Several teens who came home from a trip abroad with ugly ulcerated skin lesions in 2014 got vague and unhelpful diagnoses: Physicians thought they had bug bites. True, but that was only part of the story. It took an alert dermatologist and Facebook to identify the true cause, spread the word, and stop the outbreak.

“Social media facilitated communication between patients, crowd sourcing a diagnosis,” said Kanokporn Mongkolrattanothai, MD , who treated three of the teens at Children’s Hospital Los Angeles.

What did the kids have? Read on and see if you can make the diagnosis yourself.

The story begins in the early summer of 2014 when about 50 teens were on an adventure trip to Israel. Among other things, they camped outdoors in the Southern part of Israel’s Negev Desert.

Upon their return, pruritic red papules appeared on a 16-year-old girl’s ankle and thigh. They transformed into ulcers with raised edges and a central crater, according to a report that published online in Pediatric Dermatology ( 2016 Sep;33[5]:e276-7. doi: 10.1111/pde.12910). At least 12 teens from the trip had similar ulcerated lesions, mostly in exposed areas like arms and legs, said Dr. Mongkolrattanothai, an infectious disease specialist at Children’s Hospital Los Angeles and a coauthor of the report.

Six patients received a diagnosis of insect bites, and one was diagnosed with a bacterial skin infection, noted Dr. Mongkolrattanothai of the University of Southern California, Los Angeles. But these diagnoses were incorrect.

Andrew Krakowski, MD, a pediatric dermatologist in West Conshohocken, Pa., solved the mystery after examining the 16-year-old: The teens had been infected with cutaneous leishmaniasis , caused by protozoan parasites that are transmitted by the bites of female sand flies.

“The light bulb really came on when she mentioned that the lesions were still present several months after the trip to Israel,” said Dr. Krakowski, who was at Rady Children’s Hospital–San Diego at the time. “On physical exam, the lesions were ulcerated and eroded and did not look to be typical bug bite reactions.” The Centers for Disease Control and Prevention confirmed the diagnosis.

On Facebook, the teenager posted a picture of a T-shirt with the words “I went to Israel, and all I got was leishmaniasis.” At the same time, another traveler on the same trip posted pictures of lesions. This set off a wave of awareness that sent affected teens to seek care at Children’s Hospital Los Angeles, Mattel Children’s Hospital UCLA, Cedars-Sinai Medical Center, Kaiser Permanente Woodland Hills Medical Center, and Rady Children’s Hospital–San Diego.

“It is likely that our patients became infected with leishmaniasis while camping in the Negev Desert, sleeping on sand dunes at night without use of mosquito netting or tents,” Dr. Mongkolrattanothai said in an interview. “Most of the affected teens did not take precautions against insect bites, which would have included appropriate clothing to minimize areas of exposed skin and the use of repellent products. This placed them at risk for sand fly bites, as sand flies are most active in twilight, evening, and nighttime hours.”

As for treatment, 12 patients were treated with topical paromomycin therapy with the addition of gentamicin to a petroleum base, and one was observed without treatment, she added. “All patients are recovering well with no recrudescence of disease and no appearance of new lesions.”

Cutaneous leishmaniasis can lead to permanent scarring, and another form, visceral leishmaniasis, can be fatal.

What helped Dr. Krakowski crack the case? “Training at the University of California at San Diego, in such close proximity to the Navy’s Balboa Medical Center, we are taught from day 1 to think outside of the box because ‘there are zebras in Africa,’ ” he said. “With so much international travel in and out of the region, including to locations where leishmaniasis is endemic, it is warranted to consider that specific diagnosis on the differential. Normally, I do not have to biopsy ‘bug bites,’ but considering the patient’s entire presentation, you almost have to do a biopsy to make sure the lesions were not leishmaniasis.”

Dr. Krakowski praised the CDC. “They have a tremendous amount of resources dedicated to helping investigators work through diagnostic dilemmas such as this, and they helped us – free of charge – to confirm the diagnosis, type the leishmaniasis, and plot a treatment course to resolution,” he said. “They also were instrumental in helping us identify and educate other potentially exposed patients from the camping trip.”

In November, the Infectious Diseases Society of America and the American Society of Tropical Medicine and Hygiene published new guidelines about leishmaniasis in Clinical Infectious Diseases ( doi: 10.1093/cid/ciw670 ). The societies warn that leishmaniasis is becoming more common in the United States, in part because of ecotourists infected in Central and South America and returning soldiers infected in Afghanistan and Iraq.

Dr. Mongkolrattanothai and Dr. Krakowski reported no relevant financial disclosures.


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