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Travel to developing countries - InDepth

  Cholera - InDepth; Dengue fever - InDepth; Traveler's diarrhea - InDepth; Malaria - InDepth; Schistosomiasis - InDepth; Typhoid - InDepth; Yellow fever - InDepth; Zika - InDepth

An in-depth report on travel-related health risks and how to prepare ahead of time to reduce these risks.


Planning Your Trip

Planning for a safe and healthy trip should be part of your travel preparations. If you plan to Travel to developing countries, you should allow plenty of time before your departure to:

  • Educate yourself about the health risks in the countries you will be visiting. The Centers for Disease Control (CDC), World Health Organization (WHO), and U.S. State Department have websites that provide specific information by country (see "Resources" below).
  • Schedule a visit to a travel clinic at least 4 to 6 weeks before your departure. A travel clinic can provide the latest up to date information on medications and immunizations you will need. Before you travel, you should be up to date on all of your routine immunizations. You may need additional vaccinations or booster shots, depending on where you will be traveling.
  • Schedule a visit with your health care provider to have a thorough check-up. This is especially important if you have any chronic health conditions. Make sure to get prescriptions for any medications you take so you will not run out during your trip. Take a list of medications and a brief summary of your medical history with you on your trip.
  • Make a list of first aid items and other supplies you should pack.

Food and Water Precautions

Traveler's diarrhea is the most common health problem a traveler encounters. To avoid contaminated food or water, "Boil it, peel it, cook it, or forget it" is a useful mantra to remember. Specific tips include:

  • Eat only food that is fully cooked and served hot. Peel all fruits and vegetables before consuming. Avoid salads, uncooked and unpasteurized foods, and items sold by street vendors.
  • Drink only beverages made with boiled water or commercially bottled water or other beverages that come sealed. Use bottled watered when brushing teeth. Wipe the outsides of bottles or cans before drinking from them.
  • Never consume any amount of tap water or items (such as ice cubes) made with tap water. Do not ingest any water when swimming, showering, or brushing teeth.

Insect Protection

Malaria and other disease can be transmitted by mosquitoes (most commonly), flies, and ticks. Make sure you:

  • Wear insect repellant products that contains DEET, picaridin, IR3535, or oil of lemon eucalyptus (para-menthane-3, 8-diol).
  • Wear permethrin-treated clothing.
  • Consider bringing a permethrin-treated bed net.
  • Get a yellow fever vaccine if traveling to affected countries.
  • Take preventive medication if traveling to malarial regions. Learn about your options for anti-malaria drugs.


Travel to developing countries can be a fun and rewarding experience. But it is important to make sure that health problems do not interfere with enjoyment of your trip. Careful preparation can help prevent problems on, and down, the road.

Infectious diseases are a concern when traveling to underdeveloped regions. These conditions are caused by organisms such as:

  • Viruses. Yellow fever, dengue fever, chikungunya, Zika, hepatitis, Ebola, encephalitis, polio, rabies, and others.
  • Bacteria. Cholera, typhoid fever, meningococcal meningitis, tuberculosis, and others.
  • Parasites. Malaria, schistosomiasis, leishmaniasis, African trypanosomiasis, and others.
  • Fungi. Ringworm, sporotrichosis, and others.

Pathogens may transmit through:

  • Contaminated food and water
  • Insect bites
  • Contaminated air
  • Unprotected sex

In addition to infectious diseases, travelers should be aware of other relevant health issues, such as:

  • Air pollution is a particular concern for travelers with breathing problems. If you have a respiratory condition, discuss your travel plans with your health care provider. Bring along a face mask and any necessary medications.
  • Motor vehicle accidents are a leading cause of preventable death and injury due to bad roads and poorly maintained vehicles. Try to avoid traveling at night and wear seat belts whenever possible.
  • Motion sickness can affect travelers on boats and vehicles, while altitude sickness is a concern in mountainous regions. Drinking plenty of fluids can help. Scopolamine is a drug patch that is effective for motion sickness.
  • Jet lag is common when traveling between time zones, especially when flying from west to east. Drink plenty of water and sleep on the plane if you can. When you arrive, stay outside during the day so that your body recalibrates. Some people find melatonin supplements helpful for recovering from jet lag.
  • Dangerous wildlife can be the most ignored aspect of a travel plan. If exploring wilderness areas, travel with a local guide or try to gather as much information as possible about the local flora and fauna beforehand. Do not touch or feed wild animals.

Before You Go

Education and preparations are critical for ensuring safe travels. Travelers should educate themselves on the health risks associated with their specific destinations. Resources from the Centers for Disease Control and Prevention (CDC) Traveler's Health, the U.S. State Department, and the World Health Organization can provide valuable information. Research their websites as part of your travel preparation (see "Resources" below).

