How to leap away from leptospirosis

A zoonotic disease that is naturally transmissible from animals to humans, leptospirosis cases have been on the rise due to exposure to contaminated water during heavy rains, writes Sriram Natarajan

Leptospirosis is a significant public health problem in India and outbreaks of leptospirosis are increasingly being reported in states such as Kerala, Gujarat, Tamil Nadu, Maharashtra and Karnataka and the union territory of Andaman and the Nicobar Islands, especially during heavy monsoon rains and flooding. From rotting livestock, and rodent-infested warehouses, to stagnant waters — there are multiple factors contributing to the outbreak of what is also known as rat fever. Leptospirosis is a water-borne bacterial disease caused by the spiral-shaped bacteria of the genus leptospira. It is a zoonotic disease that is naturally transmissible from animals to humans. It mainly spreads through the urine and faeces of infected animals. Rats are the primary reservoir of the leptospira bacteria, although farm animals and livestock such as pigs, dogs, horses or cattle, and even wild animals can be hosts of this bacteria. Leptospirosis is spread through the urine of such infected animals, which gets into water or soil and can survive there for weeks to months. Animals become infected due to direct contact with this contaminated water or soil. Humans can become infected when the bacteria enter through cuts in the skin or mucous membranes (eyes, nose, or mouth). Outbreaks of leptospirosis are usually caused by exposure to contaminated water during heavy rains, waterlogging situations, and stagnant water during and after flooding. Person-to-person transmission is rare.

What are the symptoms?

Leptospirosis can cause a wide range of symptoms such as high fever, chills,
headache, muscle ache, vomiting, jaundice (yellow skin and eyes), diarrhoea,
abdominal pain, and rash. These symptoms lead to it being commonly misdiagnosed for other diseases such as dengue fever. The general incubation period from a person’s exposure to a contaminated source and becoming sick is two days to four weeks. Leptospirosis may occur in two phases. After the first phase of flu-like symptoms, the patient may feel better and recover. The second phase, though uncommon, may follow and is usually more severe, and can lead to life-threatening conditions such as kidney or liver failure, meningitis, respiratory problems, and haemorrhage.

How is leptospirosis diagnosed?

Leptospirosis can be diagnosed only by laboratory tests because of its nonspecific clinical features. Microscopy and antibody tests are the commonly used laboratory methods but both suffer from poor sensitivity and specificity. Microscopic Agglutination Test (MAT), although considered the gold standard, is less sensitive in the early phase and is labour-intensive and complicated, and is only available in reference laboratories. Molecular tests such as Polymerase Chain Reaction are sensitive and specific for the early detection of leptospira bacteria.

What is the treatment for
leptospirosis?

Early and accurate diagnosis is important to start the treatment. Leptospirosis can successfully be treated with appropriate antibiotics as early as possible in the course of the illness to avoid the development of severe disease.

How can leptospirosis be
prevented?

The risk of acquiring leptospirosis can be greatly reduced by avoiding swimming or wading barefoot in stagnant water that might be contaminated with animal urine, and eating and drinking from clean utensils, especially in rodent-infested areas. Protective clothing or footwear should be worn by those regularly exposed to potentially contaminated water due to occupational activities.

(The author is an expert on molecular diagnostics.)