The case involved a man in his 30s who had recently returned from Europe. The ministry said the patient had close contact with someone who was later diagnosed with monkeypox before returning to Tokyo in mid-July.
He developed fever, rash, headache, and malaise before testing positive for the monkeypox virus. According to the ministry, the patient is in stable condition and is being treated at a hospital in Tokyo.
“We will collect information while keeping close attention to the infection situation in other countries, in cooperation with the governments of each country, WHO [World Health Organization], and experts,” the ministry said in a statement.
The government also urged residents returning from overseas to seek medical attention if they were feeling unwell or developing symptoms, and issued the lowest “Level 1” alert for the virus, urging residents to take extra precautions when traveling abroad.
The Monkeypox virus can cause symptoms similar to those of smallpox patients, but it’s clinically less severe, according to the WHO.
The virus is transmitted through contact with bodily fluids, lesions on the skin, or internal mucosal surfaces. Symptoms of monkeypox include headache, fever, sore throat, malaise, fatigue, rash, and swollen lymph nodes.
Cases Concentrated to Men
WHO director-general Tedros Adhanom Ghebreyesus declared the monkeypox virus a “public health emergency of international concern” on July 23, despite a lack of consensus among experts.
Tedros based his decision on the global growth in monkeypox cases, which have now been reported in 75 countries and territories, with over 16,000 reported cases. Of these, only five deaths have been recorded.
“So in short, we have an outbreak that has spread around the world rapidly, through new modes of transmission, about which we understand too little, and which meets the criteria in the International Health Regulations,” he said in a statement.
“For all of these reasons, I decided that the global monkeypox outbreak represents a public health emergency of international concern,” Ghebreyesus said.
“Although I am declaring a public health emergency of international concern, for the moment this is an outbreak that is concentrated among men who have sex with men, especially those with multiple sexual partners,” he added.
Some committee members opposed the declaration of monkeypox as a global health emergency, claiming that the disease isn’t severe enough to warrant such attention and that it could risk hampering response efforts.
A WHO emergency committee decided last month that monkeypox did not constitute a public health emergency of international concern, which at the time had 3,040 cases reported in 47 countries.
In the United States, New York has seen the most monkeypox cases with 990 cases, followed by California with 356 cases, and Illinois with 344 cases, according to data provided by the CDC. The majority of reported cases are attributed to international arrivals.
The first major peer-reviewed study of monkeypox infections has since confirmed that the virus is primarily being transmitted through the sexual activity of gay and bisexual men in the United States and around the world.
The Journal of New England Medicine published a study last week that looked at monkeypox infection across 16 countries between April and June, when cases began to emerge in countries outside of Africa.
Caden Pearson contributed to this report.
Update: This article has been updated to include the alert from Japan’s foreign ministry.