More than 100 cases of “monkeypox” have been reported, yet the transmission chain is still unknown!
Since May 13, 2022, 12 countries and territories in non-monkeypox endemic regions have reported confirmed cases of monkeypox to WHO, according to the WHO’s official website. As of May 21, 92 confirmed cases and 28 suspected cases of the disease had been recorded in a number of countries, including the UK, Portugal, and Spain. No related fatal cases have been reported.
A monkeypox outbreak was first reported in the United Kingdom, which was the first pandemic-free country to do so. This was followed by Israel, Switzerland, Germany and the Netherlands, which reported their first confirmed cases of monkeypox around May 21. WHO is concerned that there may be more cases of monkeypox in the future as surveillance efforts in non-infected countries continue to expand.
In addition, the BBC reported on May 22 that Israel, Switzerland and Austria have also reported confirmed cases of monkeypox in the past two days, bringing the number of countries reporting confirmed cases to 15 in this round.
In fact, monkeypox is a rare viral disease that is rarely found outside of Africa and is not readily transmitted from person to person. Monkeypox is transmitted through close contact with body fluids (e.g., saliva from a cough) and is “nothing” compared to the aerosol transmission of SARS-CoV-2.
Meanwhile, previous studies have found that the basic transmission number (R0) of monkeypox is in the range of 0.6–1.0, while the R0 of the SARS-CoV-2 variant, Omicron, is around 7. In general, R0 < 1 means that the disease is under control or spreading less rapidly. Therefore, at first scientists were more optimistic that monkeypox would not be a pandemic situation like COVID-19.
However, in the past 10 days, 12 non-epidemic countries and regions have reported confirmed cases of monkeypox; and many confirmed and suspected cases of monkeypox have not traveled to infected areas, and the route of infection for patients is unclear. This has put the world in a state of critical alert.
“It’s mind-boggling to see such transmission!” Anne Rimoin, an epidemiologist from UCLA who has been studying monkeypox in the Democratic Republic of Congo for more than a decade, expressed shock.
To date, preliminary sequencing of virus genomes recently released by researchers in Portugal, Belgium and the United States shows that the DNA sequences of three monkeypox viruses initially show homology to the same mild West African strain, closely related to monkeypox viruses found in the United Kingdom, Singapore and Israel in 2018 and 2019.
Monkeypox is usually self-limiting, but can cause serious consequences in special populations, such as children, pregnant women, or people who are immunosuppressed due to other health conditions. According to WHO, there are two main spectrums of the monkeypox virus: the West African branch and the Congo Basin (Central Africa) branch, with a mortality rate of 3.6% and 10.6%, respectively.
Raina MacIntyre, an epidemiologist from the University of New South Wales in Australia, believes that mutations in the monkeypox virus that enhance its transmissibility may explain the outbreak.
However, unlike the RNA virus SARS-CoV-2, which frequently mutates, monkeypox virus is a relatively large DNA virus that is better at detecting and repairing mutations on its own. In other words, DNA viruses are less likely to mutate, which is one of the major reasons why smallpox, a “relative” of monkeypox, was eliminated.
Recent analysis in the United States has shown that the current outbreak of the monkeypox virus has a total of 94 nucleotide changes and 51 amino acid changes compared to the previous one. This is a very high mutation rate for a stable DNA virus.
