The US' public health agency described the toddler and infant concerned as being in good health and receiving treatment.

Two children in the United States have been diagnosed with monkeypox, US health officials said on Friday.

One of the two children is a toddler in California and the other is an infant who is not a US resident, according to public health agency Centers for Disease Control and Prevention.

The children were described as being in good health and receiving treatment.

Officials said that the source of the cases was being investigated, and that it was likely household transmission.

What is monkeypox?

Monkeypox is endemic to parts of Africa. This year, more than 15,000 cases have been reported in other countries.

In the US and Europe, most infections have been detected among men who have sex with men.

In Europe, there have been at least six cases among minors.

In Africa, monkeypox infections in children are more common. Higher proportions of severe cases and deaths have been noted among children.

Dr. James Lawler, a doctor at the University of Nebraska Medical Center, was cited by the AP news agency as saying that one of the possible reasons for this is the fact that many older people were vaccinated against smallpox, which may give them some protection against monkeypox.

CDC director Dr. Rochelle Walensky told AP that the US government's response is growing stronger every day and vaccine supplies will soon surge.

"I think we still have an opportunity to contain this," Walensky said.