The Mainichi Shimbun answers some common questions readers may have about monkeypox, an infectious disease that has recently surfaced in succession in Europe and the United States.
Question: What causes monkeypox and what are the symptoms?
Answer: Monkeypox is caused by the monkeypox virus. After an incubation period of about seven to 14 days, symptoms such as bumpy rashes on the face and body, a fever, and a headache develop. These symptoms generally subside naturally. Children are more likely to develop severe cases compared to adults. The disease was first reported in 1958 in a monkey used in research and was given this name, but it is known to infect a variety of animals, including squirrels and rats, and is mainly transmitted from animals to humans.
In 1970, human infection was reported in Africa, followed by sporadic outbreaks in the region. Since January this year, more than 1,000 cases have been reported in the Democratic Republic of the Congo. The symptoms, including rashes, are said to resemble "smallpox."
Q: I've heard of smallpox. What is it?
A: It was once feared as a deadly plague. Although the smallpox and monkeypox viruses lie in the same family, the World Health Organization (WHO) says that the mortality rate for smallpox patients was about 30%, while the recent mortality rate for monkeypox is about 3 to 6%. No monkeypox deaths have been reported in developed countries.
The number of smallpox cases decreased with the spread of vaccinations, and the WHO declared smallpox to have been eradicated worldwide in May 1980. There have been no smallpox cases in the world since then. In Japan, there was an epidemic of smallpox after World War II, but due to emergency vaccinations and other measures, there hasn't been a single case from 1956 onward.
Q: Is the smallpox vaccine effective against monkeypox?
A: It is said to be effective in preventing monkeypox, but no vaccinations against smallpox have been conducted in Japan since 1976, and people born after that are considered to have no immunity. Although person-to-person transmission is considered to be rare, infection can occur through droplets, bodily fluids, or by touching the rash area.
In Europe and the United States, monkeypox has occasionally been found in people returning from Africa. According to the WHO and other sources, since May, more than 100 people have been infected in countries outside of Africa, including those in Europe, the U.S., Canada, and Australia, with some patients having no history of overseas travel.
In the U.K. and Europe, monkeypox cases have been confirmed among gay men, and sexual intercourse is believed to be the route of infection. Experts believe that there will be no major outbreak of the disease like COVID-19, but the Japanese government is tightening its guard against it.
Q: Have there ever been confirmed cases of monkeypox in Japan?
A: Under the infectious disease control law, doctors who diagnose a patient with monkeypox are required to report it, but there have been no confirmed cases since collection of statistics commenced in 2003. To prevent the spread of monkeypox if it is confirmed in Japan, the Ministry of Health, Labor and Welfare on May 20 provided information on the disease's symptoms to local governments and medical institutions, and requested that any suspected cases be reported.
(Japanese original by Mikako Shimogiri, Lifestyle and Medical News Department)