The article to read to understand monkey pox, the virus of which circulates in around thirty countries

A “unusual situation”, but no reason to panic. The World Health Organization (WHO) does not fear a global monkeypox pandemic. Since the United Kingdom declared a confirmed case of this disease on May 7, more than 550 other patients have been reported in 30 countries usually spared from this virus. France had 33 identified cases on Wednesday, according to data published Thursday, June 2 by Public Health France.

After two and a half years of the Covid-19 pandemic, news related to the spread of the monkeypox virus may cause concern. But what are the symptoms? Can we die from it? Are there treatments?

What is monkey pox?

It is a viral zoonosis, i.e. a disease transmissible from animals to humans, caused bysimian orthopoxvirus. It was first identified and isolated in 1958 in macaques arriving at the Serological Institute of Denmark from Singapore. “It’s a rather misnamed virus, because its natural host today is mostly rodents, like Gambian rats”warns Olivier Schwartz, director of the Virus and Immunity unit at the Institut Pasteur.

This disease is therefore not new. It has been circulating endemic since the 1980s. “In general, there are a few thousand cases each year”, details the specialist with franceinfo. The disease is present in two main forms on the African continent, in areas close to tropical rainforests. The first spread in the Democratic Republic of Congo (DRC) and Republic of Congo, the second mainly in Nigeria, including in urban areas, which made it easier for the virus to leave the territory. “It is this second, less dangerous strain that is currently found in Europe and North America”specifies to France 24 Matthias Altmann, epidemiologist at the University of Bordeaux and specialist in infectious diseases in Africa.

The WHO has come forward in recent weeks because clusters of cases, not directly linked to travel to endemic areas, have emerged in countries where the disease does not usually circulate.

Is it the same as traditional smallpox?

Monkey pox belongs to the same family as human smallpox, eradicated worldwide in 1980. It was first identified in humans in 1970, in the DRC. The two viruses “share 90% of the same genetic sequence”, says Olivier Schwartz. So they are cousins “but infections seem less pathogenic with monkeypox than with human smallpox”adds the virologist.

“The West African stock [de la variole du singe] has already made an incursion into the United States in 2003, following the importation of infected animals”recalls in an interview with The Conversation Camille Besombes, infectious disease doctor at the Institut Pasteur. “The American patients had been contaminated after contact with infected prairie dogs, purchased from pet stores, where they had rubbed shoulders with Gambian rats imported from Ghana and carriers of monkeypox”, continues the specialist. A total of 47 suspected cases had been counted but no human-to-human transmission had occurred.

Why does the disease circulate outside the usual foci?

This is the main gray area of ​​the recent wave of contamination. “Analysis of recent samples in Europe shows that the virus circulating is identical to the strain present in West Africa. This suggests that it is not a new, more transmissible variant of the disease”, as was the Omicron variant against the Sars-CoV-2 strain, notes Olivier Schwartz. The specialist also notes that the monkeypox virus is a DNA virus, more stable and less subject to mutations than an RNA virus such as Sars-CoV-2.

Another possible explanation would be the existence, at the start of the contamination chain, of a “super-spreader” event, during which a large number of infections would have taken place. The patients could then have infected other individuals.

These numerous contaminations have also benefited from fertile ground, estimates for franceinfo Paul Loubet, infectiologist at the CHU of Nîmes (Gard): since the eradication of the disease in 1980, the vaccine against smallpox is no longer administered in the population general. The absence of a vaccination campaign may have lowered the immunity of the youngest patients against this family of viruses.

What are the symptoms ?

The incubation period of the virus generally varies from six to sixteen days. The symptoms that appear afterwards are very similar to those caused by human smallpox. At first, the infected patient suffers from fever, strong headaches, muscle aches, as well as inflammation of the lymph nodes. Back pain and fatigue may also appear.

Photo dated 1997 provided by the US Centers for Disease Control and Prevention.  It shows the right arm and torso of a patient, whose skin showed a number of lesions due to monkeypox.  (CDC / AP / SIPA)

Characteristic buttons then appear. “The vesicles are more concentrated on the face, the palms of the hands and soles of the feet. The mucous membranes are also affected, in the mouth and the genital area”, describes Public Health France. The disappearance of symptoms takes, in most cases, two to three weeks.