You should check your health insurance to see what coverage your policy provides for travel abroad. (Medicare does not provide coverage outside of the United States.) Depending on your destination, you might consider purchasing a short-term travel medical insurance policy that provides emergency medical evacuation.

A visit to your doctor or hospital travel clinic should be scheduled at least 4 to 6 weeks before your trip. Providers who specialize in travel medicine are up to date on the latest warnings, outbreaks, and precautions for global regions. During your visit, the travel doctor will review your medical history and current medications, recommend non-prescription and prescription medications for (such as an antibiotic for traveler's diarrhea), and provide required or optional immunizations.

It can take 2 weeks for immunizations to take effect, and some immunizations require multiple doses, so it is important not to wait until the last minute. If you are traveling to a region where malaria is prevalent, you may need to start anti-malarial medication a few days before your departure.

If you are traveling while pregnant or have a chronic health condition (diabetes, asthma, or heart disease), it is very important to discuss your travel plans with your provider so you can be informed of specific precautions to take. Pregnant women should not travel to countries with Zika virus infection. If you will be traveling for long distances and are at risk for deep vein thrombosis (DVT) or pulmonary embolism (PE), your provider may recommend compression stockings, medications, or specific exercises to stretch your calf muscles.


When preparing to travel, you should make sure you and your children are up to date with all routine immunizations. Routine vaccinations include:

  • Seasonal influenza
  • Tetanus-diphtheria-pertussis (TDP or Tdap)
  • Measles-mumps-rubella (MMR)
  • Varicella (chickenpox) for children and Zoster (shingles) for adults
  • Pneumococcal (PCV13 or PPSV23)
  • Hepatitis A and B
  • Polio
  • Meningococcal disease
  • Haemophilus influenzae type b (Hib) -- for children or adults with immune system problems
  • Rotavirus (for infants only)

Depending on your itinerary, and the specifics of your medical history, you may also need required vaccinations for crossing international borders. There are 3 vaccines that are required for entering or leaving certain countries. These 3 vaccines include:

  • Polio vaccine a one-time booster is currently required to exit after a stay of 4 weeks of more in Afghanistan, Laos, Nigeria, and Pakistan. This list of nations may change frequently.
  • Meningococcal vaccine a single dose quadrivalent ACWY meningococcal vaccine is required to enter The Kingdom of Saudi Arabia for Hajj.
  • Yellow fever vaccine is required for entry by many countries if you are traveling from countries with risk of yellow fever.

Other travel-specific vaccines that may be necessary, although not required for crossing borders include:

  • Typhoid vaccine (available in both oral and injectable forms)
  • Japanese encephalitis vaccine
  • Rabies preexposure vaccine
  • Tick-borne encephalitis (not available in the United States and Canada, but available in endemic areas in Europe)

The U.S. Centers for Disease Control and Prevention (CDC) website provides up to date vaccine recommendations listed by country or by disease.

What to Pack

First aid and other supplies for travelers should include:

  • Antiseptic cleanser
  • Antibiotic ointment
  • Hydrocortisone cream
  • Antifungal cream
  • Anti-diarrhea medication such as loperamide (Imodium) and bismuth subsalicylate (Pepto-Bismol)
  • Over-the-counter pain reliever (acetaminophen, ibuprofen, or naproxen)
  • Hand sanitizer and disinfectant wipes
  • Small packets toilet paper or tissues
  • Bandages and gauze
  • Sunblock (15 SPF or higher)
  • Insect repellent
  • Digital thermometer
  • Supplies to purify or filter water
  • Extra pair of prescription glasses or contact lenses
  • EpiPen if you have any food or insect allergies

Pack your prescription medications in your carry-on luggage and keep them in their original labeled containers. You should also bring:

  • Extra amounts of your medications in case you run out.
  • A list of generic and brand drug names in the countries you will be visiting in case you need to purchase medication while abroad. (For example, acetaminophen, the generic name for Tylenol, is sold as paracetamol outside the United States.)
  • A medical summary of your conditions and a list of your current medications.

In addition to your passport, other documents to pack include:

  • Your passport and identification.
  • International Certificate of Vaccination (Yellow Card). You will need to present this if you are traveling to a country that requires proof of yellow fever vaccination for entry.
  • List of U.S. consulate or embassy locations in countries you will be visiting.
  • Health insurance information.

