hospitalized Mexican children with ARI symptoms, attending to the same school. For that, a PCR/RFLP assay was designed for a region of the hexon gene, which was chosen, based on the bioinformatical analysis of AdV genomes obtained from GenBank. A total of 100 children's nasopharyngeal samples were collected from January to June, 2005, and used for viral isolation in A549 cells and PCR/RFLP analysis. Only 15 samples produced cytopathic effect, and in all of them AdV C was identified. AdV C was also identified in eight additional nasopharyngeal samples which were negative for viral isolation. In summary, this outpatient population showed a rate of AdV infection of 23 percent, and only AdV C was detected.