Disease: Travel Medicine

    Why should travelers see a physician before they leave on a trip?

    Travelers should see a physician before leaving for a trip if

    • they are going to developing countries,
    • they are visiting sites that are not on the usual tourist routes or traveling to high altitudes,
    • they have chronic diseases that could be affected by travel,
    • they are visiting countries that require vaccinations before they allow travelers to enter the country.

    The goal of a pre-travel medical evaluation is to help travelers protect themselves against (1) common diseases that may be mild but that will disrupt their trip, and (2) less common diseases that may be serious or even fatal. All travelers need to be up to date on routine vaccines they would normally get if they were not traveling. For example, an annual influenza vaccination (flu shot) is recommended if traveling during influenza season. Travelers should also be up to date on tetanus vaccines. If a tetanus booster is needed, your physician may elect to use the Tdap vaccine that also provides continuing protect against adult pertussis. No vaccinations are required for re-entry into the United States after travel.

    What diseases occur in travelers, and how can disease be prevented?

    Travelers can pick up infections from contaminated food or water, from insect bites, animal bites, or from other people. Vaccinations, medications, and simple precautions can reduce or eliminate the risk of many of these travel-related infections. While infections are the most common problem for travelers, it is important to remember that the most common cause of death in travelers is motor vehicle accidents. Be sure to look both ways before crossing the street (especially in the United Kingdom, where oncoming traffic comes from the right), don't get in the car if the driver is drunk, and use seat belts if available both at home and when traveling.

    This review will cover diseases commonly encountered by travelers or those for which vaccinations are recommended. For a more complete discussion, please refer to the CDC travel medicine web site (http://www.cdc.gov).

    Traveler's diarrhea

    Traveler's diarrhea is the most common medical complaint in travelers, occurring in up to 50% of travelers to developing countries. It occurs when infectious organisms are inadvertently ingested by travelers, resulting in one to five days of loose stools. The stools are often watery and may be accompanied by abdominal cramps. Although not fatal, traveler's diarrhea can cause dehydration, vomiting, low-grade fever, and discomfort to the point that some travelers have to change their itineraries. It is important to note that traveler's diarrhea is not associated with bloody stools, severe abdominal pain, or high fever. These symptoms are suggestive of more serious conditions and should prompt medical attention.

    Traveler's diarrhea is spread when bacteria or other infectious agents such as viruses are ingested. Traveler's diarrhea is most often spread through contaminated food or water, or by putting contaminated hands in the mouth. Even small amounts of contamination can cause infection. Although bacteria are the most common cause of traveler's diarrhea, there have been outbreaks of diarrhea on cruise ships caused by noroviruses. Noroviruses are very small (only visible on ultrathin-section electron microscopy) and spread readily from person to person.

    Travelers can get diarrhea in most areas of the world, but some countries pose a higher risk. High-risk areas include most of Asia, the Middle East, Africa, and Central and South America. Risk is increased if the traveler is adventurous with his or her diet, eats foods from street vendors, or travelers to areas off the usual tourist routes.

    Protective measures may help prevent or shorten the duration of traveler's diarrhea. All travelers should wash their hands often and understand basic food and water precautions (see below). However, it has been shown that even well-informed travelers often choose to eat foods that pose an increased risk of traveler's diarrhea. Therefore, travelers at risk should carry along an antimotility agent such as loperamide (Imodium; Kaopectate II; Imodium A-D; Maalox Anti-Diarrheal Caplets; Pepto Diarrhea Cont) and start taking it if they get symptoms. Bismuth subsalicylate (Pepto-Bismol) is also helpful.

    Many physicians also recommend that travelers carry along an antibiotic to take in case they get diarrhea. Fluoroquinolones are the most commonly prescribed antibiotic; azithromycin (Zithromax, Zmax) or rifaximin (Xifaxan) are alternatives. Because bacteria are developing resistance to many antibiotics, many of the older antibiotics do not work well. If an antimotility agent (a drug that reduces gastrointestinal motility) and an antibiotic are started at the first sign of diarrhea, symptoms may be shortened to only a few hours instead of a few days. In rare cases, physicians might prescribe daily antibiotics or daily bismuth subsalicylate to prevent diarrhea, but this is not needed for most travelers. Affected people should stay hydrated. Pregnant women and children need special advice because many of these drugs are not appropriate for them.