While Traveling

Some basic tips for safe health while traveling include:

  • If traveling long distances, flex and straighten your legs, feet, and toes to help prevent deep vein thrombosis. For extended air travel, get up periodically and walk.
  • Eat only food that is fully cooked and served hot. Peel all fruits and vegetables before consuming. Avoid salads, uncooked and unpasteurized foods, and items sold by street vendors. Do not eat "bushmeat" such as bats, monkeys, or other wild game.
  • Drink only beverages made with boiled water or commercial bottled water or other beverages that come sealed. Use bottled watered when brushing teeth. Wipe the outsides of bottles or cans before drinking from them. Never consume any amount of tap water or items (such as ice cubes) made with tap water.
  • If swimming, brushing your teeth, or showering, take care not to ingest any water. Never swim if you have any open cuts, sores, or abrasions. If traveling to an area where schistosomiasis is common, avoid swimming or wading in fresh water.
  • Use DEET insect repellant and wear permethrin-treated clothing to prevent bites from disease-carrying mosquitoes, flies, and ticks.

After You Return

If you develop any symptoms of illness after you return to the United States, be sure to immediately contact your health care provider or travel clinic doctor and volunteer the details of your travel history. Some infections can take over 30 days to develop so it is important to remind your provider of your past travel even if it was months prior. Let your provider know where you have been, in addition to what symptoms you are experiencing. Symptoms to watch for include fever, rash, fatigue, and respiratory or stomach problems.

If you are traveling to a country where tuberculosis (TB) is prevalent and you may have prolonged exposure to someone with TB, your doctor may recommend you get a skin or blood TB test before you depart and a repeat test 8 to 10 weeks after you return.

Traveler's Diarrhea

Traveler's diarrhea (TD) is the most common health problem a traveler encounters. It is almost always caused by ingesting certain organisms (viruses, parasites, or bacteria) in contaminated food or water:

  • Escherichia coli (E coli) is the most common bacterial and overall cause of traveler's diarrhea. Other bacterial causes include Campylobacter jejeuni, Shigella, and Salmonella. Some of these infections are associated with bloody diarrhea (dysentery).
  • Giardia, a protozoa, is the most common parasitic cause of diarrhea. Other parasitic causes include Entamoeba histolytica, Cryptosporidia, Cystoisospora, Cyclospora, and Microsporidia.
  • Noroviruses, also called Norwalk-like viruses, are an increasingly common cause of traveler's diarrhea in Central American countries and on cruise ships. Other viral causes include rotaviruses, adenoviruses, and astroviruses.


Symptoms of traveler's diarrhea may include:

  • Loose, watery stools
  • Stomach cramps
  • Fever (uncommon in norovirus infection)
  • Vomiting
  • In severe cases, bloody diarrhea (dysentery)

The onset and course of traveler's diarrhea depends on the type of organism that causes it:

  • Bacterial and viral diarrhea comes on rapidly 6 to 48 hours after exposure to the pathogen. If not treated, it can last for 2 to 5 days.
  • Protozoal diarrhea tends to emerge more gradually 1 to 2 weeks after exposure to the parasite. If not treated, it can persist for weeks or months.
  • People who have a severe or prolonged case of traveler's diarrhea may continue to experience gastrointestinal symptoms even after the initial infection goes away.

Traveler's diarrhea is rarely life threatening, although it can be severely debilitating, especially in children. Dehydration (loss of fluids) is the main concern. Symptoms of dehydration include:

  • Lack of urine or tears
  • Dry mouth
  • Sunken eyes
  • Dizziness and weakness

Seek immediate medical attention if you or your child has symptoms of severe dehydration, high fever, bloody stools, or persistent vomiting.


There is no vaccine to prevent traveler's diarrhea. Certain precautions can help reduce (although not completely prevent) your risk:

  • Use hand sanitizers or disinfectant wipes before eating.
  • Be careful in choosing food and drinks (see below).
  • Take 2 tablets of bismuth subsalicylate (Pepto Bismol) 4 times a day (do not use if under 12 years old, allergic to aspirin, or take anticoagulants or methotrexate. Be aware that this medicine causes black stools.)
  • Prophylactic (preventive) antibiotics are not usually recommended for travelers.

Food and Beverage Precautions

"Boil it, cook it, peel it, or forget it" is an easy way to remember food and water precautions.

To avoid contaminated food:

  • Eat hot, well-cooked foods. But do not eat hot foods that have been sitting around for a long time and are now room temperature.
  • Do not eat raw fruits and vegetables unless you peel them. Wash all fruits and vegetables in clean water before eating them.
  • Do not eat raw leafy vegetables (e.g. lettuce, spinach, or cabbage) because they are hard to clean. It is best to avoid salads.
  • Do not eat salsa or other condiments made with raw vegetables.
  • Do not eat raw or undercooked meat, fish, or eggs. Hardboiled eggs are safe.
  • Do not consume unpasteurized dairy products (milk, cheese, and yogurt).
  • Do not buy food from street vendors.

