Parkinson's disease is a progressive neurological disorder characterized by the gradual loss of dopamine-producing neurons in the brain, leading to motor symptoms such as tremors, stiffness, and impaired movement control.

Dandruff, particularly in its severe form, is often due to seborrheic dermatitis—a chronic inflammatory condition affecting scalp, eyebrows, ears, and nose folds. It is linked to yeast overgrowth (Malassezia) and skin oil imbalance.

Chikungunya is a viral disease transmitted to humans by the bite of infected Aedes mosquitoes. It causes fever, joint pain, and fatigue, and may mimic symptoms of dengue or viral arthritis.