Epidemics of Leptospirosis occur from July to October in Southeast Asia, including Thailand. Leptospirosis outbreaks occur with some regularity during periods of flooding in Thailand as a result of people wading through contaminated water. Most cases occur among agricultural workers, notably rice producers.
Leptospirosis is caused by bacteria belonging to the genus Leptospira. It is a zoonosis – an animal disease that can spread to humans – affecting domestic and wild animals such as cattle, dogs, cats, pigs, and rodents. Humans can become sick when they come into contact with water, food, soil, and mud contaminated with the urine of infected animals. The bacteria can enter through skin abrasions and mucous membranes of the mouth, eyes, and nose.
Leptospira bacteria are present worldwide, but are endemic (usually seasonally) in tropical and subtropical areas with poor sanitation and in agricultural areas with livestock operations or rodent infestations. Outbreaks can also occur after storms, heavy rainfalls, or floods. Travellers involved in adventure travel or outdoor activities such as swimming, canoeing, whitewater rafting, kayaking, or camping are at risk. Visiting farms, rice paddies, or sugar cane fields can also increase risk of exposure. Leptospirosis is an occupational hazard for farmers, veterinarians, rescue workers and military personnel.
The infection is characterized by flu-like symptoms which can appear 2 to 30 days (usually 7 to 10 days) after exposure to the bacteria. Symptoms include sudden fever, headache, muscle pain, chills, red itchy eyes, difficulty urinating, a skin rash, nausea, vomiting, and diarrhea. A second, more severe, phase of the illness – also known as Weil's disease – may progress to kidney or liver failure, jaundice, cardiac failure, meningitis (inflammation of the brain), and respiratory failure. Treatment usually includes antibiotics. Human to human transmission of leptospira bacteria is rare.
There is currently no commercially available vaccine against Leptospirosis for humans.
Leptospira bacteria images, life cycle, and distribution maps:
Information last updated: August 20, 2020