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Exploring travel medicine with the CDC

It was a historical moment for the International Society of Travel Medicine who celebrated its 25th anniversary this year at the 15th Conference of the International Society of Travel Medicine (CISTM15) in sunny Barcelona.

We asked Phyllis Kozarsky, Professor of medicine and chief medical editor for the CDC Yellow Book 2018, a few questions around the connections between travelers and antimicrobial resistance, environmental crises, new vaccines and pre-travel medical checks, and extreme altitudes.

What is the role of travelers in the spread of resistant organisms, and what can travelers do to prevent the spread of antimicrobial resistance?

In recent years, there have been reports of travelers becoming infected with drug-resistant travelers’ diarrhea and spreading it in their home countries. Using antibiotics to treat diarrhea while traveling increases a person’s risk of acquiring a drug-resistant organism, and a traveler can decrease this risk by limiting the use of antibiotics. Travelers’ diarrhea almost always goes away by itself in a couple of days, so travelers may want to just manage their symptoms with bismuth subsalicylate (Pepto-Bismol or Kaopectate) or loperamide (Imodium) for mild or moderate cases. For severe diarrhea, however, antibiotics can be an important tool to prevent someone’s business travel or vacation from being ruined.

How might environmental crises (such as natural disasters or air pollution) impact a traveler’s health, and what precautions can they take?

Natural disasters present physical risks to travelers (damaged infrastructure, downed power lines) and strain local health systems. Flooding from a natural disaster can compromise water quality and prompt outbreaks of waterborne diseases such as cholera or leptospirosis in areas where these diseases are a risk. As much as possible, travelers should avoid areas that have experienced a natural disaster unless they are part of a group that is engaged in aid activities and have received appropriate health guidance. If travel is unavoidable, they should know the risks, ensure they have access to a health kit, and have a plan for getting medical care if they need it.

Pollution by Jason Blackeye. CC BY 2.0 via Unsplash.

Air pollution has decreased in many parts of the world but is increasing in some industrializing countries. Polluted air can be impossible to avoid, but the risk to healthy short-term travelers is low. People with pre-existing conditions such as asthma or chronic obstructive pulmonary disease should limit strenuous or prolonged outdoor activity in polluted areas.

What are some significant ways that extreme altitudes can affect travelers who aren’t used to these conditions?

Travelers who go from a low altitude to a very high altitude (higher than 8,000 feet [2,500 m] above sea level) quickly can develop altitude illness. Symptoms are similar to those of a hangover—headache, feeling tired, nausea, and vomiting. Mild cases should go away after a few days, but if symptoms get worse at the same altitude, the traveler should descend to a lower altitude. Severe manifestations of altitude illness can include symptoms of extreme fatigue, confusion, loss of coordination, and being out of breath. Travelers with severe complications should descend to a lower altitude right away.

The best way to prevent altitude illness is to ascend gradually so that travelers can become accustomed to the decreased oxygen level. If the itinerary doesn’t allow gradual ascent, medications are available that can prevent altitude illness.

Mountain by Georg Nietsch. CC BY 2.0 via UnSplash.

How is the development of new vaccines going to affect people’s pretravel medical checks?

As new vaccines become available, clinicians will need to carefully weigh the risks and benefits of vaccination in the context of the traveler’s risk. For example, a new cholera vaccine was recently licensed in the United States. Cholera can be severe, but it is extremely rare in travelers, and areas of active transmission may be limited to specific regions within a country. When counseling a person who is traveling to a country where cholera is a potential risk, the clinician will need to assess the person’s risk of cholera, risk of developing severe disease, and whether there is active cholera transmission at the destination.

It remains true that the vast majority of travel-related illnesses cannot be prevented with a vaccine. There are ongoing efforts to develop vaccines to prevent other travel-related illnesses, but the process can take years. Travelers should be counseled on preventative behaviors and encouraged to take action to protect their health during their trip.

The 15th Conference of the International Society of Travel Medicine (CISTM15) was from Sunday 14 May 2017 to 18 May 2017 in Barcelona, Spain.

Featured image credit: Launching by Dominik Scythe. CC BY 2.0 via Unsplash.

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