Flood Health Risks, Types of Diseases and Prevention

Natural disasters like floods have significant health consequences, even in the long term. It is not just the immediate danger of drowning, injuries or hypothermia that are a concern. Flooding increases the risk of various diseases that may not have otherwise been a major health problem in an affected area. While a flood may not be preventable, these health risks can be minimized and even prevented altogether.

Types of Diseases

These are some of the diseases that are more likely to arise and pose a health problem in flooded areas. There may be other health risks and diseases that also need to be considered and which can vary regionally. Local health authorities and disaster relief personnel are better suited to advise on specific health issues that may be present in a flooded area. Always seek medical treatment as soon as possible.

Diarrheal Illnesses

Diarrheal illnesses are one of the main health concerns during a flood. Various viral, bacterial and protozoal pathogens may be responsible for these diarrheal illnesses. Cholera, entamoebiasis, giardiasis, hepatitis A, rotavirus and norovirus infections as well as a host of other infectious causes of diarrhea are commonly seen in natural disasters. There also is a greater risk of dehydration in these situations largely due to the lack of clean water and medical care.

Respiratory Infections

Respiratory infections tend to spread rapidly during natural disasters like floods. Both upper and lower respiratory tract infections due to viruses and bacteria may occur and even lead to outbreaks. From the common cold to influenza viruses and pneumonia, these respiratory infections can be serious and even life-threatening. People with pre-existing respiratory diseases like asthma or COPD (emphysema or chronic bronchitis) are at a greater risk.


Dehydration arises with a lack of clean drinking water. Attempting to drink available free-flowing or standing water may lead to diarrheal illnesses. The subsequent vomiting and diarrhea in turn increases the risk and severity of dehydration. Furthermore people with existing kidney diseases, diabetes and those using diuretics may be at greater risk. Inadequate cooling in hot environments which leads to excessive sweating as well as a fever due to infections may further contribute to dehydration.

Mosquito Diseases

Mosquitoes can multiply rapidly in flood conditions since standing water can persist for days, weeks or even months. In areas where mosquito-borne diseases are common or endemic, there can be sudden major outbreaks of these diseases. Malaria, dengue fever, chikungunya and the West Nile disease are some of the common mosquito-borne diseases that pose a problem with  a flood.

Bites and Stings

Flooding often causes insects to emerge in large numbers and these organisms may multiple rapidly. Bites and stings are a common problem. Even non-venomous insects, including mosquitoes that do not carry any human diseases,  can still pose a health risk if the bites are extensive and the wounds may become infected. Venomous insects and reptiles like snakes pose a greater risk. However, both wild and domestic animals may slo be responsible for bites which could also be a health issue, especially when there is limited medical treatment available.

Read more on flood facts.

Prevention of Flood-Related Health Risks

Some of the following measures may help to prevent or minimize the health risks associated with natural disasters like floods. However, it is important to seek professional advice from local authorities about the best course of action to prevent, treat and manage diseases during a time of crisis. Always seek medical care when even minor injuries and illnesses arise as it can quickly lead to complications during natural disasters.

Clean Water

Sourcing clean drinking water is imperative. This should be done as soon as possible. If there are no operational faucets with clean drinking water or no bottled water sources then available water needs to be cleaned. The water may need to first be filtered and then disinfected by boiling or using water purification chemicals that renders water fit for human consumption. This water should be used for both drinking and cooking, as well as washing hands.

Personal Hygiene

Maintain good personal hygiene as far as possible. Washing hands is one of the most important ways to prevent various diseases. Ideally the hands should be washed with clean water and an antibacterial  soap. Antiseptic handwashes should be used regularly. It is particularly important to wash hands after using the toilet and before eating. Regular bathing is also important if possible.

Read more on hand hygiene.

Food Preparation and Storage

Securing a safe food source is equally important. Clean water should always be used when preparing food and hands must be properly washed and disinfected. Fruits and vegetables should not be eaten raw due to the risk of waterborne diseases. Similarly meat and meat products must be thoroughly cooked. Refrigeration is essential and pre-cooked food must be heated adequately by any available means.

Constantly Hydrate

Constant hydration is very important even if there are no diarrheal illnesses, high fevers or other factors that may hasten dehydration. Only clean water free of contaminants should be consumed. It is advisable to consume electrolytes with the water where possible. Oral rehydration solutions should be prepared if available or energy drinks can be diluted with water. Diuretics like alcohol and caffeinated drinks should be avoided.

Sufficient Heat and Cooling

Depending on the environmental conditions, there may be a risk of hypothermia or hyperthermia. Always dry thoroughly after being immersed in water. Clothing should be changed and it is important to be near a heat source until body temperature returns to normal. In very hot conditions, it is advisable to use air conditioning or an electric fan where possible. Wear light colored and airy clothing and avoid long periods in the sun.

Evacuate When Advised

One of the most effective ways to prevent the health risks associated with flooding is to evacuate the affected area. Where possible, this should be done before the flooding arises. Although many people do not wish to leave their homes for various reasons, it is important to understand that the associated health risks can be life-threatening even if there is adequate protection from the flooding.


  1. www.who.int/hac/techguidance/ems/flood_cds/en/

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