Evaluation of risk factors for the spread of low pathogenicity H7N2 avian influenza virus among commercial poultry farms.
OBJECTIVE
To identify risk factors associated with the spread of low pathogenicity H7N2 avian influenza (AI) virus among commercial poultry farms in western Virginia during an outbreak in 2002.


METHODS
Case-control study.


METHODS
Questionnaires were used to collect information about farm characteristics, biosecurity measures, and husbandry practices on 151 infected premises (128 turkey and 23 chicken farms) and 199 noninfected premises (167 turkey and 32 chicken farms).


RESULTS
The most significant risk factor for AI infection was disposal of dead birds by rendering (odds ratio [OR], 73). In addition, age > or = 10 weeks (OR for birds aged 10 to 19 weeks, 4.9; OR for birds aged > or = 20 weeks, 4.3) was a significant risk factor regardless of poultry species involved. Other significant risk factors included use of nonfamily caretakers and the presence of mammalian wildlife on the farm. Factors that were not significantly associated with infection included use of various routine biosecurity measures, food and litter sources, types of domestic animals on the premises, and presence of wild birds on the premises.


CONCLUSIONS
Results suggest that an important factor contributing to rapid early spread of AI virus infection among commercial poultry farms during this outbreak was disposal of dead birds via rendering off-farm. Because of the highly infectious nature of AI virus and the devastating economic impact of outbreaks, poultry farmers should consider carcass disposal techniques that do not require off-farm movement, such as burial, composting, or incineration.
McQuiston
Jennifer H
JH
United States Public Health Service, Commissioned Corps Readiness Force, CDC, 1600 Clifton Rd MS G-44, Atlanta, GA 30333, USA.
Garber
Lindsey P
LP
Porter-Spalding
Barbara A
BA
Hahn
John W
JW
Pierson
F William
FW
Wainwright
Sherrilyn H
SH
Senne
Dennis A
DA
Brignole
Thomas J
TJ
Akey
Bruce L
BL
Holt
Thomas J
TJ
D000367:Age Factors; D000822:Animal Husbandry / Q000379:methods*; D000818:Animals; D016022:Case-Control Studies; D004196:Disease Outbreaks / Q000662:veterinary; D005260:Female; D009980:Influenza A virus / Q000472:pathogenicity*; D005585:Influenza in Birds / Q000453:epidemiology / Q000635:transmission* / Q000821:virology; D008297:Male; D010058:Oviposition; D011201:Poultry Diseases / Q000453:epidemiology / Q000635:transmission* / Q000821:virology; D012307:Risk Factors; D014422:Turkeys / Q000821:virology*; D014768:Virginia / Q000453:epidemiology