When patients get the travel bug, dermatologists should beware

NEW YORK – All dermatologists, including those who are office based, should know how to recognize and treat infectious diseases and infections from all over the world.

That was the unifying message put forth by dermatologists who spoke at the American Academy of Dermatology summer meeting during a session on infectious diseases and infestations in returned travelers.

Key to recognizing such diseases is knowing what questions to ask, said Vikash S. Oza, MD, director of pediatric dermatology at New York University.“It’s important to know where the patient went to understand the endemic issues,” as well as the purpose of the patient’s visit, said Dr. Oza. “Patients who travel to be with family come back with a higher burden of illness,” possibly because they are less likely to seek medical advice prior to travel and more likely to mingle with local populations, drink from local water supplies, and come into contact with livestock during travel, he added.

Watch out for children

Children are at particular risk: One analysis found that 25% of children suffer at least one skin disorder after international travel, he said.

Dr. Vikash S. Oza

In the United States, the spirochete infection tends to be caused by the bacterial species Borrelia burgdorferi, which is typically transmitted by a tick bite. Hosts include the white-footed mouse, chipmunks, and even robins. In the Northeastern United States, Lyme season peaks from June through August; children aged 5-10 years of age tend to be at highest risk.

Changes to the skin are an important part of the clinical spectrum, with erythema migrans developing 1-2 weeks after infection and continuing for months. It can affect the cranial nerves, causing Bell’s palsy, meningitis, and carditis. In the late stage, large joint arthritis can occur.

But doctors cannot depend on the classic bull’s eye associated with erythema migrans, since it occurs only rarely in the United States, Dr. Oza pointed out. “More often, it is a homogenous, expanding area.”

Only about one in four children who present with Lyme disease display multiple erythema migrans rashes, he said. And the vector is rarely noticed. “Twenty-five percent recall a tick bite,” he added.

Erythema migrans can also occur among people who do not live in areas where Lyme disease is endemic. So doctors should be alert to Southern Tick–Associated Rash Illness, which is endemic to much of the Southeast – caused by the bite of the Lone Star tick. Unlike Lyme, this disease tends to be self-limiting and does not tend to cause a late-stage illness to develop neurologic or joint-related problems, he said.

Prevention

The best defense is to prevent tick bites, and liberal use of DEET has proved to be effective as has permethrin-impregnated clothing, which kills the tick.

Ticks tend to be found on long blades of grass or in leaf debris. They neither jump nor fly, “but reach out in desperation,” said Dr. Oza, who urges hikers to take a shower after hiking, check the scalp and behind the ears, and place all clothing in a hot dryer for 10 minutes, which will kill any deer ticks.

Pets, too, should be checked – even on their eyelids, he added. If a tick is found and removed within 48 hours, it has little chance of infecting its host, he said.

Aedes aegypti mosquitoes pose multiple threats

Common causes of rash and fever in travelers include malaria, dengue, spotted fever, rickettsia, yellow fever, chikungunya, and Zika, said Jose Dario Martinez, MD, of the departments of internal medicine and dermatology, University Hospital, Monterrey, Mexico.

The latter has proved to be a major challenge. In just a few months, the Zika virus has swept across all of the Americas, with the exception of Canada and Chile. It is spread by Aedes aegypti, which thrives and breeds close to homes and is a difficult vector to eradicate, he said. The same mosquito also transmits yellow fever, dengue, and chikungunya.

This year, the Aedes aegypti mosquito has been disrupting tropical vacations because of its ability to transmit not only Zika but dengue, chikungunya, and yellow fever.

Again, the 60-year-old product DEET plays a major defensive role. It lasts the longest of any such products, repels a broad array of insects, and is recommended by the Centers for Disease Control and Prevention and the American Academy of Pediatrics, but it is not recommended for children younger than 2 months of age.

Picaridin, which has been available in the United States since 2005, is also recommended by AAP. It is odorless and does not irritate the skin. Oil of lemon eucalyptus is commonly used in China, but has not been tested for children under aged 3 years.

“If you’re going camping, probably the best thing you can do is wear permethrin-treated clothing and shoes,” Dr. Oza said.

Bedbugs

No discussion of infections among travelers would be complete without a discussion of bedbugs, whose numbers have rebounded since the 1950s, when DDT nearly wiped them out, said Theodore Rosen, MD, professor of dermatology, Baylor College of Medicine, Houston.

Dr. Theodore Rosen

Mother Nature offers little help, since bedbugs can survive winters. And they are not always easy to notice, since their saliva contains an anesthetic, which can mask the feeling of a bite. “Insects can thus feed undetected for 5-10 minutes,” Dr. Rosen said. But, though experiments have shown them to be competent vectors at spreading disease, “in real life, they have not been demonstrated to be the purveyors of human disease,” he noted.

So far, the best way to get rid of them is “thermal remediation,” which entails heating infested areas to 120-140° F for 5-8 hours.

Also effective, but less practical, would be to set any infested structures ablaze.

Advice for the traveler: Keep your suitcases zipped in hotel rooms, and store them up high or in the shower, since bedbugs have a tough time jumping or gaining traction on porcelain. And make sure you launder your clothes once you get home.

Dr. Rosen, Dr. Martinez, and Dr. Oza had no disclosures.