There are now 21 confirmed monkeypox, or orthopoxvirus, cases in the United States, according to the Centers for Disease Control and Prevention (CDC).

The agency upgraded the monkeypox alert level to level 2 on June 6, advising travelers to wear masks and take other precautions such as regularly washing hands and keeping away from sickly people. However, the recommendation to wear a mask was no longer visible on the CDC website as of June 7, although the rest of the travel advice remains.

As of June 7, California and New York each had four cases, Florida had three, Colorado and Utah each had two, and Georgia, Illinois, Massachusetts, Pennsylvania, Virginia, and Washington state each had one, according to the CDC.

Last week, public health officials in several cities across the United States reported possible instances of monkeypox in their communities.

CLICK HERE TO GET THE DALLAS EXPRESS APP

Philadelphia Public Health tweeted that a local citizen likely has monkeypox based on preliminary tests.

Authorities from the City of Chicago and the State of Illinois claimed that their first likely case was a male who had just been to Europe. The man has quarantined himself at home and is in good condition.

Last week in Georgia, the Department of Health announced that a male resident of the metro Atlanta area who has a history of overseas travel tested positive for the orthopoxvirus that was proven to be present in the area.

The Department of Public Health in Los Angeles County said it is waiting for formal confirmation from the CDC on its first suspected case of monkeypox infection.

Per a CDC alert, monkeypox cases have been reported in Europe, North America, South America, Africa, Asia, and Australia.

“What’s likely happened is an endemic infectious disease from Africa found its way into a social and sexual network and then was greatly aided by major amplification events, like raves in Belgium, to disseminate around the world,” said Dr. Amesh Adalja, a senior scholar at the Johns Hopkins Center for Health Security, to NBC News.

There are more than 550 confirmed monkeypox cases in 30 countries where the illness is not endemic, the World Health Organization (WHO) reported.