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Infectious Disease
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Common Infectious Diseases in Malaysia During the Flood Season

23 December 2022 · 15 mins read


The rise of infectious diseases during the flooding season is common in Malaysia. Learn about common infectious diseases and their preventive measures.

Floods are a prevalent seasonal geo-environmental occurrence in Asia. Malaysia faces regular flooding over its two monsoon seasons, typically around late May to September and November to March.

This recurrent flooding comes in the form of flash floods from intensive heavy rains, or river flooding as a result of rivers bursting through their banks. These incidents in certain flood-prone areas in Malaysia have necessitated massive evacuation and disaster relief efforts throughout the last decade.

During the flood season, Malaysians are exposed to the risk of infectious and waterborne disease outbreaks.

Statistics of infectious diseases

Infectious diseases are caused by pathogenic microorganisms (pathogens) such as bacteria, viruses, parasites, and fungi. Infectious diseases are contagious diseases that can spread directly or indirectly from one individual to another.

In their update on the Western Pacific’s dengue situation, WHO reported a total of 52,977 dengue cases in Malaysia from January to the start of November 2022. 37 of these cases were fatal.

Tuberculosis, a leading single infectious agent, manifests an incidence rate of 92 per 100,000 people in Malaysia. In fact, there were 25,173 cases recorded nationally in 2018, which translated to almost 70 new cases daily.

Common infectious diseases during floods in Malaysia

Monsoon winds increases the possibility of flooding during the local tropical wet season characterised by heavy and regular rainfall. This leads to fluctuations in water levels, storm surges, or the hammering of waves.

The subsequent flooding aftermath then facilitates the breeding of mosquitoes, and later outbreaks of infectious diseases. Some of the infectious disease cases prevalent in Malaysia in the wake of flooding are food and waterborne diseases. These commonly include bacterial diarrhoea, vector-borne diseases such as dengue fever, and water-contact diseases such as leptospirosis.

Following are some frequently observed infectious diseases in Malaysia during the flooding season.

  • 1. Typhoid fever

    Typhoid fever is a systemic bacterial infection caused by Salmonella enterica and spread mainly by contaminated food, water, or close contact with infected patients. Most patients show a common symptom of sustained high fevers, which, left untreated, can prove fatal.

  • 2. Cholera

    Caused by infection of the intestine with vibrio cholerae bacteria, cholera is primarily a diarrheal illness that occurs when humans consume contaminated food or water. This diarrheal infection often demonstrates mild symptoms but can escalate with severe and life-threatening symptoms—for example, shock and seizures.

  • 3. Hepatitis A

    Hepatitis is essentially a family of viral diseases that appears in the form of liver inflammation that affects liver functions acutely, or even chronically. Hepatitis A is particularly spread via the consumption of food and water contaminated with faecal matter.

    It is common in areas of poor sanitation and victims exhibit fever, jaundice, and diarrhoea. Unfortunately, approximately 15% of Hepatitis A victims experience prolonged symptoms for over 6 to 9 months. Fortunately, this disease has a working vaccine that can be administered to members of the public.

  • 4. Dysentery and food poisoning

    Dysentery is caused by a few types of bacteria and parasites. The bacteria shigella that causes dysentery can spread through contaminated food or water. A key symptom of the disease is bloody diarrhoea. However, many cases also manifest symptoms of abdominal pain, fever, cramps and malaise (feeling of discomfort, illness, or unease).

  • 5. Leptospirosis

    Leptospirosis is a bacterial disease caused by the genus Leptospira. Leptospirosis outbreaks are common in regions that experience recurrent flooding. In fact, leptospirosis infection mainly occurs via contact with water or food contaminated by animal urine.

    Its symptoms are mainly high fever, incessant headache, vomiting, jaundice, and diarrhoea. If left untreated, the disease can quickly result in kidney damage, meningitis, liver failure, or respiratory distress. However, fatality rates are relatively low.

  • 6. Dengue fever

    Dengue fever is a common infectious disease caused by ribonucleic acid (RNA) virus from the flaviviridae family transmitted via mosquito vectors known as Aedes aegypti.

    As a viral disease associated with urban environments, dengue fever manifests as a sudden onset of fever and severe headache. In some instances, it occasionally produces shock and haemorrhage, leading to death in approximately 5% of cases.

