Monsoon rain and upstream water flood large parts of Bangladesh, and town streets can stay waterlogged for days. In a report published by BBC Bangla on 14 July 2026, Dr Mushtaq Hossain, a public health expert and former adviser to the government's Institute of Epidemiology, Disease Control and Research (IEDCR), explained which diseases follow. The greatest danger, specialists say, comes from diarrhoea, cholera, typhoid, various skin diseases and, in some cases, water-borne infections such as hepatitis A and E.
The causes differ: contaminated food or water, mosquitoes, or long exposure to damp. Dr Hossain divided the risk in two: the shortage of clean water, safe food and sanitation, and the accidents and environmental hazards that floods and waterlogging bring.
No safe water: diarrhoea and cholera
"There is a lot of water all around, but no water fit to drink. That is one of the biggest public health problems during a flood," Dr Hossain said. Passing loose stools three or more times in 24 hours is generally counted as diarrhoea, and it drains water and minerals from the body quickly. Children are affected most.
According to the World Health Organization (WHO), cholera is caused by eating food or drinking water contaminated with the bacterium Vibrio cholerae. Symptoms appear 12 hours to 5 days after infection, and the severe watery diarrhoea it causes can be fatal within hours if untreated. WHO says most patients can be treated successfully with prompt oral rehydration solution (ORS). Dr Hossain likewise stressed preventing dehydration: give ORS early and take severe cases to hospital.
Illnesses that appear days or weeks later
Some diseases show later. Typhoid, a leading water-borne disease in Bangladesh, is caused, WHO says, by the bacterium Salmonella Typhi and usually spreads through contaminated food or water; it brings prolonged high fever, fatigue, headache, abdominal pain and constipation or diarrhoea, and it is treated with antibiotics. Figures from the Directorate General of Health Services quoted by BBC Bangla put typhoid cases in the country at about 478,000 a year, with about 8,000 deaths, 68 per cent of them children.
Hepatitis A and E, which cause jaundice, also rise in waterlogged areas. WHO says hepatitis E is transmitted mainly through contaminated drinking water and appears 2 to 10 weeks after exposure. It is especially dangerous in pregnancy: up to 20 to 25 per cent of pregnant women can die if infected in the third trimester. Safe water, including for washing and bathing, is the main defence.
The US Centers for Disease Control and Prevention (CDC) says leptospirosis spreads through the urine of infected animals and that the risk is higher after heavy rain or flooding, when animal urine in the soil gets into floodwater. Dr Hossain added that crowding in shelters can spread scabies and other skin diseases, respiratory infections among children and older people, and urinary tract infections where safe toilets are lacking. On dengue, he said floodwater can wash away Aedes eggs and larvae, but clean water left standing after it recedes lets the mosquito breed.
Who is most at risk and what helps
Children, older people, pregnant women and people with long-term conditions such as diabetes, heart disease or asthma face the highest risk, and need prompt hospital care if serious symptoms appear. Dr Hossain urged that relief include baby food and clean water to prepare it, space in shelters for mothers to breastfeed safely, and attention to menstrual hygiene. The second kind of risk includes children drowning, snakebite and cuts from glass or tin while wading; the unvaccinated also risk tetanus.
The main precautions given in the report and in CDC flood guidance are:
- Avoid floodwater as far as possible, and do not walk or drive across flooded roads.
- After wading, wash hands and feet with soap and change wet shoes and socks quickly.
- Cover any cuts or wounds and keep them away from contaminated water.
- Know when you last had a tetanus shot.
- Use only safe water for drinking, cooking and washing, and start ORS at the first sign of diarrhoea.
Photo: Nayeemibnmatiur / Wikimedia Commons (CC BY-SA 4.0)
Sources: BBC Bangla, World Health Organization (cholera, typhoid and hepatitis E fact sheets), US Centers for Disease Control and Prevention (CDC)
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