Introduction Before leaving home, the medical volunteer must take a few simple steps to help ensure a healthy return. Many volunteer trips and foreign vacations have been ruined by an unexpected, but possibly preventable illness. Medical problems encountered by travelers can range from a simple sunburn to a life-threatening case of drug-resistant malaria. One should start several weeks, if not a few months, in advance to ensure enough time to do the necessary research, and to make sure that all appropriate vaccinations are up to date. This section will discuss the vaccinations which may be legally required as well as those which are recommended by authorities such as the World Health Organization; communicable diseases which travelers may be exposed to; environmental factors influencing health; and several other related topics. Health conditions around the world frequently change. For the most current recommendations about specific countries or illnesses, the reader is encouraged to consult a qualified travel clinic, WHO publications, or American Health Consultants Travel Medicine Advisor and to contact the embassy of the country to which one is planning to travel. The CDC and other organizations maintain information-rich webpages. Vaccinations Yellow fever is the only disease for which vaccination may legally be required for international travel (though some countries may ignore the relevant international agreements and require others). This viral disease is endemic in certain areas of Africa and South America, and is fatal in more than half of cases in non-immune adults. The vaccine is extremely effective and is well tolerated. Even if not specifically required for entry into a particular country, persons who will be traveling in endemic zones, particularly outside of major urban centers, are strongly encouraged to receive this vaccine. An International Certificate of Vaccination must be obtained from an officially designated vaccine center (a list is published by the World Health Organization) and is valid for 10 years, beginning 10 days after vaccination. Smallpox has been eradicated and vaccination is no longer necessary. Some countries have required proof of immunization against cholera in the past, but this should no longer be the case. There is currently no safe and effective vaccine against cholera. Perhaps the most important vaccinations for the international traveler are those for hepatitis A and hepatitis B. Hepatitis A can also be prevented by the use of immune globulin, although its protection is temporary. All health care workers should be certain of their immunity to hepatitis B. Vaccinations which are considered routine in the US and other developed countries are also highly recommended before foreign travel. Measles, mumps, rubella, poliomyelitis, tetanus, diphtheria, and pertussis are all common in various parts of the world and can be prevented by safe and effective vaccines. The traveler's immune history should be reviewed before leaving home, and any deficiencies corrected. Rabies is much more common in other parts of the world than in the US. Those who will be working with animals, staying in highly endemic areas, or will be isolated from medical care should consider pre-exposure vaccination. If exposed to rabies, the pre-immunized individual still requires post-exposure vaccination, but does not require immune globulin. Other vaccinations recommended by the WHO in 1995 for travelers in endemic areas include typhoid, BCG (for the prevention of tuberculosis in children and young adults; contraindicated in the presence of symptomatic HIV infection), meningococcal meningitis, influenza (for elderly or otherwise high-risk persons) and Japanese encephalitis. Insect-Borne Illnesses Avoidance of insect bites, particularly mosquitoes, is very important. Malaria is one of the world's greatest health problems, and the list of arthropod-borne illnesses also includes yellow fever, dengue fever, filariasis, viral encephalitides, leishmaniasis, African trypanosomiasis, onchocerciasis, typhus, Lyme disease, Rocky Mountain spotted fever, relapsing fever, tungiasis and plague. Drug prophylaxis against malaria is not 100% effective. The first step in preventing malaria is preventing or at least minimizing mosquito bites. Dusk and dawn are the times at which mosquito bites are most common. Staying indoors and wearing long-sleeved, dark colored clothing can reduce exposure. The use of "deet" (N,N-diethyl-m-toluamide) or dimethyl phthalate containing insecticides on the skin is also recommended. Buildings with tight doors, windows, and screens help to keep mosquitoes out, but mosquito netting over the bed may also be needed. After entering the net to sleep, it should be inspected from the inside to make sure that all edges are tightly tucked in, there are no holes, and there are no mosquitoes inside with you. Spraying the netting with permethrin or deltamethrin, or using mosquito coils or other insecticides is also useful. Travelers should check with a reliable source before their trip to establish whether malaria is endemic in the area of travel (International Travel and Health, WHO). Pregnant women and small children should avoid travel to