The stomach-churning facts: The two most common parasites in this country, according to CDC data, are frequently found in contaminated water: giardia, which infects 2 million people every year, and cryptosporidium, which infects 300,000 annually. Both inflict diarrheal diseases and are contracted by coming into contact with infected stools, whether through water we drink or in swimming pools or other recreational water facilities. Another similar parasite, cyclospora, is contracted the same way but is less common than the other two.
How to protect yourself: Pay attention to bulletins about local drinking water quality, and always follow orders to boil water when you hear about them. Don't swallow water at swimming pools (and do your part by always bathing before taking a dip).
The stomach-churning facts: Raw or undercooked meat, especially pork, lamb, or venison, is a frequent source of the third most common intestinal parasite seen in this country, toxoplasma. It's estimated that 60 million people carry the parasite, of whom 1.5 million actually get infected with toxoplasmosis every year, but most people who are infected aren't even aware of it. It's also the third-leading cause of death from foodborne illness.
Eating undercooked pork is also how people most often contract the intestinal parasites Trichinella, roundworms that live in the muscle tissue of meat-eating animals, and Taenia, a tapeworm that can grow up to 23 feet long. There aren't any hard figures for tapeworm infections in the U.S., but Taenia is one of the most common culprits, according to the CDC. Taenia parasites also cause another disease, cysticercosis, which you contract from the larval cysts of the tapeworm. They can infect brain and muscle tissue and are a major cause of adult-onset seizures in most low-income countries. But you don't have to live in a low-income country to catch this unfortunate infection, which has been targeted by the CDC as one of five Neglected Parasitic Infections that require prompt public health action. Infected food workers who haven't washed their hands can pass along cysticercosis.
How to protect yourself: Cooking your pork, lamb, or venison to an internal temperature of 160 degrees should kill off any wrigglies in the meat. And don't eat bear, cougar, fox, dog, wolf, horse, seal, or walrus meat—they all harbor Trichinella, as well.
The stomach-churning facts: The same parasites that infect your drinking water can infect your produce, too. They're spread by contaminated water used to irrigate the crops. While E. coli bacteria usually cause the most publicized cases of contaminated crops, giardia and cryptosporidium can also be found in produce. The roundworm Ascaris, the most common cause of human worm infections, has been found on unwashed lettuce and other kinds of produce irrigated with water contaminated by human or pig feces. It isn't common in the U.S., but a few cases have been reported in rural areas.
How to protect yourself: Wash your hands thoroughly before handling fruits and vegetables, and wash your produce with a solution of 1 part vinegar and 9 parts water to kill germs.
The stomach-churning facts: That tasty piece of raw sushi on your plate may be harboring another kind of tapeworm, Diphylobothrium, also called the salmon tapeworm. While infections of this type are rare in the U.S., they've been on the rise in Asia and Latin America, where raw sushi and ceviche are eaten regularly. In Japan, the number of cases went from virtually zero in the late 1990s to 15 per year in 2008, and in Brazil, there was one case of Diphylobothrium infection between 1998 and 2003, but 18 between 2004 and 2005.
How to protect yourself: A spokesperson from the CDC told us that sushi chefs are taught to recognize infected fish and that eating at a high-quality sushi restaurant shouldn't put you at risk. That being said, you might want to stick with cooked-fish sushi; just be sure to buy species that are responsibly harvested and don't contain high levels of environmental pollutants like mercury and polychlorinated biphenyls (aka PCBs).
More: 12 Fish You Should Never Eat
The stomach-churning facts: Unless you eat your cat, you won't be exposed to parasites like Trichinella or Diphylobothrium, but cleaning up after kitty may expose you to toxoplasma, which lives in cat feces. In addition to triggering miscarriage in pregnant women, a recent study from Denmark found that all women, pregnant or not, exposed to the parasite could be at risk of suicide, schizophrenia, and other mental disorders. Women in the study who'd been exposed to toxoplasma were 53 percent more likely to attempt suicide than women who hadn't, and the risk of suicide went up with the levels of parasites in the body.
How to protect yourself: Change the litter box regularly, and wash your hands with soap and water immediately afterward (it also helps to wear gloves). If you can't keep your cat indoors, keep sandboxes covered and wash your hands after gardening or handling soil that could be contaminated with cat poop. And if you're pregnant, stay away from litter boxes. One bit of good news for cat lovers: Though toxoplasmosis, the disease caused by toxoplasma, is a real risk from cat waste, the most common source of exposure remains undercooked pork, even for cat owners.
The stomach-churning facts: Good night, good night, don't let the kissing bugs, um, do their thing. These ironically named bugs, so called because they latch on and bite humans around the mouth, are vectors of a parasite called Trypanosoma cruzi, which causes Chagas' disease, a parasitic infection that, if left untreated, can lead to chronic heart disease and problems with your colon and digestive system. The disease is pretty rare in the U.S., but a recent CDC analysis found that the number of kissing bugs in the U.S. infected with the parasite is growing due to climate change, and agency researchers suspect that the transmission of Chagas' disease to humans will increase, too. CDC listed it among its Neglected Parasitic Infections to research.
How to protect yourself: Kissing bugs are drawn to light at night and can easily maneuver under doors and into your bed or your pet's. Shut off unnecessary lights in your home at night. And if you're camping in the southern sections of the country, where kissing bugs are more common, opt for a tent with screens, and make sure you close them at night.
Your Weekend Hike
The stomach-churning facts: Ticks—they're tiny, disgusting, and vectors for multiple parasites. In fact, ticks aren't even classified as insects; they're known in the scientific world as ecto-parasites. There are 840 species of them on the planet, and many are known to cause bacterial diseases (like Lyme disease) and viral illnesses (like Colorado tick fever). But the CDC is particularly concerned about an infection called babesiosis, caused by the Babesia microti parasite that infects red blood cells. A malaria-like ailment with symptoms that include fever, chills, headache, nausea, muscle pains, fatigue, and even anxiety and panic, babesiosis has seen a 20-fold increase between 2001 and 2008 in some Northeastern states, according to CDC data. Because of climate change, warmer winters, and a decline in the number of natural predators, the agency expects the incidence to rise even further.
How to protect yourself: Preventing babesiosis means preventing tick bites. Try these 5 ways to keep ticks out of your yard, and when hiking in areas where babesiosis is problematic—primarily New England, New York, New Jersey, Minnesota, and Wisconsin—use an insect repellent containing DEET. Although the ingredient can be harmful, DEET-based repellents are the most effective against ticks. Spray the chemical only on your clothing (not on exposed skin) and choose a product with the lowest concentration you can find.
Your Cousin Who's Always Borrowing Money
The stomach-churning facts: Perhaps the most difficult parasite to get rid of, financially dependent relatives can make you feel like there's a tapeworm living in your bank account. Most financial advisers will tell you that lending money to family members is a bad idea on all fronts, but considering our current economic climate, sympathy may trump good judgment.
How to protect yourself: If you have to do it, here are a few tips:
• Be clear that you expect to get paid back. Family loans may inadvertently turn into gifts, unless you set ground rules from the get-go. Set up a pay schedule that defines how much you expect at what time of the month.
• Draw up a contract. Look for financial institutions online to find one that can help facilitate small personal loans. Making the loan more formal can make your relative more inclined to pay it back, and some of these agencies can set up automatic withdrawals, helping to underscore the expectation that you expect a payback.
• Don't lend money you can't afford to lose. You might feel inclined to pass along a few hundred bucks to a cousin in need, but if you're dipping into your own rainy-day fund, you could end up the loser in the deal if you're later hit by an unexpected crisis.