6 infections acquired by travelers

Unprepared and unprotected travelers are at increased risk for acquiring a range of infections. Here, Infectious Disease News presents information on six important infections that pose serious risks to patients who travel in the United States and abroad.

Measles

The CDC recently reported that measles cases have hit a 20-year high in the US. Almost all (97%) of the cases were imported from unvaccinated travelers.

“This is a reminder that measles is still common in certain parts of the world, and it is also one of the most contagious diseases in the world,” Anne Schuchat, MD, director of the CDC’s National Center for Immunization and Respiratory Diseases, said during a media briefing. “Vaccination is the best way to prevent measles. The measles vaccine is very effective, but only if it’s used.”

Anne Schuchat

In 2011, an unvaccinated traveler was identified as the source of one of two outbreaks in Utah.

Before international travel, the CDC recommends that infants aged 6 to 11 months should have one dose of measles vaccine; children aged 12 months and older should have 2 doses at least 28 days apart; and unvaccinated adolescents and adults who have not had measles should get 2 doses at least 28 days apart.

MERS

The WHO International Health Regulations Emergency Committee recently expressed concern over the sharp rise in cases of Middle East respiratory syndrome, or MERS, coronavirus. The committee said more studies are urgently needed to clarify the role of animals in the transmission of the virus, which is now affecting over a dozen countries, including the United States.

So far, two cases of infection with MERS have been confirmed in the US — both health care workers who traveled from Saudi Arabia. A suspected third case — a close contact of one of the two health care workers — was determined not to have been infected, according to the CDC.

Health care providers are advised to remain vigilant. Patients who recently traveled to the Middle East and develop severe acute respiratory infections should be tested for MERS, according to WHO. Although no specific treatment is available for MERS, the CDC updated its clinical guidelines for the evaluation and management of suspected and confirmed MERS cases.

Rabies

Human Rabies is rare in the United States, but the disease is lethal once symptoms set in, and its vectors can be found across the country.

Of the two to three human rabies cases that occur each year in the US, one is usually acquired while traveling internationally in rabies-endemic areas, according to Jesse Blanton, MPH, an epidemiologist in the CDC’s poxvirus and rabies branch.

The average traveler should have some level of concern, but most travelers do not need rabies vaccination, according to Stephen Gluckman, MD, professor of medicine at the Hospital of the University of Pennsylvania and medical director of Penn Global Medicine.

“I see several hundred people a year for travel advice, and I give the rabies vaccine about five times per year,” Gluckman told Infectious Disease News. “If it were less expensive, that threshold might change. A course of rabies vaccine costs about $1,500, and it’s never covered by insurance when given pre-exposure.”

Dengue

Scott B. Halstead, MD, an independent consultant and dengue expert, recently characterized the severity of dengue illness in adults: “For 3 days you’re afraid you’re going to die, and for the next 2 days you’re afraid you’re not going to die,” he said.

Over 4 billion people worldwide are at risk for dengue, but there are currently no licensed dengue vaccines on the market today. The challenge has been to develop a single-dose vaccine that protects against all four serotypes.

Scott B. Halstead

Recently, researchers developed an early warning system to assess the likelihood of a dengue epidemic in Brazil during the World Cup, which may be useful to direct disease prevention and control strategies before thousands of visitors arrive for the matches.

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Chikungunya

Researchers warn that chikungunya virus has great potential to become a severe epidemic in the Americas — including in the United States — based on new data. Since the first indigenous cases were reported on the French side of the island of St. Martin in November 2013, the disease has spread swiftly across the Caribbean.

There are now over 60,000 suspected cases of infection in the Western Hemisphere.

According to the CDC, the high level of viremia in humans and the wide distribution of Aedes aegypti and A. albopictus mosquitos increase the risk of importation of chikungunya virus into new regions by infected travelers.

Like dengue, chikungunya has no vaccine.

Lyme disease

Lyme disease continues to be the most commonly reported vector-borne illness in the US, according to the CDC.

Most Lyme disease cases in 2012 were reported from Connecticut, Delaware, Maine, Maryland, Massachusetts, Minnesota, New Hampshire, New Jersey, New York, Pennsylvania, Vermont, Virginia and Wisconsin.

According to Margaret C. Fisher, MD, medical director at The Unterberg Children’s Hospital at Monmouth Medical Center in Long Branch, N.J., patient history is central to diagnosing Lyme disease.

Margaret C. Fisher

“The patient must have resided or traveled to an area where Ixodes ticks are present, and they must have spent time in an activity that would allow them to be bitten by a tick,” she said during a presentation at the 25th Annual Infectious Diseases in Children Symposium. “The clinical findings should suggest and be consistent with Lyme disease.”

A Lyme disease vaccine (Lymerix, GlaxoSmithKline) was available in the US from 1998 to 2002, but the vaccine was removed from the market. There are currently no vaccines available for tick-borne diseases in the United States.