To avoid contaminated water and other drinks:

  • Do not use tap water to drink or brush your teeth.
  • Do not use ice or other items (popsicles, iced tea, or coffee) made from tap water.
  • Choose water or other beverages that are commercially bottled and sealed. Wipe the outside of the bottle or can before consuming.
  • Hot beverages (coffee, tea) are safe to drink.

You can make water safe to drink by purifying it. There are several methods:

  • Boiling is the simplest method. Boil water for at least 1 minute.
  • Use iodine or chlorine tablets.
  • Use a device that emits ultraviolet light.
  • Handheld water filters can help remove bacteria and parasites but are not effective for viruses.



Antibiotics are effective for treating diarrhea caused by bacteria. You should pack a prescription antibiotic that you can take if you have:

  • 3 or more loose stools in an 8-hour period
  • 5 or more loose stools in a 24-hour period

Fluroquinolones (ciprofloxacin or levofloxacin) are usually the antibiotics prescribed. (Fluroquinolones are generally not recommended for pregnant women or children under 18. Fluroquinolones may increase the risk for tendinitis and tendon rupture, especially in adults over age 60.) You will take 1 pill every 12 hours until the diarrhea goes away. Most people feel better after 1 or 2 pills. Your health care provider may prescribe an alternative antibiotic (such as azithromycin) if you are traveling in a region that has ciprofloxacin resistance.

For nonprescription medication, you can take loperamide (Immodium) as directed.


To help yourself feel better, you should:

  • Drink plenty of (purified) clear fluids. Water or an oral rehydration solution is best.
  • Eat small meals every few hours instead of three big meals.
  • Eat easily digestible salty foods, such as salted crackers or pretzels.
  • Eat foods that are high in potassium, such as bananas.
  • Avoid caffeinated beverages.

Fluid Replacement

If diarrhea develops, the most important steps to take are preventing dehydration and replacing lost fluids and electrolytes.

Dehydration can be especially dangerous for children. Rehydration products contain an important balance of sugars and salts. If traveling with children, bring along products such as pre-packaged oral rehydration salts (ORS). These are often sold in health agency pharmacies. A homemade solution can be prepared with ½ tsp salt; 2 tbsp sugar; ½ tsp baking powder; 1 liter (about one quart) of clean water.

In cases of severe dehydration, seek medical assistance.

Other Intestinal Diseases

Other diseases spread by contaminated water and food include:

  • Cholera. Is caused by the bacterium Vibrio cholerae. It causes massive amounts of loose, watery stools ("rice-water stools") and if untreated lead to fatal dehydration. Vaccines for cholera prevention are not available in the United States.
  • Typhoid fever. Is caused by the Salmonella typhi bacterium. It is an infection that causes fever and bloody diarrhea. You can get an injected or oral typhoid vaccine to prevent typhoid fever.
  • Hepatitis A. Is a viral infection that causes liver disease and can be transmitted through fecal-contaminated food and water. You can receive a vaccine to prevent hepatitis A. [For more information, see Other Infectious Diseases section.]

Insect-Borne Diseases

The following are some common diseases caused by viruses or parasites transmitted by infected insects.


Malaria is a major health problem in many tropical and subtropical regions of the world, and especially in sub-Saharan Africa.

Malaria is a serious and potentially life-threatening disease. It is caused by a Plasmodium parasite transmitted through the bite of an infected female Anopheles mosquito. There are several types of Plasmodium human malaria; P. falciparum is the most common and deadly type in Africa.

Anopheles mosquitoes acquire the parasites when they bite and feed from the blood of someone infected with malaria. The parasites develop and reproduce inside the mosquito and are then transmitted again when another person is bitten. Malaria can also be transmitted from a pregnant mother to her unborn baby and by blood transfusions.

When a person is infected by Plasmodium, the parasites travel first through the bloodstream to the liver where they mature and multiply, and then enter and infect red blood cells. Symptoms usually develop 7 to 14 days after infection, but can occur up to several months later. Some people experience relapse attacks months or years after infection.


Seek immediate medical attention if you experience symptoms of malaria. A malaria attack lasts 6 to 10 hours and is accompanied by symptoms such as:

  • Intense chills followed by fever
  • Headache, body aches, and vomiting
  • Sweating and fatigue

Anemia (low red blood cell count) and jaundice (yellowing of skin) may also be present. In severe cases, malaria can cause seizure, brain infection, and liver, kidney, or respiratory failure. Severe malaria can be fatal.


