Health Library Content

Emerging Infectious Diseases

What are emerging infectious diseases?

According to the National Institute of Allergy and Infectious Diseases, emerging infectious diseases are commonly defined as:

  • Outbreaks of previously unknown diseases 

  • Known diseases that are rapidly increasing in incidence or geographic range in the last two decades

Emerging diseases include HIV infections, SARS, Lyme disease, Escherichia coli O157:H7 (E. coli), hantavirus, dengue fever, and West Nile virus.

Re-emerging diseases are diseases that reappear after they have been on a significant decline. Re-emergence may happen because of a breakdown in public health measures for diseases that were once under control. They can also happen when new strains of known pathogens appear. Human behavior affects re-emergence. For example, overuse of antibiotics has led to drug-resistant pathogens and allowed a return of diseases that once were able to be treated with drugs.

Re-emerging diseases include malaria, tuberculosis, cholera, pertussis, influenza, pneumococcal disease, and gonorrhea.

Travelers should be aware that some diseases thought to be under control in the United States may be experiencing an outbreak in other countries. Ask for information and take precautions before being exposed to one of these diseases.

What is the risk of emerging infectious diseases?

Traveling abroad can put you at risk for infectious diseases that are not widespread in the United States. Travelers who become ill in a country where treatment for these diseases may be somewhat limited are even more at risk. All people planning travel should become informed about the potential hazards of the countries they are traveling to and learn how to minimize their risk of acquiring these diseases.

Why are travel-related infectious diseases on the rise?

It is believed that increased global travel is the reason for the recent resurgence of many infectious diseases in the United States. The number of people traveling internationally is increasing every year, and more people are taking trips to remote parts of the world, which often have unfamiliar health problems as well as underdeveloped health care services. Many travelers are also unaware of potential hazards in different parts of the world and do not take the necessary precautions, such as getting necessary vaccines or preventive medicine.

Many of the newly discovered infections have actually been in existence for a long time, but doctors have not seen them in areas where new outbreaks occur. With people's ability today to travel anywhere in the world within 36 hours or less, formerly little-known infections are picked up and rapidly spread to areas where they previously did not exist.

How can travelers minimize their risk from infectious diseases?

Travel abroad does not need to result in an illness from infectious diseases. Taking these measures can help minimize the risk to people traveling internationally:

  • Seek information as far before traveling as possible, even if the destination is one you have previously visited. Health conditions can change quickly in certain areas of the world. Get as much information as possible about current health risks for the country or countries you are visiting and learn about special risks for children, pregnant women, people with chronic diseases, and people with weakened immune systems who might be traveling with you.

  • For specific recommendations, see a travel medicine specialist or a doctor familiar with the area you will be visiting at least four to six weeks before your trip.  

  • Make sure your routine vaccinations, including the seasonal flu vaccine, are up-to-date.  

  • Get the immunizations and take the preventive medications recommended by your doctor. Since some of these must be administered or taken weeks before travel, contact your doctor as early as possible to ensure the effectiveness of these measures.

  • If medication is needed for prevention of malaria, be sure to take it as prescribed. Follow dosage instructions carefully. Malaria preventive medications must be started before your trip to ensure good levels in your body before any exposure to mosquitos at your destination; check with your health care provider or pharmacist to be sure you begin them early enough. They must be continued throughout your trip and for a specific number of days after you return, depending on which medication you are prescribed.

  • Put together a traveler's first aid kit with specific items geared to your destinations and to last the duration of your trip. Your doctor can help you identify what should be included in your kit.

  • Research emergency medical care during your trip and what medical evacuation services are available in case of serious illness. Contact your health insurance plan to find out what is covered in other countries. If you are traveling as part of an organized tour, contact the agency regarding medical services available and any additional insurance that might be available.

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