||Symptoms include fever, headache,
chills, muscle aches, vomiting, jaundice, anemia, and sometimes
a rash. The incubation period usually is 10 days, with a range
of 4-19 days. If not treated, the patient could develop kidney
damage, meningitis, liver failure, and respiratory distress.
In rare cases, death occurs.
||Leptospires-- long, thin motile
spirochetes, best viewed by dark-field microscopy. They may
be free-living or associated with animal hosts and survive
well in fresh water, soil, and mud in tropical areas. These
organisms are antigenically complex, with over 200 known pathogenic
serologic variants. Molecular taxonomic studies at CDC and
elsewhere have identified 13 named and 4 unnamed species of
pathogenic leptospires. Although certain geographic regions
contain specific leptospiral serovars and species, the serologic
characterization of an isolate is not an absolute predictor
of its species designation.
||In the United States 100-200 cases
are identified annually; about 50% occur in Hawaii. Although
incidence in the United States is relatively low, leptospirosis
is considered to be the most widespread zoonotic disease in
||The clinical course is highly variable.
The serious icteric form (Weil’s disease) is not common, but
hemorrhage, hepatomegaly, and jaundice are among the severe
features. In Nicaragua, anicteric leptospirosis was seen with
pulmonary hemorrhage and death in 1% of cases.
||Occurs through direct or indirect
transmission through a mammalian host. Indirect transmission
is thought to be responsible for most of cases.
||Workers in rice fields, sugar cane
plantations, mines, sewer systems, and slaughterhouses; animal
caretakers and veterinarians. Recreational exposures can include
rafting, kayaking, and swimming.
||Currently reportable nationally,
but it is reportable in numerous states (including Hawaii).
The CDC leptospirosis reference laboratory is a useful source
of information on laboratory-confirmed cases of leptospirosis.
To determine the incidence of leptospirosis in high-risk areas,
special studies will be required.
||Leptospirosis continues to re-emerge
as a notable source of morbidity and mortality in the Western
Hemisphere. The largest recorded outbreak in the continental
U.S. (110 cases in a group of 775 exposed persons) occurred
in June and July 1998. Significant increases in incidence
were also reported from Peru and Ecuador following heavy rainfall
and flooding in the spring of 1998.
||Current diagnostic tests are problematic.
The confirmatory microscopic agglutination test (MAT) is too
labor intensive and not widely available. There is a critical
need to validate recently developed rapid diagnostic tests.
||The MSPB/DBMD/CDC WHO leptospirosis
collaborating center is working to identify new diagnostic
tests and testing algorithms that may decrease reliance on
the MAT for diagnosis of leptospirosis. Community-based trials
of weekly doxycycline for prevention of leptospirosis during
periods of high risk may be useful in developing an approach
to control leptospirosis epidemics.