Can we die from it?

While mortality from human smallpox could approach 30%, monkeypox as we know it usually heals spontaneously. Severe cases occur more frequently in children and are related to the extent of exposure to the virus, the patient’s medical condition and possible complications.

In African countries where the disease is endemic, the mortality rate varies from 1 to 10%. The European Center for Disease Prevention and Control (in English) specifies that the viral strain detected in Europe, originating from West Africa, has an average lethality rate of 3.6%.

“We do not know to what extent this rate is transposable to us: we generally have relatively little information on the characteristics of infected patients in epidemics in Africa and our health systems are very different from those of the countries concerned”, comments for franceinfo the infectiologist Paul Loubet. Proper medical management greatly reduces the risk and most people recover spontaneously. In countries where the disease has been spotted recently, no deaths have been recorded.

How is the disease transmitted?

The cases of monkeypox usually reported in African countries result from direct contact with blood, body fluids or lesions on the skin or mucous membranes of infected animals. Eating undercooked meat from infected animals is also considered risky.

The so-called secondary transmission, that is to say between humans, is more complex. “There is a risk of transmission via droplets (spitting, spitting), but the predominant mode of contamination is close and prolonged skin contact with an infected person”, adds Paul Loubet. This conclusion allows the European Center for Disease Prevention to affirm, in a report published on May 23 (PDF in English)that the risk posed in Europe by monkeypox is “weak” in the general population.

Several experts point out that if this virus could be caught during sexual activity, it is not a sexually transmitted disease. This transmission could be due to intimate contact during sexual intercourse, and not to the sexual intercourse itself.

To date, cases have been identified in Europe “mainly, but not exclusively, among men who have sex with men”reports SPF. “To say that this is a disease that only affects gay men is inaccurate”warns however in the columns of the World Matthew Kavanagh, deputy director of UNAIDS, United Nations program on HIV. According to him, the homophobic comments that sometimes accompany publications on this disease are particularly likely to deter patients. “to consult their carer, for fear of being identified with a group”.

Are there treatments or vaccines?

There is no specific treatment or vaccine for monkeypox, but drugs and vaccines designed for smallpox can be used against monkeypox. In terms of vaccines, “It has been shown, through several studies, that vaccination against smallpox [humaine] is 85% effective in preventing monkeypox”, recalls the WHO. A “very good efficiency”according to virologist Yannick Simonin, specialist in emerging viruses, interviewed by franceinfo.

To limit the risks of epidemics in France, the High Authority for Health recommended on Tuesday May 24 to vaccinate adults, including health professionals, who have had risky contact with a patient. “We have strategic stocks and it will be targeted vaccination. We are not talking about total vaccination”said the next day the Minister of Health, Brigitte Bourguignon, on RTL.

On the treatment side, certain antiviral drugs, designed in particular against smallpox, can also be used to treat or limit the effects of monkeypox, such as tecovirimat.

I was too lazy to read everything, can you give me a summary?

The monkeypox virus is already well known, having been circulating in certain areas of Africa since the 1980s. Unlike Covid-19, the expression of which can vary greatly from one individual to another. , the symptoms of monkeypox are very identifiable: fever, headache, muscle aches during the first five days, then appearance of a large amount of rashes on the face, the palms of the hands, or the soles of the feet . Patients usually recover spontaneously and symptoms last for two to three weeks. In countries where the disease has been identified recently, the cases observed are mostly mild and no deaths have been recorded.

The way the virus spreads is also very different from that of Sars-CoV-2. “Closer contact than with Covid-19 is necessary to become infected. The probability of an airborne infection exists, but the risks are greater with saliva or postillions than with aerosols”, lists Olivier Schwartz, director of the Virus and Immunity unit at the Institut Pasteur. Finally, several studies show that vaccination against smallpox [humaine] is 85% effective in preventing monkeypox. In France, contact cases deemed to be at risk are invited to be vaccinated to stem the spread.

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