References:
- Global Infectious Diseases and Epidemiology Online Network: Infectious Diseases of the Philippines, 2013 eBook Edition, ISBN 978-1-61755-582-4, by Stephen Berger. Accessed here.
| Agent | BACTERIUM. Leptospira interrogans An aerobic non-gram staining spirochete |
| Reservoir | Cattle Dog Horse Deer Rodent Fox Marine mammal Cat Marsuipal Frog |
| Vector | None |
| Vehicle | Water Soil Urine contact |
| Incubation Period | 7 to 12 days (As early or late as 2 to 26 days) |
| Diagnostic Tests | Culture on specialized media Dark field microscopy of urine or CSF Serology |
| Typical Adult Therapy | Doxycycline 100 mg BID X 5 to 7d |
| Typical Pediatric Therapy | Age >= 8y: Doxycycline 2.2 mg/kg BID X 5 to 7d. Age < 8y: IV Penicillin G 50,000u/kg q6h X 5 to 7d |
| Clinical Hints | ”Sterile” meningitis, nephritis, hepatitis, myositis and conjunctivitis; often follows recent skin contact with fresh water in rural or rodent-infested areas; case-fatality rates of 5% to 40% are reported. |
| Synonyms | Andaman hemorrhagic fever, Canefield fever, Canicola fever, Field fever, Fish handler’s disease, Fort Bragg fever, Japanese autumnal fever, Leptospira, Leptospirose, Leptospirosen, Leptospirosi, Mud fever, Pre-tibial fever, Rat fever, Rice field fever, Swamp fever, Swineherd disease, Weil’s disease. |
WHO Case Definition for Surveillance
Clinical description: acute febrile illness with headache, myalgia and prostration associated with any of the following symptoms:
- Conjunctival suffusion
- Meningeal irritation
- Anuria or oliguria and/or proteinuria
- Jaundice
- Hemorrhages (from the intestines; lung bleeding is notorious in some areas)
- Cardiac arrhythmia or failure
- Skin rash and a history of exposure to infected animals or an environment contaminated with animal urine.
- Other common symptoms include nausea, vomiting, abdominal pain, diarrhea, arthralgia.
Laboratory criteria for diagnosis
- Isolation (and typing) from blood or other clinical materials through culture of pathogenic leptospires
- Positive serology, preferably Microscopic Agglutination Test (MAT), using a range of Leptospira strains for antigens that should be representative of local strains
Case classification
- Suspected: A case that is compatible with the clinical description.
- Probable: Not applicable.
- Confirmed: A suspect case that is confirmed in a competent laboratory. Note: Leptospirosis is difficult to diagnose clinically in areas where diseases with symptoms similar to those of leptospirosis occur frequently.
SPECIAL ASPECTS
- Serology by Microscopic Agglutination Test (MAT) may provide presumptive information on causative serogroups.
- Attempts should be made to isolate leptospires, and isolates should be typed to assess locally circulating serovars.
- Questioning the patient may provide clues to infection source and transmission conditions.
- Animal serology may give presumptive information on serogroup status of the infection Isolation followed by typing gives definite information on serovar.
Acute Phase
Subclinical infection is common.
- Overt leptospirosis (90% of cases) is characterized by a self-limited, systemic illness.
- Patients are at risk for severe and potentially fatal illness which may present with renal failure, liver failure, pneumonia or hemorrhagic diathesis.
- Illness begins abruptly with such symptoms as fever (38 to 40 C), headache (over 95% of cases), rigors, myalgia (over 80%), conjunctivitis (30 to 40%), abdominal pain (30%), vomiting (30 to 60%), diarrhea (15 to 30%), cough, muscular (calf) tenderness, pharyngitis (20%) and a pretibial maculopapular rash (fewer than 10%).
- Additional findings may include lymphadenopathy, splenomegaly, atypical lymphocytosis, thrombocytopenia, transitory paraparesis, hepatomegaly or pancreatitis.
- During the acute illness, bacteria can be recovered from or seen in blood, CSF, or tissue using specialized techniques.
- Organisms are demonstrated in urine after the 5th to 7th days. Pyuria, hematuria and proteinuria may be evident as well.
- Severe hypomagnesemia has been reported during the acute phase of infection.
Latency and Relapse
The acute phase is followed by an asymptomatic period of 4 to 30 days.
- At this point, illness reappears, with conjunctival suffusion, photophobia, eye pain, myalgia, lymphadenopathy and hepatosplenomegaly.
- Additional findings may lymphocytic meningitis (70 to 80% of patients) with normal glucose levels; pretibial purpura, uveitis, iridocyclitis or chorioretinitis, facial nerve palsy, thrombocytopenia, hypotension, myopericarditis and pancreatitis.
- Weil’s disease is characterized by hepatic and renal function which may progress to severe and even fatal hepatorenal failure which carries a case-fatality rate of 5 to 40%.
- Renal involvement, principally interstitial nephritis and tubular necrosis may be severe, even in the absence of jaundice.
- Pulmonary infiltrates, severe hemorrhagic pneumonia and acute pulmonary distress syndrome may be encountered, even in the absence of hepatic and renal failure.
- Congestive heart failure is rare; however, cardiac arrhythmias may occur and result in sudden deaths.
- Acute disseminated encephalomyelitis has been reported as a complication of leptospirosis.
- Relatively severe infection is reported among pregnant women.