Monkeypox outbreak outside of Africa — up to date updates
About 500 cases have already been recorded of infection with monkeypox in Europe, America, and Australia. Approximately half of the cases are confirmed, and the remaining half require confirmation [1]. Moreover, the virus is often found in unrelated people. In the past week alone, the number of cases of monkeypox infection in countries outside of Africa has exceeded all previous cases since 1970, when the virus was first detected in humans [5]. Why did the outbreak occur and is there any cause for concern?
This compilation summarizes all the basic information on the topic from the best quality scientific journals (The Lancet, JAMA, Nature, Science, BMJ, PNAS, etc.) and authoritative organizations (WHO, CDC, etc.) that I could find. I tried to divide the information into the most informative headings. The collection is read in ~5–15 minutes.
I. History
Monkeypox is a misnomer
Monkeypox is the name given to the discovery of two outbreaks of the virus in 1958 in laboratory monkeys in Denmark. Most likely, monkeys are the only carriers, and the natural hosts of the virus are rodents and other small mammals. However, the animal reservoir has not yet been installed; there may be several such reservoirs. In 1970, the virus was first detected in a human, it was a 9-year-old boy in the Democratic Republic of the Congo, Africa [4, 6, 9, 16, 18].
Complete eradication of smallpox
Smallpox has been a huge human scourge for centuries, killing up to 30% of those infected. But the massive vaccination campaign in the 1960s and 1970s greatly reduced the spread of the infection. In 1977, there was the last reported case of smallpox infection. In the same year, the vaccination campaign ended. And in 1980, the WHO announced that thanks to vaccination, smallpox had been eradicated. To date, it is the only completely eradicated pathogen! Samples of the virus are available only in laboratories in Russia and the USA [9].
Smallpox and monkeypox
Smallpox vaccination sometimes caused serious side effects and killed about 1 in 1,000,000 vaccinated people. But the benefits of a vaccine against a highly lethal infection far outweighed the risks. This vaccine curbed the spread of monkeypox, among other things. Therefore, it is to be expected that immunity to smallpox in the population of various countries has been greatly weakened. The number of those ever vaccinated has also decreased: if in 1980 there were ~ 80% vaccinated, now there are ~ 30% vaccinated against smallpox. The number of new cases of monkeypox infection in Africa has increased from year to year [5, 6, 9, 24].
II. How often have you been infected before?
Infections in Africa
African countries experience at least several thousand monkeypox infections each year. Infected mainly in Central and West Africa. For example, monkeypox re-emerged in Nigeria in 2017 and caused an outbreak after 40 years without a reported infection. However, until recently, the virus was transmitted outside the continent only in isolated cases. And now, for some reason, we see a much faster spread of infection than it was in recent years [3, 5, 13].
Infections outside of Africa
In 2003, the first outbreak occurred outside of Africa, in the United States, which resulted in several dozen human infections. Then, infected small mammals from Ghana were brought into the country. They infected domestic dogs, which then infected their owners.
Since then, from 2018 to 2022, there have been rare cases of monkeypox importation into the UK, Israel, Singapore, and the USA [6, 7, 9]. Over the past 5 years, there have been only 8 cases of importation of monkeypox to countries outside of Africa. In addition, each case was associated with a recently visited person in Nigeria, where monkeypox is spreading [24].
How did the outbreak happen now? Spread from gays and bisexuals
On April 29, 2022, a British traveler in Nigeria began to show skin symptoms of an infection. On May 4, he flew to the UK, and then a possible cause of the monkeypox plant was registered outside Africa, and the traveler was isolated. Interestingly, this individual had nothing to do with any of the other infections outside of Africa to date [2].
Another interesting feature is that most monkeypox infections outside of Africa have been in men aged 20–50, many of whom are homosexual or bisexual. Monkeypox is most likely not sexually transmitted. But the sexual activity itself is close contact, which may be enough for the virus to be transmitted by airborne droplets [5, 7, 8]. However, this does not give the right to stigmatize certain segments of the population, as happened with the Chinese in 2020 during the spread of SARS-CoV-2 [20].
At the moment, monkeypox infections have been recorded in Australia, Argentina, Belgium, Great Britain, Germany, Greece, Denmark, Israel, Spain, Italy, Canada, Morocco, the Netherlands, Portugal, the USA, France, and Sweden [1].
What threatens the current spread of the virus?
Distribution speed. Monkeypox spreads quite quickly. If on May 23, when this article was first published, there were about 200 infected, then on May 26, when the last edits are made to the article, about 350 people are already infected [1].
Countries. At the moment, monkeypox infections have been recorded in Australia, Austria, England, Argentina, Belgium, Bolivia, Germany, Greece, Denmark, Israel, Spain, Italy, Canada, Morocco, the Netherlands, UAE, Portugal, Slovenia, Czech Republic, USA, Finland, France, Scotland, and Sweden [1].
New reservoir. Because small animals can become infected with monkeypox from humans, this could create reservoirs of infectious animals in countries outside of Africa. If this happens, it will become even more difficult to fight the spread of the virus [18].
