CDC: Up to Five Monkeypox Cases Now Presumed in the U.S.

With one confirmed case and four presumptive cases of monkeypox in the U.S., clinicians should continue to be on high alert if their patients report new onset of rash, especially in the genital or perianal area, CDC staff said Monday.

The one confirmed case in Massachusetts had over 200 close contacts, the majority of whom were healthcare workers, said Capt. Jennifer McQuiston, DVM, deputy director of CDC’s Division of High Consequence Pathogens and Pathology. Right now, contacts of known cases, including healthcare providers, are being vaccinated “if they fall into a high-risk category and warrant” vaccination, she said.

The other four presumptive cases — one in New York City, one in Florida, and two in Utah — have tested positive for orthopox virus, but McQuiston explained that only CDC can verify if the specimen is monkeypox (or as one reporter put it, “monkeypox until proven otherwise”). All are men with a history of international travel, she added.

The strain in the Massachusetts man is genetically similar to a strain from Portugal, where monkeypox cases have been reported, which is similar to the West African strain of the virus, McQuiston said. Some patients reported onset in early May, but travel in early April.

Monkeypox is spread via large respiratory droplets and “prolonged” close contact. “Many” of the patients in the current worldwide outbreak identify as men who have sex with men (MSM). Patients tend to recover within 2 to 4 weeks.

McQuiston said that the CDC is working on providing images of monkeypox rash on its website to aid healthcare providers, as it could be mistaken for other sexually transmitted infections.

John Brooks, MD, of CDC’s Division of HIV/AIDS Prevention, noted that one case of monkeypox was mistaken for severe herpes. He urged patients with an unusual rash on the genital or anal areas to contact their primary care provider, or if they don’t have one, a sexual health clinic for testing.

“We are concerned enough with the pace new cases are developing worldwide to raise everyone’s attention,” he said, adding that lesions have been “a little atypical from what we expect.”

Brooks urged MSM to step back from socialization if they don’t feel well and to get evaluated by a provider as soon as possible. The virus may present with “flu-like symptoms,” and lesions can start in the throat or mouth in the “pre-rash” period, in which people may already be infectious, he noted.

“Louis Pasteur famously said, ‘chance favors the prepared mind,'” he added.

More unusual symptoms include swollen lymph nodes that impair breathing or lesions occurring in the eye, which could affect eyesight, but McQuiston said that researchers have been seeing mild and “primarily self-limiting” symptoms in this outbreak. Those with immunosuppression will likely face a more severe clinical course, such as prolonged illness, larger lesions, and more bacterial infections, she added.

CDC staff said there are two live-virus smallpox vaccines available, which appear to work on monkeypox: the newer vaccine Jynneos, which is a non-replicating vaccine with fewer adverse events, and ACAM2000, a replicating vaccine with a higher chance of adverse events, especially among immunocompromised individuals and those with atopic dermatitis.

Brooks added that while data from people living with HIV and monkeypox are very limited, those with well-controlled HIV will likely do as well as “anyone else” with the vaccine. Antivirals are also available for those at risk of severe disease.

There are about a thousand doses of Jynneos available, but production is expected to be ramped up quickly in the coming weeks, McQuiston noted. There are about 100 million doses of ACAM2000 available.

CDC is undertaking a time-tested strategy used to treat infectious disease outbreaks around the world: isolate, test, and contact trace. Brooks stressed that contact tracing is effective at limiting the spread of this monkeypox outbreak.

“We want to encourage people to come forward and urge them to seek care,” he said.