Leptospirosis in Indonesia, and why the wet season changes the risk

The US CDC lists leptospirosis on its Indonesia traveller page and sets out how most people catch it:

• touching urine or other body fluids from an infected animal
• swimming or wading in urine-contaminated fresh water, or contact with urine-contaminated mud
• drinking water or eating food contaminated with animal urine

Its advice: avoid contaminated water and soil, and avoid floodwater.

NaTHNaC adds the context. Leptospirosis is “a bacterial infection which can infect humans and animals (most commonly rodents, cattle, pigs and dogs)”; the activities that raise the risk are “kayaking, outdoor swimming, fishing or working with animals or animal parts”; and “travellers visiting areas where flooding is a problem may also be at risk.” It occurs frequently throughout tropical areas, and person-to-person transmission is rare.

Sources: US CDC — Indonesia traveller page, read 6 October 2026; NaTHNaC — Leptospirosis (Weil's disease), published 23 November 2018, read 6 October 2026.

In the dry months, leptospirosis is a question about the activities you choose: a river swim, a kayak trip, a waterfall. In the wet season it stops being optional, because floodwater brings contaminated water to the street outside.

The CDC's own Indonesia page points at the same season for a second reason. Alongside leptospirosis it lists melioidosis, which it ties to “contact with contaminated fresh water, mud, or soil, especially after heavy rains.” Two separate infections, one shared lesson: after heavy rain, mud and standing water are where the risk sits.

Our rainy-season guide covers what the wet months change in Bali day to day. The leptospirosis-specific version is short. Cover cuts and grazes. Don't wade through floodwater if there is another way. Wear footwear in mud. Since there is no vaccine, avoidance is the whole of the prevention.

NaTHNaC lists the early signs as “a high temperature, headache, feeling nauseous and vomiting, aching muscles and joints, red eyes and loss of appetite.” In the wet season that list is easy to mistake for dengue, which is also at its most common then.

The serious form it describes as “yellow skin and eyes (jaundice), swollen ankles, feet or hands, chest pain, shortness of breath and coughing up blood.” Treatment “is usually with antibiotics, most people fully recover in a few days or weeks,” and “more serious infection may require hospital treatment.”

The single most useful thing you can do is tell the doctor about the water. A fever after floodwater, a river or a muddy trek changes what gets tested for. The treatment decision is the doctor's.

Leptospirosis caught after arrival is an acute infection, on the ordinary side of a health policy. The cost sits in the cases that need a hospital.

Two exclusions matter on this page. The policy wording excludes a Hazardous Activity unless it was declared and accepted before you started, with what counts “as determined by” the insurer — caving is specifically excluded. If rafting, kayaking or similar is part of your life in Indonesia, declare it when you buy. And evacuation is an optional add-on, up to US$100,000 for transfer to the nearest country with appropriate facilities, while air, sea and mountain rescue are always excluded.

Worth knowing for remote workers: Indonesia's remote worker visa (E33G) lists no insurance requirement, so nothing at immigration ensures you have cover. The cover we arrange is worldwide — the United States is the one exception — and pre-existing conditions are excluded.