A within-host mathematical model of H9N2 avian influenza infection and type-I interferon response pathways in chickens.

Chickens infected with avian influenza virus (AIV) transmit the virus via respiratory and cloacal shedding. While previous mathematical models have shown that the innate immune response is necessary for the early suppression of virus production in infected respiratory cells, the different pathways by which the innate immune response can affect cloacal viral shedding have not been studied in chickens. The present study aims to evaluate the sensitivity of H9N2 low pathogenic AIV shedding in chicken gastrointestinal cells to different type-I interferon (IFN) response pathways, and to determine the impact of a cellular eclipse phase (latent period) on the time to peak virus shedding using a mathematical model describing within host viral kinetics. Our model results demonstrate that a mechanistic model that incorporates 1) the intracellular antiviral effects of type-I IFN on virus production, 2) destruction of infected cells by type-I IFN activated Natural Killer cells, and 3) an eclipse phase is most consistent with experimental cloacal virus shedding data. These results provide a potential mechanistic explanation for the delay to peak cloacal virus shedding observed in experimental studies conducted in chickens, as well as an improved understanding of the primary type-I IFN pathways involved in the control of cloacal virus shedding, which may lead to the development of more targeted vaccine candidates.

Seroprevalence of antibodies against highly pathogenic avian influenza A (H5N1) virus among poultry workers in Bangladesh, 2009.

We conducted a cross-sectional study in 2009 to determine the seroprevalence and risk factors for highly pathogenic avian influenza A (H5N1) [HPAI H5N1] virus antibodies among poultry workers at farms and live bird markets with confirmed/suspected poultry outbreaks during 2009 in Bangladesh. We tested sera by microneutralization assay using A/Bangladesh/207095/2008 (H5N1; clade 2.2.2) virus with confirmation by horse red blood cell hemagglutination inhibition and H5-specific Western blot assays. We enrolled 212 workers from 87 farms and 210 workers from three live bird markets. One hundred and two farm workers (48%) culled poultry. One hundred and ninety-three farm workers (91%) and 178 market workers (85%) reported direct contact with poultry that died during a laboratory confirmed HPAI H5N1 poultry farm outbreak or market poultry die-offs from suspected HPAI H5N1. Despite exposure to sick poultry, no farm or market poultry workers were seropositive for HPAI H5N1 virus antibodies (95% confidence interval 0-1%).

Epidemiology, geographical distribution, and economic consequences of swine zoonoses: a narrative review.

We sought to review the epidemiology, international geographical distribution, and economic consequences of selected swine zoonoses. We performed literature searches in two stages. First, we identified the zoonotic pathogens associated with swine. Second, we identified specific swine-associated zoonotic pathogen reports for those pathogens from January 1980 to October 2012. Swine-associated emerging diseases were more prevalent in the countries of North America, South America, and Europe. Multiple factors were associated with the increase of swine zoonoses in humans including: the density of pigs, poor water sources and environmental conditions for swine husbandry, the transmissibility of the pathogen, occupational exposure to pigs, poor human sanitation, and personal hygiene. Swine zoonoses often lead to severe economic consequences related to the threat of novel pathogens to humans, drop in public demand for pork, forced culling of swine herds, and international trade sanctions. Due to the complexity of swine-associated pathogen ecology, designing effective interventions for early detection of disease, their prevention, and mitigation requires an interdisciplinary collaborative "One Health" approach from veterinarians, environmental and public health professionals, and the swine industry.