If you are traveling to an area where malaria is endemic, you should take a medication to reduce your risk prior to traveling. There are several types of malaria prophylaxis medications. Discuss your options with your doctor. Some of these drugs have substantial side effects or are inappropriate for people with certain current or prior health conditions. Your destination is also a factor -- in some geographic regions, the malaria parasites have become resistant to certain medications.

Malaria prevention drugs include:

  • Atovaquone-proguanil (Malarone) is taken as a single daily dose for 3 days. You should begin taking it 1 to 2 days before departure. Side effects are rare.
  • Doxycycline is started 1 to 2 days before departure and then taken once daily during travel. You should continue to take it for 4 weeks after returning. This antibiotic drug can increase sun sensitivity so it is important to avoid direct sun exposure and to regularly apply sunscreen.
  • Mefloquine (Lariam) is begun at least 2 weeks before departure, taken once week during travel, and continued for 4 weeks after return. Some people experience severe psychiatric symptoms with this drug. It should not be prescribed to people with a history of depression, anxiety, schizophrenia, or psychotic disorders.
  • Chloroquine is started 1 to 2 weeks before departure, taken once a week during travel, and continued for 4 weeks after return. Many malaria parasites are resistant to chloroquine so it is only prescribed for areas where resistance is low. This drug can worsen psoriasis.
  • Primaquine is started 1 to 2 days before departure, taken daily during travel, and continued for 7 days after return. This drug is only prescribed for regions where malaria caused by P. vivax (not P. falciparum) is common.

Anopheles mosquitoes are most active between dusk and dawn. You should wear long-sleeved shirts and pants, and also protect yourself with an insect repellant that contains 20% to 30% concentration of DEET. During the day, apply sunscreen before applying the insect repellant. Pre-treat your clothing with permethrin. You may also consider bringing a permethrin-treated bed net. Sleeping in an air conditioned or screened environment helps reduce the risk for mosquito exposure.


Malaria can be treated if caught early. Delayed treatment can be fatal. Atovaquone-proguanil is the main drug recommended, though others are also used based on where you travelled when you contracted malaria. Other less effective drugs may be used overseas.

Dengue Fever

Dengue fever, also known as breakbone fever, is a viral infection spread by the female Aedes aegypti mosquito. It causes severe flu-like symptoms including high fever, headache, rash, and deep pain in the joints, muscles, and behind the eyes. There may be mild bleeding from the nose or gums. Symptoms usually develop about a week after infection and last for up to 10 days.

A very small number of dengue fever cases develop into dengue hemorrhagic fever (DHF), which is a severe form of this infection. DHF begins with dengue fever symptoms but then worsens with severe abdominal pain and bleeding from nose, mouth, and under the skin. A shock-like state can follow.

There are 4 types of dengue viruses (DENV-1 to DENV-4). People who have had dengue fever become immune to the initial virus that infected them, but they are still at risk for contracting the other viruses. If you have had dengue fever and are then subsequently infected with a new dengue virus, you may be at increased risk for DHF.

There is no available vaccine for dengue fever. The best way to reduce your risk is to avoid getting bitten by mosquitoes. Use DEET insect repellant on your skin, and wear permethrin-treated clothing. Unlike the Anopheles and other mosquitoes, the Aedes mosquito feeds primarily in the daytime. It is most active from early morning until dusk.

Treatment for dengue fever is to rest, drink plenty of fluids, and take acetaminophen (Tylenol) pain reliever. Do not take aspirin or other NSAIDs because they may increase bleeding. Treatment for DHF may require intravenous fluids and specialized supportive care.

Yellow Fever

Yellow fever is caused by a flavivirus transmitted by an Aedes or Haemogogus mosquito. The disease can range from mild to severe. Initial symptoms include flu-like symptoms but 15% of cases become severe with jaundice (yellow color), high fever, hemorrhagic bleeding, shock, and organ failure. If left untreated, severe yellow fever can be fatal. Fortunately, yellow fever can be prevented by immunization. Yellow fever vaccine is given as a single dose to the people ages 9 months or more, traveling or living in risk areas. Additional doses may be required in:

  • HIV patients
  • Travelers who has taken the vaccine 10 years ago
  • Women who were pregnant at the time of vaccination
  • Laboratory workers who handle the wild- type yellow virus in routine
  • People who went under hematopoietic stem cell transplant after last dose of yellow fever vaccine


Chikungunya is caused by a Togaviridae virus transmitted by infected Aedes species mosquitoes. Symptoms usually begin 4 to 8 days after being bitten. The illness begins with fever followed by muscle and joint pain, headache, and rash. Most people recover within a week, but severe joint pain and fatigue can persist for several months. Treatment focuses on relief of symptoms. A person who gets chikungunya is protected from future infections.

