June 13, 2022
When Esther Freeman, MD, PhD, thinks back on what she learned about monkeypox during her training as a dermatologist and an infectious disease epidemiologist, it was widely considered a viral disease with rare outbreaks limited primarily to Central and Western Africa.
"Monkeypox is something we have traditionally only seen very rarely in the U.S.," Freeman, director of Global Health Dermatology at Massachusetts General Hospital and Harvard Medical School, Boston, said in an interview. "In the past, outbreaks in the U.S. have been related to international travel or import of exotic pets, which is very different than what we're seeing as a global community now."
Monkeypox virus belongs to the Orthopoxvirus genus in the family Poxviridae. According to the Centers for Disease Control and Prevention, symptoms develop 5-21 days after infection and may include fever, chills, and swollen lymph nodes. Typically, within 1-3 days of the fever, a rash develops, followed by the formation of monkeypox lesions. These lesions progress from macules to papules, vesicles, pustules, and scabs, before falling off. The illness typically lasts 2-4 weeks.
What makes the 2022 monkeypox outbreak different from others is clear evidence of community transmission. According to worldwide data from the CDC, as of June 9, 2022, there were 1,356 confirmed cases in 31 countries, including 44 cases in the United States. This means that person-to-person spread of the monkeypox virus is occurring among individuals who have not traveled outside of their own country.
"This is likely an underestimate, especially when we think about the U.S., which only has 44 confirmed cases at this time," Freeman said. "However, at present, monkeypox cases have to be confirmed by the CDC, so there are a lot more suspected cases that are likely to be confirmed in the coming days. As with any outbreak, it's a rapidly changing situation."
A Different Clinical Presentation
The clinical presentation of monkeypox cases in the current outbreak also differs from that of previous outbreaks. In the past, monkeypox rashes often morphed from a macule to a pustule and commonly affected the face, hands, feet, and trunk, with some patients harboring as many as 200 lesions at once. That pattern still occurs, but increasingly, the presentation is characterized by a more localized spread, especially in the genital region, which Freeman described as "unusual and not an area we traditionally thought of in the past as a focus for monkeypox."
Also, affected individuals in the current outbreak may develop fewer lesions, sometimes between 1 and 5 instead of up to 200. "This doesn't apply to everybody, but it is a bit of a different picture than what we've seen in case descriptions and photographs in the past from places like Central Africa," she said. "What's being reported out of case clusters from the United Kingdom and Spain is a mix, where some people are having more generalized involvement while others have more localized involvement." Visual examples of the monkey pox rash can be found in photos from the United Kingdom, the country with the highest number of confirmed cases, on the CDC's website, and in a report from Spain.
Clusters of monkeypox cases have been reported worldwide in men who have sex with men, "but this is not limited to a particular subgroup of people," emphasizes Freeman, who is also a member of the American Academy of Dermatology's Ad Hoc Task Force to Develop Monkeypox Content, which created an online resource for clinicians. "There are several mechanisms of spread, but direct contact with lesions or infected fluids is one," she notes.
Moreover, "lesions associated with herpes, syphilis, and molluscum can look similar to a monkeypox lesion. If you have a patient with a new genital lesion and you're not sure what it is, testing for monkeypox in addition to classic sexually transmitted infections like HSV or syphilis would be reasonable during the current outbreak situation."
The 2022 monkeypox outbreak may pale in comparison to the spread of COVID-19 in terms of case numbers and societal impact, but dermatologists may be the first point of contact for a person infected with the monkeypox virus. "It's important for dermatologists to be able to recognize monkeypox, because by recognizing cases, we can stop the outbreak," Freeman said. "In theory, an infected person could show up in your clinic, regardless of where you practice in the U.S. But at the same time, it's important not to panic. This is not COVID-19 all over again; this is different. Yes, it is an outbreak, but we already have a vaccine that works against monkeypox, and while one of the possible modes of transmission for monkeypox is respiratory, it's much harder to transmit that way than SARS-CoV-2 – it requires closer and longer contact."
Confirmation of a monkeypox virus infection is based on results of a PCR test based on swabs of a lesion. The AAD task force recommends contacting the local hospital epidemiologist, infection control personnel, and/or state health department about suspected cases, "as different locations will have different regulations on where to send the [PCR] test. If appropriate, the state health department will contact the CDC."
According to the CDC, current recommendations for personal protective equipment for possible and confirmed monkeypox cases include gown, gloves, a National Institute for Occupational Safety and Health-approved N-95 mask, and eye protection.
Topical Antiviral an Option
If the lesions in a patient with suspected monkeypox have turned into pustules while waiting for the PCR test results, one option is to prescribe 3%-5% topical cidofovir, according to Stephen K. Tyring, MD, PhD, of the departments of dermatology, microbiology & molecular genetics, and internal medicine at the University of Texas Health Science Center, Houston. "That's the effective antiviral that is most available," he said. Generic cidofovir is also now available.
Tyring recommends rapid referral of immunocompromised patients with suspected monkeypox to an infectious disease expert and/or consulting with the CDC. "The pediatric population also seems to be at somewhat more risk, as has been seen in sub-Saharan Africa," said Tyring, who is one of the editors of the textbook Tropical Dermatology. "Also, by definition, pregnant women are at more risk because their immune systems aren't up to par. You also want to make sure that if monkeypox is on a person's skin that they don't get it in their eyes, because they could lose their vision." He added that sub-Saharan Africa has a monkeypox mortality of up to 10%, "which is something we don't see in the U.S. or Europe. Those of us who grew up in the 20th century got routine smallpox vaccines, and we therefore probably have a degree of immunity to monkeypox. But for the past 40 years or so, unless you are in the military, you are not going to get a routine vaccine to prevent smallpox."
Incubation Period, Appearance of Lesions
Monkeypox has a long incubation period. According to Freeman, from the point of exposure to the development of symptomatic lesions is typically 7-14 days but can vary from 5-21 days. "It's important for people to be aware that their exposure may have been in the more distant past, not just a few days ago" she said. "Identifying cases as quickly as possible gives us a window where we can vaccinate close contacts."
Freeman and Tyring reported having no relevant financial disclosures.
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