    Malaria

    Malaria is an infection caused by a tiny organism called a protozoan. It enters red blood cells and multiplies until the cells burst open. The broken cells release the young protozoa into the bloodstream where they infect more red blood cells. This release of young protozoa causes high fevers that can last for several hours. The fever of malaria often comes and goes in a defined pattern, coinciding with when the infected red cells burst open. With some types of malaria, the protozoa can hide in the liver and cause episodes of fever over many years. In serious cases, malaria can cause the kidneys to shut down, can infect the brain, or cause death.

    Malaria is spread to people by mosquitoes. The mosquitoes bite between dusk and dawn. Malaria occurs in many tropical areas and a few areas that have a milder climate. Travelers to sub-Saharan Africa, South America, and Asia may be at risk for the disease. Some countries in Central America and the Caribbean also have malaria. Not every area of a country will be infected. A doctor can evaluate your itinerary to see if you might be exposed to malaria. The Centers for Disease Control and Prevention (CDC) has a web page that tells where malaria occurs (http://wwwn.cdc.gov/travel/).

    Malaria can be prevented by avoiding mosquito bites (see the section on insect precautions) and by taking preventive medications. Travelers who will be exposed to malaria should take medications starting before travel to the area and continuing for a time after they leave the area. Several different medicines are available. Some are taken only once a week, and others are taken daily. In some countries, malaria has become resistant to older medicines. Your physician will choose which medicine to use based on what countries you are visiting.

    Meningococcal meningitis

    Meningococcal meningitis is an infection of the lining and fluid around the brain and spinal cord. The cause is a bacterium called Neisseria meningitides. The disease can be quite severe or even fatal. The infection is spread from person to person by close contact through coughing or sneezing or other respiratory means.

    Meningococcal meningitis occurs at low rates throughout the world, including the United States. However, some countries have high rates of disease and pose a special risk to travelers. This includes many countries in the "meningitis belt" of sub-Saharan Africa. Saudi Arabia has experienced outbreaks when pilgrims travel to religious sites.

    There are two effective vaccines to prevent meningitis. The choice of vaccine depends on the age of the patient. The vaccines are synthetic (meaning that they do not contain live infectious agents). They should not be given to people who have previously had a neurological illness called Guillain-Barré syndrome. Vaccination is now routinely recommended for adolescents and college freshmen in the United States. It is also recommended for travelers who are going to areas that have high rates of infection. Vaccination is required for pilgrims to religious sites in Saudi Arabia, and proof of vaccination (preferably an International Certificate of Vaccination) will be required at the border. The vaccination is effective for three to five years (depending on which of the two vaccines is given), after which revaccination may be recommended for travelers who travel to areas with high rates of infection.

    Yellow fever

    Yellow fever is caused by a virus that attacks the liver. In many people, the disease is mild and goes away. In others, the liver can fail or internal bleeding can occur which can lead to death. Yellow fever is spread by the bite of a mosquito.

    Yellow fever occurs in areas of sub-Saharan Africa, Central America, and South America. Not all countries in these areas have yellow fever. Even within a country, some areas may have yellow fever while others do not.

    There is a very effective vaccine available to prevent yellow fever. It contains a live virus that has been modified ("attenuated") to make it safer. Vaccine side effects are usually mild. Rarely (a few cases per million doses), the vaccine virus can spread and cause severe disease. Patients with suppressed immune systems (for example, people with certain chronic diseases, HIV infection, or who are receiving cancer chemotherapy) should not receive the live vaccine.

    Vaccination is recommended for travelers who will be exposed to yellow fever. The vaccine may be required for entry into some countries. Check the CDC web site to see if vaccination is required for your trip. If you get vaccinated, you should receive an International Certificate of Vaccination, signed and validated with the center's stamp where the vaccine was given. Take the certificate with you on your trip. You may need it to enter your destination country. This certificate is valid for 10 years. The vaccine is given at local health departments and travel clinics. To find a place to get yellow fever vaccine, go to http://wwwnc.cdc.gov/travel/yellow-fever-vaccination-clinics-search.aspx.

