Epizootiology of Avian Influenza: Simultaneous Monitoring of Sentinel Ducks and Turkeys in Minnesota

Abstract

Isolation-reared mallards (Anas platyrhynchos) were placed on ponds in turkey-rearing areas in Minnesota, and their cloacae were periodically swabbed to attempt isolating virus from embryonated chicken eggs. Nearby turkeys were sampled by taking cloacal and tracheal swabs as well as blood samples. Hemagglutinating viruses were identified at the National Veterinary Services Laboratory, U.S. Department of Agriculture, Ames, Iowa. During this two-year study, the weekly influenza virus-isolation rate from ducks varied from 0 to 24.4%. A total of 213 influenza viruses were isolated from the ducks. Twenty-six influenza virus subtypes were detected. Ninety-seven flocks of turkeys were diagnosed as having influenza by virus isolation and/or serology. Eight influenza virus subtypes were involved in the turkey outbreaks, and seven of these were also detected in the ducks and/or other avian species. The weekly infection rate of the sentinel ducks correlated directly with observations of wild ducks at the monitoring sites. Influenza virus was isolated from water samples collected near the sentinel duck sites during the study.

Detection of Influenza A viruses at migratory bird stopover sites in Michigan, USA

“…Only 5% of the 210 water samples tested in this study were positive by RT-qRT-PCR for the Influenza A matrix gene. Similar studies have documented higher detection rates in water samples, though reported prevalence varies widely by study, and in some cases with higher detection rates the water samples were collected near trapped sentinel birds or domestic ducks [43–45,49]. The prevalence of influenza positive fecal samples in this study is similar to other studies of environmentally collected fecal samples in North America [20,48,50].…”

“…Since then, other researchers have attempted to isolate or detect avian influenza viruses in environmental samples for the purposes of surveillance. In North America, Influenza A has been detected in water samples collected in Minnesota, Alaska, Oklahoma, and California [20,45–48]. Only 5% of the 210 water samples tested in this study were positive by RT-qRT-PCR for the Influenza A matrix gene.…”

“…At these temperatures, intact influenza virus could persist, enabling detection of virus particles deposited in the environment by transient waterfowl. Other studies have found increased detection rates in environmental water and fecal samples during fall months [21,45,61]. …”

Pathogenesis in Eurasian Tree Sparrows Inoculated with H5N1 Highly Pathogenic Avian Influenza Virus and Experimental Virus Transmission from Tree Sparrows to Chickens

“…In tests conducted in the U.S. in 1980-81, when mallards that had tested negative were put together with turkeys, virus (H4N8, H4N2, H5N2) was isolated from the mallards before or at the same time that avian influenza of the same type viruses was detected in the turkeys. However, there were also cases in which, though detected in the turkeys, the virus was not detected in the mallards (Halvorson et al, 1983). In Cambodia, H5N1 virus was first detected at the Wildlife Rescue Center (combined with the zoo) in the suburbs of Phnom Penh in December 2003.…”

Outbreaks of avian influenza H6N2 viruses in chickens arose by a reassortment of H6N8 and H9N2 ostrich viruses

“…The virus was initially typed as a low pathogenic avian influenza (LPAI) H6N2 strain at the VLA Weybridge laboratory, UK. In South Africa, testing of archival material from the same region traced the infection back to June 2001, but the exact source of the H6N2 outbreak was never determined.Most outbreaks ofAI in domestic poultry are thought to have originated by the transfer of viruses from feral birds [1,2]. Chickens are generally not considered to be natural hosts for AI viruses and H6 viruses have never been associated with serious disease in poultry.…”