Could monkeypox become a new pandemic? This option is unlikely, but it cannot be completely ruled out [18]. In the coming time, we are likely to see a large number of identified new infections in countries outside of Africa.
III. Comparison of monkeypox virus with SARS-CoV-2
Names
The virus and the infection have similar names: monkeypox virus and monkeypox. The names are simpler than in the case of the 2019 strain of coronavirus when the virus is SARS-CoV-2, and the name of the infection it causes is COVID-19.
Virus isolation
The monkeypox virus strain now circulating in Europe was first sequenced on 19 May 2022 in Portugal from a swab taken from an infected man who had skin lesions due to the infection on 4 May [4].
The following is a list of significant differences between the monkeypox virus and SARS-CoV-2.
1. Genome, size, and mutation rate.
SARS-CoV-2 is an RNA-based, about 30,000 base pairs long. And the monkeypox virus is DNA-based, the virus is bigger and more complex, about 20 times bigger than HIV, and over 200,000 base pairs in size. DNA-based viruses mutate much more slowly than RNA-based ones [18]. It is not yet clear whether the new strain of the monkeypox virus is associated with mutations that allowed it to be transmitted much more efficiently.
2. Asymptomatic infection
SARS-CoV-2 can be transmitted asymptomatically, and the monkeypox virus is most likely not transmitted asymptomatically. Monkeypox infection is much easier to detect by skin manifestations than SARS-CoV-2 infection [5].
3. Transfer rate
At the moment, the most common variant of SARS-CoV-2 (omicron) has an exceedingly high transmission rate. Even if the rate of transmission of monkeypox has increased due to some mutation of the virus, it is unlikely to be as huge as in the case of SARS-CoV-2. In the past, most human smallpox-infected monkeys did not infect anyone else [6].
4. Way of transmission
The main route of transmission of SARS-CoV-2 is aerosol when the virus is transmitted in exceedingly small droplets of liquid that can hang for minutes or tens of minutes in the air before evaporating and are invisible to the eye. And only after it the second method is airborne, through small and large drops. At the same time, the monkeypox virus, most likely, the main mode of transmission is airborne, mainly through large droplets.
5. How long is an infected person contagious?
The vast majority of people with SARS-COV-2 can be contagious days before symptoms appear and up to 10 days after symptoms appear. At the same time, those infected with chickenpox are considered contagious from the onset of a rash on the body until the period of skin peeling and the disappearance of the rash, for example, 4 weeks after the onset of the rash [16].
IV. Monkeypox: practically essential information
From whom and how do they get infected?
From whom: from wild animals (rodents, etc.) or humans [5, 16, 24].
How: mainly by airborne droplets, with close contact; household contact, in contact with the affected surface of the body, or contact with the things of the infected person (bed linen, clothes) [5, 7].
What are the symptoms and how long do they last?
Let’s analyze the infection and the disease in stages [5, 7, 8, 9]:
- Incubation Period: Usually 6–13 days, but maybe 5–21 days.
When symptoms appear, they can be divided into 2 stages:
2. Period of invasion, 0–5 days from onset of symptoms.
The disease begins with flu-like symptoms: fever, chills, body aches, back pain, headaches, and swollen lymph nodes.
3. Skin manifestations, 1–3 days after the onset of fever.
Distinctive features of the infection lead to lesions on the body filled with pus and begin with the appearance of a rash. Usually, the rash first appears on the face, and then it spreads to other parts of the body. Lesions on the body resemble cases of infection with chickenpox or syphilis.
Skin manifestations most often occur on the following parts of the body [9]:
- face (95% of cases)
- palms and feet (75%)
- mucous membranes of the oral cavity (70% of cases)
- genitals (30%)
4. Recovery. Symptoms usually disappear 2 to 4 weeks after onset.
How dangerous is the infection?
There are two main clades of the monkeypox virus [2, 5, 7, 16, 20, 24]:
- Central African hoard (hoard of the Congo Basin). The mortality rate (CFR) is quite high, 10% to 11%. If we take mortality in the Congo, then 9.8% according to data for 1981–1986 and less than 5% according to data for 2001–2013.
- West African hoard. Causes milder disease, mortality (CFR) about 1%, up to 4%. The outbreak in Nigeria had a fatality rate of 2.8%. But outbreaks in Europe had a fatality rate of 3.6%. During the outbreak in the United States, when there were several dozen infected people (which I wrote about above), there was not a single death among them. Mortality is higher in children, young people, and immunocompromised people.
In addition to the risk of death, there is another risk: survivors often have scars on the skin and other complications [16].
Now we are dealing with a strain that originated from the West African clade. However, it is not known how different the new strain is from Western European strains of monkeypox [5].
Preparations
There are the following drugs that have been tested on animals against viruses closely related to smallpox [7, 11, 12, 19, 20]:
- Tecovirimat (TPOXX), was approved by the US FDA in 2018, and the European EMA in 2022.
