Wading through stagnant waters can be risky

The monsoon can drench besides forcing you to wade through flooded stagnant waters in cities or make you to start working happily in the rice fields in rural areas. Rainwater puddles in the fields or stagnant waters in cities are often mixed with water from animal and rodent waste, and sewage in urban areas. Do you know that this can cause diseases such as leptospirosis? 

What is leptospirosis?

Leptospirosis is a zoonotic disease (transmitted from animals to humans) that affects both animals and humans and has led to more than 10 lakh cases and around 50,000 deaths worldwide. The paper titled 'Clinico epidemiological study of human leptospirosis in hilly area of South India - A population based case control study' authored by Sharvanan E. Udayar, Narasimha B. Chengalarayappa, Ashwini Madeshan, Manjunatha Shivanna, Krishnaveni Marella from the Indian Journal of Community Medicine informs that there is little information available in India about the disease due to lack of awareness among health care personnel and poor diagnosis due to absence of  diagnostic facilities. The positivity rate of the disease in south India is around 25.6 percent while it is 8.3 percent in north of India.

Leptospira are transmitted through domestic, wild, and peridomestic animals. They can survive for weeks in warm wet soil and water and can get in direct contact with humans in urban and rural settings. On entry, leptospira spread to major organs of the body after an incubation period of 2 to 30 days and appears in the form of symptoms like muscle ache, headache, fever and chills, vomiting, nausea, and abdominal pain for around 4 to 7 days.

Exposure to contaminated urine of animal carriers or contact with contaminated soil or water either directly or indirectly can lead to disease transmission in humans. Studies in tropical countries have found that people living near cattle farms and doing farming jobs that involve walking and working barefooted in paddy fields, or those working or walking near water or flood water contaminated with sewage can be vulnerable to the disease.

Although basic determinants of the disease seem to be common, the nature and magnitude of these factors vary from region to region. Regionwise and local studies can thus be useful to understand the risk factors responsible for disease transmission and design effective strategies for prevention and control of the disease. 

A population based case control study was done to assess the risk factors associated with leptospirosis  in Kodagu district, a hilly area of southern India.

What does this study from Kodagu show?

Kodagu is a hilly district in southern part of Karnataka state in India and is not an endemic area for leptospirosis. It has a population of 5.5 lakhs with majority (85.4 percent) living in rural areas. It is the place of origin of the Cauvery and the district receives an average annual rainfall of 3,000 to 3,800 mm and temperature of 11°C to 28°C . The area is prone to seasonal floods. The main occupation of people in the region is agriculture involving paddy cultivation and coffee plantations with many warehouses for storage of agriculture produce.

Seventy patients who had a confirmed diagnosis of leptospirosis were interviewed for the study. Majority of them were in the age group of 18-30 (34.3 percent) followed by 31-45 years (30 percent) and 41-60 years (25.7 percent). More than 80 percent of people lived in rural areas and nearly 47 percent were farmers. 

Environmental and occupational  risk factors

Open water source and lack of waste disposal facilities increased the risk of leptospirosis

Individuals who were exposed to flood water or collection of water in and around the house, presence of open sewers within the vicinity of the house and garbage in open areas were found to be at a higher risk of contracting leptospirosis.

Overflow of sewer drainage and collection of water is common during rainy season mainly because of many tributaries of the river present in this area resulting in frequent flooding and landslides leading to disruption of health services might be the reason for water contamination during monsoon season.

There was a significant association between leptospirosis and environmental factors like open water source as a cause of contamination and absence of waste disposal facility around the house.

Animal farming was an important risk factor for leptospirosis

Animal farming was identified as an important risk factor for leptospirosis and the risk of leptospirosis was three times higher in relation to involvement in animal farming. This  could be due to animal and poultry waste which attracts rodents resulting in frequent transmission of the disease through contamination of soil with urine.

The study also noted that rodent exposure factors like presence of rodents in the house and at the workplace and also presence of grain storage areas like godowns had a higher risk for leptospirosis. There is a high chance of soil contamination by infected urine of rodents which are present in the house and at the workplace resulting in disease transmission

Farming increased risk of people to leptospirosis due to constant contact with water

The occupation of farming was found to be an important risk factor for the disease. Presence of skin cuts or abrasion during work, contact with water or mud during work, and agricultural activities served as the strongest occupational risk factors responsible for leptospirosis. 

Preventing leptospirosis

Leptospirosis is a potential public health problem and human behavioral factors are important components in leptospirosis prevention. Measures like using protective devices such as gum boots and gloves would reduce the chances of getting exposed to contaminated stagnant water which requires health education and sensitisation programs focusing mainly on social and cultural aspects of the risk groups. 

Interventions such as prevention of sewage from mixing into water sources, integrated rodent control measures and identification of high risk zones followed by emphasis on target population through surveillance activities by healthcare workers would be significantly beneficial in reducing the burden of this neglected tropical disease.

Knowing about leptospirosis is crucial in the Indian context as cases of leptospirosis are increasing in the country. 

What can you do to prevent leptospirosis

• Avoid touching freshwater or soil that may be contaminated with animal urine
• Prevent rodent infestation in your house or in your storage places through regular cleaning and pest control
• Avoid touching objects that may be contaminated with animal urine, such as animal bedding
• Don't wade, swim, or put your head in floodwaters or water from lakes, rivers, or swamps. Especially avoid freshwater contact after flooding or heavy rain.
• If it is not possible to avoid wading in floodwaters or other fresh water, wear protective clothing like footwear and cover cuts and wounds with waterproof bandages or dressing.
• Make water safe to drink by boiling or using an appropriate chemical [1]
• Administration of prophylaxis for individuals at high risk of exposure, and animal vaccination can also be useful. Prophylaxis can also include consumption of doxycycline for individuals with high likelihood for exposure to leptospirosis in endemic environments over a defined period [2].