Parasitic Infections Health Article

Causes & symptoms

Risk factors for getting parasitic infections include:

• an immune system weakened by disease or long-term exposure to toxic chemicals or environmental pollution
• prolonged antibiotic use
• alcohol and/or drug abuse
• smoking
• emotional and/or physical stress
• diet high in fat and sugar and low in fiber
• food allergies
• malabsorption syndrome
• obesity

Causes

There are more than 100 types of human parasites. The following describe some of the most common species in America.

ARTHROPODS (INSECTS). In the United States, because of high sanitary standards and a temperate climate, parasitic insects do not flourish. Common bugs such as ticks, mites, fleas, lice, and bedbugs may cause intense itching in affected areas. They are a nuisance but not a major health risk. One exception is the deer tick, which is associated with the debilitating Lyme disease. Other parasites, spread by mosquitoes, cause more serious diseases like western and eastern equine encephalitis, malaria, Dengue fever, and yellow fever.

INTESTINAL PARASITES. Some of the most common intestinal parasites include:

• Pinworms. This is the most common parasitic infection in the United States. The worm resides in the colon, yet it lays eggs outside the body, usually near the anus, a process that causes severe itching. The disease can be transmitted from one individual to another through dirty hands, clothing, bedclothes, and toys.
• Tapeworms. The two most common tapeworms are Taenia solium (pork tapeworm) and Taenia saginata (beef tapeworm). Taenia solium infestation is caused by eating undercooked pork while Taenia saginata (pork tapeworm) infestation is associated with consuming raw beef. Adult tapeworms may become quite big, some as long as 20 feet (6.1 m). Pork tapeworm is the more harmful. It often causes anemia and weight loss. More seriously, when adult pork tapeworm eggs, excreted in human feces, are ingested by other people (which can happen with poor hygiene and sanitation), the parasitic life cycle that occurs in pigs and cattle takes place in the human host. Once in the human digestive system, the tapeworm eggs, called proglottids, develop into an embryonic form of the parasite called onchospheres that burrow through the intestinal wall and into the bloodstream. From there they migrate into the muscles, eyes, and the brain, a condition called cysticercosis. Cysts in the brain often cause epileptic seizures.
• Protozoa (one-celled organisms) such as Giardia lamblia, Entamoeba histolytica, or Cryptosporidium. These organisms are some of the most common and infectious parasites in the world. They can be transmitted through contaminated food and water. They can also be spread from one person to another. Protozoa may spread throughout the body, causing abscesses in the lungs, liver, heart, and brain. Cramps, watery diarrhea, abdominal pain, and serious weight loss are common symptoms of Giardia infection. Entamoeba histolytica can cause dysentery, a severe form of intestinal infection, as well as liver and lung damage. Cryptosporidia can cause severe diarrhea in AIDS or cancer patients who have weakened immune systems.

CNS PARASITIC INFECTIONS. Toxoplasma gondii is the most common parasite that invades the central nervous system (CNS). Humans become infected with this organism by eating raw or undercooked meat or by handling infected cat litter, which can contain eggs. Pregnant women who are infected may miscarry or deliver stillborn babies. Infected babies are born with congenital toxoplasmosis, and have symptoms that include eye inflammation, blindness, jaundice, seizures, abnormally small or large heads, and mental retardation. In people with weakened immune systems, such as AIDS patients, toxoplasmosis can affect the whole body, causing inflammation, convulsions, trembling, headache, confusion, paralysis in half of the body, or coma.