    Learn more about: yellow fever vaccine

    Hepatitis A

    Hepatitis A is caused by a virus that infects the liver. People get sick two to six weeks after they get the virus. Symptoms include nausea, yellowing of the skin and eyes (jaundice), dark urine, pale stools, loss of appetite, and fatigue. The symptoms take two to six months to completely resolve. Unlike some other hepatitis viruses, hepatitis A does not cause chronic liver disease. In other words, once the person gets better, he or she is completely cured. Some infected people (especially children) are asymptomatic, meaning that they do not develop symptoms.

    Hepatitis A is spread when human waste is mistakenly ingested. Even a small amount can cause disease, such as might occur by shaking hands with someone and then touching the mouth. Food preparers have transmitted disease by mistakenly contaminating food. It is also possible to get hepatitis A through sexual contact or contaminated needles or blood. Hepatitis A occurs throughout the world but is more common in developing countries.

    There is an effective vaccine that is quite good at preventing hepatitis A. If you are traveling to a developing country, your doctor will probably recommend vaccination. In a few cases, your doctor might recommend a more temporary measure called gamma globulin. Remember to follow food and water precautions.

    Typhoid fever

    Typhoid fever is an infection caused by a bacterium called Salmonella typhi. Most people who get sick develop a headache, a very high fever (up to 103 F or 104 F), and fatigue. Nausea, abdominal pain, diarrhea, or constipation may also occur.

    The disease spreads when infected human waste contaminates food or water or is otherwise ingested. Some people are able to carry the bacteria inside their body and continue to spread the disease for a very long time. People who get sick may be given antibiotics by their doctor. In addition to the antibiotics, people should make sure they wash their hands so that they don't spread the disease to anyone else.

    Typhoid fever occurs in many areas around the world, especially Asia, Africa, and South America. Vaccines are available to reduce the risk of getting typhoid. Ask your doctor or local public-health department about typhoid vaccination before you travel. Food and water precautions (see below) also reduce the risk of disease. The saying "Boil it, cook it, peel it, or forget it!" provides some advice on how to prevent becoming sick with typhoid fever.

    Polio

    Polio is a viral illness that can lead to severe neuromuscular problems. Polio is spread from person to person. Infected secretions and feces can cause disease. Many people have no symptoms, but some have neurological problems such as weakness and paralysis. Symptoms are especially severe if they involve the breathing muscles.

    Thanks to a major public-health campaign, many countries no longer have polio. A few countries in Africa, South Asia, Southeast Asia, and the Middle East still have outbreaks. The list of infected countries is constantly changing, as some countries successfully eliminate the infection and others become reinfected. Check with the CDC web site (cdc.gov/travel) for an updated list to see if your itinerary includes any of these countries.

    The inactivated polio vaccine is recommended if the traveler is going to an area where polio is still occurring. A single booster dose in adulthood is sufficient if the traveler has received the usual vaccine series in childhood. If the traveler has not been fully vaccinated in the past (has not received all doses at recommended times), more doses may be needed.

    Cholera

    Cholera is an infection caused by bacteria (Vibrio cholerae) that look like curved rods when viewed under the microscope. The bacteria attach to the inside of the intestines and secrete a toxin. The cholera toxin can cause the cells in the intestines to pour out large amounts of fluid. In severe cases, the excess water loss leads to massive amounts of watery diarrhea that can contain cells from the body and bacteria. The term "rice water" is often used to describe this diarrhea because of the appearance of small white flecks of mucus in liquid.

    Cholera spreads when human waste contaminates water and food. Because it takes high numbers of bacteria to cause infection, the contamination usually has to be quite significant. For example, in areas of poor sanitation, cholera can be spread when the drinking water supply is contaminated by feces from people who are sick.

