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:
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 the mantra to remember. Specific tips include:
Malaria and other disease can be transmitted by mosquitoes, flies, and ticks. Make sure you:
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:
Pathogens may transmit through:
In addition to infectious diseases, travelers should be aware of other relevant health issues, such as:
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.
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:
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:
Optional travel-specific vaccines include:
The U.S. Centers for Disease Control and Prevention (CDC) website provides up to date vaccine recommendations listed by country or by disease.
First aid and other supplies for travelers should include:
Pack your prescription medications in your carry-on luggage and keep them in their original labeled containers. You should also bring:
In addition to your passport, other documents to pack include:
Some basic tips for safe health while traveling include:
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 (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:
Symptoms of traveler's diarrhea may include:
The onset and course of traveler's diarrhea depends on the type of organism that causes it:
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:
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:
"Boil it, cook it, peel it, or forget it" is an easy way to remember food and water precautions.
To avoid contaminated food:
To avoid contaminated water and other drinks:
You can make water safe to drink by purifying it. There are several methods:
Antibiotics are effective for treating diarrhea caused by bacteria. You should pack a prescription antibiotic that you can take if you have:
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:
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 diseases spread by contaminated water and food include:
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:
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 medication to reduce your risk. 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:
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. Other less effective drugs may be used overseas.
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 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 with 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:
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 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.
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:
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:
Zika infections are asymptomatic in many cases. When present, symptoms of Zika may resemble other arbovirus infections, such as dengue, and include:
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 risk areas for Zika. If traveling 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 8 weeks (women) to 6 months (men) after the last possible exposure or symptoms, and should practice safe sex in the meantime.
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:
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:
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 no available vaccine for preventing H5N1. (The U.S. government is stockpiling 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.
Hepatitis is inflammation of the liver. Viral forms of hepatitis are caused by hepatitis viruses:
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.
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:
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, 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.
There is currently no available vaccine to prevent Ebola. The CDC advises that people who are traveling to an Ebola-affected area should:
Aronson JK. Fluoroquinolones. In: Aronson JK, ed. Meyler's Side Effects of Drugs. 16th ed. Philadelphia, PA: Elsevier; 2016:368-381.
Basnyat B, Paterson RD. Travel medicine. In: Auerbach PS, Cushing TA, Harris S, eds. Auerbach's Wilderness Medicine. 7th ed. Philadelphia, PA: Elsevier; 2017:chap 79.
Bomsztyk M, Arnold RW. Infections in Travelers. Med Clin North Am. 2013;97(4):697-720. PMID: 23809721 www.ncbi.nlm.nih.gov/pubmed/23809721.
Bope ET, Kellerman RD. The infectious diseases. In: Bope ET, Kellerman RD. Conn's Current Therapy 2017. Philadelphia, PA: Elsevier; 2017:chap 8.
Centers for Disease Control and Prevention. Adult Immunization Schedule. cdc.gov Web site. www.cdc.gov/vaccines/schedules/hcp/imz/adult.html. Updated February 6, 2017. Accessed June 28, 2017.
Centers for Disease Control and Prevention. Chikungunya Virus. cdc.gov Web site. www.cdc.gov/chikungunya/index.html. Updated November 16, 2015. Accessed June 28, 2017.
Centers for Disease Control and Prevention. Choosing a Drug to Prevent Malaria. cdc.gov Web site. www.cdc.gov/malaria/travelers/drugs.html Updated November 9, 2012. Accessed June 28, 2017.
Centers for Disease Control and Prevention. Clinical Update Interim CDC Guidance for Travel to and from Countries Affected by the New Polio Vaccine Requirements. cdc.gov. Web site. wwwnc.cdc.gov/travel/news-announcements/polio-guidance-new-requirements. Updated March 14, 2017. Accessed June 28, 2017.
Centers for Disease Control and Prevention. Ebola (Ebola Virus Disease-Transmission). cdc.gov. Web site. www.cdc.gov/vhf/ebola/transmission/index.html. Updated July 22, 2015. Accessed June 28, 2017.
Centers for Disease Control and Prevention. Information on avian flu. cdc.gov. Web site. www.cdc.gov/flu/avianflu/index.htm. Updated April 13, 2017. Accessed June 28, 2017.
Centers for Disease Control and Prevention. Middle East Respiratory Syndrome (MERS): Information for healthcare providers. cdc.gov. Web site. www.cdc.gov/coronavirus/mers/hcp.html. Updated July 23, 2016. Accessed June 28, 2017.
