Here's what you need to know about mpox after CDC sent alert to doctors

Doctors are encouraging Americans not to panic about mpox even after a recent severe case was detected in California and federal health officials sent out a notice to physicians to be on the lookout for symptoms, especially in travelers from parts of Africa where the virus is more widespread.

The Centers for Disease Control and Prevention issued an alert this week to health care workers to be aware of mpox symptoms and to report cases of the more severe strain to public health authorities as soon as possible.

The alert came just two days after California reported the first domestic case of the more severe strain in a traveler from Africa who experienced mild illness and is now recovering.

No additional cases of the more severe strain have been reported in the U.S., and the CDC says the risk to the general public remains low.

"At the moment, mpox is occurring at extremely low levels in the United States," Dr. William Schaffner, a professor of preventive medicine at Vanderbilt University Medical Center in Nashville, told ABC News. "So, I think general public awareness is always a good thing, but I don't think they really need to be concerned."

Dr. Kelly Gebo, a professor of medicine at Johns Hopkins University, told ABC News the CDC has sent out similar alerts for other diseases spreading in other parts of the world to let health care providers know what is happening.

"I think they're trying to make sure that health care providers are paying attention, as it could be that [mpox] is presenting in a patient who might not be considered for the disease," she said. "I don't think they're trying to cause alarm for the general population, but trying to get health care providers to be more active in screening."

There are two types of mpox: clade I and clade II, with clade roughly meaning they are descended from a common ancestor organism. Clade I has historically been associated with severe illness and death, and is endemic to parts of central and western Africa, according to the CDC.

People with mpox, which was formerly known as monkeypox, often get a rash that can be located on hands, feet, chest, face, mouth or near the genitals, the CDC said.

Mpox cases have been rising dramatically in the Democratic Republic of Congo this year. Since Jan. 1, there have been 9,000 confirmed cases in Congo and more than 40 confirmed deaths, although the number of suspected cases and deaths is much higher, according to the CDC.

In the U.S., there have been 2,368 cases of the less severe strain of mpox reported this year as of Nov. 1, according to CDC data. This figure is much lower than the roughly 32,000 cases associated with the 2022 mpox outbreak in the U.S.

"People who are traveling, or who are engaging in high-risk activities with people who have traveled to, potentially, areas where mpox is more prevalent, would be at risk," Gebo said. "But in general, I think for the average American citizen, the risk is very low."

She added that the incubation period for mpox is generally between three and 18 days, so those who traveled weeks or months ago to areas in Africa where mpox is endemic are not at high risk.

Schaffner said the CDC issuing a warning is a sign the public health agency is being proactive as opposed to reactive.

"Mpox had kind of receded because the cases were so low in the United States, in certainly the public's mind, but also in the mind of public health," he said. "And so this was a reminder [of] what you've heard about that's going on in Africa, actually cases are coming to Europe, and here we've had one in the United States. So let's refresh ourselves about mpox, be on the alert for it."

Schaffner said one big difference between 2022 and now is that there is a vaccine readily available to help prevent mpox.

Currently, the JYNNEOS vaccine, a two-dose vaccine approved by the Food and Drug Administration to prevent smallpox and mpox, is the only vaccine being used in the U.S.

Data from Africa has shown that two doses of JYNNEOS are at least 85% effective in preventing mpox infection. There is currently no recommendation for a booster in those who are considered high-risk and already fully vaccinated.

To increase the number of JYNNEOS doses available, the FDA authorized a proven strategy in August 2022 to inject the vaccine intradermally, just below the first layer of skin, rather than subcutaneously, or under all the layers of skin. This allows one vial of vaccine to be given out as five separate doses rather than a single dose.

Schaffner recommended that at-risk groups get vaccinated and the general population should continue to stay alert.

"The likelihood that there will be a few cases imported into this country, as well as perhaps into Canada and into Western Europe, seems a reasonable expectation," Schaffner said. "We would like to identify them as quickly as possible, provide appropriate treatment for the individual, and then do case investigation for all those contacts."

ABC News' Youri Benadjaoud contributed to this report.