Conference Coverage

Measles, scarlet fever among infectious diseases to watch for in 2020


 

REPORTING FROM ODAC 2020

Dermatologists may have to contend with some of mankind’s oldest diseases – from group A streptococcus to measles – leading into 2020, Justin Finch, MD, said at the ODAC Dermatology, Aesthetic, & Surgical Conference.

Dr. Justin Finch of Cromwell, CT, dermatologist

Dr. Justin Finch

While group A streptococcus has declined over the past century, there has been “an unprecedented” resurgence in severe, invasive group A streptococcal infections and severe epidemics of scarlet fever worldwide, including in industrialized regions like the United Kingdom. Shedding some light on why this may be occurring, Dr. Finch referred to a recently published population-based molecular epidemiologic study identified a new dominant emm1UK lineage of Streptococcus pyogenes associated with such cases in England (Lancet Infect Dis. 2019 Nov;19(11):1209-18). This new lineage of S. pyogenes was genotypically distinct from other emm1 isolates and had greatly increased expression of the streptococcal pyrogenic exotoxin A, one of the exotoxins responsible for the clinical features of scarlet fever.

“We have not, to my knowledge, seen the strain yet in the United States,” said Dr. Finch, of Central Connecticut Dermatology in Cromwell. “Have it on your radar. With all of the worldwide travel patterns, I expect that you will see this in the United States at some point in the not-too-distant future.”

Also in 2019, promising data on the safety and effectiveness of the recombinant herpes zoster vaccine in immunocompromised patients became available for the first time. A randomized clinical trial published in JAMA of 1,846 patients who were immunosuppressed after autologous hematopoietic stem cell transplantation and received two doses of a recombinant zoster vaccine found that the patients had a reduced incidence of herpes zoster after a median follow-up of 21 months (JAMA. 2019 Jul 9;322[2]:123-33). The study found that the recombinant vaccine was both safe and effective in these immunocompromised patients, “so we can easily generalize this to our dermatology population as well,” Dr. Finch said. In comparing the live attenuated and recombinant vaccines, he noted the recombinant vaccine requires two doses but appears to be slightly more effective. “The number needed to treat to prevent [one case] of zoster is about half as high as that for the live vaccine, and most importantly for us is, it’s safe in immunocompromised patients.”

2019 also saw a record high in the number of measles cases in the United States, the highest since 1993, Dr. Finch pointed out. Most cases were seen in the area in and around New York City, but the percentage of people across the United States who are vaccinated against measles is below the threshold for herd immunity to protect immunocompromised patients. Measles requires a population vaccination rate of 94%, and less than half of U.S. counties in 2014 and 2015 reached that vaccination rate.

“Furthermore, if we look at that over the last 20 years, comparing the domestic measles cases to imported measles cases, we are increasingly breeding these measles epidemics right here at home, whereas they used to be imported from throughout the world,” said Dr. Finch. Patients with measles can be treated with vitamin A, he added, referring to a Cochrane review showing that 200,000 units of vitamin A given daily for 2 days decreased the mortality rate of measles by about 80%. Measles is on the Centers for Disease Control and Prevention’s list of reportable diseases, so should be reported to local health authorities, and will be followed up with confirmatory testing.

In 2019, a study examining herd protection of oral human papillomavirus infection in men and women compared the prevalence of oral HPV infection based on the 4 HPV types present in the quadrivalent HPV vaccine with 33 nonvaccine types from 2009 to 2016. There was no change in the prevalence of nonvaccine type oral HPV infections among men who were unvaccinated, but the prevalence of oral HPV infections because of the four strains in the quadrivalent HPV vaccine declined from 2.7% in 2009-2010 to 1.6% in 2015-2016 (JAMA. 2019 Sep 10;322[10]:977-9). Among unvaccinated women, the prevalence of nonvaccine- and vaccine-type oral HPV infections did not change between the two time periods.

“Notably, this only occurred in men,” Dr. Finch said. Herd immunity is being achieved in men “because we’re vaccinating all women, [but] we’re not seeing that herd immunity in women. Which begs the question: Why are we still vaccinating only half of our population?”

One study published in 2019 (Br J Dermatol. 2019 Nov;181[5]:1093-5) described a patient with CARD9 mutations, which predispose individuals to deep invasive infections – a disseminated Microsporum infection in this case, Dr. Finch said. “You shouldn’t see that,” he added, noting that these mutations are known to predispose individuals to severe Trichophyton infections and familial candidiasis.

“What I think is interesting about this is that, as we look forward to 2020, we’re going to increasingly see studies like this that are identifying specific mutations in our community that underlie a lot of these weird infections,” he added. “I wouldn’t be surprised if within the span of our careers, we find that a lot of those severe treatment-refractory reports that so commonly plague your everyday clinic have some underlying, specific immunity.”

Dr. Finch reported no relevant conflicts of interest.

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