Centers for Disease Control and Prevention. Recommended Immunization Schedule for Children and Adolescents Aged 18 Years or Younger, UNITED STATES, 2017. cdc.gov. Web site. www.cdc.gov/vaccines/schedules/hcp/child-adolescent.html. Updated March 6, 2017. Accessed April 23, 2017.
Centers for Diseases Control and Prevention. Risk of exposure. cdc.gov. Web site. www.cdc.gov/vhf/ebola/exposure/index.html. Updated December 09, 2015. Accessed June 28, 2017.
Centers for Disease Control and Prevention. Travel Smart: Get Vaccinated. cdc.gov. Web site. www.cdc.gov/features/vaccines-travel/index.html. Updated May 22, 2017. Accessed June 28, 2017.
Centers for Disease Control and Prevention. World Map of Areas with Risk of Zika. cdc.gov. Web site. wwwnc.cdc.gov/travel/page/world-map-areas-with-zika. Updated May 16, 2017. Accessed June 28, 2017.
Centers for Diseases Control and Prevention. Yellow fever vaccine information for healthcare providers. cdc.gov. Web site. www.cdc.gov/yellowfever/healthcareproviders/vaccine-info.html. Updated May 16, 2017. Accessed June 28, 2017.
Freedman DO. Approach to the patient before and after Travel. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 286.
Freedman DO. Infections in Returning Travelers. In: Bennett JE, Dolin R, Blaser, MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, Updated Edition. 8th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 324.
Freedman DO. Protection of travelers. In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, Updated Edition. 8th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 323.
Gold Standard Drug Database. Drug Monograph: Bismuth Subsalicylate. www.clinicalkey.com/#!/content/drug_monograph/6-s2.0-69. Accessed June 28, 2017.
Keystone JS, Freedman DO, Kozarsky PE, Connor BA, Nothdurft HD, eds. Travel Medicine. 3rd ed. Philadelphia, PA: Elsevier Saunders; 2013.
Kim DK, Bridges CB, Harriman KH. Advisory committee on immunization practices recommended immunization schedule for adults aged 19 years or older - United States, 2015. MMWR Morb Mortal Wkly Rep. 2015;64(4):91-92. PMID: 25654609 www.ncbi.nlm.nih.gov/pubmed/25654609.
Kim DK, Riley LE, Harriman KH, Hunter P, Bridges CB. Recommended Immunization Schedule for Adults Aged 19 Years or Older, United States, 2017. Ann Intern Med. 2017;166(3):209-219. PMID: 28166560 www.ncbi.nlm.nih.gov/pubmed/28166560.
Kotlyar S, Rice BT. Fever in the returning traveler. Emerg Med Clin North Am. 2013;31(4):927-944. PMID: 24176472 www.ncbi.nlm.nih.gov/pubmed/24176472.
Parker S, Gaines J. Saudi Arabia: Hajj/Umrah Pilgrimage. Centers for Disease Control and Prevention. cdc.gov Web site. wwwnc.cdc.gov/travel/yellowbook/2018/select-destinations/saudi-arabia-hajj-umrah-pilgrimage. Updated May 31, 2017. Accessed June 27, 2017.
Semrad CE. Approach to the patient with diarrhea and malabsorption. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016: chap 140.
Thomas SJ, Endy TP, Rothman AL, Barrett AD. Flavovirus (Dengue, Yellow fever, Japanese encephalitis, West nile encephalitis, St. Louis encephalitis, Tick-Borne encephalitis, Kyasanaur forest disease, Alkhurma hemorrhagic fever, Zika). In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, Updated Edition. 8th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 155.
Treanor JJ. Influenza (including avian influenza and swine influenza). In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, Updated Edition. 8th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 167.
Wallace GS, Seward JF, Pallansch MA. Interim CDC guidance for polio vaccination for travel to and from countries affected by wild poliovirus. MMWR Morb Mortal Wkly Rep. 2014;63(27):591-594. PMID: 25006826 www.ncbi.nlm.nih.gov/pubmed/25006826.
World Health Organization. Ebola virus disease. who.int. Web site www.who.int/mediacentre/factsheets/fs103/en. Updated June 2017. Accessed June 28, 2017.
World Health Organization. Zika virus. who.int Web site. www.who.int/mediacentre/factsheets/zika/en. Updated September 6, 2016. Accessed June 28, 2017.
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.