  • 7. Malaria

    Malaria is a common infectious disease caused by single-cell parasitic protozoa called plasmodium that is transmitted to humans through the bite of a female Anopheles mosquito.

    As a result, plasmodium parasites multiply in the human liver and attack the red blood cells, and this leads to fever cycles and sporadic sweating accompanied by anaemia. If left untreated, malaria often leads to death or damage to vital organs due to the interruption of blood supply to the brain.

  • 8. Japanese encephalitis

    Japanese encephalitis is essentially a viral brain infection spread through mosquito bites and common in rural areas in southeast Asia. The virus is mainly found in pigs and birds but is passed to mosquitoes when they bite infected animals.

    If left untreated, the mosquito-borne disease (spread by culex tritaeniorhynchus mosquito) can progress to paralysis, coma, and even death.

  • 9. Conjunctivitis

    Conjunctivitis is a minor infection that manifests as pinkeye. As an inflammation of the conjunctiva (the white eye component and the inner eyelids), conjunctivitis causes irritation and can be caused by bacterial or viral infection.

  • 10. Measles

    Measles is fundamentally an acute viral respiratory illness characterised by a prodrome of fever, cough, total body rash and conjunctivitis. By nature, measles is a very contagious respiratory infection that spreads through the air by respiratory droplets as an infected individual coughs or sneezes.

Flooding increases spread of infectious diseases

Flooding comes with a number of health consequences including drowning, physical injury, gastroenteritis outbreaks, respiratory infections, epidemic diseases such as cholera, diarrhoea, and dengue fever, amongst others.

While certain rare infections can also occur due to flooding, the majority of infectious diseases are gastrointestinal, respiratory, or febrile vector-borne illnesses.

These are common during flooding disasters simply because floods create unsanitary conditions for the breeding and multiplication of harmful pathogens and disease vectors.

Protect yourself from diseases during and after floods in Malaysia

Here are some important prevention techniques that can help one stay safe during the flooding season.

  • 1. Get the available vaccinations

    Many infectious diseases such as Hepatitis A and B, Influenza, Japanese Encephalitis, etc. have effective vaccines that have been tested and proven by the scientific community over time.

    These vaccines help to reduce the spread of diseases to others, especially those who are immune-compromised or susceptible to infections during flooding seasons.

    Visit Gleneagles Hospitals for information on vaccines for infectious diseases.

  • 2. Take care of food hygiene

    Since infectious diseases are easily spread through food and water, it is imperative to ensure access to safe water for and hygienic food during the floods. This can be the first line of defence against a potential infectious disease outbreak.

  • 3. Take care of personal hygiene

    Relatedly, personal hygiene is a significant component of infectious disease prevention during flooding seasons. Frequently wash hands with soap and clean water or use alcohol-based hand sanitisers (consisting at least 60% alcohol).

  • 4. Keep the surroundings clean

    Poor sanitary conditions can easily escalate infectious disease spread. For example, leptospirosis outbreaks typically occur through rodent urine contaminating water. Generally, unsanitary conditions can foster rodent breeding.

    As such, it is vital to ensure that your surroundings are constantly kept clean following the occurrence of a flood.

  • 5. Look out for breeding grounds for mosquitoes

    Try to clear stagnant water to prevent the breeding of mosquitos. Furthermore, sleep under mosquito nets, use mosquito repellents and even residential window screens to reduce exposure to mosquitoes that are disease vectors during flood seasons.

Infectious diseases treatment

There is always a high risk of infectious disease transmission and outbreak shortly after a natural disaster like flooding. 

Part of the challenge is that flooding leads to the emergence of overcrowded shelters with poor water and sanitation conditions amongst the affected. Not forgetting, insufficient personal hygiene and vaccination coverage, and often limited access to health care services.

Therefore, it is important to have access to professional emergency team of specialists at Gleneagles Hospital.

Efficient medical services have a primary role in controlling infectious disease epidemics, administer vaccines, and improve deteriorating health conditions amongst disaster victims.

Make an appointment at Gleneagles Hospitals

If you encounter a situation that requires medical attention, please seek immediate medical attention at the Accident and Emergency (A&E) department at your nearest Gleneagles Hospital.


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