Leptospirosis is a neglected zoonotic disease with a worldwide distribution, yet disproportionally affects
poor rural subsistence farmers in the tropics. The animal reservoirs for spill-over infection to humans in
such settings in the South Pacific have not been well delineated, thus hampering effective control efforts.
We conducted a case control investigation among households that participated in a seroprevalence survey
for leptospirosis in Western Fiji. We surveyed domestic animals and trapped rodents at 45 cases and 73
control households who had one or more, and no inhabitants with evidence for anti-leptospire
agglutinating antibodies. We performed serology among all animals and used polymerase chain reaction
to detect Leptospira DNA in kidneys of trapped rodents. One or more seropositive animals were
identified among 78% of the 96 households with domestic animals or trapped rodents. There was not a
significant difference between the presence of seropositive animals between case and control household
(67% vs 85%, respectively). Agglutinating antibodies were detected from a high proportion of households
with horses (85%) and cattle (73%), indicating that the seroprevalence of leptospirosis in livestock was
high in this region. Agglutinating antibodies against serogroup Australis, which was recognized by 64%
of the seropositive human inhabitants, were detected from six of the seven animal species. Additionally, a
proportional similarity index analysis indicated that cattle, horses, dogs, rodents and humans form a
transmission network. There was a non-significant trend for Leptospira DNA positive rats to be trapped
in case vs control households (OR 5.71, p=0.09). Our studying findings indicate that there exists a
complex network of transmission between livestock, domestic animals and rodents in Western Fiji, and
the source for human leptospirosis cannot be attributed to a single reservoir species. Therefore, control of
leptospirosis in rural Fiji and similar high transmission settings will need to rely on multiple intersectorial
strategies that target prevention of leptospirosis in livestock, rodent control, the use of personal protection
and barrier approaches, and reduction of high risk behaviors.