The following tips for preventing parasitic infections apply mainly to people who travel to developing countries but also to those who encounter local warnings at home (for instance, about a contaminated water supply) or who hike in the wilderness anywhere in the world.
- Practice good hygiene, as you would to prevent other kinds of transmittable infections: Wash your hands regularly with soap and water, including before eating and after touching shared objects.
- Avoid exposure to contaminated food or water. In parts of the world where the public water supply may not be safe, that means drinking water only from a sealed bottle or if it has been boiled or otherwise purified, and avoiding raw fruits and vegetables that may have been grown or washed in contaminated water. Also avoid undercooked or raw meat and fish, especially if you are immunocompromised, elderly, or pregnant.
- Don’t drink untreated water from rivers or streams. You can use a portable disinfectant device, which applies UV light to remove or deactivate protozoa such as Giardia and Cryptosporidium (as well as most bacteria and viruses that cause gastrointestinal infections). Some portable filters also remove parasites.
- Avoid swimming in potentially contaminated bodies of water, especially if you are immunocompromised, since you may accidentally swallow or inhale the water. Never swim or even wade in water (includingrivers, lakes, and oceans) if there is a storm drain nearby, or after a heavy rainfall (for rivers or lakes). Some free-living amoebas (notably Naegleria fowleri) can be a problem in warm freshwater lakes, rivers, and hot springs around the world. If they enter the nose, they can travel to the brain via the sinuses, where they cause a serious, usually fatal, infection.
- To protect against parasites transmitted by insect bites, wear a long-sleeve shirt and long pants and use an effective, long-lasting EPA-registered insect repellent. DEET (at least 20 to 30 percent concentration) is most effective. Other options are oil of lemon eucalyptus (the label should list its active ingredient, p-menthane-diol, or PMD), picaridin (preferably 20 percent), and IR3535. You can also spray your clothes (not skin) with the insecticide permethrin or wear garments that have been permethrin-treated by the manufacturer.
This article first appeared in the UC Berkeley Wellness Letter.