Why can humans be infected with monkeypox? How can we prevent it?

Audit expert: Peng Guoqiu

Deputy Chief Physician, Fourth Medical Center, PLA General Hospital

According to the official website of the Chinese Center for Disease Control and Prevention, a cluster outbreak of monkeypox virus subclade Ib was discovered in my country recently.

So far, no infected persons have been found among the general contacts. The infected persons and risk persons are receiving medical treatment and health observation, and the epidemic has been effectively dealt with. What is monkeypox virus and why can humans be infected? How can we prevent it?

Monkeypox is a zoonosis caused by infection with the monkeypox virus, which is divided into clade I and clade II. It is called "monkeypox" because the virus was first discovered in monkeys. **Although the name "monkeypox" contains the word "monkey", its true source is not monkeys, but rodents. **Direct (contact, bite or scratch) or indirect contact with infected animals can lead to animal-to-human transmission.

Monkeypox virus is an enveloped double-stranded DNA virus belonging to the genus Orthopoxvirus of the family Poxviridae. In the past, monkeypox outbreaks were mainly prevalent in Africa, and gradually spread to most countries and regions in the world after 2022. Clinical manifestations mainly include fever, rash, swollen lymph nodes and other symptoms.

01 What is monkeypox virus subclade Ib?

The monkeypox virus subclade Ib was first discovered in the Democratic Republic of the Congo in September 2023. Since July 2024, the monkeypox virus subclade Ib has gradually spread from the Democratic Republic of the Congo to neighboring countries, causing sustained community transmission, and has been gradually imported into other African countries and countries and regions outside Africa through international travel. On August 14, 2024, the World Health Organization once again declared the monkeypox epidemic an "international public health emergency."

The basic characteristics of the monkeypox virus clade Ⅰb have not changed significantly. Compared with the clade Ⅰa, the infectivity of the clade Ⅰb has increased, but the severity of infection has decreased.

The monkeypox virus clade Ib is mainly transmitted through close contact such as sexual contact, close contact within the family, and unprotected medical care contact. The risk of infection from other general contact such as daily meals and riding in the same car is lower.

There have been sporadic reports of other monkeypox virus subbranches being able to be transmitted through droplets under conditions of prolonged close contact in a closed environment, but there have been no reports of subbranches being able to be transmitted through droplets at present.

Monkeypox is a self-limiting disease, and most cases have mild symptoms, mainly fever, headache, rash, swollen lymph nodes, etc. After symptomatic treatment and supportive treatment, most patients' symptoms disappear, and the rash scabs and disappears within a few weeks. For young children, pregnant women, and people with weakened immune function, if treatment is not timely, they may develop severe illness or death.

02 What are the differences between the symptoms of monkeypox and chickenpox?

Monkeypox and chickenpox are infectious diseases caused by different viruses. The pathogen of chickenpox is varicella-zoster virus.

Both have rash symptoms. The rash caused by monkeypox is mostly spherical and hard in texture. It scabs and falls off in about 2 to 4 weeks, and some may leave scars. The rash caused by chickenpox is mostly vesicular rash with thin blister walls. It scabs and falls off in about 1 to 2 weeks, and generally does not leave scars.

03 How to prevent monkeypox virus subclade Ib infection?

Be the first person responsible for your own health, learn about monkeypox prevention and control, and enhance your awareness of self-protection. Avoid close contact with monkeypox patients or those with suspected symptoms of monkeypox, which can effectively prevent monkeypox infection. Do not come into contact with wild or unknown rodents, monkeys, apes and other primates in daily life.

Before leaving the country, you should understand the epidemic situation of monkeypox virus subclade Ib in the destination in advance, take personal protection measures, avoid contact with local wild animals, and avoid close contact with monkeypox patients or people with suspicious symptoms; abide by relevant national entry and exit management regulations, and cooperate with entry and exit quarantine inspections.

04 Is there currently a vaccine to prevent monkeypox?

There is currently no monkeypox vaccine approved for marketing in my country. Relevant departments are organizing efforts to accelerate the scientific research and review and approval of monkeypox vaccines, and promote the development and marketing of products as soon as possible.