(Bloomberg) -- The US identified its first case this year of monkeypox virus, adding to a growing number of confirmed and suspected infections in the UK, Portugal and Spain.

The Massachusetts Health Department reported on Wednesday the case of an adult male who had recently traveled to Canada, where more than a dozen monkeypox infections have been identified. The man traveled via private transportation, according to the US Centers for Disease Control and Prevention, which said it’s working with Massachusetts health officials on monitoring the situation. 

Monkeypox is a rare but potentially serious viral illness that usually begins with flu-like symptoms before progressing to a rash, which could be confused with sexually transmitted infections like syphilis or herpes. Infections usually last from two to four weeks, according to the CDC. 

Most of the cases have been in men who have sex with men, but anyone can contract monkeypox virus regardless of sexual orientation, the agency said. The CDC is urging health-care providers to be on the lookout for signs of possible monkeypox infections, such as rashes, in all patients. 

“Many of these global reports of monkeypox cases are occurring within sexual networks,” Inger Damon, a poxvirus expert and director of the CDC’s Division of High-Consequence Pathogens and Pathology, said in a statement. “However, health-care providers should be alert to any rash that has features typical of monkeypox.”

The US has antiviral therapies and vaccines available for use against smallpox, a virus that’s closely related to monkeypox. On Thursday, Danish biotech company Bavarian Nordic said that the US government will exercise a $119 million contract option for a freeze-dried version of its smallpox and monkeypox vaccine called Jynneos. The vaccine is one of three cleared by the Food and Drug Administration for smallpox. 

Shares of Bavarian Nordic rose as much as 32%, the biggest intraday gain in seven years.  

In 2018, the FDA approved tecovirimat, sold as Tpoxx in the US, an antiviral therapy for smallpox that has also shown activity against monkeypox. Manufacturer SIGA Technologies Inc. said Thursday that it had received FDA approval for an intravenous formulation of the drug for smallpox treatment. Its stock rose as much as 23% in New York, the most intraday since 2016. 

Texas and Maryland each reported one person with monkeypox infection in 2021, both of whom had recently traveled to Nigeria. The case in Massachusetts is the first reported infection in the US this year.

Monkeypox doesn’t spread easily between people, according to Massachusetts health officials, but it can be transmitted through respiratory droplets, bodily fluids, or contact with infected skin lesions and contaminated materials. Less severe infections may spread undetected. 

Children are also at a higher risk of contracting the virus, according to the World Health Organization, and infection during pregnancy can lead to birth complications or congenital monkeypox. Common household disinfectants can kill the virus on surfaces, the CDC said. 

The WHO also released an update on the UK monkeypox cases Wednesday afternoon, which says that unlike past monkeypox outbreaks with travel links to countries in west and central Africa where the virus circulates at endemic levels, no source of infection has yet been identified for the current cases. Since early May, the UK has identified nine cases of monkeypox.

“The extent of local transmission is unclear at this stage and there is the possibility of identification of further cases,” the WHO said in a statement.

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