Monkeypox is once again a global threat. Is it a sexually transmitted disease?

Monkeypox is the second virus, after Ebola, to constitute two "public health emergencies of international concern."

Written by Li Qingchao (Shandong Normal University)

On August 14, 2024, Tedros Adhanom Ghebreyesus, Director-General of the World Health Organization, announced that the monkeypox outbreak once again constituted a "Public Health Emergency of International Concern" (PHEIC). This is the second time that monkeypox has posed a global health threat since the World Health Organization (WHO) announced the monkeypox outbreak as a PHEIC on July 23, 2022; it is also the second virus to cause two PHEICs after the Ebola virus. There have been a small number of monkeypox cases in my country before, and scientists and doctors have begun to actively respond to this new health threat.

“PHEIC” and the “EID” behind it

A "Public Health Emergency of International Concern" (PHEIC) refers to "an unusual event that poses a public health risk to other countries through the international spread of disease and that may require a coordinated international response." This is the official statement of the "Emergency Committee" of the International Health Regulations (IHR) established by the World Health Organization (WHO) after the 2022-2024 Severe Acute Respiratory Syndrome (SARS) epidemic on public health events. The announcement of a PHEIC means that the public health event "occurs suddenly" - serious, sudden and unusual; "has a wide impact" - in addition to the currently affected countries or regions, it may threaten global human health; and "urgently requires disposal" - immediate international action is required, and countries have a legal obligation to respond quickly to PHEICs.

Although PHEIC is not limited to public health events caused by infectious diseases, the eight PHEICs announced by WHO so far are all emerging and re-emerging viral diseases, involving pathogens such as influenza virus, polio virus, Ebola virus, Zika virus, new coronavirus and the newly announced monkeypox virus. Among them, the emergence of SARS, smallpox, wild polio virus and new subtypes of human influenza will automatically become PHEIC.

So far, WHO has declared PHEIC eight times.

It is worth noting that emerging infectious diseases (EIDs) have continued to emerge in the past few decades and have become an important source of threat to human health. Emerging infectious diseases have three characteristics: suddenness, unexpectedness, and severity, which are also the main factors of public health emergencies. The three characteristics of emerging infectious diseases are inseparable from their "newness". They mainly refer to those that humans have never encountered before or have never appeared in a certain area (Newly emerging), such as HIV/AIDS (1981), Nipah virus (1999), SARS (2002), MERS (2012), COVID-19/SARS-CoV-2 (2019); or the infectious disease has disappeared for a period of time or no longer poses a serious threat, but the pathogen re-emerges (Re-emerging), such as methicillin-resistant Staphylococcus aureus and West Nile virus (1999).

Monkeypox (formerly Monkeypox, now Mpox) virus is not a new virus. It was first discovered in a Danish laboratory monkey in 1958. It was not until 1970 that human cases of monkeypox infection were discovered and reported in Congo. The virus was once limited to local epidemics in West and Central Africa, but it caused a local outbreak in the United States in 2003. The reason was also due to the trafficking of African wild animals, and people were infected by contact with wild animals carrying the virus.

On July 23, 2022, the Director-General of the World Health Organization declared the monkeypox epidemic at the time (affecting 75 countries and more than 17,000 reported cases) a PHEIC, and terminated the PHEIC event on May 11, 2023. However, just halfway through this year, the number of monkeypox cases reported in Congo has far exceeded the total number of last year, with 15,000 infected cases and more than 500 deaths. According to analysis, the monkeypox virus that is prevalent this time is a new strain of the virus, belonging to the 1b branch, which is more pathogenic, mainly transmitted through sex, and has spread to four surrounding countries.

Gao Fu, former director of the Chinese Center for Disease Control and Prevention and academician of the Chinese Academy of Sciences, once pointed out that new and unknown emerging infectious diseases, including influenza viruses and new coronaviruses, continue to have a huge impact on human health, threatening human health and posing a major threat to global public health. Continuing to maintain a high level of vigilance, strict monitoring and timely early warning signals are still the best strategy at present, which will also help researchers develop countermeasures against monkeypox virus and buy precious time for the global fight against the epidemic.

Vaccination can prevent smallpox

Monkeypox virus is a zoonotic virus of the Poxviridae family and the Orthopoxvirus genus. Based on its sequence analysis and evolutionary relationship, monkeypox virus can be divided into two groups: Congo type and West African type. Since the main host of monkeypox virus is not monkeys, and the classification and naming method associated with the region is prone to unfavorable associations between the disease and Africa, the virus has been renamed Mpox (the Chinese translation corresponding to Mpox has not yet been proposed), and the group is named after the two evolutionary branches I and II. The epidemic strain of this epidemic is the Ib branch cluster, with a mortality rate of about 5%, far exceeding the 0.2% mortality rate caused by the IIb branch cluster virus last time.

Smallpox virus, which belongs to the same genus as monkeypox virus, was once a nightmare for mankind. According to research, it has existed for at least three thousand years. Smallpox is one of the most destructive diseases known to mankind, forcing people to develop primitive vaccination methods (China invented the human pox vaccination method as early as around 1000 AD during the reign of Emperor Zhenzong of Song Dynasty). The big devil, smallpox virus, was "harmed" by its "weak chicken and pig teammate" cowpox virus. In the 18th century, British scientist Edward Jenner successfully used cowpox to prevent smallpox. In the end, smallpox was eradicated in 1980, becoming the first and only human viral disease eradicated by humans (but polio has not been completely eliminated).