There is no vaccine or treatment available for chikungunya. Follow insect protection precautions including wearing DEET insect repellant.

Chikungunya is present in many regions throughout the world, including Africa, Asia, and Indian sub-continent. In 2013, the first Western Hemisphere chikungunya cases were identified in Saint Martin. Since then, chikungunya has become widespread throughout the Caribbean region.


Leishmaniasis is caused by a protozoa parasite transmitted through the bite of various species of sandflies. There are several forms of the disease. Cutaneous leishmaniasis causes skin sores and ulcers. It is more common in parts of Central and South America and the Middle East. Visceral leishmaniasis affects internal organs such as the spleen and liver. It is more common in the Indian subcontinent and East Africa.

Sandflies are most active from dusk to dawn. The best way to prevent leishmaniasis is to avoid going out during these hours. If you do, minimize exposed skin by wearing permethrin-treated long-sleeved clothing and pants. Apply DEET insect repellant to exposed skin.

Viral Encephalitis

Arboviruses (viruses carried by arthropods like mosquitos or ticks) are an important cause of encephalitis worldwide. The predominant types vary from one region to another:

  • Western hemisphere -- Eastern and Western equine, La Crosse, Venezuelan, and West Nile
  • Australia and New Guinea -- Murray Valley
  • Russia and Eastern Europe -- Tick-borne
  • Asia and Western Pacific -- Japanese encephalitis

Japanese encephalitis (JE) which can be fatal, has high rates of infection in countries like Bangladesh, Cambodia, China, Indonesia, Japan, Nepal, and Thailand.

Symptoms can range from mild flu-like illness to fever, headache, and vomiting. This infection can cause inflammation of the brain (encephalitis), which can lead to coma and paralysis.

There is a vaccine available to prevent JE. It is approved for children and adults age 2 years and older. The vaccine is recommended for travelers who will be spending more than 1 month in areas where JE is common, or for travelers staying less than 1 month who plan on spending time in rural or agricultural areas.


Zika is caused by an arbovirus transmitted by infected Aedes mosquitoes. Zika infection during pregnancy may cause certain birth defects.

The Zika virus was first identified in Uganda in 1947 and the first large outbreak was reported in Island of Yap (Federated States of Micronesia) in 2007. Outbreaks of Zika virus disease have since been recorded in Africa, the Americas, Asia and the Pacific.

The CDC recommends that the following groups of people be tested for Zika virus:

  • A person with symptoms who has recently traveled to areas with risk of Zika.
  • Pregnant women with or without symptoms who have recently visited areas with risk of Zika.

Zika infections are asymptomatic in many cases. When present, symptoms of Zika may resemble other arbovirus infections, such as dengue, and include:

  • Mild fever
  • Conjunctivitis
  • Skin rash
  • Muscle and joint pain
  • Headache
  • Malaise

No specific treatment exists for Zika infection. Zika infection in pregnant women can cause fetal brain defects such as microcephaly, as well as miscarriage and stillbirth. Zika infection has also been linked to Guillain-Barré syndrome in risk areas. There is no vaccine available for Zika.

CDC recommends that pregnant women not visit areas with a current outbreak of Zika. If traveling to risk areas is unavoidable, they should take steps to avoid mosquito bites and sexual transmission during and after the trip. Travelers who are planning to conceive should wait for at least 2 months (women) to 3 months (men) after the last possible exposure (if asymptomatic) or after diagnosis or the first symptoms (if symptomatic), and should practice safe sex in the meantime.

All travelers to risk areas for Zika should avoid mosquito bites for 3 weeks after returning, to prevent the spread of Zika to mosquitoes that could spread the virus to other people.

Respiratory Viruses

Respiratory viruses range from the common cold to more serious infections. All travelers should take general precautions to protect themselves from respiratory viruses. Tips for prevention include:

  • Get up to date with all your immunizations, including the seasonal flu vaccine.
  • Wash hands frequently with soap and water or an alcohol-based hand sanitizer.
  • Clean and disinfected commonly touched surfaces and objects.
  • Avoid close personal contact and sharing eating and drinking utensils or other personal items with infected people.

Avian (Bird) Influenza

Avian influenza, commonly called bird flu, is caused by avian (bird) types of the influenza A virus. Influenza viruses are commonly found in wild birds, especially water fowl, and can also cause outbreaks in domestic poultry such as chickens, ducks, and geese.