    Cholera is most common in areas that have poor sanitation, with faulty sewage systems or contaminated drinking water. Cholera can be prevented by using proper sanitation and sewage treatment. Boiling, filtering, or chlorinating water can help to prevent the spread of cholera. There is no vaccine for cholera that is approved in the United States. Fortunately, cholera is very rare in travelers.

    What about diseases for which there is no vaccine or preventive medication?

    There are several diseases of concern for travelers for which there is no vaccine or medicine to prevent infection. Among these are some viral infections, sexually transmitted diseases, and parasitic infections.

    Many viral infections can be spread by biting insects such as ticks or mosquitoes. These include serious infections like hemorrhagic fever, a viral infection that causes high fever and bleeding. Another virus causes Chikungunya fever, which is common in Africa and Asia. Spread by mosquitoes, Chikungunya fever causes high fever and severe joint pain and usually lasts for days or weeks. Another viral illness is dengue fever, which occurs throughout the world in tropical areas. Symptoms of dengue fever are high fever, headache, and occasionally bleeding (hemorrhage). The key to reducing the risk of getting these infections is to follow insect precautions (see section on insect precautions).

    Sexually transmitted diseases can be acquired anywhere in the world. The only sure way to prevent disease is to abstain from sexual intercourse. Use of condoms will reduce risk. HPV vaccines now available will reduce the risk of acquiring infection with the human papillomavirus virus that causes genital warts and cervical cancer.

    Parasites occur in most areas of the world but are especially common in tropical and subtropical regions. Some are spread by eating contaminated food (see food and water precautions), while others are spread by direct contact with infected water or soil. Most travelers do not get parasitic infections, but those who are going into rural areas of developing countries should ask their doctors about parasites they might encounter.

    Infectious-disease outbreaks occur periodically and officials may recommend additional precautions. Examples have included outbreaks of bovine spongiform encephalitis (mad cow disease) or severe acute respiratory syndrome (SARS). Travelers should check the CDC web site to obtain health and risk information specific to their destination country.

    What is safe to eat and drink while traveling?

    • In general, it is best not to drink tap water in a developing country.
    • Ice is not safe in areas where the water supply may be contaminated. Freezing water does not destroy most infections.
    • Boiled water and drinks made from boiled water (tea) are usually safe.
    • Alcohol (beer, wine) is usually safe.
    • Carbonated bottled water or sodas are usually safe. Uncarbonated bottled water may be safe, but even bottled water may be filled up from the local tap water source.
    • Iodine tablets or commercially available water filters may be used to purify water when camping.
    • In general, foods that you peel yourself (bananas) are safe.
    • Hot, well-cooked foods are usually safe.
    • Spices do not kill bacteria. Food can be so spicy that it burns your mouth and still cause traveler's diarrhea or more serious diseases.
    • Foods that put the traveler at high risk for infection include undercooked meat and seafood.
    • Foods washed in contaminated water may have a residue of bacteria.

    What can I do to avoid insect bites?

    • Wear light, protective clothing.
    • Use insect repellents that contain DEET (most popular brand-name insect repellents in the United States contain DEET). Reapply according to directions. When using sunscreen, apply sunscreen first and then repellent.
    • If you are hiking, tuck your pant leg into your sock. Check yourself over for ticks at the end of the hike.
    • Use mosquito nets or window screens if they are available.
    • Products that contain permethrin (NIX, an insect repellent) are available to spray on your clothes or tent for added protection.

    What should be in my travel first aid kit?

    • Prescription medications that you take at home
    • Medications that your doctor recommended to prevent travel-related illness, including malaria medications, if indicated
    • Over-the-counter medicines to treat minor illnesses (heartburn, headache, head cold, mild diarrhea, motion sickness)
    • Sunscreen, lotion to use to treat sunburn
    • Insect repellents
    • Bandages, tape, thermometer, and tweezers
    • Adventure travelers who are far from medical help will need to consider additional items
    • Women who get vaginal yeast infections should consider carrying along a treatment course (pills or vaginal products)
    • Other items according to your itinerary

    What are the medical concerns with jet lag?

    Jet lag happens when travelers cross several time zones and disrupt their normal sleep-wake cycle.

