Human-to-human transmission has occurred! Is it from the same family as "smallpox"? How to prevent...

Expert of this article: Zhang Zhidan, chief physician of infectious disease department, the First Affiliated Hospital of China Medical University, professor

Recently, countries including the United Kingdom, Portugal, Spain, Italy, Sweden and Belgium have reported more than 100 confirmed and suspected cases of monkeypox.

“Available information suggests that human-to-human transmission is occurring among people in close physical contact with symptomatic cases,” WHO noted.

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According to Belgian Evening News and other media reports, after discovering multiple cases of monkeypox, the Belgian health department issued a statement on the 19th local time, requiring monkeypox cases to self-isolate for 21 days. This is also the first country in the world to require monkeypox cases to self-isolate.

Asked whether community transmission was now the standard pattern of monkeypox transmission in the UK, Susan Hopkins, chief medical adviser at the Health Security Agency, said: "Absolutely," AFP reported from London.

So what exactly is monkeypox virus and how can we protect ourselves?

What is monkeypox virus?

Monkeypox virus and smallpox virus belong to the same genus as orthopoxvirus and can be cultured and grown in African green monkey kidney cells.

Monkeypox is a zoonotic disease caused by infection with the monkeypox virus. The symptoms of patients are similar to those observed in smallpox patients in the past, but the clinical severity is milder.

Since smallpox was eradicated from the world in 1980, monkeypox virus has become the most serious orthopoxvirus and is present sporadically in parts of Africa, mainly in central and west Africa, usually near tropical rainforests, and has increasingly appeared in urban areas.

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The animal reservoirs of monkeypox virus include a range of rodents and primates.

Although monkeypox sounds like a virus that comes from monkeys, that's because scientists first discovered the virus in laboratory monkeys in 1958 and named it monkeypox virus. However, the main carriers and spread of the virus are actually rodents such as mice and squirrels.

What are the symptoms of monkeypox virus infection?

The incubation period for monkeypox virus is usually 6 to 16 days. The infection can be divided into two stages:

Onset period (0-5) days

Fever, severe headache, swollen lymph nodes, back pain, myalgia, severe fatigue and weakness, and swollen lymph nodes are a distinctive feature of monkeypox compared to other diseases that may initially appear similar (varicella, measles, smallpox).

Rash stage (1-3 days after fever appears)

The rash tends to be more concentrated on the face and extremities than on the trunk. The most common sites are the face (95%), the palms and soles (75%). Also affected are the oral mucosa (70%), genitals (30%), and conjunctiva (20%), as well as the cornea.

The rash varies from maculopapular to vesicles, pustules, and crusts that dry and fall off. The number of lesions varies from a few to several thousand.

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How is monkeypox virus spread?

Transmission from animals to humans can occur through direct contact with blood, body fluids, skin or mucous membrane lesions of infected animals.

Eating inadequately cooked meat and other animal products from infected animals is also a possible risk factor. People living in or near forested areas may be exposed indirectly or at low levels to infected animals.

Human-to-human transmission is usually caused by close contact with respiratory secretions of an infected person, skin lesions of an infected person, or indirect contact with contaminated objects.

Transmission via respiratory droplets usually requires prolonged face-to-face contact. Transmission of monkeypox virus can also occur transplacentally from mother to fetus, thus causing congenital monkeypox, or during close contact during and after birth.

But it is still unclear whether monkeypox virus can be transmitted specifically through sexual transmission.

Is monkeypox a global threat?

Monkeypox cases have been reported in many countries. Has the strain causing this outbreak mutated significantly compared to previous ones? Will it become a large-scale infectious disease?

There have been several previous outbreaks of monkeypox outside of Africa, but these usually involved only a small number of cases and had very limited local transmission.

However, in the latest round of monkeypox outbreak, more than 100 confirmed and suspected cases have been reported in at least 12 countries and regions around the world that had not previously experienced monkeypox. Some of these cases had no obvious source, meaning that the strain is likely to be more transmissible than previous strains. However, accidental events, such as the virus being carried by a "super spreader," can help the virus spread more widely.

Researchers are currently sequencing samples of the virus, which will reveal whether all known cases are related.

British researchers have not completely ruled out the possibility of a pandemic, but believe the possibility is low. Dr. Colin Brown, director of emerging infections at the UKHSA, said: "It is not easily transmitted between people, and transmission requires close contact with someone who is infected and has symptoms. The overall risk to the public remains low."

The World Health Organization held a meeting of experts and technical advisory groups on May 20, 2022, and concluded that the discovery of monkeypox cases in multiple countries where monkeypox is not endemic was an "atypical" situation.

How can we prevent monkeypox virus?

There is currently no specific treatment for monkeypox or vaccine based on the monkeypox virus.

Clinically, symptomatic supportive treatment is the main approach. On July 13, 2018, the U.S. FDA approved Tecovirimat capsules from Siga Technologies for the treatment of smallpox. Tecovirimat targets the VP37 protein of the orthopoxvirus genus and inhibits its activity, blocking its interaction with cellular GTPase and TIP47. In animal studies, tecovirimat significantly increased the survival rate of animals infected with monkeypox.

Previous information has shown that smallpox vaccination can prevent monkeypox infection and reduce clinical symptoms after infection. People with a history of smallpox vaccination have a 5-fold lower risk of monkeypox infection than those who have not been vaccinated.

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However, since smallpox was eradicated in my country, smallpox vaccines are no longer routinely administered. Therefore, the best way is to avoid contact with animals (rodents, marsupials, primates) that may carry monkeypox virus and items they have touched, and avoid eating or handling wild game.

The best way for overseas compatriots to protect themselves is to avoid going to African forests where the epidemic has occurred and to avoid contact with potentially infected animals, including marmots, monkeys, etc. Once a case of monkeypox is discovered, isolation measures should be taken in a timely manner to prevent human-to-human transmission.

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