The disease and how it affects people
Leptospirosis is a bacterial zoonotic disease with varied manifestations. The early stages of the disease may include high fever, severe headache, muscle pain, chills, redness in the eyes, abdominal pain, jaundice, haemorrhages in skin and mucous membranes (including pulmonary bleeding), vomiting, diarrhoea and a rash.
Pathogenic Leptospira spp. cause leptospirosis. Human infection occurs through direct contact with the urine of infected animals or by contact with a urine-contaminated environment, such as surface water, soil and plants. The causative organisms have been found in a variety of both wild and domestic animals, including rodents, insectivores, dogs, cattle, pigs and horses. Leptospires can gain entry through cuts and abrasions in the skin and through mucous membranes of the eyes, nose and mouth. Human-to-human transmission occurs only rarely.
Leptospirosis occurs worldwide, in both rural and urban areas. The disease is most prevalent in tropical and subtropical regions. It is an occupational hazard for rice and sugar-cane field workers, farmers, sewer workers, veterinarians, dairy workers and military personnel. It is also a recreational hazard to those who swim or wade in contaminated waters. In endemic areas the number of leptospirosis cases may peak during the rainy season and outbreaks can occur following excessive rainfall or flooding.
Scope of the Problem
The number of human cases worldwide is not well-documented. It probably ranges from 0.1 to 1 per 100 000 per year in temperate climates to 10 or more per 100 000 per year in the tropical or subtropical areas. During outbreaks and in high-risk groups, 100 or more per 100 000 may be infected. Outbreaks following typhoons have been reported in the region, e.g. outbreaks were reported in the Philippines following typhoons Ondoy and Pepeng in 2009.
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. Treatment of suspected cases with appropriate antibiotics should be initiated as early as possible. Clinicians should never wait for the results of laboratory tests before starting treatment with antibiotics.
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). 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.