South Pacific – Leptospirosis

Dr Colleen Lau

Leptospirosis is a bacterial infection that is often misdiagnosed as dengue because symptoms can be very similar. The bacteria are carried by animals (including rodents, pets, livestock, and wildlife), and excreted in their urine. Humans can become infected by direct contact with animals, or contact with water and soil that has been contaminated by animal urine. The risk of infection is especially high after flooding, because floodwaters can spread the bacteria, and wash them into rivers and streams. During flooding, people often have to wade in water and therefore have cuts, wounds, and waterlogged skin, all of which increase the risk of infection. In the Pacific Islands, recent outbreaks have occurred after cyclones and flooding on some islands including Fiji and New Caledonia. People participating in outdoor activities are also at risk because of contact with fresh water and soil. The risk of infection can be reduced by wearing protective clothing and boots, cleaning and covering wounds, and avoiding swimming in freshwater streams and rivers after heavy rainfall. The bacteria do not survive in seawater, so there is no risk of leptospirosis from swimming in the ocean.

Leptospirosis research team at work in American Samoa. Left: Unloading fieldwork gear on the remote Manu’a Islands in the far east of American Samoa. Right: Collecting blood samples and questionnaire data. Our study collected data from over 800 people from 5 islands in American Samoa, and found that about 15% of people have had previous leptospirosis infections. The study investigated environmental factors that increased the risk of leptospirosis transmission, produced maps to predict high-risk areas, and provided information to improve public health interventions.

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