Evidence of Previous Avian Influenza Infection among US Turkey Workers

Abstract

The threat of an influenza pandemic is looming, with new cases of sporadic avian influenza infections in man frequently reported. Exposure to diseased poultry is a leading risk factor for these infections. In this study, we used logistic regression to investigate serological evidence of previous infection with avian influenza subtypes H4, H5, H6, H7, H8, H9, H10, and H11 among 95 adults occupationally exposed to turkeys in the US Midwest and 82 unexposed controls. Our results indicate that farmers practising backyard, organic or free-ranging turkey production methods are at an increased risk of infection with avian influenza. Among these farmers, the adjusted odds ratios (ORs) for elevated microneutralization assay titres against avian H4, H5, H6, H9, and H10 influenza strains ranged between 3.9 (95% CI 1.2-12.8) and 15.3 (95% CI 2.0-115.2) when compared to non-exposed controls. The measured ORs were adjusted for antibody titres against human influenza viruses and other exposure variables. These data suggest that sometime in their lives, the workers had been exposed to low pathogenicity avian influenza viruses. These findings support calls for inclusion of agricultural workers in priority groups in pandemic influenza preparedness efforts. These data further support increasing surveillance and other preparedness efforts to include not only confinement poultry facilities, but more importantly, also small scale farms.

H6 Influenza Viruses Pose a Potential Threat to Human Health

“…Although human influenza virus genes have not yet been detected in H6 viruses, one cannot rule out the possibility that such reassortment will occur in the future. The 2009/H1N1 pandemic virus is still circulating in humans and pigs around the world (75)(76)(77)(78), and H6 virus infection of pigs and humans has been recorded in different geographic areas (28,29,79,80). Clearly, the possibility exists for H6 reassortants that are transmissible by respiratory droplet in mammals to be generated by deriving genes from transmissible human influenza viruses.…”

Genetics, Receptor Binding, and Virulence in Mice of H10N8 Influenza Viruses Isolated from Ducks and Chickens in Live Poultry Markets in China

“…There have been several reports of human infections caused by H10 viruses (11,15,21), but only the H10N8 virus has thus far caused fatal outcomes (21). To understand the virulence of the H10N8 viruses in mammals, we tested the replication and lethality of the eight viruses in mice.…”

“…Since then, viruses bearing H10 HA and different neuraminidase (NA) subtypes have been widely detected in wild birds and domestic poultry around the world (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19). Moreover, an H10N4 virus caused an outbreak of a respiratory disease in mink in Sweden in 1984 (20), and more recently, several U.S. turkey workers tested seropositive for H10 influenza virus (15). In March 2010, an H10N7 virus caused an outbreak on a chicken farm in Australia; after processing clinically normal birds from the farm, seven abattoir workers reported conjunctivitis and minor upper respiratory tract symptoms and H10 virus infection was detected in two of the seven workers (11).…”

Sensitivity and Specificity Estimation for the Clinical Diagnosis of Highly Pathogenic Avian Influenza in the Egyptian Participatory Disease Surveillance Program

“…29 Avian influenza A(H6N1) viruses commonly circulate in domestic bird populations in the region 30 and throughout the world. Although previous serological studies have documented antibodies to influenza A(H6) in humans 31,32,33 this is the first report of a symptomatic human infection with an avian influenza A(H6N1) virus. Taipei CDC reported that the genome sequence of the virus isolated from the case was highly similar to avian influenza A(H6N1) viruses circulating in local domestic poultry.…”

“…29 Des virus de la grippe aviaire A(H6N1) circulent couramment dans les populations d'oiseaux domestiques de la région 30 et dans le monde entier. Bien que des études sérologiques anté-rieures aient attesté la présence d'anticorps contre la grippe A(H6) chez l'homme, 31,32,33 c'est le premier rapport d'une infection humaine symptomatique avec un virus de la grippe aviaire A(H6N1). Les CDC de Taipei ont indiqué que la séquence géno-mique du virus isolé à partir du cas était très similaire à celle des virus de la grippe aviaire A(H6N1) en circulation chez les volailles domestiques locales.…”