First published: 29 May 2022



Beatriz Cabanillas1*, Rafael Valdelvira1, Cezmi A. Akdis2, 3

To the Editor:

While the COVID pandemic is still raging in some parts of the world, a global outbreak of monkeypox appeared as an additional public health threat. Monkeypox is a zoonosis caused by monkeypox virus, a double-stranded DNA virus that belongs to the Orthopoxvirus genus same as other viruses such as variola virus (the causative agent of smallpox) or vaccinia virus. In May 2022 an outbreak of monkeypox was reported in more than 20 countries of the European Union, in the UK, North America, and Australia with more than 340 suspected or confirmed cases. The peculiarity of this outbreak, which is the largest and most widespread that has been reported outside Africa so far, is that the transmission in the majority of the cases occurs through human-to-human contact with no connection with travels to African countries where the disease is endemic.1 Monkeypox virus was identified for the first time in 1958 in monkeys, however, rodents have been identified as the main viral reservoir. The disease induced by monkeypox virus was diagnosed for the first time in humans in 1970 in the Democratic Republic of the Congo where monkeypox is considered an endemic disease. Other areas such as Central and West Africa are also commonly affected by the disease. The most frequent mode of transmission of monkeypox virus involved contact with infected animals, however, human-to-human infection, although less recognized, is also possible. The mortality rate due to monkeypox has been reported as 1-10 % in Africa.2 A recent systemic review found that monkeypox cases have increased 10-fold since 1970 in Africa and sporadic outbreaks outside Africa have been reported from 2003 to 2021. The cases outside Africa were reported in the United States (49 cases: 47 in the initial outbreak in 2003 and 2 cases in 2021), the UK (7 cases), Israel (1 case), and Singapore (1 case),3,4 which represent a total of 58 cases in 18 years (Figure 1). Many of these cases were described in individ u a ls who traveled from African countries affected by monkeypox, but cases of human infection due to contact with pets infected by rodents imported from Africa were also described.5,6 ...