Top 8 Infectious Diseases in Malaysia You Should Know About
15 June 2026
Like anywhere in the world, Malaysia has its share of infectious diseases, with most of which are common, manageable and treatable if caught early, and preventable with the right precautions.
However, many of these diseases can become serious if left untreated, and many start with symptoms that could initially be mistaken for a common illness, making them easy to overlook.
Whether you are Malaysian or are just visiting, a little awareness goes a long way. Dr Lee Kok Soon, our Consultant Physician & Infectious Diseases Specialist, shares the 8 top infectious diseases you should know about, including symptoms to watch out for and how to protect yourself.
1. Dengue Fever
Dengue is one of Malaysia's most persistent public health threats. It is spread through bites from Aedes mosquitoes that breed easily in clean, stagnant water.
Symptoms: High fever (above 40°C), severe headache, joint and muscle pain, pain behind the eyes, skin rash, nausea, and vomiting, typically lasting between two days to a week.
In severe cases, one may develop abdominal pain, bleeding from the nose or gums, vomiting blood or blood in the stool 24 to 48 hours after the fever subsides. If this happens, seek immediate medical attention at your nearest hospital’s emergency department.
How to protect yourself: Eliminate standing water around your home weekly, apply mosquito repellent on exposed skin, and wear long-sleeved clothing. Fit window and door screens to prevent mosquitoes from entering your home.
A dengue vaccine is available and especially recommended for those previously infected, as reinfection raises the risk of severe complications.
2. Tuberculosis (TB)
TB is a serious bacterial lung infection that remains prevalent in Malaysia. It spreads through airborne droplets when an infected person coughs, sneezes, and speaks, and the risk of spreading is higher in indoor areas, crowds and places with poor air circulation. Left untreated, TB can lead to severe lung damage and death.
Symptoms: Persistent cough lasting more than 2 to 3 weeks, prolonged cough (sometimes coughing up blood or sputum), chest pain, night sweats, fever, unexplained weight loss, and fatigue. However, one can have TB but also be symptomless.
How to protect yourself: Avoid prolonged close contact with TB patients in poorly ventilated spaces. If diagnosed, complete the full course of antibiotics as directed by your doctor. Stopping early leads to drug-resistant TB, which is far harder to treat.
3. HIV / AIDS
Human immunodeficiency virus (HIV) attacks the immune system, weakening the body's ability to fight infections and certain cancers. Left untreated, it can progress to AIDS, which is the most advanced stage of infection.
It can spread through contact with body fluids such as blood, semen, vaginal fluids, and breast milk, commonly through unprotected sex and shared needles. It does not spread through saliva, sweat, or tears.
Symptoms: Many people experience no symptoms early on. Acute infection can resemble a flu-like illness about a month after exposure, with symptoms such as fever, sore throat, fatigue, and swollen lymph nodes.
AIDS-stage symptoms include rapid weight loss and being prone to infections that do not usually affect healthy people.
How to protect yourself: Practice safe sexual behaviours, and get tested regularly if at higher risk. While there is currently no cure for HIV, antiretroviral therapy (ART) can help slow the progression of the disease.
ART can also be used preventively. Ask your doctor about pre-exposure prophylaxis (PrEP) for ongoing risk, or seek post-exposure prophylaxis (PEP) within 72 hours of possible exposure.
4. Leptospirosis
Leptospirosis, also known as “kencing tikus”, is a bacterial infection spread through contact with water or soil contaminated by animal urine, most commonly rats. Infection can occur through the eyes, nose, mouth, or breaks in the skin. In Malaysia, outbreaks are frequently linked to contaminated food or drink, flooding, waterfall visits, and hiking. Without treatment, it can lead to kidney damage, meningitis, liver failure and death.
Symptoms: High fever, headache, intense muscle pain, abdominal pain, red eyes, vomiting, diarrhoea, chills and rashes. If the infection worsens after 3 to 10 days, symptoms can progress to chest pain, coughing up blood, difficulty breathing, black tarry stools, and blood in the urine.