    To reduce the duration and the symptoms of jet lag, try to be outside when the sun is up. It may make for a very long (or short) first day, but it will help you adjust more quickly. Some travelers also try to change their sleep-wake habits before they leave.

    Medicines are available that can promote sleep, but there are few studies on how well they work with jet lag. Zolpidem (Ambien) is a prescription sedative that promotes sleep. Another group of prescription drugs known as benzodiazepines also promotes sleep, but they may have more side effects, including temporary amnesia. Melatonin is a natural hormone available as an herbal preparation in the United States. Doses of approximately 5 mg have been shown to induce sleep. Melatonin is available over the counter.

    Learn more about: Ambien

    Traveler's diarrhea

    Traveler's diarrhea is the most common medical complaint in travelers, occurring in up to 50% of travelers to developing countries. It occurs when infectious organisms are inadvertently ingested by travelers, resulting in one to five days of loose stools. The stools are often watery and may be accompanied by abdominal cramps. Although not fatal, traveler's diarrhea can cause dehydration, vomiting, low-grade fever, and discomfort to the point that some travelers have to change their itineraries. It is important to note that traveler's diarrhea is not associated with bloody stools, severe abdominal pain, or high fever. These symptoms are suggestive of more serious conditions and should prompt medical attention.

    Traveler's diarrhea is spread when bacteria or other infectious agents such as viruses are ingested. Traveler's diarrhea is most often spread through contaminated food or water, or by putting contaminated hands in the mouth. Even small amounts of contamination can cause infection. Although bacteria are the most common cause of traveler's diarrhea, there have been outbreaks of diarrhea on cruise ships caused by noroviruses. Noroviruses are very small (only visible on ultrathin-section electron microscopy) and spread readily from person to person.

    Travelers can get diarrhea in most areas of the world, but some countries pose a higher risk. High-risk areas include most of Asia, the Middle East, Africa, and Central and South America. Risk is increased if the traveler is adventurous with his or her diet, eats foods from street vendors, or travelers to areas off the usual tourist routes.

    Protective measures may help prevent or shorten the duration of traveler's diarrhea. All travelers should wash their hands often and understand basic food and water precautions (see below). However, it has been shown that even well-informed travelers often choose to eat foods that pose an increased risk of traveler's diarrhea. Therefore, travelers at risk should carry along an antimotility agent such as loperamide (Imodium; Kaopectate II; Imodium A-D; Maalox Anti-Diarrheal Caplets; Pepto Diarrhea Cont) and start taking it if they get symptoms. Bismuth subsalicylate (Pepto-Bismol) is also helpful.

    Many physicians also recommend that travelers carry along an antibiotic to take in case they get diarrhea. Fluoroquinolones are the most commonly prescribed antibiotic; azithromycin (Zithromax, Zmax) or rifaximin (Xifaxan) are alternatives. Because bacteria are developing resistance to many antibiotics, many of the older antibiotics do not work well. If an antimotility agent (a drug that reduces gastrointestinal motility) and an antibiotic are started at the first sign of diarrhea, symptoms may be shortened to only a few hours instead of a few days. In rare cases, physicians might prescribe daily antibiotics or daily bismuth subsalicylate to prevent diarrhea, but this is not needed for most travelers. Affected people should stay hydrated. Pregnant women and children need special advice because many of these drugs are not appropriate for them.

    Malaria

    Malaria is an infection caused by a tiny organism called a protozoan. It enters red blood cells and multiplies until the cells burst open. The broken cells release the young protozoa into the bloodstream where they infect more red blood cells. This release of young protozoa causes high fevers that can last for several hours. The fever of malaria often comes and goes in a defined pattern, coinciding with when the infected red cells burst open. With some types of malaria, the protozoa can hide in the liver and cause episodes of fever over many years. In serious cases, malaria can cause the kidneys to shut down, can infect the brain, or cause death.