Monkeypox (left) and smallpox (right) are both orthopoxviruses. Poxvirus infections produce a typical pustular rash, and smallpox is far more severe than monkeypox.

"Blessings and disasters lie in the same place." After smallpox was eradicated in 1980, people no longer received the cowpox vaccine, and basic research on poxviruses was relatively rare. It was not until 2019 that the structure of the poxvirus polymerase was solved. This situation left the entire world in a state of "unprotected" smallpox and other poxviruses, making smallpox a highly threatening potential terrorist biological weapon.

This pox is not that pox

The course of monkeypox is similar to other poxvirus infections, with general symptoms of viral infection such as fever, malaise, headache, sore throat, swollen lymph nodes, etc.; characteristic skin lesions of poxviruses also appear, accompanied by pain and itching; from the earliest erythema, it develops into papules and blisters, followed by pustules containing pus, and finally the pustules heal with scabs, but scars will be left. The rash caused by monkeypox mainly appears on the mouth, tongue or face, and then spreads to the limbs, hands and feet.

Since monkeypox is not commonly transmitted, during the diagnosis process, it is necessary to distinguish it from other infectious diseases that can cause skin lesions, including but not limited to herpes viruses such as varicella, syphilis, measles, etc. Note: Varicella (herpes virus) and monkeypox (pox virus) are not related and there is no cross-immunity protection.

However, there are patients with atypical clinical symptoms of monkeypox. Hidden spreaders pose a great threat to the diagnosis, treatment and prevention of monkeypox. Medical staff are also at high risk of infection when treating patients, or medical staff are more likely to be exposed to monkeypox diagnostic tests. WHO recommends that full personal protective equipment should be worn when treating patients with monkeypox.

At the same time, it must be emphasized that this PHEIC monkeypox outbreak is unique compared to previous outbreaks.

1. The first PHEIC monkeypox outbreak was mainly prevalent in Europe and the United States. The second monkeypox outbreak mainly occurred in Congo, but there is a trend of spreading.

2. The first PHEIC monkeypox outbreak affected mainly young and middle-aged men, most of whom had sex with men, and had a low mortality rate. The second monkeypox outbreak was also spread through homosexual or bisexual networks, but it could also be spread through ordinary intimate contact. In terms of mortality, the second outbreak had a more serious impact on infants and young children, with a relatively high mortality rate, which was related to the lack of local nutrition and medical resources.

Is monkeypox a sexually transmitted disease?

Given that the primary mode of transmission for both monkeypox cases was sexual, primarily among males, and that male-to-male sex is suspected to be a high-risk mode of transmission, is it a sexually transmitted disease?

Sexually transmitted diseases refer to infectious diseases that can be transmitted through sexual intercourse. Given the close contact during sexual intercourse, infectious diseases that are transmitted through other routes also have a chance of being transmitted during sexual intercourse. The monkeypox virus is mainly transmitted through contact between mucous membrane or skin lesions and contaminants containing the virus. It can also be transmitted through a large number of respiratory droplets during long-term face-to-face interactions. According to current research, monkeypox virus DNA can indeed be detected in semen, but in comparison, the virus content in skin lesion secretions is much higher than that in semen. Therefore, it is generally believed that monkeypox is not a sexually transmitted disease, although sexual intercourse can transmit monkeypox.

Monkeypox prevention and treatment

Based on the current transmission characteristics of monkeypox, the lessons learned from the entry of human immunodeficiency virus (HIV) into the country, and the prevention and control experience, my country can use the HIV prevention and control publicity channel to promote monkeypox prevention and control publicity and keep monkeypox out of the country as much as possible.

Under the premise of advocating single sexual partners and safe sex, monkeypox prevention and control must keep in mind one thing: avoid contact with any skin lesions such as rashes. This is because skin lesion tissue and exudate contain high concentrations of viruses, and transmission through contact with skin lesions is the main way monkeypox is transmitted. Sexually transmitted diseases often cause skin lesions or skin growths on the genitals or perianal area, which is a symptom that is very easy to observe before sexual intercourse. Once you find that you or your sexual partner has skin lesions such as rashes, you should avoid sexual intercourse and get timely diagnosis and treatment; at the same time, you can avoid the spread of sexually transmitted diseases such as genital herpes and genital warts. In addition, sharing towels, bedding and personal hygiene products with others also poses a risk of spreading monkeypox.

Smallpox vaccine can be used to prevent monkeypox, but based on the current situation of the monkeypox epidemic and its transmission method, universal vaccination is not required at present. It is only recommended that high-risk groups be vaccinated with the vaccine to prevent monkeypox.

There is currently no specific treatment approved for monkeypox, but small molecule drugs against DNA viruses and immunoglobulin therapy may be considered.

Special Tips

1. Go to the "Featured Column" at the bottom of the menu of the "Fanpu" WeChat public account to read a series of popular science articles on different topics.

2. Fanpu provides a function to search articles by month. Follow the official account and reply with the four-digit year + month, such as "1903", to get the article index for March 2019, and so on.

Copyright statement: Personal forwarding is welcome. Any form of media or organization is not allowed to reprint or excerpt without authorization. For reprint authorization, please contact the backstage of the "Fanpu" WeChat public account.