Transmission, symptoms, treatments… What we know about the virus

She dethroned the Covid-19 from our disturbing topics of conversation. A disease endemic to Central and West Africa, monkeypox is generally a harmless disease. But while the coronavirus pandemic is not yet behind us, the multiplication of contaminations with this virus in around twenty countries usually not affected by this virus, mainly in Europe and the United States in recent days, is worrying.

So, should we be worried that monkeypox has left its geographical cradle? How is it transmitted? Is it a dangerous virus? Are there treatments? 20 minutes reviews what is known to date about monkeypox.

Where is the virus circulating today and what are the modes of transmission?

Like Covid-19, monkeypox is a zoonosis, a disease initially transmitted to humans by an infected animal. “Indisputably, this virus has its origin in the animal world, confirmed this Thursday during a press briefing from the ANRS infectious diseases Steve Ahuka Mundeke, head of the virology department at the National Institute for Biomedical Research in the Democratic Republic of the Congo (DRC). However, very few publications exist, research has not yet clearly specified which are the reservoirs of the virus, but it is probably rodents. An endemic disease in West and Central Africa, monkeypox leads to “epidemic outbreaks mainly in remote, forest or rural areas, affecting people who are frequently in contact with the animal world, and rarely in large cities. Thus, two-thirds of cases are zoonotic and one-third result from human-to-human transmission,” he added.

A pattern “different from what we currently see in the West”, continued Steve Ahuka Mendeke. “This international outbreak of monkeypox was launched in May, first with the detection of six non-traveller cases in the UK, with no direct links to countries or people returning from countries where the virus usually circulates in Africa. Concomitantly, there was an ongoing investigation in Portugal of infectious syndromes associated with skin rashes in a group of MSM people, men who have sex with men,” raising the question of a possible new mode of disease transmission.

What is known is that human-to-human transmission “takes place mainly by direct contact of injured skin or mucous membrane with healthy skin or mucous membrane, and also by droplets, or by contact with linen infected, detailed Thursday Alexandra Mailles, epidemiologist at Public Health France. The international toll as of May 31 is 321 cases in the EU, mainly in Spain (120 cases), Portugal (96 cases) and the Netherlands (26 cases), and 236 cases outside the EU, including the United Kingdom. with 179 cases. As of June 1, France has identified 33 confirmed cases: 24 in Ile-de-France, 2 in Auvergne-Rhône-Alpes, 1 in Hauts-de-France, 1 in Centre-Val-de-Loire, 4 in Occitanie and 1 in Normandy”. These cases identified in recent weeks concern “the vast majority of men, declaring themselves to be MSM, and among them, a significant proportion declaring that they have sex with several partners. But to date, monkeypox is not considered an STI, it is a disease whose transmission is mainly by direct contact of damaged skin or mucous membrane with healthy skin or mucous membrane, and also by droplets, insisted the epidemiologist. Consequently, it is not the sexual relationship as such that is called into question, but the contact with the lesions during sexual intercourse”.

What are the symptoms of monkeypox and is it a serious illness?

The disease is mainly manifested by “the appearance of fever, intense headache, adenopathy (swollen lymph nodes), back pain, myalgia (muscle pain) and marked asthenia (lack of energy) “, describes the World Health Organization (WHO). In the wake of the fever then occurs “the rash, adds the WHO. It generally focuses more on the face (in 95% of cases) and the palms of the hands and soles of the feet (in 75% of cases). The oral mucous membranes (in 70% of cases), the genitals (30%) and the conjunctivae (20%), as well as the cornea are also affected”.

However, in the current outbreak, “there is a strong predominance of genital and anal lesions”, said Thursday Xavier Lescure, infectiologist in the infectious and tropical diseases department at the Bichat Claude-Bernard AP-HP hospital. But “none of these people required hospitalization because of the severity of their infection and no death has been recorded”, reassured Alexandra Mailles.

Monkeypox “usually heals spontaneously and symptoms last 2 to 4 weeks. Severe cases occur more frequently in children and are linked to the extent of exposure to the virus, the patient’s medical condition and the nature of the complications, says the World Health Organization (WHO). . The case fatality rate of monkeypox has historically ranged from 0-11% in the general population, with higher numbers in young children. Lately, the case fatality rate was around 3-6%.” In endemic countries, deaths caused by monkeypox are “mainly linked to late treatment, since cases occur in remote areas, which are less medically equipped, said Steve Ahuka Mundeke. With respiratory complications or bacterial superinfections linked to skin lesions. On the other hand, rapid and appropriate medical care considerably reduces the risks.

Are there preventive or curative treatments?

An antiviral drug, tecovirimat, designed for smallpox, was approved by the European Medicines Agency (EMA) for monkeypox in 2022, based on data from animal and human studies. It is not yet widely available, “it is indicated against severe forms” of the disease, recalled Xavier Lescure.

A third-generation vaccine against classic smallpox (non-replicating live vaccine, that is to say that does not replicate in the human body) has been authorized in Europe since July 2013. A vaccine which offers “cross-immunity” against to monkeypox, said Thursday Brigitte Autran, professor emeritus of immunology at the Faculty of Medicine of Sorbonne University. But “for the moment, there is no need to design a preventive vaccination campaign because of the low number of cases and the low severity of the disease”. On the other hand, with a virus having “an incubation period of one and three weeks, it is interesting to use it post-exposure” for contact cases, she continued, “to prevent or prevent the spread of infection.

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