    Malaria is spread to people by mosquitoes. The mosquitoes bite between dusk and dawn. Malaria occurs in many tropical areas and a few areas that have a milder climate. Travelers to sub-Saharan Africa, South America, and Asia may be at risk for the disease. Some countries in Central America and the Caribbean also have malaria. Not every area of a country will be infected. A doctor can evaluate your itinerary to see if you might be exposed to malaria. The Centers for Disease Control and Prevention (CDC) has a web page that tells where malaria occurs (http://wwwn.cdc.gov/travel/).

    Malaria can be prevented by avoiding mosquito bites (see the section on insect precautions) and by taking preventive medications. Travelers who will be exposed to malaria should take medications starting before travel to the area and continuing for a time after they leave the area. Several different medicines are available. Some are taken only once a week, and others are taken daily. In some countries, malaria has become resistant to older medicines. Your physician will choose which medicine to use based on what countries you are visiting.

    Meningococcal meningitis

    Meningococcal meningitis is an infection of the lining and fluid around the brain and spinal cord. The cause is a bacterium called Neisseria meningitides. The disease can be quite severe or even fatal. The infection is spread from person to person by close contact through coughing or sneezing or other respiratory means.

    Meningococcal meningitis occurs at low rates throughout the world, including the United States. However, some countries have high rates of disease and pose a special risk to travelers. This includes many countries in the "meningitis belt" of sub-Saharan Africa. Saudi Arabia has experienced outbreaks when pilgrims travel to religious sites.

    There are two effective vaccines to prevent meningitis. The choice of vaccine depends on the age of the patient. The vaccines are synthetic (meaning that they do not contain live infectious agents). They should not be given to people who have previously had a neurological illness called Guillain-Barré syndrome. Vaccination is now routinely recommended for adolescents and college freshmen in the United States. It is also recommended for travelers who are going to areas that have high rates of infection. Vaccination is required for pilgrims to religious sites in Saudi Arabia, and proof of vaccination (preferably an International Certificate of Vaccination) will be required at the border. The vaccination is effective for three to five years (depending on which of the two vaccines is given), after which revaccination may be recommended for travelers who travel to areas with high rates of infection.

    Yellow fever

    Yellow fever is caused by a virus that attacks the liver. In many people, the disease is mild and goes away. In others, the liver can fail or internal bleeding can occur which can lead to death. Yellow fever is spread by the bite of a mosquito.

    Yellow fever occurs in areas of sub-Saharan Africa, Central America, and South America. Not all countries in these areas have yellow fever. Even within a country, some areas may have yellow fever while others do not.

    There is a very effective vaccine available to prevent yellow fever. It contains a live virus that has been modified ("attenuated") to make it safer. Vaccine side effects are usually mild. Rarely (a few cases per million doses), the vaccine virus can spread and cause severe disease. Patients with suppressed immune systems (for example, people with certain chronic diseases, HIV infection, or who are receiving cancer chemotherapy) should not receive the live vaccine.

    Vaccination is recommended for travelers who will be exposed to yellow fever. The vaccine may be required for entry into some countries. Check the CDC web site to see if vaccination is required for your trip. If you get vaccinated, you should receive an International Certificate of Vaccination, signed and validated with the center's stamp where the vaccine was given. Take the certificate with you on your trip. You may need it to enter your destination country. This certificate is valid for 10 years. The vaccine is given at local health departments and travel clinics. To find a place to get yellow fever vaccine, go to http://wwwnc.cdc.gov/travel/yellow-fever-vaccination-clinics-search.aspx.

    Learn more about: yellow fever vaccine

    Typhoid fever

    Typhoid fever is an infection caused by a bacterium called Salmonella typhi. Most people who get sick develop a headache, a very high fever (up to 103 F or 104 F), and fatigue. Nausea, abdominal pain, diarrhea, or constipation may also occur.

    The disease spreads when infected human waste contaminates food or water or is otherwise ingested. Some people are able to carry the bacteria inside their body and continue to spread the disease for a very long time. People who get sick may be given antibiotics by their doctor. In addition to the antibiotics, people should make sure they wash their hands so that they don't spread the disease to anyone else.

    Typhoid fever occurs in many areas around the world, especially Asia, Africa, and South America. Vaccines are available to reduce the risk of getting typhoid. Ask your doctor or local public-health department about typhoid vaccination before you travel. Food and water precautions (see below) also reduce the risk of disease. The saying "Boil it, cook it, peel it, or forget it!" provides some advice on how to prevent becoming sick with typhoid fever.

