First potential human-to-human transmission of monkeypox detected in the United States

The first potential cases of human-to-human transmission of monkeypox in the United States this year have been detected.

This weekend four cases have been spotted overall — with two in California and one each in Colorado and New York. 

It brings the U.S. tally to 14 infections across eight states, with most of the infections among gay and bisexual men. 

Health officials in California said their second case identified this weekend was a ‘close contact’ of an initial patient diagnosed three days earlier. Both are now isolating in separate homes.

In Colorado, another individual being probed for the virus is a ‘close contact’ of a young gay or bisexual man who was found to be infected a day beforehand.

The first patients in each state fell ill shortly after returning from trips abroad to Europe and Canada respectively, which are facing outbreaks of the virus endemic to West Africa.

The explosion of cases across 24 countries prompted the World Health Organization (WHO) to upgrade the threat level from the virus to ‘moderate’.

They warned that should infections continue to increase then vulnerable people and children — who are more likely to die from the virus — could start to catch it.

There are also growing concerns that the disease will spill into wild animals allowing it to become endemic across the world.

In California, the case was detected in Sacramento — a city of 500,000 — and traced back to the initial infection spotted three days earlier.

Health chiefs in the state insisted the risk to the public was ‘very low’, although contact tracing was still ongoing.

On May 24, they revealed a suspected case in an individual who had returned from Europe — which is experiencing an outbreak — a day earlier.

In Colorado, officials said their new case was in Denver and a ‘close contact’ of the case spotted just a day beforehand.

They also said the risk to the public ‘remains low’.

It was not revealed how the other two cases in California and New York may have become infected.

Testing is underway at the Centers for Disease Control and Prevention (CDC) to confirm that these are monkeypox infections.

Most of the infections are among men, but in Virginia the case is in a woman who recently returned from West Africa.

The virus has been spotted in California, Colorado, Florida, Massachusetts, New York, Utah, Virginia and Washington.

Only symptomatic people can spread the virus, usually through physical contact with infectious skin lesions.

Although not a sexually transmitted infection, health chiefs say the virus may be spreading through touching in the genital area.

More than 400 cases across 24 countries where the virus is not endemic have so far being spotted, prompting the WHO to raise its threat level. 

In a risk assessment published on Sunday, they warned that its ‘moderate’ grading could be pushed to ‘high’ if the virus ‘exploits the opportunity to establish itself as a human pathogen’ and spreads to vulnerable groups.

The ‘sudden appearance’ and ‘wide geographic scope’ of cases suggests widespread human transmission of the virus — which spreads through skin-to-skin contact and an infected persons’ droplets — is underway, the WHO said.

It also warned the surge in monkeypox infections suggests the virus ‘may have been circulating unrecognized for several weeks or longer’.

Reported cases have so far been mild but there is a risk the virus has a ‘greater health impact’ if it spreads to at-risk people, including children and immunocompromised people, such as some HIV patients, who ‘may be especially at risk of more severe disease’.

Monkeypox can kill up to 10 per cent of people it infects. The milder strain causing the current outbreak kills one in 100 — similar to when Covid first hit. The virus death rate has been higher among children in previous outbreaks.

The WHO warned there is a ‘high risk’ of further spread of the virus though skin-to-skin contact between families and sexual partners, as well as due to contact with contaminated materials, such as utensils, bedding and clothing.

Health chiefs have warned monkeypox, a virus endemic in parts of Africa and is known for its rare and unusual rashes, bumps and lesions, could also spread to some pets and become endemic in Europe. Undated handout file image issued by the UK Health Security Agency of the stages of Monkeypox

‘However, at present, the risk for the general public appears to be low,’ the agency said.

It cautioned that a ‘large part’ of the population is vulnerable to monkeypox due to the discontinuation of the smallpox vaccination scheme.

Very few people under the age of forty have been vaccinated. In the U.S., youngsters were routinely offered this jab until four decades ago, around the point at which the virus was eradicated.

Because smallpox and monkeypox are so similar, those who received the jab are thought to have up to 85 percent immunity against the circulating strain.

No monkeypox cases have been logged among medics in the current outbreak, it noted, but an NHS worker became infected in 2018 after treating a patient who had returned from NIgeria.

In its report, the WHO also warned that people who have recently had multiple sexual partners — either where they live or abroad — ‘may be at risk’ of having monkeypox.

It said health chiefs should reach out to at risk communities, which ‘at the present time’ includes men who have sex with men and their close contacts.