Dr Yeap Li Ling
BPharm, PhD, RPh
Leptospirosis, better known among the locals as “rat urine disease” is in the public eye once again. This is following the release of forensic investigations that uncovered leptospirosis infection as the actual cause of death of a young student from Johor, whose assault case made headlines in recent weeks. In fact, most Malaysians are aware of leptospirosis as several public warnings are made almost yearly during its seasonal outbreak in the country.
Leptospirosis is most common in areas with high rainfall and humidity such as the tropics and subtropics, even though the disease can occur in any part of the world. Leptospirosis often begins at the onset of the rainy season and declines as the rainfall recedes. Sporadic cases may occur any time throughout the year and extreme change of weather such as during the monsoon season and flooding may often trigger an outbreak.
What is leptospirosis?
Leptospirosis is caused by a corkscrew-shaped bacterium of the genus Leptospira. The bacteria can be carried in the kidneys of wild and domestic animals such as cows, buffaloes, horses, sheep, goat, pigs, deer, rabbits and dogs. Almost all mammalian species can harbour and act as reservoirs for the leptospires. However, rodents and in particular rats are the most common cause of illnesses in human. The infected animals may have no symptoms of the disease and excrete large number of the leptospires in their urine, which can survive in water sources and soil for weeks to months.
Humans can be infected through direct contact with the infected urine or indirectly through contact with contaminated water or soil. Leptospires can get enter the human body through cuts and abrasions in the skin, through intact mucous membranes (nose, mouth, eyes) and possibly through waterlogged skin. They may also occasionally be transmitted via the inhalation of droplets of urine or drinking contaminated water, but leptospirosis is not known to spread from human to human.
What are the symptoms?
Symptoms usually develop after an incubation period of 7 to 10 days (this can range from 2 to 30 days) and the illness can last from a few days to 3 weeks or longer.
Leptospirosis may present with a broad spectrum of symptoms and clinical signs. In 90% of cases, leptospirosis only causes mild flu-like symptoms such as a fever, headache, chills, vomiting and muscle pain. Some infected persons may have no symptoms at all.
Nevertheless, in some cases the infection is more severe and can cause life-threatening problems, including organ failure and internal bleeding. In its most severe form, leptospirosis is also known as Weil’s disease of which kidney failure, jaundice (yellow colouration of the skin and eyes) and bleeding in the skin and mucous membranes may occur. In some cases, meningitis (inflammation of the lining of the brain) and bleeding in the lungs can also occur.
As the clinical features of leptospirosis are non-specific, with signs and symptoms similar to those seen in many other infectious diseases such as dengue fever and typhoid, a diagnosis of leptospirosis can sometimes be tricky. A series of blood and urine tests to detect specific antibodies can be used to confirm the infection but these are not always available.
Who are at risk?
People who work outdoors or with animals, such as agricultural workers, mineworkers, sewer workers, slaughterhouse workers, veterinarians, animal caretakers and military personnel are at higher risk to contract the disease. Other groups at high risk of contracting leptospirosis include rescue workers and survivors of natural disasters (e.g. tsunami, flooding). Recent years, we also see an increasing cases of people engaging in recreational water sports e.g. white water rafting, kayaking, wading and swimming in natural rivers and lakes. The risk is likely greater for those who participate in these activities in tropical or temperate climates.
What is the treatment?
Leptospirosis is highly curable if treated with the correct antibiotics in a timely manner. Treatment with effective antibiotics should be initiated as soon as the diagnosis of leptospirosis is suspected and preferably before the fifth day after the onset of illness. If you suspect that you might have contracted leptospirosis due to recent environmental exposure, seek medical attention IMMEDIATELY.
For mild forms of leptospirosis, the treatment is antibiotic tablets that can be taken at home. Most people with more severe leptospirosis will be admitted to hospital to receive appropriate intravenous antibiotic therapy and also other supportive care.
Can the disease be prevented?
Yes, definitely. The best way to prevent leptospirosis is to avoid or minimize contact with animal urine, infected animals or contaminated environments. If you are unable to avoid these, you should wear adequate protective clothing (such as rubber boots and gloves), cover your wounds with waterproof dressings, and wash with clean water immediately after exposure.
Pre-exposure prophylaxis with antibiotics is sometimes used for people at high risk of exposure to potentially contaminated sources (e.g. in soldiers going into jungles, emergency workers working in disaster zones, animal workers, persons taking part in adventurous water sports), but the evidence of its effectiveness and risks remains unclear. Other prevention and control measures include:
- Keep your homes, surroundings, as well as recreational areas free from rubbish to minimize rodent infestation.
- Eliminate nesting sites and set up traps to control rodent populations.
- Seal up gaps and holes at home to prevent rodent entry.
- Store food in thick plastics or metal containers with lids.
- Wash containers which have been contaminated by rat urine using a detergent solution and dry for at least an hour before use.
- Drink only sealed bottled water or fresh water that has been boiled.
- Vaccinate your pets against leptospirosis.
- Put pet food away after use and do not leave pet food or water bowls out overnight.
Even though human vaccination is a common practice in countries such as China, Cuba and France, vaccination against the disease is not common in Malaysia as these vaccines do not confer long-term protection and do not provide cross-protective immunity against different strains of the bacteria.
In conclusion, leptospirosis is a potentially serious disease that is relatively common in tropical Malaysia, but it is preventable and can be treated if prompt and proper action is taken.
- Disease Control Division, Ministry of Health Malaysia (2011). Guidelines for the diagnosis, management, prevention and control of leptospirosis in Malaysia
- Regional Office for South-East Asia, World Health Organization. Leptospirosis Fact Sheet.