William Penn Life, 2003 (38. évfolyam, 1-12. szám)
2003-06-01 / 6. szám
HealthPage instructions should be followed. If water is cloudy, the number of tablets used should be doubled; if water is extremely cold (less than 41° Fahrenheit), you should try to warm the water, and the recommended contact time should be increased to achieve reliable disinfection. Cloudy water should be strained through a clean cloth into a container to remove any sediment or floating matter, and then the water should be boiled or treated with iodine. Chlorine, in various forms, can also be used for chemical disinfection. However, it can produce less consistent levels of disinfection in many types of water. Chemically treated water is intended for short-term use only. If iodine-disinfected water is the only water available, it should be used for only a few weeks. Portable filters currently on the market will provide various degrees of protection against microbes. Reverse-osmosis filters provide protection against viruses, bacteria, and protozoa, but they are expensive, are larger than most filters used by backpackers, and the small pores on this type of filter are rapidly plugged by muddy or cloudy water. In addition, the membranes in some filters can be damaged by chlorine in water. Microstrainer filters with pore sizes in the 0.1- to 0.3-micrometer range can remove bacteria and protozoa from drinking water, but they do not remove viruses. To kill viruses, travelers using microstrainer filters should disinfect the water with iodine or chlorine after filtration, as described previously. Filters with iodine-impregnated resins are most effective against bacteria, and the iodine will kill some viruses; however, the contact time with the iodine in the filter is too short to kill the protozoa Cryptosporidium and, in cold water, Giardia. Proper selection, operation, care, and maintenance of water filters is essential to producing safe water. The manufacturers' instructions should be followed. The Centers for Disease Control and Prevention (CDC) cannot identify which specific brands or models of filters are most likely to remove bacteria and viruses. A list of filters that have passed tests for parasite removal can be obtained by calling 1-800-673-8010; by writing to NSF International (an independent testing company) at 789 North Dixboro Road, P.O. Box 130140, Ann Arbor, Michigan 48113-0140; or online at www.nsf.org. As a last resort, if no source of safe drinking water is available or can be obtained, tap water that is uncomfortably hot to touch might be safer than cold tap water; however, proper disinfection, filtering, or boiling is still advised. Watch what you eat To avoid illness, you should select food with care. All raw food is subject to contamination. Particularly in areas where hygiene and sanitation are inadequate, you should avoid: • salads • uncooked vegetables • unpasteurized milk • milk products such as cheese • undercooked and raw meat, fish and shellfish Eat only food that has been cooked and is still hot, or fruit that you have peeled yourself. Cooked food that has been allowed to stand for several hours at room temperature can provide a fertile medium for bacterial growth and should be thoroughly reheated before serving. Also, it's best to resist the tempting aromas wafting from sidewalk carts and grills. Consuming food and beverages obtained from street food vendors has been associated with an increased risk of illness. Some species of fish and shellfish can contain poisonous biotoxins, even when well cooked. The flesh of the barracuda is the most toxic laden and should always be avoided. Red snapper, grouper, amberjack, sea bass, and a wide range of tropical reef fish contain toxins at unpredictable times. Scombroid is another common fish poisoning that occurs worldwide in tropical, as well as temperate, regions. Fish of the Scombridae family (for example, bluefin, yellowfin tuna, mackerel, and bonito), as well as some nonscombroid fish (for example, mahimahi, herring, amberjack, and bluefish) may contain high levels of histidine in their flesh. With improper refrigeration or preservation, histidine is converted to histamine, which can cause flushing, headache, nausea, vomiting, diarrhea, and urticaria. Cholera cases have occurred among people who ate crab brought back from Latin America by travelers. You should not bring perishable seafood home when you return to the United States from high-risk areas. [j|p[ Health Links For more information on how you can stay healthy while traveling abroad, log onto the website of the Centers for Disease Control and Prevention at: 4 www.cdc.govltravell Or, visit the website of the World Health Organization at: ■4 www.who.intlenl William Penn Life, June 2003 7
