Leptospirosis (Rat Fever) in Sri Lanka: Symptoms, Treatment and Prevention

Leptospirosis, called "rat fever" or "mee-ura" in Sinhala, is a bacterial infection that is a significant public health problem in Sri Lanka, especially in rural farming areas and after floods. It is caused by Leptospira bacteria excreted in the urine of infected animals. Many cases are mild and mistaken for flu or dengue, but severe disease can be life-threatening. The key message is: if you have fever and have been exposed to muddy water, fields or floods, seek medical care early.

How it spreads

• Infected animals, mainly rats, but also cattle, buffalo, pigs and dogs, shed bacteria in their urine into water and soil.
• People are infected when contaminated water or mud touches cuts, scratches or soft, wet skin, or enters the eyes, nose or mouth.
• It is not usually spread from person to person.
• Bacteria survive for weeks in warm, wet, slightly alkaline conditions, which is why cases rise during the rainy season and after floods.

Who is at risk?

• Paddy farmers and agricultural workers, especially those who work barefoot in wet fields (peak seasons: planting and harvest)
• Rubber tappers, tea and coconut workers, livestock handlers and butchers
• Sewer, drain and canal workers, and sanitation workers
• People who wade through flood water or swim in rivers, canals and ponds
• Children playing in muddy water
• Military, hunters, campers and adventure sports participants
• Households with rat infestation and poor waste management

Symptoms

Symptoms usually start 2-30 days (often 5-14 days) after exposure.

Early (first phase), 4-7 days:

• Sudden high fever with chills
• Severe headache
• Intense muscle pain, especially in the calves and lower back, and tenderness when the muscles are pressed
• Red eyes (conjunctival redness without discharge)
• Nausea, vomiting, diarrhoea, abdominal pain
• Cough, sore throat, rash

Second (immune) phase, in some: fever returns or persists, meningitis-type headache, and organ complications.

Severe leptospirosis (Weil's disease)

About 5-15% of cases become severe, with:

• Jaundice (yellow skin and eyes), and dark urine
• Kidney failure: very little urine, swelling
• Bleeding: from the nose, gums, gut or lungs, bruising
• Lung involvement: cough, breathlessness, coughing blood (pulmonary haemorrhage), which is a major cause of death
• Heart inflammation with irregular heartbeat or low blood pressure
• Brain involvement: confusion, neck stiffness, drowsiness

Go to hospital immediately if any of these occur.

Leptospirosis or dengue?

Both cause fever, aches and headache and occur in the same season, but there are clues:

• Leptospirosis: severe calf pain, red eyes, jaundice, reduced urine, a history of mud or flood water contact.
• Dengue: pain behind the eyes, rash, falling platelets and warning signs after day 3. See dengue warning signs.

Some people have both infections. Only a doctor can tell which illness you have, so do not self-diagnose.

Diagnosis

• A detailed history of exposure to farms, floods or animals
• Blood tests: full blood count, liver and kidney tests, CRP, urine tests
• Specific tests: leptospira antibody tests (such as MAT, IgM ELISA or rapid test), PCR, and culture in selected cases. Tests may be negative very early, so doctors often treat on suspicion.

Treatment

• Antibiotics started as early as possible, ideally within the first days, are the mainstay. Mild cases are usually treated with oral doxycycline (or azithromycin if doxycycline is unsuitable) for about 5-7 days. Severe cases need intravenous penicillin or ceftriaxone in hospital.
• Supportive care: fluids, careful monitoring, and treatment of kidney failure (including dialysis), bleeding, breathing support and shock in severe disease.
• Fever and pain: paracetamol, with the correct dose. Use our paracetamol dose calculator. Avoid NSAIDs such as diclofenac, ibuprofen and aspirin, which can worsen kidney injury and bleeding.
• Rest and plenty of fluids if you are well enough to drink.
• Do not wait for the test results if you are very ill. Tell the doctor about your exposure.

Seek treatment early. Delay of even a few days raises the risk of complications.

Prevention

For individuals:

• Wear protective gear: rubber boots, gloves and waterproof clothing when working in paddy fields, drains or flood water.
• Cover cuts and scratches with waterproof dressings. Do not enter water with open wounds.
• Avoid wading, swimming or bathing in flood water, canals and stagnant ponds. Wash with clean water and soap afterwards.
• Do not drink or use contaminated water. Boil water when in doubt.
• Store food in covered containers and dispose of waste to avoid rats.
• Wash hands after handling animals.

Rodent control at home and work: keep kitchens clean, seal gaps, use traps, and manage rubbish and stored grain.

Chemoprophylaxis: Sri Lanka's health authorities recommend doxycycline, usually 200 mg once a week, for people at high risk of occupational or short-term exposure, such as paddy farmers during planting and harvest seasons, in areas of high incidence. It is distributed through the Medical Officer of Health or Public Health Inspector. Ask your local health office, and follow instructions, because doxycycline is not suitable for everyone, such as pregnant women and young children.

Animals: vaccinate pets and livestock where available, and avoid contact with their urine.

During and after floods

Avoid wading through flood water when possible. If you must, wear boots, and see a doctor if you develop fever in the 2-3 weeks after exposure. Clean floors and wells with disinfectant after the water recedes.

When to see a doctor

See a doctor the same day if you have fever with severe headache and muscle pain after contact with floodwater, fields, drains or animals, especially if there are red eyes, yellow skin, reduced urine, cough with blood or bleeding. Tell the doctor about your work and exposure. See also cold vs flu for other causes of fever.

References

• World Health Organization: leptospirosis fact sheet and human leptospirosis guidance
• Sri Lanka Ministry of Health, Epidemiology Unit: leptospirosis guidelines and weekly epidemiological reports
• Centers for Disease Control and Prevention: leptospirosis clinical information
• Haake DA, Levett PN. Leptospirosis in humans. Current Topics in Microbiology and Immunology, 2015