The presence of parasites in humans causes numerous health problems, some of which are life-threatening if left untreated. Parasites typically enter the body through food or water that is ingested. When in the digestive tract, the symptoms of parasites in humans can include fatigue, irregular or excessive bowel movements, weight loss, nausea and cramps. Other types of parasites can reside in the blood and skin and cause itching, muscle and joint pains or anemia. These symptoms have many potential other causes, so parasites can be difficult to spot without an X-ray exam.
The larger parasites such as roundworms and tapeworms attach themselves to the intestinal wall and siphon nutrients that would otherwise travel through the body. In severe cases, this leads to overall malnutrition and weight loss. In the large intestine, larger worms can clog the interior of the intestine and prevent regular bowel movements. They also cause cramps and gas. Eating improperly cooked meat makes a worm infection more likely.
The symptoms of parasites in humans can also be confused for the flu. Blood parasites cause flu-like symptoms at early onset: fever, chills, vomiting and diarrhea. Severe infection causes digestive problems and difficulty swallowing, as well as anemia. Typically, blood parasites spread when an infected insect such as a mosquito bites a human and leaves feces inside the bite. Severe inflammation, swelling or pain around the bite area indicates a possible parasite infection.
Fungal parasites rely on moisture to thrive. They can live and breed best in areas that are exposed to a large quantity of sweat or other moisture; the armpits, groin, feet and inner thighs are main problem areas. Consistently itchy, dry and peeling skin or flaking dead skin are also symptoms of parasites in humans. Ringworm, another common fungal parasite, causes a circular rash on the skin at the area of infection.
Taking preventive measures can stem the symptoms of parasites in humans and stop parasite infection altogether. Avoiding parasites requires observation of sanitary food preparation, and having pets wormed regularly can also prevent worms. Using insect repellent and covering skin removes an access method for blood parasites via mosquitoes. Removing excess moisture from the skin stops the growth of fungi such as athlete's foot. Anyone who believes that he or she has a parasite infection based on known symptoms should visit a physician as soon as possible to have a full exam performed, because an untreated parasite infection could be lethal.