What is AIV?
The virus is common in ducks, shorebirds, gulls and other seabirds although it usually does not cause obvious signs of disease. Chickens and turkeys are also susceptible to infection with the virus. Most cases cause only mild symptoms and slight decreases in productivity. However, some AIV types can cause rapid death in domestic birds. The virus is transmitted to birds through inhalation of influenza particles in nasal and respiratory secretions and from contact with the feces of infected birds.
In many states, spread of the disease is controlled by active surveillance programs that monitor birds for evidence of exposure to the virus and isolate and destroy infected flocks.
Can AIV spread to humans?
Avian influenza viruses do not usually cause disease in humans; however, several instances of human infections and outbreaks have been reported in Asia and Europe since 1997. Since the Fall of 2003, a growing number of Asian countries have reported outbreaks of avian influenza in chickens and ducks. The rapid spread of highly pathogenic AIV in Asia is of growing concern for human health as well as for animal health.
Symptoms in humans typically range from localized eye infections to influenza-like symptoms such as fever, cough, sore throat and muscle aches. In more severe cases, pneumonia, acute respiratory distress, and other life-threatening complications can occur. When such infections occur, public health authorities monitor the situation closely because of concerns about the potential for more widespread infection in the human population.
Documented cases of human avian influenza in North America are extremely rare and none have been fatal. Thus AIV concerns in the United States and Canada are primarily directed at the health of poultry flocks rather than the general human population.
Should the mushroom growers be concerned about AIV?
Many mushroom growers who use chicken litter in their compost are asking if they should be concerned about AIV on their farms. AIV is a virus and, like all viruses, can only replicate inside an infected animal. Once it leaves a living host, it cannot remain active for very long.
In fact, a recent paper published by researchers from the Penn State Animal Diagnostics Laboratory indicated that AIV in chicken manure dies quite rapidly. Virus particles in chicken manure were completely inactivated after 6 days at 15-20°C (59-68°F), 36 hr at 28-30°C, and after only 20 min at 56°C (133°F). Based on this data, there is more than enough time for the virus to be completely inactivated during Phase I and Phase II composting.
According to Dr. Patricia Dunn, co-author of the Penn State study, it is also highly unlikely that litter from a known infected flock would be released from the poultry farm until several weeks after the birds have been destroyed or removed from the premises and tests indicate that no live AIV can be detected.
As further protection, growers should receive assurances from their poultry manure suppliers that biosecurity control measures are followed on their farms and that they are participating in an active AIV surveillance program.
References and Information
- H. Lu, A. E. Castro, K. Pennick, J. Liu, Q. Yang P. Dunn, D. Weinstock, and D. Henzler. 2003. Survival of Avian Influenza Virus H7N2 in SPF Chickens and Their Environments. Avian Diseases 47:1015-1021.
- For additional information on AIV and other mushroom food safety issues, visit the Penn State Extension website