A parasitic infection is a disease caused by parasites that live in or on the human body and depend on the host for food and survival. Parasites include protozoa, helminths (worms), and ectoparasites such as lice and mites. These infections can spread through contaminated food or water, poor hygiene, insect bites, contact with infected people or animals, or exposure to contaminated soil. Common symptoms include diarrhea, abdominal pain, nausea, vomiting, weight loss, fatigue, itching, skin rashes, and fever, although symptoms vary depending on the type of parasite. Diagnosis is usually made through stool, blood, or other laboratory tests, and treatment involves antiparasitic medications prescribed according to the specific infection. Preventive measures include maintaining good personal hygiene, drinking safe water, eating properly cooked food, washing fruits and vegetables, wearing footwear outdoors, and protecting against insect bites.