Standing water after a flood creates the ideal breeding ground for mosquitoes. — Photos: Filepic
Floods in Malaysia, an annual challenge during the monsoon season from October to March, bring not only destruction to properties but also significant health risks.
Floodwaters, often contaminated with pathogens, can expose residents to dangerous bacteria, viruses and parasites, posing severe threats if proper precautions are not taken.
Recent studies highlight the exacerbating role of extreme weather events, such as floods, in the spread of infectious diseases.
For instance, in May 2024, floods in southern Brazil triggered a leptospirosis outbreak, especially in urban areas with poor sanitation.
Similar findings show that floods facilitate the transmission of various pathogens, which thrive in contaminated water.
One study, published last year in the journal, Water, shows that bacterial populations in rivers increase significantly during the monsoon season, which raises the risk of waterborne diseases.
Residents in urbanised midstream areas are more susceptible due to favourable environmental conditions for disease transmission.
According to a systematic review published in the Environmental Research: Health journal in August 2024, there is an association between climate factors and infectious diseases like tuberculosis, leptospirosis, and hand, foot, and mouth disease (HFMD).
For example, temperature variations correlate with the incidence of these diseases, with close proximity to water bodies increasing leptospirosis risks.
Floods create ideal conditions for the spread of waterborne bacterial infections, particularly typhoid fever, cholera and leptospirosis.
Typhoid fever, caused by Salmonella enterica serotype Typhi, is transmitted through contaminated food or water and symptoms often include high fever, headaches and gastrointestinal distress like nausea and abdominal pain.
Left untreated, it can lead to serious complications such as intestinal perforation or septicaemia.
Similarly, cholera, caused by Vibrio cholerae, manifests as acute watery diarrhoea, which can quickly lead to dehydration, shock and death if not addressed immediately.
The severity of this disease makes it one of the most dangerous during flood situations.
Another major concern is leptospirosis, a zoonotic infection spread by contact with water contaminated with the urine of infected rodents, which is commonly found in floodwaters.
It typically presents with high fever, muscle aches and in severe cases, can lead to kidney damage, liver failure, meningitis or respiratory complications.
Early intervention with antibiotics is crucial for reducing the severity and preventing long-term damage from leptospirosis.
Keep tabs on your kids playing in floodwaters as accidentally swallowing contaminated water can lead to infections.
Floods also exacerbate the transmission of vector-borne viral diseases i.e. diseases that result from an infection transmitted to humans and other animals by blood-feeding arthropods, such as mosquitoes, ticks and fleas.
Of particular concern in Malaysia is dengue fever.
The standing water left behind after floods provides the perfect breeding ground for the Aedes mosquito, which transmits the dengue virus.
Symptoms of dengue include severe fever, joint and muscle pain, and in some cases, life-threatening haemorrhagic fever.
Dengue outbreaks are common in flood-prone regions, as stagnant water increases mosquito populations.
Another viral risk is hepatitis A, which is spread through ingestion of contaminated food or water.
This infection can cause symptoms such as jaundice, fatigue, nausea, abdominal pain and gastrointestinal distress.
Ensuring safe drinking water and proper sanitation in flood-affected areas is key to preventing these viral outbreaks.
Though often overlooked, parasitic infections can also emerge in the aftermath of floods, particularly through exposure to contaminated water.
Waterborne parasites, including Giardia, Cryptosporidium, and Blastocystis, can cause gastrointestinal diseases such as giardiasis, cryptosporidiosis, and blastocystosis.
These parasites are commonly transmitted through cysts or eggs present in contaminated water and can cause symptoms such as diarrhoea, nausea, vomiting and abdominal pain.
Children and the elderly are especially vulnerable to severe dehydration from these infections, which can lead to more serious health complications if not treated promptly.
If you or your family members experience symptoms of any infectious disease-such as high fever, persistent diarrhoea, vomiting, unexplained rash, difficulty breathing, or severe fatigue, it’s important to seek medical attention without delay.
For children who may accidentally swallow floodwater while playing, closely monitor them for any signs of illness.
Symptoms such stomach cramps, diarrhoea, or fever may require immediate medical consultation, as early treatment can help prevent complications and improve recovery outcomes.
Here are some ways:
> Water and food safety
Ensuring access to clean water is critical.
Boiling water or using bottled water not exposed to floodwaters is advised.
Alternatively, water purification tablets or chlorine drops can be used.
For food, discard any items that have been in contact with floodwaters, especially perishables like meat and dairy.
If power outages compromise refrigeration, perishable items left at unsafe temperatures for more than two hours should also be discarded.
> Hygiene and sanitation
Thorough cleaning of flood-affected homes and areas is essential to prevent infections.
Wearing gloves and using a disinfectant solution-such as chlorine bleach diluted with clean water can effectively sanitise surfaces.
Pay special attention to corners, cracks and commonly touched areas like doorknobs to reduce pathogen presence.
> Avoiding vector breeding grounds
Standing water in flood-hit areas creates ideal conditions for mosquito proliferation.
Efforts should be made to drain or treat these water sources.
Local health authorities often conduct spraying to curb mosquito populations, but community participation is equally vital.
> Protective measures
First aid kits should be readily available during a flood, in case of an injury.
Individuals cleaning flood-impacted spaces should wear protective clothing to minimise direct contact with potentially contaminated materials.
Skin wounds should be covered and first aid kits should be readily available in case of accidental injuries.
In flood rescue centres, it is essential to follow these simple steps to protect yourself and your family from waterborne diseases and other health risks.
> First, ensure safe drinking water by using water purification tablets or boiling water.
> Keep your hands clean by using hand sanitisers or washing with soap and clean water frequently, especially before eating.
> Avoid contact with contaminated water, wear protective footwear and use insect repellent to prevent vector-borne diseases.
> Ensure children are supervised and avoid consuming food that may have been exposed to floodwater.
> Lastly, stay informed and follow official guidelines for safety.
Experts emphasise the role of public awareness and community action in reducing flood-associated health risks.
Programmes such as Communication for Behavioral Impact (COMBI) play a crucial role in educating communities about proper hygiene, vector control and disease prevention.
Additionally, the programme initiated by the World Health Organization and implemented by the Health Ministry provides essential guidance to communities, ensuring that they are well-informed and prepared for emerging health threats in flood-affected areas.
As floods are an annual occurrence and challenge in our country, a concerted effort involving government agencies, local communities and individuals can significantly mitigate health risks.
By adopting proper preventive measures and remaining vigilant, the nation can reduce the burden of flood-related diseases and safeguard public health effectively.
Dr Vinoth Kumarasamy is a parasitologist and lecturer at Universiti Kebangsaan Malaysia. For more information, email starhealth@thestar.com.my. The information provided is for educational and communication purposes only, and should not be considered as medical advice. The Star does not give any warranty on accuracy, completeness, functionality, usefulness or other assurances as to the content appearing in this article. The Star disclaims all responsibility for any losses, damage to property or personal injury suffered directly or indirectly from reliance on such information.