malarious areas if at all possible, particularly areas where chloroquine-resistant p. falciparum exists. Multidrug-resistant malaria has been reported in certain areas of Southeast Asia for which there is no safe and effective prophylaxis for pregnant women and young children. Specific recommendations for malaria prophylaxis are beyond the scope of this section, but several general points should be made: There is no prophylactic regimen which is 100% effective. If you travel to a malarious area, no matter what you do, you might get malaria. Malaria is a serious disease, with a case-fatality rate of about 1% (for p. falciparum). All prophylactic regimens are associated with side effects. Prophylaxis must begin 1-7 days before travel (depending on what drug is used), must be taken exactly as directed without fail, and must be continued for 4 weeks after leaving the area. Malaria is much more likely to be fatal if it is diagnosed and treated late in the course. Early diagnosis is therefore essential. Fever occurring any time from one week after arrival to 2 months (or even longer) after return home potentially represents malaria, particularly in children. Malaria progresses rapidly in young children. It is also associated with increased maternal and fetal death, stillbirth, and neonatal death when it occurs in pregnant women. These groups should not travel to endemic areas unless absolutely necessary. Travelers who will be in remote areas with no readily accessible health care should bring their own "stand-by" treatment, to be started if the symptoms of malaria occur. This is not a substitute for seeking care, particularly for children, but is a temporary measure while further care is pursued as rapidly as possible. Since prophylactic drugs can cause side-effects, they should only be taken if the traveler is actually at risk of catching malaria. Some urban areas in otherwise endemic countries may be malaria-free. An individual's general health, other medical problems, drug allergies, concomitant medications, and other factors will determine which prophylactic regimen should be used. This decision should be made with a physician's advice. Symptoms which should prompt a suspicion of malaria are fever, with or without associated headache, myalgias, weakness, vomiting or diarrhea, and cough. The symptoms may initially be mild. Anyone staying in a malarious area for over one month is more likely to catch malaria. It would be a good idea to locate local doctors with experience in prolonged prophylaxis and treatment of malaria. Dengue and the associated dengue hemorrhagic fever and dengue shock syndrome are mosquito-borne viral illnesses for which there is no effective vaccine. Your only defenses against dengue are avoidance of mosquito bites and prompt, appropriate medical treatment. The mosquito species which carry dengue are much more likely to bite during daylight hours, so travelers to areas where dengue is present should also use mosquito repellents during the daytime. Dengue is characterized by severe, abrupt headache, eye pain, and muscle, bone and joint pain, and fever. Scleral injection (red eyes) is common. Dengue hemorrhagic fever is more likely to exhibit cough, sore throat, loss of appetite, nausea, vomiting and abdominal pain rather than bone, joint, or muscle pain. It may progress to spontaneous bleeding and low platelet count, and then to agitation and circulatory failure, followed by profound shock. These latter stages constitute dengue shock syndrome. Food and Water-Borne Illnesses Diarrhea is one of the most common problems to afflict travelers, and is largely preventable. The most important preventative measure is the careful selection and preparation of all food and drink to be consumed. All foods should be cooked thoroughly, and either consumed hot or stored at a temperature below 10°C. Water and other beverages should either be bottled, chemically disinfected and filtered, or boiled. Perfectly safe bottled water can be contaminated by using ice made from contaminated water. Fruits and vegetables should be considered potentially contaminated unless they can be peeled by you. High risk foods include raw shellfish, unpasteurized milk, ice cream, and dishes containing raw eggs. Some seafoods may contain toxins which are not destroyed by cooking; one should consult local authorities before eating unknown species. There is no single prophylactic drug which can prevent all of the possible causes of diarrhea. Bacterial, protozoal, and helminthic infections each requires a different specific medical treatment. Oral rehydration is vitally important in the treatment of diarrheal illnesses, and travelers should consider carrying rehydration salts in their medical kit. Severe cases (such as with cholera) may require intravenous hydration. Bathing in fresh water (other than chlorinated pools) and walking in bare feet in high risk areas may expose the traveler to a variety of infestations, and should be avoided. Hepatitis A is spread through contaminated food, and persons from developed countries are unlikely to be immune unless they receive proper vaccination or immune globulin pretreatment. Immune globulin offers temporary immunity, the duration