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Why the Atypical Symptoms in the Latest Monkeypox Cases?

— Experts agree these cases are unusual, but not necessarily a concern for viral mutation

MedpageToday
A computer rendering of monkeypox viruses.

In mid-May, a young man appeared at a hospital in Montreal with a single lesion on his genitals. About a week earlier he had sexual contact with someone who tested positive for monkeypox. Over the next several days, his lesion grew in size and more lesions appeared, but they weren't painful. He had no fever and the lesion remained contained.

This was one of the first monkeypox cases in Canada. The details, including all of the atypical symptoms, were shared by one of the patient's physicians, Sébastien Poulin, MD, of Saint-Jerome Hospital in Montreal, .

As monkeypox cases continue to rise in the U.S. -- with as of Friday -- questions are being raised about the nature of the atypical symptoms appearing in several of the cases. Lack of a fever or a pervasive rash, both of which are typically associated with monkeypox, are not appearing in many of the cases.

Could this be a sign of viral mutation in this strain of monkeypox? Experts who spoke with ֱ said not necessarily.

Aaron Glatt, MD, the chair of the department of medicine and the chief of infectious diseases at Mount Sinai South Nassau in New York, said that the symptoms currently being reported are consistent with what we know about the virus. Monkeypox cases typically present with a fever, a rash, and swollen lymph nodes, but those are not guaranteed to present in all cases. He also pointed out that many reported cases appear to involve direct genital exposure to the viral lesions.

"That is probably why you're seeing somewhat of a skewed presentation because there's probably a direct inoculum in the general area, which has led to a very specific type of a presentation," Glatt said. "The critical factor is, there's nothing here that's shocking or surprising based upon the events that occurred for these individuals."

The ability of monkeypox to transmit from human to human has been known for a long time, according to Grant McFadden, PhD, a researcher of immunotherapy, vaccines, and virotherapy at Arizona State University. The virus can spread through direct contact with the usual lesions, especially when they have broken open. He added that respiratory droplets are also a known mode of transmission, but that would require prolonged, very close contact similar to the sexual encounters being reported in the cases in the U.S. and Europe.

"There's nothing magical going on in the biology of the virus," McFadden told ֱ. "There's nothing magical going on in what we see in terms of the disease. What seems to be different is the mode of close human contact, that seems to be the driver of this current outbreak."

The atypical presentation of some of the symptoms does suggest that there is more to learn about this virus though, according to Anne Rimoin, PhD, an epidemiologist at the University of California Los Angeles Fielding School of Medicine.

"Most of the knowledge we have is based on data from rural communities in Africa, or peri-urban communities, that don't resemble the communities in which it's spreading right now," Rimoin said. "So it's important to be treating this with care and caution and to do the research that's necessary to understand what we're seeing now, as opposed to what we've seen in the past."

The virus has not changed so much as the attention and the location of the outbreak have, Rimoin explained. She recommended that the medical community remain humble and focus on understanding this virus as it does present. The best way to achieve that is by funding more research into this virus both domestically and international. In the meantime, however, she said there is more work to do to contain this current outbreak, starting with identifying the undiagnosed cases.

"If you shine a flashlight in the dark, you're gonna see something," she said. "And we haven't even been using a pen light."

McFadden stressed the point that the infectious disease community is prepared to handle this outbreak, even as it continues to be revealed. The decades of work developing the smallpox vaccine and treatments has led to a stockpile of medical supplies that are almost perfectly tailored to handling a monkeypox outbreak as well, he said.

The of monkeypox in the U.S. -- one driven by animal-to-human transmission primarily from pet prairie dogs -- offers an important lesson, said McFadden. As cases started appearing across the Midwest, suspicious physicians who knew the signs for poxvirus alerted the state authorities to the concern and the outbreak was discovered and contained. The awareness of the frontline healthcare providers helped to identify and curb the spread of the monkeypox outbreak, and McFadden said that is exactly what we need to do this time as well.

"We've got all the tools we need to nip it in the bud," McFadden said. "The question is, will we do it properly?"

  • author['full_name']

    Michael DePeau-Wilson is a reporter on ֱ’s enterprise & investigative team. He covers psychiatry, long covid, and infectious diseases, among other relevant U.S. clinical news.