Interview with Camille Besombes, a doctor specializing in infectious diseases, who has been involved in Afripox for the past three years, a project that aims to better understand the monkeypox virus in its endemic region.
Since the beginning of May, a thousand confirmed cases of monkeypox, a disease native to Africa, have been reported in at least 30 non-endemic countries such as the United Kingdom, Spain, Portugal, France, the United States, Australia and the United Arab Emirates. United and Israel. . But what is this virus? Who is affected? And do we have to worry about the recent increase in cases?
To answer these questions, we caught up with Camille Besombes, a doctor specializing in infectious diseases, who has been involved for the last three years in Afripox, a project that aims to better understand the virus in its endemic. region. He is currently conducting a doctoral research within the unit led by the project coordinator, Arnaud Fontanet, a leading medical epidemiologist and specialist in emerging infectious diseases at the Institut Pasteur.
Camille Besombes: Monkeypox is a virus that belongs to the genus Orthopoxvirus, a family that also includes smallpox. Like smallpox, it is a large DNA virus with a particular appetite for skin tissue. However, smallpox only affected humans, which meant that we were able to eradicate it through mass vaccination worldwide, while monkeypox is carried by an animal viral reservoir. And despite their name, the natural reservoir are not really monkeys.
The term “monkey smallpox” was coined when the virus was first identified in captive primates (in Denmark in 1958), but in nature, the virus is most often found in squirrels and other rodents. In 1970, the first human case of smallpox in a nine-month-old child was documented in the Democratic Republic of the Congo, amid growing efforts in the campaign to eradicate smallpox.
There are two strains of smallpox we know. The type that affects Nigeria, Liberia, Sierra Leone and Côte d’Ivoire is the so-called West African strain, with a mortality rate of 1 to 3%. This is what has been detected in recent cases in Europe. The second is the “Congo Basin” strain, which circulates in the Democratic Republic of the Congo (DRC), the Republic of the Congo, the Central African Republic (CAR) and Gabon. Both strains are now circulating in Cameroon: cases of infections involving the West African strain, imported from Nigeria, have recently been reported. Associated with more severe clinical forms, the Congo Basin strain has a mortality rate of around 10%.
We must also keep in mind that these figures come from countries where there is some lack of medical care, especially in more remote regions. In Europe, several patients are currently hospitalized with the disease, but no deaths or serious forms have been detected on the continent.
TC: What are the symptoms of this disease?
CB: After a relatively long incubation (usually lasting 6 to 13 days, and up to 21 days), it presents its first symptoms over a two-day period known as the “prodromal” phase. These symptoms may include high fever, headaches, swollen lymph nodes (which are a hallmark of smallpox), muscle aches, and fatigue. It is at this stage that patients are considered to be contagious.
Smallpox from the monkey causes injuries that gradually spread through the body of the infected person. Jean-Marc Zokoé, Provided by the author
The patient then develops a rash, which usually begins on the face and gradually spreads to the rest of the body. This rash causes intense pain and itching due to the inflammation that occurs around the skin lesions. In the West African strain, these lesions may initially be infrequent and unobtrusive and may therefore go unnoticed. The disease usually lasts two to four weeks and tends to go away spontaneously in most cases.
Major complications of monkeypox include dehydration due to loss of water due to numerous and more widespread lesions, secondary bacterial infection of the lesions, sepsis, and corneal or ocular lesions that can lead to vision loss. In addition, cases of encephalitis have also been documented (ed. Note: “inflammation of the brain”), especially in a child during the 2003 U.S. outbreak.
Children are more likely to develop more severe forms of the disease. Jean-Marc Zokoé, Provided by the author
Children who have been infected with monkeypox are more likely to have complications and therefore have a higher mortality rate than adults. Immunocompromised individuals (especially those who are HIV-positive) are also thought to have a higher risk of developing a serious form of the disease, but there is not yet enough data to know for sure. During the Nigerian outbreak of 2017-18, four out of seven people who died from the disease were HIV positive. Pregnant women could also be affected by less moderate forms and we observed cases of mother-to-child transmission.
