2. • Zoonosis caused by aerobic, motile spirochetes of
the genus Leptospira.
• Leptospira spp. are thin, helix-shaped members of
the phylum Spirochaetes.
• Leptospirosis has a worldwide distribution, most
human cases occur in tropical and subtropical
countries.
3. • Infected animals excrete spirochetes in their
urine for prolonged periods.
• Globally, most human cases result from
exposure to water or soil contaminated with
rat urine.
4. • High-risk occupations include agricultural
workers, veterinarians, abattoir workers, meat
inspectors, rodent control workers, laboratory
workers, sewer workers, and military personnel.
• Exposure to contaminated floodwaters.
• Transmission via animal bites and directly from
person to person has been rarely reported.
5. Pathology and Pathogenesis
• Leptospires enter human hosts through
mucous membranes (primarily eyes, nose, and
mouth), transdermally through abraded skin,
or by ingestion of contaminated water.
• After penetration, they circulate in the
bloodstream, causing endothelial damage of
small blood vessels with secondary ischemic
damage to end organs.
6. Clinical Manifestations
• The spectrum ranges from asymptomatic
infection to severe disease (5–10% of
infections) with multiorgan dysfunction and
death.
• The onset is usually abrupt, and the illness
may follow a monophasic or the classically
described biphasic course.
7. • IP: 2 to 30 days, following which there is an
initial or septicemic phase lasting 2-7 days,
during which leptospires can be isolated from
the blood,CSF, and other tissues.
• This phase may be followed by a brief period
of well-being before onset of a second
symptomatic immune or leptospiruric phase .
8. • This phase has appearance of circulating IgM
antibody, disappearance of organisms from
the blood and CSF, and appearance of signs
and symptoms associated with localization of
leptospires in the tissues.
• Despite the circulating antibody, leptospires
can persist in the kidney, urine, and aqueous
humor.
9. • The immune phase can last for several weeks.
• Symptomatic infection may be anicteric or
icteric.
10.
11. DIAGNOSIS
• Leptospirosis should be considered in the
differential diagnosis of acute flulike febrile
illnesses with a history of direct contact with
animals or with soil or water contaminated
with animal urine.
• Confirmed by serologic testing and less often
confirmed by isolation of the infecting
organism from clinical specimens.
12. • The gold standard diagnostic method is the
microscopic agglutination test, a serogroup-
specific assay using live antigen suspension of
leptospiral serovars and dark-field microscopy
for agglutination.
• A 4-fold or greater increase in titer in paired
sera confirms the diagnosis.
13. • Agglutinins usually appear by the 12th day of
illness and reach a maximum titer by the 3rd wk.
• Low titers can persist for years.
• Approximately 10% of infected persons do not
have detectable agglutinins, presumably because
available antisera do not identify all Leptospira
serotypes.
14. • Additionally, enzyme-linked immunosorbent
assay (ELISA) methods, latex agglutination, and
immunochromatography are commercially
available, and DNA PCR diagnostics have been
developed.
• Phase-contrast and dark-field microscopy are
insensitive for spirochete detection, but
organisms may be identified using Warthin-Starry
silver stain or fluorescent antibody staining of
tissue or body fluids.
15. • Unlike other pathogenic spirochetes,
leptospires can be recovered from the blood
or CSF during the first 10 days of illness and
from urine after the 2nd wk by repeated
culture of small inoculum (i.e., one drop of
blood or CSF in 5 mL of medium)
16. TREATMENT
• Leptospira spp. demonstrate in vitro
susceptibility to penicillin and tetracyclines,
but in vivo effectiveness of these antibiotics in
treating human leptospirosis is unclear due to
the naturally high spontaneous recovery rates.
• Treatment with penicillin G, cefotaxime,
ceftriaxone, or doxycycline (in children ≥8 yr of
age) should be instituted early when the
diagnosis is suspected.
17. • A short (<2 wk) course of doxycycline may be
safely used in children >2 yr of age.
• Parenteral penicillin G (6-8 million U/m2 /day
divided every 4 hr IV for 7 days) is
recommended, with doxycycline 2 mg/kg/day
divided in 2 doses with maximum of 100 mg
twice daily as an alternative for patients
allergic to penicillin.
18. • Cefotaxime, ceftriaxone, and azithromycin
demonstrated equivalent effectiveness with
doxycycline.
• These antibiotics can be used as alternatives
in patients for whom doxycycline is
contraindicated.
19. • In mild illness, oral doxycycline, amoxicillin,
and ampicillin have been used successfully.
