Fever

Most fever is due to an infection, and the point is to find what is infected. Most common infections are in the parts of the body that’s exposed to external world, ie

• skin anywhere from scalp till foot
• the alimentary tract from mouth till anus
• the respiratory tract from nose through throat till lungs
• the ears
• the eyes
• urinary tract (from urethra till bladder)

So the first step of finding out the infection is to ask for symptoms that are related to any of the above (itching, redness, pain, pus, irritation, cough, cold, watering, frequent urination, painful urination)

If none of that involved, it’s a bit complicated. It could either be that there is no symptom, but there is an infection (like a tuberculosis), or that there is an infection somewhere else

The non-obvious “sites” of infection are:

• blood - like in dengue, malaria
• internal organs like gall bladder, heart, brain - like typhoid, rheumatic fever, …

Then there are conditions that are not infections, but increase temperature. Like injury, cancer, etc.

In such situations, unless we get a clue like someone else being sick in the family, it might warrant investigations — like complete blood count, dengue test, covid test, etc.