The treatment of the disease is largely based on the symptoms and involves methods such as disinfection of the lesions, administration of antibiotics in cases of secondary infection, and rehydration. It is currently being investigated whether certain antiviral molecules such as tecovirimat could be effective against monkeypox, but the results are not yet conclusive.
TC: Is this the first time the virus has spread outside the African continent? How many cases have been reported so far and where?
CB: No, it’s not the first time. Although the Congo Basin strain has never traveled beyond Africa, the West African strain managed to reach the United States in 2003 using imported animals that had been infected. More recently, however, several countries have reported several human-caused cases.
In 2003, a number of individuals in the United States caught the virus of infected prairie dogs purchased from pet stores where the animals had been in contact with smallpox-carrying shrimp rats (Cricetomys gambianus) imported from Ghana. A total of 47 suspected cases of human infection were reported, all as a result of zoonotic transmission (i.e., from animal to human). There were no cases of interhuman transmission. At the time, U.S. authorities were concerned that the virus could take over a reservoir of local species, but that did not happen.
Tammy Kautzer takes care of her prairie dog in Dorchester, Wisconsin, on June 9, 2003. This mother was among a number of U.S. residents that year forced to quarantine their homes after entering in contact with prairie dogs infected with monkeypox virus. Mike Roemer / Getty Images North America / AFP
Then, in September 2017, there was a more serious outbreak in Nigeria, which had not experienced any smallpox epidemic in the previous 39 years. This particular epidemic is still ongoing, sustained by sporadic and regular transmissions, both zoonotic and interhuman. To date, at least 500 suspected cases have been reported (215 of which have been confirmed). It is reassuring, though sadly, only 8 deaths have been documented in the last 5 years.
However, the Nigerian epidemic had marked a major shift in the epidemiology of monkeypox and should have acted as a warning to us. While the virus had tended to thrive in low-lying forest regions, in 2017 it affected the most urban areas of the country and on a larger scale. This is how it spread most easily across the continent, with cases arising in 2018 in Singapore, Israel and England, returned by travelers returning from Nigeria.
In the case of England, local human-to-human transmission occurred when a British healthcare worker became infected while cleaning a patient’s bed. There was no endemic viral circulation at that time, but in 2021 more infections arose, again linked to travelers returning from Nigeria and occurring in both the United Kingdom and the United States (where two cases were reported).
In the UK in 2018, scientists also studied the risk of an endemic animal reservoir. Species such as the common squirrel (Sciurus vulgaris) and the house mouse (Mus musculus) were thought to be especially prone to the virus, while other rodents (campos, dormice, other mice) or hedgehogs were still considered possible reservoirs.
TC: What’s different in the current context?
CB: The situation is very different this time. We know that the first case of the current epidemic, recorded on May 7 in the United Kingdom, was that of an individual traveling from Nigeria. However, several other cases in the United Kingdom have since been confirmed that are apparently unrelated to this May 7 case. No case of foreign travel (to African countries) associated with infections has yet been demonstrated and direct transmission chains have not been identified, suggesting the existence of several transmission chains and local circulation of the virus.
As of June 6, 1,000 cases had been detected in at least 30 different countries worldwide, with the highest number of cases located in the United Kingdom (287 confirmed), Spain (189 confirmed), Portugal (143 confirmed). French authorities have reported 51 confirmed cases. So far, all infections recorded outside Africa have been mild. Only a few patients have been hospitalized and no death or life threatening has been reported. A significant proportion of cases were reported among HIV + patients.
That said, these local circulations of the disease are unprecedented. Another new aspect is that cases have been reported almost exclusively among young men, mainly gay men (in the UK, the authorities emphasized that “currently most cases have been in gay, bisexual or have sex with men). men ”). Not more…