Leptospirosis

What is leptospirosis?#

Leptospirosis is a disease that spreads from animals to humans, caused by infection with the bacteria Leptospira. The most common sources of infection are contact with the urine of infected animals and/or contaminated soil or water. Outbreaks may follow periods of heavy rain or flooding.

Leptospirosis occurs worldwide, but is more common in tropical and sub-tropical areas with high rainfall. Within affected countries it tends to be concentrated in particular regions, often warmer and wetter areas.

Symptoms#

People with leptospirosis can have a wide range of symptoms, which may include fever, headache, muscle aches and sore throat. Symptoms generally start around ten days after exposure, but may begin anywhere between two and twenty-nine days afterwards.

The illness generally lasts from a few days to three weeks, but may occasionally last longer. Between 5 and 15 per cent of infected people develop severe symptoms and need hospital care, and in this group the disease can be fatal.

Where does it come from?#

Many mammals carry Leptospira bacteria without showing signs of disease. Depending on the region, these can include livestock (cattle, pigs, sheep, goats and deer), pets (dogs, horses and cats), wildlife (such as possums and other native animals) and pests (rats and mice).

Soil, mud and water contaminated by the urine of infected animals can harbor the bacteria. Warm, humid climates, marshy or wet areas and regions with alkaline soils help the bacteria survive in the environment. In some regions, a common source of human infection is working with cattle, particularly on dairy farms. Other common sources include recreational activities associated with rivers, lakes, waterways and marshy areas, including during overseas travel.

How does it spread?#

Human infection can occur directly from infected animals (through contact with urine, milk, vaginal discharge, placenta and aborted fetuses) or indirectly through contact with contaminated soil and water.

The bacteria can enter the body by three main routes:

• Direct contact — bacteria enter through a break in the skin or through intact mucous membranes, for example an open wound exposed to contaminated water or soil
• Eating or drinking — for example, swallowing bacteria in contaminated food or from unwashed, contaminated hands
• Inhalation — for example, breathing in aerosolized urine from infected cattle, rats or mice

Recurrent infections with different strains can cause repeated illness. Although person-to-person transmission is rare, it has been documented through sexual intercourse and breastfeeding.

Who is at risk?#

There is a risk of infection for people who have contact with infected animals, or with soil or water where the bacteria are present. Occupations at higher risk include farmers (especially dairy farmers), veterinarians and abattoir workers. Higher-risk activities include swimming and other water sports (such as white water rafting), camping and gardening.

Diagnosis and treatment#

Leptospirosis is generally diagnosed with a blood test. Two blood tests, taken more than two weeks apart, are often needed to confirm the diagnosis.

Treatment with appropriate antibiotics as early as possible in the course of the illness is recommended to avoid severe disease. There is no vaccine available for use in humans.

How can I avoid it?#

General measures to avoid leptospirosis include:

• Avoid contact with water that may be contaminated by animal urine
• Wear appropriate footwear outdoors, especially when walking in mud or moist soil
• Cover wounds and abrasions with waterproof dressings if contact with contaminated animal urine, soil or water is likely
• Control rodents by cleaning up rubbish and removing food sources close to housing
• Use gloves when gardening
• Wash hands with soap and water before eating
• Avoid feeding raw offal to dogs

For livestock owners and people who work with animals:

• Wear personal protective equipment (face mask, gloves, overalls) when working with potentially infected animals, especially when working closely with urine and birth products, as the bacterial load is higher
• Vaccinate cattle, pigs and dogs. Vaccination typically covers two of the most common strains. While vaccination prevents disease in animals, most vaccines do not stop the animal from shedding the bacteria; some cattle vaccines, if given before natural infection, have been shown to prevent shedding of the strains they cover. Consult your veterinarian about the most appropriate vaccine and schedule for your livestock
• Practice good on-farm hygiene to reduce environmental contamination and rodent numbers
• Prevent livestock contact with contaminated water and with neighboring livestock or wildlife that could be infected, for example through fencing
• Purchase Leptospira-free livestock
• Reduce risk in the workplace through good design, for example splash guards
• Design and implement a biosecurity plan for your farm, and consult your local veterinarian for advice

Key points#

• The most common sources of infection are contact with the urine of infected animals and/or contaminated soil or water
• Leptospirosis occurs worldwide, but is more common in tropical and sub-tropical areas with high rainfall
• Within affected countries it tends to be concentrated in particular regions
• People with leptospirosis can have a wide range of symptoms
• Between 5 and 15 per cent of infected people develop severe symptoms and need hospital care

Where to get help#