Objective—To identify major environmental and farm
management factors associated with the occurrence
of tuberculosis (TB) on cattle farms in northeastern
Sample Population—17 cattle farms with infected
cattle and 51 control farms.
Procedure—Each case farm (laboratory confirmed
diagnosis of Mycobacterium bovis infection) was
matched with 2 to 4 control farms (negative whole-herd
test results within previous 12 months) on the basis of
type of farm (dairy or beef) and location. Cattle farm
data were collected from in-person interviews and
mailed questionnaires. Wildlife TB data were gathered
through state wildlife surveillance. Environmental data
were gathered from a satellite image-based geographic
information system. Multivariable conditional logistic
regression for matched analysis was performed.
Results—Major factors associated with increased
farm risk of TB were higher TB prevalence among wild
deer and cattle farms in the area, herd size, and ponds
or creeks in cattle housing areas. Factors associated
with reduced farm risk of TB were greater amounts of
natural open lands in the surrounding area and reducing
deer access to cattle housing areas by housing cattle
in barns, barnyards, or feedlots and use of electrified
wire or barbed wire for livestock fencing.
Conclusions and Clinical Relevance—Results suggest
that certain environmental and management factors
may be associated with risk of TB on cattle
farms. (J Am Vet Med Assoc 2002;221:837–842)
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.
Procedure—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], 7.3). In addition, age ≥ 10 weeks (OR for birds aged 10 to 19 weeks, 4.9; OR for birds aged ≥ 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 and Clinical Relevance—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 offfarm movement, such as burial, composting, or incineration. (J Am Vet Med Assoc 2005;226:767–772)