    Polio

    Polio is a viral illness that can lead to severe neuromuscular problems. Polio is spread from person to person. Infected secretions and feces can cause disease. Many people have no symptoms, but some have neurological problems such as weakness and paralysis. Symptoms are especially severe if they involve the breathing muscles.

    Thanks to a major public-health campaign, many countries no longer have polio. A few countries in Africa, South Asia, Southeast Asia, and the Middle East still have outbreaks. The list of infected countries is constantly changing, as some countries successfully eliminate the infection and others become reinfected. Check with the CDC web site (cdc.gov/travel) for an updated list to see if your itinerary includes any of these countries.

    The inactivated polio vaccine is recommended if the traveler is going to an area where polio is still occurring. A single booster dose in adulthood is sufficient if the traveler has received the usual vaccine series in childhood. If the traveler has not been fully vaccinated in the past (has not received all doses at recommended times), more doses may be needed.

    Cholera

    Cholera is an infection caused by bacteria (Vibrio cholerae) that look like curved rods when viewed under the microscope. The bacteria attach to the inside of the intestines and secrete a toxin. The cholera toxin can cause the cells in the intestines to pour out large amounts of fluid. In severe cases, the excess water loss leads to massive amounts of watery diarrhea that can contain cells from the body and bacteria. The term "rice water" is often used to describe this diarrhea because of the appearance of small white flecks of mucus in liquid.

    Cholera spreads when human waste contaminates water and food. Because it takes high numbers of bacteria to cause infection, the contamination usually has to be quite significant. For example, in areas of poor sanitation, cholera can be spread when the drinking water supply is contaminated by feces from people who are sick.

    Cholera is most common in areas that have poor sanitation, with faulty sewage systems or contaminated drinking water. Cholera can be prevented by using proper sanitation and sewage treatment. Boiling, filtering, or chlorinating water can help to prevent the spread of cholera. There is no vaccine for cholera that is approved in the United States. Fortunately, cholera is very rare in travelers.

    What about diseases for which there is no vaccine or preventive medication?

    There are several diseases of concern for travelers for which there is no vaccine or medicine to prevent infection. Among these are some viral infections, sexually transmitted diseases, and parasitic infections.

    Many viral infections can be spread by biting insects such as ticks or mosquitoes. These include serious infections like hemorrhagic fever, a viral infection that causes high fever and bleeding. Another virus causes Chikungunya fever, which is common in Africa and Asia. Spread by mosquitoes, Chikungunya fever causes high fever and severe joint pain and usually lasts for days or weeks. Another viral illness is dengue fever, which occurs throughout the world in tropical areas. Symptoms of dengue fever are high fever, headache, and occasionally bleeding (hemorrhage). The key to reducing the risk of getting these infections is to follow insect precautions (see section on insect precautions).

    Sexually transmitted diseases can be acquired anywhere in the world. The only sure way to prevent disease is to abstain from sexual intercourse. Use of condoms will reduce risk. HPV vaccines now available will reduce the risk of acquiring infection with the human papillomavirus virus that causes genital warts and cervical cancer.

    Parasites occur in most areas of the world but are especially common in tropical and subtropical regions. Some are spread by eating contaminated food (see food and water precautions), while others are spread by direct contact with infected water or soil. Most travelers do not get parasitic infections, but those who are going into rural areas of developing countries should ask their doctors about parasites they might encounter.

    Infectious-disease outbreaks occur periodically and officials may recommend additional precautions. Examples have included outbreaks of bovine spongiform encephalitis (mad cow disease) or severe acute respiratory syndrome (SARS). Travelers should check the CDC web site to obtain health and risk information specific to their destination country.

    What is safe to eat and drink while traveling?

