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What is Infectious Disease

Infections are caused by germs (microorganisms) that under certain conditions, develop to cause certain diseases. There are numerous types of microorganisms, and they cause a wide range of different infections. A particular organ in the body can be infected by different microorganisms (e.g. lung infections called pneumonia), while a single type of microorganism can affect different parts of the body (e.g. dengue). Every living person has had encounters with infections. Most infections are relatively minor, e.g. a common cold or sore throat. Sometimes, however, infections can be life threatening if they cause the infected organ to start failing (e.g. pneumonia can lead to difficulty breathing); or if the infection spills over into the blood (sepsis); or if the person infected does not have strong defenses against the germ (e.g. diabetes and other diseases that limit the body’s immune system to fight off germs). 


Infections are also notorious for being able to spread, either within the family, the community and even within hospitals. Depending on the germ, they can spread either through an unsuspecting person breathing it in, accidentally consuming contaminated foods, through breaks in the skin, through sexual activity or through animal or insect bites. Learning how to prevent infections is just as important as how to treat them.

The most common symptoms of an infection

The most common symptoms of an infection are fever, feeling tired and having a poor appetite. Most infections will also give rise to other symptoms depending on the part of the body that is affected. There are exceptions though. Certain infections might not produce a fever (e.g. when the immune system is weak) and not all fevers are due to infections (e.g. cancers can also cause fevers). Trying to detect an infection, identifying the germ involved and then managing these symptoms alongside eradicating the infection is the main aim of a doctor.

Infectious Disease (ID)

Infectious disease (ID) is a relatively new subspecialty in the field of medicine in Malaysia. Generally, all doctors are equipped to manage infections. However, under certain circumstances, a consultation with an infectious disease specialist might be helpful. These might be for the following reasons:

  • Difficulty identifying the microorganism involved or the organ involved (e.g. sepsis, meningitis)
  • Being unable to ascertain if the fever and illness are due to an infection or a mimic of an infection (e.g. autoimmune diseases, cancers)
  • The infection is potentially severe and possibly life or limb threatening (e.g. dengue, leptospirosis, pneumonia)
  • The infection does not seem to be eradicated (e.g. hepatitis, melioidosis, abscesses, herpes, syphilis)
  • When a rare infection is suspected (e.g. malaria, rabies)
  • Suspecting that an infection might be contracted from unusual sources (e.g. food borne infections, animal bites, sexually transmitted infections)
  • When the patient’s immune system is weak (e.g. diabetes, HIV, post chemotherapy or transplant infections)
  • When the infection is resistant to standard antibiotics (e.g. MRSA, ESBL, multi-resistant infections)
  • Treating infections that have a high potential to spread (e.g. TB, measles, chicken pox)
  • When advice is needed on how to prevent the disease from spreading (e.g. avoiding contracting infections while travelling like influenza or typhoid)
ID Specialists

ID specialists provide expert insight into which tests and examinations are needed to diagnose and understand the infection as well as halt the infection from recurring or spreading. From there, suitable treatment can be determined and the appropriate prevention methods taken.

The ID specialist may serve as the primary care physician, but more often than not, the regular doctor is still required. Their role is primarily to diagnose and provide treatment to infectious diseases. However, you may be required to return to your infectious disease specialist to ensure the infection is fully eradicated and the likelihood of it recurring is eliminated, or if you are continually likely to contract other infections.

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Meet Our Infectious Disease Specialists

Get to know our specialists here at Thomson Hospital Kota Damansara.

Dr Nor Liza Ariffin

Consultant Infectious Diseases Physician
Resident Consultant
Infectious Disease, Internal Medicine
MB BCh (Ireland) , MMed (Mal) , MRCP (Ireland)
Suite Number
Level 1 - A-L1-06
Spoken Language
English, Malay

Doctor Availability

Monday9:00am - 1:00pm, 2:00pm - 5:00pm
Tuesday9:00am - 1:00pm, 2:00pm - 5:00pm
Wednesday9:00am - 1:00pm, 2:00pm - 5:00pm
Thursday9:00am - 1:00pm, 2:00pm - 5:00pm
Friday9:00am - 1:00pm, 2:00pm - 5:00pm
Saturday9:00am - 1:00pm