Until recently, Mpox virus was only found in certain parts of Africa when humans became infected through contact with wild animals. However, in May 2022, for the first time, a major outbreak took place outside of Africa; the viruses spread solely through human-to-human transmission. This ongoing outbreak has so far reached more than 100 countries and has been classified by the World Health Organization as a Public Health Emergency of International Concern. The cases of the disease differed from previous outbreaks not only in the way they were transmitted, but also in the symptoms of the disease. These differences in virus behavior raised concerns that the currently circulating monkeypox viruses had changed to the point where they were no longer responsive to available drugs.
“We were really concerned that the virus might have evolved in a way that made it resistant to current therapies. Fortunately, this is not the case,” said study author Prof. Jindrich Cinatl from the Institute for Medical Virology, Goethe University Frankfurt/University Hospital Frankfurt. The research team isolated Mpox viruses from twelve patients in the current outbreak and multiplied them in cell cultures. The isolates were then tested for susceptibility to three available drugs used to treat: tecovirimate, cidofovir and brincidofovir. Results showed that all 12 isolates continued to respond to treatment with clinically achievable concentrations of commonly used drugs.
The mpox virus is closely related to the smallpox virus (variola virus), which caused large outbreaks with high death rates until it was eradicated by vaccination in the late 1970s. While smallpox, now eradicated, caused a very severe disease with a mortality rate of about 30 percent, mpox is a milder disease. Despite this, the death rate is still around three percent.