Most of the time, avian flu stays contained within bird populations. However, some of the viruses that cause disease in birds can mutate and spread to humans. In particular, two avian influenza viruses -- H5N1 and H7N9 -- have caused outbreaks in people.

The first case of avian influenza A (H5N1) in humans was reported in Hong Kong in 1997. The outbreak was linked to infected chickens. The virus reemerged in 2003 and since then there have been human cases in countries in Asia, Africa, the Pacific, Europe, and the Middle East (particularly Egypt). In 2013, human infection with a second avian influenza A virus (H7N9) was reported in China. Both types of viruses can cause serious and fatal illness. The disease causes flu-like symptom but can develop into pneumonia and severe respiratory distress.

Most cases of transmission involved people who came into direct contact with infected birds. In their current form, avian influenza viruses do not easily spread from person to person. However, if the viruses continue to mutate, more cases of human transmission of avian flu may occur, which would increase the possibility of a global outbreak (pandemic).

The CDC recommends that people traveling to avian influenza-affected countries:

  • Avoid live bird markets and other places where birds, especially poultry, are raised or kept.
  • Do not eat raw or undercooked poultry meat, eggs, or blood.
  • Do not touch infected birds.
  • Wash your hands frequently during travel.
  • Cover your mouth and nose with a tissue when you cough or sneeze.
  • If you develop flu symptoms, wear a face mask and seek medical attention.

Contact your health care provider if you develop any symptoms of fever, cough, sore throat, or breathing problems within 10 days of returning home. Be sure to inform your provider about your recent trip.

In May 2017, the fifth and largest to date epidemic of H7N9 has been reported from China. However, due to the current low risk assessment, neither the WHO nor the CDC have issued any travel restrictions.

There is currently an available vaccine for preventing H5N1. (The United States government is stockpiling this vaccine in the event that cases of human-to-human transmission increase.) There is no vaccine for H7N9.


Middle East Respiratory Syndrome (MERS) is an emerging viral infection that was first identified in Saudi Arabia in 2012. Since then, MERS has been reported throughout countries around the Arabian Peninsula.

MERS is caused by a coronavirus, the same family of viruses responsible for many other respiratory infections including the common cold and SARS. MERS comes on suddenly, with symptoms that include fever, cough, and shortness of breath. Other symptoms include flu-like illness, nausea, and vomiting. This disease can be fatal.

MERS may have originated as a disease in camels, which then spread to humans. The reported cases have involved close contact human-to-human transmission in people who were living with or caring for an infected person. Treatment focuses on symptom relief. There is no preventive vaccine or specific treatment available for MERS. You should follow general precautions for avoiding exposure to respiratory viruses.

The World Health Organization (WHO) advises travelers to the Arabian Peninsula who have high-risk health conditions (diabetes, chronic lung disease, and weakened immune systems) to avoid contact with camels.


Severe acute respiratory syndrome (SARS) is a respiratory illness caused by the SARS-associated coronavirus (SARS-CoV). SARS manifests as a severe pneumonia that may lead to respiratory failure and death. The infection is spread through droplets released when an infected person coughs or sneezes. A global outbreak of SARS occurred in 2003, which started in China and spread to other countries in Asia, Europe and the Americas. No new cases of SARS have been reported since 2004.

Coronavirus Disease 2019 (COVID-19)

SARS-associated coronavirus 2 (SARS-CoV-2), previously also called 2019 Novel Coronavirus (2019-nCoV) is a newly identified coronavirus responsible for an outbreak of coronavirus disease (called COVID-19) that started in December 2019 in Wuhan City, China. Infection with SARS-CoV-2 causes a respiratory illness that may range from no or mild symptoms to respiratory failure and death. COVID-19 is thought to spread from person to person through infected droplets.

Symptoms of COVID-19 occur within 2 to 14 days from exposure and include fever, coughing, and shortness of breath. It appears that the risk for more severe COVID-19 is higher in people who are older or who have chronic health problems. There is currently no vaccine to prevent COVID-19.

The best way to prevent this infection is to avoid exposure the virus, including by avoiding traveling to known locations of outbreaks. The CDC currently recommends that people do not travel to China, and that travelers from China be tested and isolated for up to 14 days. This is a rapidly evolving situation. For the most up to date information about COVID-19, you can visit the following websites:

Centers for Disease Control and Prevention (CDC) website. Coronavirus Disease 2019 (COVID-19) - www.cdc.gov/coronavirus/2019-ncov/index.html

World Health Organization website. Novel coronavirus (2019-nCoV) - www.who.int/emergencies/diseases/novel-coronavirus-2019

Other Infectious Diseases


Hepatitis is inflammation of the liver. Viral forms of hepatitis are caused by hepatitis viruses:

  • Hepatitis A can be transmitted through contaminated food and water or through coming into direct contact with someone infected with the virus.
  • Hepatitis B is transmitted through blood or other bodily fluids such as semen (sexual activity).
  • Hepatitis C is transmitted through blood.
  • Hepatitis E is transmitted through contaminated water.

