Author of Response: Gary K. Felton, Associate Professor, Environmental Science and Technology, University of Maryland gfelton@umd.edu
Transportation of poultry as well as litter can shed dust. Dust has the potential to include feces and respiratory secretions that have the potential to transmit poultry diseases. There is a far greater danger of these diseases being transmitted to other poultry and wild birds than there is of diseases being transmitted to humans.
There are several characteristics of avian respiratory viruses and of humans that inhibit transmission of viruses. Viruses do not survive well on porous surfaces (Tiwari et al., 2006). After 72 hours, virus populations have dropped considerably and after six days, virus populations decreased to almost undetectable levels. Because litter is not normally transported directly from the poultry house to the road, the probability of virus transmission is greatly diminished.
At every step of viral disease transmission, there are barriers to infecting a human. For example:
• The human respiratory tract is inhospitable to avian viruses.
• The biology of human cells is different from avian cells and is destructive to the avian virus.
• If the virus successfully replicates and exits the host cell, then the immune system inhibits infection and replication.
• Culturally, humans are a relatively clean species who reduce opportunity for infection by our observance of hygienic practices (Kuiken, et al., 2006).
Hence, even if the dust initially contains a virus, there are many barriers to the virus becoming an infection in a human, and the probability of becoming infected from trucks driving by is very low.
In times of avian influenza outbreaks, transport of litter on roads is prohibited in many states (regulations vary from state to state). Transport of birds is also either prohibited or severely restricted in the region of the outbreak.
The odors themselves have no pathogenic characteristics, but an odor is an indicator that dust may also be present. Hence, odor should be a cautionary signal.
Additional reading:
Kuiken, T., E.C. Holmes, J. McCauley, G.F. Rimmelzwaan, C.S. Williams, B.T. Grenfell. 2006. Host species barriers to influenza virus infections. Science 312:394-397.
Tiwari, A., D.P. Patnayak, Y Chandler, M. Parsad, S.M. Goyal. 2006. Survival of two avian respiratory viruses on porous and nonporous surfaces. Avian Diseases 50:284-287.
