Infectious Disease and Dermatology Crossover: What Providers Need to Know

Ted Rosen, MD

There can be significant crossover between dermatology and infectious disease, specifically for certain infections where skin presentation or involvement is a major hallmark. In other cases, the treatments for various viral, bacterial, fungal, and parasitic diseases can have skin manifestation, and so it is vital for dermatology providers to be aware of the potential implications of infectious disease.

Ted Rosen, MD, professor and vice-chair of the Dermatology Department at Baylor College of Medicine, and George Hightower, MD, PhD, associate clinical professor at UC San Diego and pediatric dermatologist at Rady Children’s Hospital, delivered an infectious disease update at Maui Derm NP+PA Fall 2024, focusing on diagnostic and therapeutic challenges.

COVID-19

Rosen began the talk by covering some current COVID-19 statistics. Many like to declare that “COVID is over,” but there are still 100 to 200 Americans dying every say from the disease, although total cases have decreased. The emerging KP.1, KP.2, and KP.2 strains could be worrisome, Rosen said.

“[The KP strains] are not terribly aggressive in terms of their ability to cause mortality or even morbidity, but they're incredibly highly transmissible, and they present in a little different way, [with] fever, sore throat, runny nose, as opposed to cough, opposed to pneumonia,” he said.

In terms of dermatologic crossover with COVID, skin manifestations are polymorphic and have become increasingly more uncommon. Data from studies on hair loss and COVID have found a higher proportion of androgenetic alopecia but, because older people were more severely affected by COVID, the alopecia likely predated their disease, Rosen said.

Mpox

Mpox is making a comeback, after a new clade emerged in countries like Burundi, Kenya, Rwanda, and Uganda. Data suggest it is more virulent an aggressive, causing the World Health Organization (WHO) to declare a public health emergency of international concern after ending the same designation just 10 months prior. Currently, it is estimated that there are > 32,000 US cases (58 deaths) and > 92,000 global cases (181 deaths). The deaths are most commonly associated with uncontrolled HIV co-infection.

Patients infected with Mpox present with lesions that are typically confined to the site of exposure. Because it is spread through sexual contact, providers will typically see the rash on the genitals, in the anorectal area, or in the mouth. There is a vaccine available but, even if a patient receives the necessary 2 doses, it is still only about 88% effective, Rosen said. Tecovirimat has been relied on as a treatment in the past, however there is data to suggest that resistance is growing.

Dengue Virus

In the United States, there are a growing number of Dengue virus infections, with 2241 cases reported as of mid-June, 1498 in Puerto Rico alone. There are currently isolated outbreaks in Florida, Arizona, Texas, and California. Dermatology providers are likely to encounter Dengue because the associated rash is non-descript; it could be any rash. However, when coupled with other symptoms — such as fever, nausea, vomiting, myalgia, arthralgia, bone pain, headache, or bleeding nose or gums, or even facial palsies — and travel history, Dengue should stay on the differential diagnosis list.

Syphilis

When it comes to non-HIV sexually transmitted diseases, syphilis is front and center right now because we are experiencing the highest rates of syphilis since World War II, with 17.7 cases per 100,000 adults. People with skin of color are disproportionality affected and, in the United States, cases are most prevalent in South Dakota and New Mexico. These are both states with federally recognized Indian tribes, which is a group currently experiencing a surge in syphilis diagnoses. Cases in women are also on the rise.

“Syphilis does not respect ethnicity, syphilis does not respect age, and syphilis does not respect gender in any way, shape, or form,” Rosen said.

Compounding the rise in cases is the global shortage of penicillin, the most common treatment for the infection. There are also data that support the use of doxycycline as post-exposure prophylaxis.

Tuberculosis

Tuberculosis (TB) is currently an emerging threat, with cases ticking upward in California, Texas, New York, and Florida. Globally, according to the WHO, there are hot spots in Bangladesh, China, the DRC, India, Indonesia, Nigeria, Pakistan, and the Philippines. A summary of 2023 TB data published in the Centers for Disease Control and Prevention’s Morbidity and Mortality Weekly Report found that 1 in 50 migrants carry TB.

On the skin, TB can look very bad, with chancres and ulcers. Or it can appear as miliary TB, which happens when it gets into the bloodstream.

Fungal Infections

Trichophyton indotineae is a new dermatophyte gaining attention. It’s a widespread, resistant fungus that originated in India but has now been recorded in southeast Asia, the Middle East, Africa, Europe, Australia, and Canada. It is highly resistant to terbinafide and itraconazole and may be associated with the use of steroids. It is thought to spread via close contact or shared fomites, so familial spread is likely. It causes multiple lesions, lots of inflammation, and a double ring of scale.

The United States saw its first case in March 2023 in New York, with others sure to follow, Rosen said.Because it is so resistant to existing antifungals, treatment can be tricky.

George Hightower, MD, PhD

“The best thing that's worked for me is Whitfield's ointment,” Rosen said. “That is an old, old product, but it doesn't rely on enzymes. It just basically sucks the skin off. It's great. It's $10 on Amazon.”

Case Studies

Hightower closed the presentation with a few case studies. One involved a case of tinea incognito where a topical corticosteroid actually altered the appearance of the underlying infection. The patient received a corticosteroid for an eczematous rash, which seemed to initially improve with use of the topical. The patient continued use of the corticosteroid but the rash never seemed to clear completely, and the curved or circular edges were still visible. The takeaway here for providers if to make sure you give a time course of when to discontinue use of a topical corticosteroid.

The second case involved an infant with respiratory syncytial virus and a rash, which turned out to be scabies. Rosen and Hightower encouraged providers to make sure everyone in the immediate family, including caregivers, receive treatment.

Lastly, a case of eczema herpeticum. With this viral co-infection, the patient experiences a sometimes widespread cutaneous vesicular eruption that can be life-threatening in infants and small children. Secondary infections are common, and empiric acyclovir is usually step 1 for treatment.

Reference:

Rosen T, Hightower G. Infectious disease update. Presented at: Maui Derm NP+PA Fall; September 15-18, 2024; Nashville, Tennessee.