of which is dose related. Hepatitis E is also transmitted through contaminated food, but there is no effective vaccine or immune globulin to prevent it. It is particularly dangerous for pregnant women. Strict avoidance of potentially contaminated food is the only protection from hepatitis E. Vaccination against typhoid is recommended for travel anywhere that sanitation may be suspect. HIV and Other Sexually Transmitted Diseases (STDs) The same precautions that apply to sexually transmitted diseases at home should be used when traveling. Abstinence, or sex with one mutually monogamous and non-infected partner are the best ways to prevent sexually transmitted diseases. Latex condoms may offer some protection against the spread of STDs. Sex with multiple partners or with prostitutes is extremely hazardous. In many parts of the world, heterosexual intercourse is the most common route of transmission of the HIV virus. Other sexually transmitted diseases are also endemic, including hepatitis B, syphilis, gonorrhea, and many others. Many STDs are more resistant to antibiotic therapy overseas. HIV, hepatitis B, and syphilis, among other illnesses, can also be spread by blood products. Transfusions should only be made when absolutely necessary, and should use only blood which has been tested for HIV, hepatitis, and other infectious agents. Poor countries may lack the technology or funds to adequately screen their blood supply. If any injections are required while traveling, one should insist on a brand new, disposable needle, or one that has been thoroughly sterilized. Other medical and dental instruments as well as tattoo needles and equipment for body piercing must also be sterilized to prevent spread of infection. Environmental Hazards Motion Sickness: Drugs are available to prevent the nausea and vomiting associated with the movement of cars, boats, and airplanes. Even over-the-counter medications have associated side effects, and should be taken only after reviewing the product instructions and consulting with a physician, if necessary. Extreme Temperatures: Many travelers will be exposed to extremes of heat or cold during their trip. Typical weather conditions should be inquired about and the proper clothing brought. Extreme heat dramatically increases the body's need for water, and an adequate supply of safe water must be ensured. Protection from sun, particularly in tropical areas where levels of ultraviolet radiation are much higher, can be achieved with long-sleeved, light-colored clothing, hats, and sun-screens. Travelers to hot locations should be familiar with the symptoms and treatment of heat cramps, heat exhaustion, and heat stroke. Similarly, if likely to be exposed to extreme cold, particularly in isolated areas, one should be prepared to prevent, recognize, and treat frostbite and hypothermia. A small number of travelers will be exposed to high altitudes. The pressurized cabins of commercial airliners prevent altitude related problems in flight, but prolonged stays in mountainous areas may expose the traveler to acute mountain sickness, high-altitude pulmonary edema, and high-altitude cerebral edema. Travelers who will be in remote or wilderness areas should familiarize themselves with potential animal hazards. Sharks, jellyfish, other poisonous marine animals, poisonous snakes, scorpions, spiders, and carnivores are among the many dangerous animals which may be encountered, depending on the location of travel. Traveler's Medical Kit/Traveling with Chronic Illnesses Medical supplies which may be inexpensive and readily available at home may be unobtainable while traveling. An adequate supply of such basic items as bandages, disinfectant, non-prescription analgesic and antipyretic, mosquito repellent, and sunscreen should be brought. Depending on the area of travel, appropriate anti-malarial medications, water purification substances, and oral rehydration salts are also basic necessities. If prescribed by a physician, antibiotics and antidiarrheals may be needed. Persons with chronic health problems or allergies should be sure to bring an adequate supply of their regular medications, and should inquire in advance as to what medical facilities will be available. If injections will be needed (for diabetics, for example), sterile syringes and needles should be brought, as they may not otherwise be available. Proper labeling or documentation of a physician's order should accompany needles or controlled substances. Some serious medical problems should be considered contraindications to travel, particularly by air. Severe anemia, serious infectious diseases, heart failure, recent heart attack or stroke, severe mental illnesses, uncontrolled epilepsy and other serious medical conditions should prompt serious consideration as to whether travel should be attempted. Health Insurance Your health insurance may not cover you for illnesses and injuries which occur outside your country of origin. It would be prudent to check with your insurance carrier before traveling, particularly if you have chronic health problems which are prone to reoccurrence. Special policies covering medical treatment abroad and/or medical evacuation are commercially available.