25yr boy having fever n bodyache WBC 3.3 n platelet 102, dengue ns1 -ve, no other illness. Wat the cause of low platelets?

Thanks for asking! Could be an occult infection. Needs more work up.
It' s Dengue! It affects the white blood cells causing fever, flu like symptoms , severe pains. It can affect the liver and bone marrow leading to reduced number of platelets, increasing risk of bleeding and low blood pressure.
Virus. Viral diseases often cause a transient lowering of all blood components, including platelets.