Understanding the role of fomites – which include dust, dander and feathers – and other factors in the transmission of HPAI in commercial poultry will be critical to preventing the virus and stopping the current outbreak.
Research indicates that feathers – and feather pulp, in particular – can contain high levels of HPAI. Numerous French studies are focusing on the link between HPAI transmission and feather pulp.
“In growing feathers, cells inside the feather shaft are full of virus. The feather shaft seems to help protect it,” said Dr. Erica Spackman, distinguished senior research scientist, Exotic and Emerging Avian Viral Diseases unit, U.S. National Poultry Research Center, U.S. Department of Agriculture (USDA)-Agricultural Research Center (ARS).
Feathers are lightweight and appear to float in the air, although more research is needed to learn about how long the virus lives in feathers before full transmissibility is known, she added.
During “What we know about HPAIV transmission,” a Poultry Science Association webinar, Spackman discussed several potential transmission HPAI pathways among poultry hosts and farms.
Host level transmission
When most people think of HPAI transmission, they think about host level transmission.
Influenza A is a “promiscuous” virus, meaning that it can infect most species. Broiler chickens aren’t a natural host for influenza A because they shed the virus for a shorter duration of time compared to ducks and other avian species. However, the current strain is circulation is much more infectious for chickens and turkeys than in past outbreaks, Spackman said.
Environmental transmission
When it comes to HPAI transmission between species – between wild birds and commercial poultry or between poultry and dairy cattle – the environmental may be a factor, although more research is needed before definitive conclusions can be drawn either way, she noted
Airborne could be a source of HPAI transmission, although it can be hard to control and test for HPAI in air samples. So far, experimental data indicates that airborne transmission of HPAI between chickens is low. Absolute humidity could matter, added Spackman. Higher humidity slows transmission of virus. Overall, preliminary research shows that HPAI cannot spread very far outside a poultry house via airborne transmission.
HPAI is also unlikely to be spread via soil, feed, water or manure. Although HPAI can survive for limited amount of time on these objects, it appears that its infectiousness diminishes quickly on all four. Water is the most likely to serve as a disease vector, especially at warmer temperatures, Spackman said.
View our continuing coverage of the global avian influenza situation.
To learn more about HPAI cases in commercial poultry flocks in the United States, Mexico and Canada, see an interactive map on WATTPoultry.com.