    • In general, it is best not to drink tap water in a developing country.
    • Ice is not safe in areas where the water supply may be contaminated. Freezing water does not destroy most infections.
    • Boiled water and drinks made from boiled water (tea) are usually safe.
    • Alcohol (beer, wine) is usually safe.
    • Carbonated bottled water or sodas are usually safe. Uncarbonated bottled water may be safe, but even bottled water may be filled up from the local tap water source.
    • Iodine tablets or commercially available water filters may be used to purify water when camping.
    • In general, foods that you peel yourself (bananas) are safe.
    • Hot, well-cooked foods are usually safe.
    • Spices do not kill bacteria. Food can be so spicy that it burns your mouth and still cause traveler's diarrhea or more serious diseases.
    • Foods that put the traveler at high risk for infection include undercooked meat and seafood.
    • Foods washed in contaminated water may have a residue of bacteria.

    What can I do to avoid insect bites?

    • Wear light, protective clothing.
    • Use insect repellents that contain DEET (most popular brand-name insect repellents in the United States contain DEET). Reapply according to directions. When using sunscreen, apply sunscreen first and then repellent.
    • If you are hiking, tuck your pant leg into your sock. Check yourself over for ticks at the end of the hike.
    • Use mosquito nets or window screens if they are available.
    • Products that contain permethrin (NIX, an insect repellent) are available to spray on your clothes or tent for added protection.

    What should be in my travel first aid kit?

    • Prescription medications that you take at home
    • Medications that your doctor recommended to prevent travel-related illness, including malaria medications, if indicated
    • Over-the-counter medicines to treat minor illnesses (heartburn, headache, head cold, mild diarrhea, motion sickness)
    • Sunscreen, lotion to use to treat sunburn
    • Insect repellents
    • Bandages, tape, thermometer, and tweezers
    • Adventure travelers who are far from medical help will need to consider additional items
    • Women who get vaginal yeast infections should consider carrying along a treatment course (pills or vaginal products)
    • Other items according to your itinerary

    What are the medical concerns with jet lag?

    Jet lag happens when travelers cross several time zones and disrupt their normal sleep-wake cycle.

    To reduce the duration and the symptoms of jet lag, try to be outside when the sun is up. It may make for a very long (or short) first day, but it will help you adjust more quickly. Some travelers also try to change their sleep-wake habits before they leave.

    Medicines are available that can promote sleep, but there are few studies on how well they work with jet lag. Zolpidem (Ambien) is a prescription sedative that promotes sleep. Another group of prescription drugs known as benzodiazepines also promotes sleep, but they may have more side effects, including temporary amnesia. Melatonin is a natural hormone available as an herbal preparation in the United States. Doses of approximately 5 mg have been shown to induce sleep. Melatonin is available over the counter.

    Learn more about: Ambien

    Source: http://www.rxlist.com

    Malaria is an infection caused by a tiny organism called a protozoan. It enters red blood cells and multiplies until the cells burst open. The broken cells release the young protozoa into the bloodstream where they infect more red blood cells. This release of young protozoa causes high fevers that can last for several hours. The fever of malaria often comes and goes in a defined pattern, coinciding with when the infected red cells burst open. With some types of malaria, the protozoa can hide in the liver and cause episodes of fever over many years. In serious cases, malaria can cause the kidneys to shut down, can infect the brain, or cause death.

    Malaria is spread to people by mosquitoes. The mosquitoes bite between dusk and dawn. Malaria occurs in many tropical areas and a few areas that have a milder climate. Travelers to sub-Saharan Africa, South America, and Asia may be at risk for the disease. Some countries in Central America and the Caribbean also have malaria. Not every area of a country will be infected. A doctor can evaluate your itinerary to see if you might be exposed to malaria. The Centers for Disease Control and Prevention (CDC) has a web page that tells where malaria occurs (http://wwwn.cdc.gov/travel/).

    Malaria can be prevented by avoiding mosquito bites (see the section on insect precautions) and by taking preventive medications. Travelers who will be exposed to malaria should take medications starting before travel to the area and continuing for a time after they leave the area. Several different medicines are available. Some are taken only once a week, and others are taken daily. In some countries, malaria has become resistant to older medicines. Your physician will choose which medicine to use based on what countries you are visiting.

    Source: http://www.rxlist.com

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