Monkeypox is "rampant" . ... But there is no reason to panic

Almost everyone has probably heard about the fact that cases of monkeypox have been reported in more than a dozen countries in Europe, America and Asia. The topic, as they say, is a hot one. I will speak out on it too, especially since the readers of this blog have asked me to do so.

I will start with the basic information about monkeypox virus (MPV or MPXV). This is a member of the poxvirus family, within which it belongs to the genus Orthopoxviruses. The best-known variola variola virus (VARV) belongs to the same genus. It is important that the toxviruses are genetically extremely stable. In addition to this, the toxviruses have mechanisms ensuring the "correction" of errors during the copying of genomic DNA. Moreover, in this respect, the poxviruses are the most effective compared to other viruses.

The main "poxvirus" (VARV) has been completely eradicated from natural circulation. Moreover, the natural host of VACV is still reliably unknown. Be that as it may, immunization with VACV vaccine effectively protects against both natural and monkeypox.

One important factor contributing to the successful elimination of smallpox virus was that the only host for this virus was humans. Unfortunately, the monkeypox virus is considerably less "fastidious" - numerous species of rodents and primates, including humans, are sensitive to it. In general, the name of this virus is misleading. The roots of this lie in the history of the discovery of MPV, which I will not go into. The important thing is that monkeys are not its natural host and, as a rule, people get MPV infection not from monkeys but from rodents. The natural host of MPV is not reliably known. But it is highly likely to be one or more species of African rodents. Transmission of the virus to humans is not uncommon in countries endemic for monkeypox in Africa. Hundreds or even thousands of cases of monkeypox are officially reported each year in these countries. Although human-to-human MPV transmission does occur, even in African endemic countries MPV is not "entrenched" in human populations.

Monkeypox is clinically similar to smallpox, but it is substantially less severe. In the vast majority of cases, patients recover. But 2% to 10% of cases in Africa are fatal. The Central African variant of MPV is more dangerous (mortality up to 10%). When the disease is caused by the East African variant of MPV, the mortality rate is lower - up to 3%. I would like to emphasize that all data on lethality were obtained in the endemic African countries, where the level of health care and the state of health of the population are considerably worse than in the developed countries.

At the end of the "educational" part another important piece of information - MPV infection is always (or almost always) manifested clinically. At least until now, asymptomatic MPV infection has not been known. Of course, this makes anti-epidemic measures much easier.

Now briefly about the "rampant" MPV in Europe and America, about which now so much is written in the media. I should note right away that I only know what is available in publicly available sources. In brief, the most significant facts are as follows:

- Most (but not all) of those infected are homosexual men, or rather men who have sex with men.

-All of them have not visited countries endemic for monkeypox in Africa.

-Most have a mild form of the disease. No fatalities have been reported so far.

-The causative agent is of East African origin. But genotyping of the virus has not been carried out in all confirmed cases.

-Sequencing of the full genome has only been done in one case so far (a patient in Portugal). Nothing unusual has been found. But these data are preliminary.

Obviously, many questions are still unanswered. The most unusual, even mysterious, is how could people living in different countries for quite a short period of time get the virus without contact with animals, which are the source of human infections in the endemic zone of Africa?

The predominance of MSM males is also unusual. It is reasonable to assume that this is due to their sexual activity. It must be said that so far there has been no evidence of sexual transmission of the monkeypox virus. But transmission by sexual intercourse can also occur "non-sexually". Say, by contact with the skin, which may have a rash characteristic of monkeypox. Why are there significantly fewer heterosexuals than MSM men? There is no clear answer to this question. But an assumption can be made. This group (MSM) is relatively small (compared to the heterosexual majority) and on average sexually more active. Provided a pathogen transmitted through "close contact" is brought into this community, the probability of the spread of the disease is increased compared to the general population. However, the question of how the monkeypox virus was "picked up" by patient zero in this group remains open.

Regarding the risk of a monkeypox epidemic, there is no significant epidemic risk in my opinion. Here are a few reasons that lead me to this conclusion:

- The monkeypox virus is genetically stable. The chances of the emergence of new, increasingly "malignant" variants are slim.

- The contagiousness of this virus is low. Even if a slight increase in infectiousness were to occur, outbreaks would still be relatively easy to control with standard anti-epidemic measures

- An effective vaccine is available and mass vaccination is not necessary to control the outbreak. Immunization of several "circles" of contacts of ill persons (primary contacts, then contacts of contacts, etc.) is sufficient.

- There is also an antiviral drug effective against VARV and MPV (although there is no experience with its clinical use yet).

2.05.2022