Before you travel, you should receive a vaccine to prevent hepatitis A and hepatitis B. (There are no vaccines for the other hepatitis viruses.)

Hepatitis A and E viruses are shed in feces. Contamination of food and water is common in regions that have poor sanitation. You can protect yourself by exercising caution in selecting food and beverage, and practicing good hygiene.

Hepatitis B and C can be spread through engaging in unsafe sex; having medical procedures with unsterilized instruments; or having blood transfusions if blood is not screened. Travelers to developing regions should also avoid having tattoos or acupuncture.

Symptoms of hepatitis can appear weeks after infection. They can range from mild to severe and include fever, nausea, fatigue, loss of appetite, and jaundice (yellowing of skin). Some people have no symptoms. Hepatitis A is an acute disease that usually clears up on its own. Hepatitis B, C, and E can have both acute and chronic forms. Chronic hepatitis poses risks for liver damage (cirrhosis) and cancer over time.

Skin Infections

People who visit tropical regions are at risk for a number of skin disorders, including infections from parasites or fungi. Bacterial infections can also develop from insect bites or abrasions. Antibacterial and anti-fungal medication can help treat these infections. If you notice any skin problems after you return from your trip, contact your health care provider.

Cleanliness is essential for preventing skin infections. Wash regularly with soap and water. To prevent fungal infections, which thrive in damp, warm climates, be sure to dry skin thoroughly. Take special care to clean and keep dry certain skin areas where infections are most likely to occur. They include creases in the skin, the armpits, the groin, buttocks, and areas between the toes. Use talcum powder in these areas. Keep socks dry.

A bad sunburn that blisters can also increase the risk for infection. To avoid sunburn:

  • Wear sunscreen SPF 30 or higher. Apply sunscreen before applying insect repellant.
  • Stay in the shade between 10am and 4pm when the sun's rays are strongest.
  • Wear light, cotton clothing to cover exposed skin, a wide-brimmed hat, and sunglasses.
  • If you do get a sunburn, apply a cool, wet towel to the burn. If there are blisters, apply dry bandages. Cortisone creams can help reduce inflammation. Do not apply petroleum jelly, which can block pores and increase the risk for infection.


Ebola is a severe and deadly disease caused by a virus. There are several species of Ebola viruses.

Ebola was previously called Ebola hemorrhagic fever. Viral hemorrhagic fevers damage the vascular system. The cause of death is not due to bleeding but to shock and multi-organ failure. Other hemorrhagic fevers include Lassa and Marburg viruses.

These diseases circulate in animal populations. Scientists think that Ebola may have originated in bat or primate (apes and monkey) populations. Outbreaks occur when a person comes into contact with an infected animal. The disease is then transmitted among people through contact with an infected human.

If a person recovers from Ebola, they may still harbor the virus in immune-privileged sites such as testicles, the inside of the eye, and the central nervous system. Relapse-symptomatic illness in recovered people is rare but may occur in the event of replication of the virus in a specific site.

In 2014 to 2016, the largest recorded Ebola outbreak occurred in West Africa. The countries of Sierra Leone, Guinea, and Liberia were principally affected. Past outbreaks have occurred in other African countries such as the Democratic Republic of Congo, Gabon, and Uganda.

In 2019, the first FDA-approved vaccine for the prevention of Ebola in adults became available. Other vaccines are in different phases of testing. Rapid and portable testing methods for Ebola have also been recently developed.

The CDC advises that people who are traveling to an Ebola-affected area should:

  • Practice strict hygiene including regularly washing hands with soap and water, or using an alcohol-based hand sanitizer.
  • Avoid contact with blood and bodily fluids. Do not handle items that may have come into contact with an infected person's blood or fluids.
  • Avoid contact with bats and monkeys. Do not consume "bushmeat" (meat prepared from these or other wild animals).
  • After you return, monitor your health for 21 days. If you experience symptoms of Ebola, seek medical assistance. Ebola symptoms include fever, severe headache, muscle and abdominal pain, diarrhea, vomiting, and bleeding or bruising. A person is only contagious while they are symptomatic.



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Review Date: 1/9/2020  

Reviewed By: Jatin M. Vyas, MD, PhD, Assistant Professor in Medicine, Harvard Medical School; Assistant in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital, Boston, MA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team. Editorial update on 02-13-20. Editorial update on 02-19-20.

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