13 August 2012

What is leptospirosis?

Leptospirosis is an infectious disease caused by bacteria belonging to the genus Leptospira. Leptospirosis occurs worldwide, but is most prevalent in tropical and subtropical regions. Outbreaks can occur following excessive rainfall or flooding.

How do people get leptospirosis?

  • Leptospirosis can be transmitted to humans through cuts and abrasions of the skin, or through the mucous membranes of the eyes, nose and mouth with water contaminated with the urine of infected animals. As animals are constantly in our environment, there is a particular danger of getting leptospirosis when flooding occurs, such as following a typhoon or very heavy seasonal rains, because of exposure to contaminated water when wading in floodwaters.
  • Leptospirosis can occasionally also be transmitted through the drinking of water or ingestion of food contaminated with urine of infected animals, often rats.
  • Human-to-human transmission occurs only very rarely.

Which animals can infect people with leptospirosis?

Virtually all wild and domestic mammals can harbour the bacteria that cause leptospirosis in their kidneys and genital tracts and act as source of infection to humans and other animals.

  • Rodents were the first recognized carriers of leptospirosis and are considered the primary source of infection to human beings.
  • Cattle, buffaloes, horses, sheep, goat, pigs and dogs are also considered common reservoirs of the bacteria that causes leptospirosis.

Who is at risk from leptospirosis?

Outbreaks of leptospirosis have been reported following natural disasters such as flooding. The risk of infection depends on exposure. Some humans have a high risk of exposure because of their occupation, the environment they live in or their lifestyle.

The main occupational groups at risk include:

  • farm and agricultural workers
  • pet shop workers
  • veterinarians
  • sewer workers
  • abattoir workers
  • meat handlers
  • military personnel
  • survivors of natural disasters (e.g., flooding)
  • people engaging in recreational water sports (swimming, etc)

In some countries, practically the whole population is at risk as a result of high exposure to contaminated water in daily activities, e.g. working in paddies and sugarcane plantations. The number of males with leptospirosis is often higher than that of females. This may reflect occupational exposure in male dominated activities.

Although leptospirosis is often considered to be a rural disease, people living in cities may also be at risk, because of exposure to infected rats.

What are the signs and symptoms of leptospirosis?

The incubation period of leptospirosis is usually 5–14 days, with a range of 2–30 days. The symptoms following infection with leptospira can vary from a mild 'flu'-like illness to a serious and sometimes fatal disease.

Leptospirosis is often difficult to diagnose clinically, as it can appear to be very similar to many other diseases such as dengue, typhoid and viral hepatitis. Although the disease is a self-limiting and often clinically inapparent illness in the majority of cases, 5-15% of untreated cases can progress to a more severe and potentially fatal stage.

How do you treat leptospirosis?

Leptospirosis can be treated with antibiotics that should be given as early in the course of illness as possible. If you have symptoms of leptospirosis and have been exposed to water potentially contaminated with urine of infected animals, consult a doctor. If leptospirosis is suspected, appropriate antibiotics will be prescribed. Treatment is most effective when started as soon as possible. Clinicians should never wait for the results of laboratory tests before starting treatment with antibiotics.

How do you prevent leptospirosis?

Risk of infection is minimized by avoiding contact with animal urine, infected animals or a contaminated environment.

Measures to prevent transmission of leptospirosis include the following:

  • Wearing protective clothing (boots, gloves, spectacles, aprons, masks).
  • Covering skin lesions with waterproof dressings.
  • Preventing access to, or giving adequate warning about water bodies known or suspected to be contaminated (pools, ponds, rivers). Try to avoid wading or swimming in potentially contaminated water.
  • Washing or showering after exposure to urine splashes or contaminated soil or water.
  • Washing and cleaning wounds.
  • Avoiding or preventing urine splashes and aerosols, avoiding touching ill or dead animals, or assisting animals in giving birth.
  • Strictly maintaining hygienic measures during care or handling all animals.
  • Where feasible, disinfecting contaminated areas (scrubbing floors in stables, butcheries, abattoirs, etc.).
  • Consuming clean drinking-water.

Although human vaccines have been used in some countries with varying degrees of success, there are no WHO pre-qualified vaccines currently available.