- Brincidofovir (Tembexa), approved by the FDA in 2021
Vaccines
A small scar on the shoulder may be evidence of a previous smallpox vaccination [9]. But do not confuse this scar with the scar on the shoulder from the BCG (tuberculosis) vaccine that most of us have! Mass vaccination against smallpox ended in 1980. However, those who are vaccinated should be aware that the vaccine protects against smallpox for about 3–5 years, and then the effectiveness of protection decreases [14]. The CDC recommends that people who may have been in contact with an infected person and were vaccinated earlier than 3 years ago should be revaccinated against smallpox [10].
There are two monkeypox vaccines in Europe and the USA [6, 24, 25, 26]:
- ACAM2000 (from Emergent BioSolutions) — approved in 2007. Similar to the old vaccine, which could cause serious side effects. (There are 100 million doses of this vaccine in the US.)
- JYNNEOS (by Bavarian Nordic) — approved by the FDA in 2019. Explicitly designed to cause fewer side effects. Uses a non-replicating form of vaccinia. This is the only vaccine approved against monkeypox so far. (There are only 1,000 doses of this vaccine in the US.)
The vaccine's effectiveness is quite high: it prevents the disease in 85%. Moreover, it can be effective up to 4 days after infection. And if you give the vaccine between 4 and 14 days after infection, it will not prevent infection, but it may help reduce symptoms of the disease.
However, both vaccines are only in reserve. They are offered only in some countries (for example, in the USA) to those in contact with the infected. The vaccine company is holding a meeting to share the vaccine with countries in need.
Donate to support the project:
Card number: EUR: 5351 0412 4843 0322, USD: 5351 0412 1237 0298
Paypal: @erofeevyury
Sources:
- https://docs.google.com/spreadsheets/d/1CEBhao3rMe-qtCbAgJTn5ZKQMRFWeAeaiXFpBY3gbHE/edit?mc_cid=73764eb731&mc_eid=afd8ccb9bc#gid=0 (list of infected)
- https://www.who.int/emergencies/disease-outbreak-news/item/2022-DON381 (16.05.22)
- https://www.cdc.gov/media/releases/2022/s0518-monkeypox-case.html (18.05.22)
- https://virological.org/t/first-draft-genome-sequence-of-monkeypox-virus-associated-with-the-suspected-multi-country-outbreak-may-2022-confirmed-case-in-Portuguese/799
- https://www.nature.com/articles/d41586-022-01421-8 (20.05.22)
- https://www.science.org/content/article/monkeypox-outbreak-questions-intensify-cases-soar (20.05.22)
- https://www.bmj.com/content/377/bmj.o1274 (20.05.22)
- https://www.gov.uk/government/news/monkeypox-cases-confirmed-in-england-latest-updates (20.05.22)
- https://www.who.int/news-room/fact-sheets/detail/monkeypox (21.05.22)
- https://www.cdc.gov/poxvirus/monkeypox/clinicians/smallpox-vaccine.html
- https://www.fda.gov/news-events/press-announcements/fda-approves-first-drug-indication-treatment-smallpox
- https://www.fda.gov/drugs/news-events-human-drugs/fda-approves-drug-treat-smallpox
- https://www.cdc.gov/mmwr/volumes/67/wr/mm6710a5.htm (more about monkeypox infections in Africa between 1970 and 2017).
- https://www.cdc.gov/smallpox/vaccine-basics/index.html
- https://www.sciencephoto.com/media/248495/view/smallpox-viruses
- https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0007791 (systematic review of smallpox in Africa).
- https://onlinelibrary.wiley.com/doi/10.1111/j.1699-0463.1959.tb00328.x (Isolation of smallpox in laboratory monkeys).
- https://www.science.org/content/blog-post/now-monkeypox (5/23/22, reviewed by Derek Lowe)
- https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(22)00228-6/fulltext (05/24/22, clinical treatment of monkeypox in 7 patients in 2018–2018 from the UK).
- https://www.bmj.com/content/377/bmj.o1321 (25.05.22)
- https://cyberleninka.ru/article/n/klinicheskie-issledovaniya-vaktsiny-protiv-ospy-na-osnove-rekombinantnogo-shtamma-ospovaktsiny-b7-5s2-s-v-usloviyah-dvukratnoy-oralnoy
- https://cyberleninka.ru/article/n/zhivye-protivoospennye-vaktsiny
- https://cyberleninka.ru/article/n/naturalnaya-ospa-37-let-spustya-after-ofitsialnoy-likvidatsii
- https://jamanetwork.com/journals/jama/fullarticle/2793012 (27.05.22)
- https://www.cdc.gov/poxvirus/monkeypox/clinicians/treatment.html (for smallpox vaccines).
- https://www.fda.gov/news-events/press-announcements/fda-approves-first-live-non-replicating-vaccine-prevent-smallpox-and-monkeypox (for the Jynneos smallpox vaccine).
I would like to thank Yury Erofeev from SQUAKE for preparing the publication.