How to protect yourself: Avoid unhygienic food vendors and eat freshly cooked food. Regularly clean and disinfect areas where rats may thrive, and keep food sealed.
Also, avoid wading, swimming, or swallowing water from potentially contaminated sources, including waterfalls, stagnant water, and floodwaters. Cover any open wounds before water exposure, and wear protective clothing in high-risk environments.
5. Food Poisoning
Food poisoning is among the most common illnesses in Malaysia. It's typically caused by bacteria or other germs, such as Salmonella, E. coli, and Vibrio cholerae, in improperly handled or stored food or unsanitary conditions, which is common with street food, buffets, and leftovers.
Symptoms: Symptoms can begin hours or days after consuming the contaminated food or drink, with symptoms like nausea, vomiting, stomach cramps, diarrhoea, and fever. The dehydration from vomiting and diarrhoea can become dangerous in young children, and prompt medical attention is crucial.
How to protect yourself: Always wash your hands before eating, as well as before and after handling food. Choose freshly cooked food served hot when eating out, and if there is any doubt on whether the food is made or stored safely, don’t hesitate to throw it away.
Avoid raw or undercooked meat and seafood, refrigerate perishables and leftovers promptly, and drink treated or boiled water.
6. Hepatitis B & C
Both Hepatitis B and C are viral liver infections that can silently cause liver damage and liver cancer over the years if undetected. Both are contagious.
Hepatitis B spreads through blood and body fluids, commonly through sexual contact, shared needles, or from mother to baby during childbirth. Hepatitis C spreads mainly through blood contact, such as shared needles.
Currently, hepatitis C is fully curable with modern antivirals, while hepatitis B has no cure but can be effectively managed with antivirals.
Symptoms: Symptoms for both forms are similar and include upper right abdominal pain, fatigue, loss of appetite, jaundice, dark urine, joint pain, and clay-coloured stools.
How to protect yourself: Get vaccinated against hepatitis B (there is no vaccine for hepatitis C). Get screened for both hepatitis B and C, practice safe sex and avoid sharing needles and razors.
7. Influenza & Pneumonia
Influenza circulates year-round in Malaysia's tropical climate. It can escalate to pneumonia for high-risk individuals and be life-threatening, particularly in the elderly, young children, and those with chronic conditions.
Symptoms: Influenza often presents with sudden fever, chills, body aches, cough, headache, and fatigue. With pneumonia, warning signs include shortness of breath, chest pain, and productive coughing with thick yellow, green or rust-coloured phlegm.
How to protect yourself: Get the annual flu vaccine and pneumococcal vaccine, especially if you are over 65 or have underlying health conditions. Also, practise proper hygiene by covering coughs and sneezes, washing your hands often, and clearing frequently touched surfaces.
8. Sexually Transmitted Infections (STIs)
STIs are infections that are transmitted through sexual contact. Some of these STIs, like gonorrhoea and syphilis, can lead to serious complications, including infertility, heart disease, and neurological damage, if left untreated.
Symptoms: Often none. When symptoms occur, common ones include unexplained and prolonged ulcers, bumps or blisters near the genitals, anus or mouth, foul-smelling or unusual discharge, itching in the genital area and painful urination.
How to protect yourself: Practice safe sex, and get tested regularly if sexually active with new or multiple partners. If diagnosed, complete any prescribed antibiotic course in full, and notify partners so they can also be tested.
What to Keep in Mind
Many infectious diseases are highly treatable when caught early but can become life-threatening if ignored, so don't wait too long before seeking medical attention.
Dr Lee adds that when visiting a doctor, you should share your recent travel history, especially if you've been to waterfalls, rural areas, flooded zones, or outdoor events. This information can help your doctor identify the cause faster and recommend the right tests and treatment.
He also adds that staying vigilant, practising good hygiene, and taking simple preventive measures go a long way in protecting yourself and your loved ones from infectious diseases in Malaysia.
If you notice any of the symptoms mentioned above, don't self-diagnose or delay. Schedule an appointment with Dr Lee for proper diagnosis and treatment by clicking below.
