US reports at least 31 cases of monkeypox among children

At least 31 children in the United States have tested positive for monkeypox, according to state officials across the country.

So far, 11 U.S. states and jurisdictions have reported monkeypox cases among children. Texas alone has identified nine pediatric cases of monkeypox, state officials told ABC News on Tuesday.

Meanwhile, Florida has detected monkeypox cases among two children under the age of 4 -- one in Brevard County and another in Monroe County, according to state data.

The Centers for Disease Control and Prevention warned in a health alert last month that preliminary evidence suggests children younger than 8 could develop more severe illness if infected with monkeypox.

Since the U.S. confirmed its first case of the year, an adult patient in Massachusetts in mid-May, at least 18,417 people across the nation have tested positive for monkeypox in the ongoing outbreak, according to the latest CDC data, though that number is expected to continue increasing. The virus has been detected in all 50 U.S. states.

California currently has the most reported infections with 3,291, but New York is not far behind with 3,273. They are followed by Florida, Texas, Georgia and Illinois, respectively, with each state reporting over 1,000 infections, according to CDC data.

Most of the cases in this outbreak have occurred during intimate skin-to-skin contact among men who have sex with other men, including those who identify as gay, bisexual, transgender and nonbinary. However, both the CDC and the World Health Organization have stressed there is no evidence monkeypox is a sexually transmitted disease and that anyone can be infected through prolonged close contact.

Monkeypox is a rare illness caused by infection with the monkeypox virus, part of the same family of viruses as the variola virus, which causes smallpox. Monkeypox symptoms are similar to smallpox symptoms, but less severe and rarely fatal, according to the CDC.

While smallpox was declared eradicated worldwide in 1980, monkeypox continues to be endemic to Africa, where it primarily occurs in rural, tropical rainforest areas of central and west African countries. The virus is occasionally exported to other regions but has rarely spread outside Africa, according to the WHO.

The CDC currently lists two vaccines that can be used to prevent monkeypox, only one of which -- JYNNEOS -- is approved by the U.S. Food and Drug Administration. Supplies and availability are currently limited.

Monkeypox is a viral zoonotic disease, meaning it can spread from animals to humans. It can also spread from humans to other humans and from contaminated objects to humans, according to the WHO.

The virus was discovered in 1958 when outbreaks of a pox-like disease occurred in colonies of monkeys that were imported to Denmark for research. Despite its name, the source of monkeypox remains unknown, according to the CDC.

The first human case of monkeypox was recorded in a 9-month-old boy in the Democratic Republic of the Congo in 1970, two years after smallpox had been eliminated in the region. Prior to 2022, most human cases were reported in Congo and Nigeria, according to the WHO.

In 2003, 47 confirmed and probable cases of monkeypox were recorded in people across six U.S. states -- Illinois, Indiana, Kansas, Missouri, Ohio and Wisconsin. All those infected became ill after having contact with pet prairie dogs that were housed near imported small mammals from Ghana. No deaths were reported and no evidence of human-to-human transmission was found. It was the first time that a human case of monkeypox was detected outside Africa, according to the CDC.

Since the start of this year, more than 41,600 confirmed cases of monkeypox, including at least 12 deaths, have been reported in 96 countries around the globe, with a vast majority of the infections occurring in the U.S., according to the WHO.