Many parasitic infections cause only mild symptoms or no symptoms at all. But some organisms can cause brain and nervous system damage or long-lasting symptoms such as chronic fatigue or muscle aches. Some of these infections can turn deadly, especially in people whose immune systems are suppressed by illness or chemotherapy.
Good news: Once you’re diagnosed (usually with a stool sample), most parasites can be eliminated with medication. Virtually all can be prevented with good hygiene and the safe handling of food and water. However, parasitic infections are notorious for going undiagnosed — largely because symptoms can be mistaken for other illnesses, and many doctors underestimate their presence in developed countries.
Common parasites in the US…
Healthy adults with this potentially dangerous single-celled organism typically have no symptoms. Occasionally, however, a scar can form on the retina. During a routine eye exam, the scar can be noted and serve as a clue to previous exposure. In people with impaired immunity, such as those undergoing chemotherapy or AIDS patients, untreated toxoplasmosis can suddenly reemerge and cause brain or nervous system damage and even can be fatal.
Although medications are usually recommended for those with compromised immunity, symptoms usually go away without treatment in people who are otherwise healthy. However, the dormant organism may reemerge.
T. gondii is often present in the feces of otherwise healthy-appearing cats. People may get infected while cleaning a cat’s litter box or working in the yard and touching soil where a cat has defecated.
Be sure to wash your hands thoroughly after contact with a cat or its feces and after yard work or gardening. The disease also can be contracted by eating any type of undercooked contaminated meat, which can harbor the organism.
Symptoms: Swollen lymph nodes, headache, fever, body aches and sometimes a sore throat.
Treatment: Pyrimethamine (Daraprim), an antimalaria drug that also kills T. gondii. It’s combined with an antibiotic to increase the effectiveness of the treatment. Treatment usually lasts several weeks, but those with compromised immunity may need to continue for the rest of their lives. Important: Pyrimethamine inhibits the absorption of folate (folic acid). Patients who take high doses for extended periods are usually advised to supplement with 400 micrograms (mcg) of folic acid daily.
Toxoplasmosis can cause problems with pregnancy, including miscarriage. Pregnant women should speak to their doctors for precautions to take.
Cysts of the parasite Giardia lamblia are excreted in the feces of people who are infected with the organism. Infection can result from ingesting as few as 10 of these cysts. This might occur, for example, if someone uses the bathroom, doesn’t wash his/her hands and then deposits the cysts on an object such as a cutting board.
The infection, known as giardiasis, can also be contracted by drinking contaminated water or eating contaminated food. Though the organism can survive in tap water, in most communities tap water is free of infectious agents, including G. lamblia. With untreated well water, not even a water filter will reliably kill G. lamblia.
Hikers, hunters, campers and anyone who spends a lot of time in nature should avoid drinking untreated water from or swimming in unclean streams, lakes or rivers. Best: Pack your own purified water.
Symptoms: Gastrointestinal upset, such as severe diarrhea, cramping and sometimes nausea, often occurs upon first exposure. Later, the symptoms may be mistaken for irritable bowel syndrome or chronic acid indigestion. Some experience fatigue and weight loss.
Treatment: The drug metronidazole (Flagyl), taken three times daily for five to seven days. Side effects include a metallic aftertaste and nausea. Avoid drinking alcohol when taking Flagyl. Combining the two can cause upset stomach, vomiting and abdominal cramps.
This one-celled parasite — and its close relative Cyclospora cayetanensis — infects the small intestine. People with this infection, known as cryptosporidiosis, release enormous quantities of the parasite in their stools. People may get infected if they drink (or swim in) contaminated water, eat uncooked foods that were prepared by someone with the infection, or touch their mouths after touching a contaminated surface or object. Note: Chlorination of water will not kill this organism.
Symptom: Watery diarrhea. This may continue for one to two weeks — or even up to a month — in people who are otherwise healthy. The infection is potentially deadly for those with weak immune systems.
Treatment: Patients who are generally healthy don’t require treatment and usually recover within two weeks. In those with compromised immunity, in addition to treating the underlying illness if possible, fluid/electrolyte replacement may be required as well as antidiarrheal medications and/or antiparasitic medications to reduce symptoms.
The largest intestinal parasite is the tapeworm. It can survive in the intestine for more than a decade and can potentially reach up to 50 feet in length. Infection is usually caused by eating infected raw or undercooked pork, beef or fish.
Symptoms: Most people have no or only mild gastrointestinal symptoms, such as occasional diarrhea. Equally important, tapeworm larvae can migrate to parts of the body outside the intestine and cause seemingly unrelated symptoms, such as seizures (if they enter the brain).
Depending on the species and the nature of the infection (worm or larval), some patients may suffer damage to the central nervous system.
Treatment: Praziquantel (Biltricide) kills adult tapeworms. A stool sample is usually taken one to three months after the initial treatment. If the parasite is still present, the drug is repeated.
It also may be useful to take probiotics to ease severe diarrhea — speak to your doctor.
Food and water sanitation, as well as good hygiene, are the best ways to prevent parasitic infections. Recommended…
• Use a countertop or under-the-sink activated carbon water filter to trap cryptosporidium, giardia and other parasites.
• Wash your hands not only after using the bathroom, but also after working in the yard or handling laundry — particularly when the laundry includes underwear or bedsheets. You would be surprised at how many people don’t follow these simple guidelines.
• Always rinse fresh fruits and vegetables. This will remove most organisms. In high-risk areas (such as tropical or underdeveloped countries), soak these foods in water disinfected with iodine. Add five to 10 drops per quart of water. Let the food soak for about 20 minutes.
• Wash knives, cutting boards and other kitchen equipment — as well as your hands — with warm, soapy water before and after handling raw meats.
• Wear gloves when cleaning a litter box, and wash your hands afterward.
• Don’t walk barefoot in the yard/garden, particularly if you have cats (or livestock).
