Conference Coverage

2019 ID update for dermatologists: Ticks are the “ride of choice” for arthropods



– New tricks from ticks, near-zero Zika, and the perils of personal grooming: Dermatologists have a lot to think about along the infectious disease spectrum in 2019, according to Justin Finch, MD, speaking at the Orlando Dermatology Aesthetic and Clinical Conference.

Courtesy CDC

Above is the lone star tick that has been linked to anaphylaxis to red meat.

Anaphylaxis from alpha-gal syndrome is on the rise, caused in part by the geographic spread of the Lone Star tick. Beginning in 2006, isolated cases of an anaphylactic reaction to cetuximab, the epidermal growth factor receptor antagonist used to treat certain cancers, began to be seen in a curious geographic distribution. “The anaphylaxis cases were restricted to the southeastern United States, the home of the Lone Star tick,” said Dr. Finch, of the department of dermatology at the University of Connecticut, Farmington.

With some detective work, physicians and epidemiologists eventually determined that patients were reacting to an oligosaccharide called galactose-alpha–1,3-galactose (alpha-gal) found in cetuximab. This protein is also found in the meat of nonprimate mammals; individuals in the southeastern United States, where the Lone Star tick is endemic, had been sensitized via exposure to alpha-gal from Lone Star tick bites.

“Alpha-gal syndrome is on the rise,” said Dr. Finch, driven by the increased spread of this tick. Individuals who are sensitized develop delayed anaphylaxis 2-7 hours after ingesting red meat such as beef, pork, or lamb. “Ask about it,” said Dr. Finch, in patients who develop urticaria, dyspnea, angioedema, or hypotension without a clear offender. Because of the delay between allergen ingestion and anaphylaxis, it can be hard to connect the dots.

A number of drugs other than cetuximab contain alpha-gal, so patients must also be told to avoid these agents, said Dr. Finch, who noted that alpha-gal syndrome isn’t the only emerging culprit for tick-borne diseases. “The tick is the ride of choice for arthropod-borne diseases in the U.S.,” he added. “Year after year, tick-borne diseases top mosquito-borne diseases in the U.S.” Zika’s explosion in 2016 made that year the exception to the rule.

Blanchable macules and papules start on the face or trunk, 3-5 days after the febrile phase of Zika virus, and become more diffuse. Dr. Stephen K. Tyring, Dr. Zeena Nawas, The University of

Blanchable macules and papules start on the face or trunk, 3-5 days after the febrile phase of Zika virus, and become more diffuse.

Now, Zika virus may be on the wane – the number of case reports have plummeted both in the United States and in Central and South America this past year – but it hasn’t completely gone away. “It looks like it fell off all the maps,” but the virus is still present at low levels, he said.

When Zika virus is symptomatic, there’s often a nonspecific maculopapular rash. Critically, Dr. Finch said, “women with a rash are four times as likely to have adverse congenital outcomes. This is the important point for us to take home as dermatologists. ... It’s really important to have a high index of suspicion and to screen these women as they are coming into our clinic.”

Turning back to ticks, Lyme disease continues to be a problem in endemic areas in the Northeast, the mid-Atlantic region, and the Midwest, said Dr. Finch, so it’s a perennial on the differential diagnosis for dermatologists.

An Asian tick new to North America was seen for the first time in New Jersey in the summer of 2017. The Asian longhorned tick carries a phlebovirus that causes severe fever with thrombocytopenia syndrome, a disease with a 15% fatality rate. The reservoir host of this virus in Asia isn’t known, said Dr. Finch, adding that no cases of the virus have yet been seen in the United States. As of November 2018, according to the Centers for Disease Control and Prevention, the tick had been found in nine states (Arkansas, Connecticut, Maryland, North Carolina, New Jersey, New York, Pennsylvania, Virginia, and West Virginia).

“What’s not on the rise? Pubic lice. We are destroying their natural habitat!” said Dr. Finch, citing surveys about personal grooming that show that more than 90% of women remove at least some of their pubic hair. Most college campuses are currently reporting essentially no cases of pubic lice, he noted.

However, the same personal grooming practices may be contributing to increases in molluscum contagiosum, herpes simplex virus, some strains of human papillomavirus, and cutaneous Streptococcus pyogenes infections, he said.

Another STI has had a resurgence in geographic pockets around the nation and among specific populations, said Dr. Finch. Syphilis is on the rise among gay and bisexual men and African Americans. Known as the “great imitator,” syphilis should be on the differential for dermatologists when the clinical picture isn’t quite adding up. “Think of this, and screen with an RPR [rapid plasma reagin],” he said.

Finally, an old enemy is back: A total of 11 measles outbreaks were reported in 2018. “We need to know about measles because of the complications,” said Dr. Finch. Even years later, such dire sequelae as subacute sclerosing panencephalitis can crop up, he added.

CDC/Dr. Heinz F. Eichenwald

This is the skin of a patient after 3 days of measles infection.

After a 2-week incubation period, measles begins with a fever and cough, congestion, and conjunctivitis. The rash begins on the head and spreads inferiorly by day 3. As the rash blooms, the classic morbilliform eruption becomes apparent. A biopsy of affected skin will be nonspecific; measles is diagnosed with a nasopharyngeal culture and serologic assay. Dr. Finch pointed out that dermatologists are unlikely to see measles in its earliest stages because their expertise will be called on only after it becomes clear that the patient is not experiencing just a mild illness with a viral exanthem.

When there’s suspicion for measles, a full-body skin exam is needed. “Koplik’s spots – the gray white papules on the buccal mucosa – are not pathognomonic in themselves, but in the clinical scenario of a person with measles” they can help the dermatologist make a definitive call, he said.

Vitamin A can be given to a patient with active measles, but prevention via immunization at age 12 months and 5 years is the only way to stop the disease, Dr. Finch noted.

Dr. Finch reported that he has no relevant conflicts of interest.

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