Objective—To determine the extent of leptospirosis
in persons exposed to infected swine, confirm the
source of disease, define risk factors for infection,
and identify means for preventing additional infections
during an outbreak in Missouri in 1998.
Sample Population—240 people and 1,700 pigs.
Procedure—An epidemiologic investigation was conducted
of people exposed to infected pigs from the
University of Missouri-Columbia swine herd. The investigation
included review of health of the pigs, a crosssectional
study of the people handling the pigs, serologic
testing of human and porcine sera, and risk-factor
analysis for leptospirosis within the human population.
Results—Serologic testing of samples collected at the
time of the investigation indicated that 59% of the pigs
had titers to leptospires, denoting exposure. Of the
240 people in the exposed study population, 163 (68%)
were interviewed, and of these, 110 (67%) submitted a
blood sample. Nine (8%) cases of leptospirosis were
confirmed by serologic testing. Risk factors associated
with leptospirosis included smoking (odds ratio [OR],
14.4; 95% confidence interval [CI],1.39 to 137.74) and
drinking beverages (OR, 5.1; 95% CI, 1.04 to 24.30)
while working with infected pigs. Washing hands after
work was protective (OR, 0.2; 95% CI, 0.03 to 0.81).
Conclusions and Clinical Relevance—Leptospirosis
is a risk for swine producers and slaughterhouse
workers, and may be prevented through appropriate
hygiene, sanitation, and animal husbandry. It is essential
to educate people working with animals or animal
tissues about measures for reducing the risk of exposure
to zoonotic pathogens. (J Am Vet Med Assoc