Transmission, symptoms, circulation, vaccination… Seven questions on the new mpox epidemic, which is spreading in several countries

A new, more contagious and dangerous variant has been hitting several African countries for months. A case was identified in Sweden on Thursday, the first in Europe.

Should we fear a new pandemic? The World Health Organization (WHO) on Wednesday, as it had already done in 2022, triggered its highest level of global alert due to the resurgence of cases of mpox (formerly called “monkeypox”) caused by a new variant of this virus (clade 1b) previously concentrated on the African continent, but which is now spreading to other countries. A case was identified in Pakistan on Friday, August 16, while another, the first in Europe, was recorded on Thursday in Sweden. For its part, China has strengthened its border controls.

What do we know about this new epidemic wave? How is this disease transmitted? What are the symptoms? How can we protect ourselves? Franceinfo takes a look at the most important questions.

1 Where does the mpox virus come from (and why this name)?

The discovery of this viral infectious disease dates back almost seventy years. MPOX was first isolated in 1958 from laboratory monkeys in Copenhagen (Denmark), recalls the Pasteur InstituteAt the time, these primates had lesions on their skin similar to those left by human smallpox.

This virus, dubbed “monkeypox” (“monkeypox” in English) when it was discovered, belonged to the same family as human smallpox, which was eradicated worldwide in the late 1970s. But several experts have considered its name inappropriate in recent years. “It’s a rather misnamed virus, because its natural host is more rodents, such as Gambian rats.”explained Olivier Schwartz, director of the virus and immunity unit at the Pasteur Institute, to franceinfo in June 2022. It is for this reason, and to avoid “racist and stigmatizing language”which WHO has decided to rename the virus “mpox” in November 2022.

2 Why did the WHO trigger its highest level of alert?

The new variant of the virus, called “clade 1b”, is more deadly, more contagious and affects more populations than previous ones. According to the emergency committee on mpox, the current situation constitutes “a public health emergency of international concern”wrote WHO chief Tedros Adhanom Ghebreyesus on Wednesday on XThe organization is particularly concerned about the mortality rate of this new strain, which is much higher, and can reach 5% in adults and 10% in children.

The African Union’s health agency announced on Tuesday a 160% increase in cases in 2024, compared to the previous year. “The number of cases recorded [en RDC] since the beginning of the year is already higher” in total recorded in 2023, with “more than 15,600 cases and 537 deaths”reported l’OMS Wednesday.

The triggering of the maximum alert allows the “countries that have vaccines in stock [de] make donations faster”Sylvie Briand, director of the WHO’s department of global preparedness for epidemic risks, explained to franceinfo. “It is also a question of ensuring, since the virus crosses borders, (…) to reduce international transmission”.

3 In which countries is MPOX currently circulating?

The new variant was first discovered in the DRC, in the displaced persons camps around Goma, in the northeast of the country, in September 2023. However, this city has an international airport and is located in a conflict region, bordering several countries. “The risks of explosion are real given the enormous population movements”Louis Albert Massing, medical coordinator for Doctors Without Borders (MSF) in the country, told AFP.

In just a few weeks, the virus has effectively spread beyond borders. According to Tedros Adhanom Ghebreyesus, quoted by AFP on Wednesday, “In the past month, approximately 90 cases of clade 1b have been reported in four neighboring countries that had never previously reported MPOS : Burundi, Kenya, Rwanda and Uganda”.

In recent days, the virus has reached two new continents, with a case reported in Sweden on Thursday and another in Pakistan on Friday. “It is likely that further imported cases of clade 1 will be recorded in the European region in the coming days and weeks”the WHO’s European branch announced in a statement Thursday evening.

4 Hasn’t there already been an epidemic in recent years?

In the spring of 2022, a wave of mpox affected part of the world. Its spread was then described as “extraordinary” by the WHO, which had declared the global health emergency in July.

But this epidemic surge, which affected around a hundred countries, was finally contained and the WHO alert lifted in May 2023. The variant of the virus, called “clade 2”, less virulent than clade 1b today, contaminated more than 87,000 people worldwide and caused 140 deaths between January 1, 2022 and May 8, 2023, according to figures communicated by l’organisation (PDF).

As of May 2023, more than 5,000 cases had been recorded in France, can we read on the Vaccination info service website. No deaths have been reported by Public Health France.

5 How is the disease transmitted?

MPOX can obviously be transmitted by direct contact with infected animals. Regarding human-to-human transmission, the Ministry of Health explains that it can occur in three ways, direct or indirect: “Un prolonged face-to-face contact by respiratory droplets [salive, éternuements, postillons] or by direct contact with an infected person; through bodily fluids, skin lesions from the disease, or internal mucous membranes such as the mouth; indirectly through objects that the sick person has contaminated, such as clothing or bed linen.”

Previous variants mostly affected gay and bisexual men. But with clade 1b, there have been many cases of transmission during heterosexual or non-sexual contact, including between mothers and children, or between children in schools. There have also been many miscarriages, and researchers are studying possible effects on fertility.

6 What are the symptoms?

Symptoms begin with a phase characterized by fever, chills, sweating, fatigue and swollen, painful lymph nodes. Sore throat, cough and body aches are also reported by sick people.

Then, a rash of pimples, sometimes urticating, spreads over the skin. They look like small bumps filled with pus or clear fluid and most often appear on the face, palms of the hands, and soles of the feet. They then turn into scabs before healing in the weeks that follow. These vesicles can also colonize the mucous membranes, including the mouth and genital areas.

As the incubation period of the virus can range from five to 21 days, “It is therefore important that patients remain isolated for the entire duration of the illness (until the last scabs have disappeared, usually three weeks)”warns the Ministry of Health.

Although it is benign in the majority of cases, the disease can nevertheless give rise to complications, wrote the Pasteur Institute in 2023which notably lists “skin superinfections, septicemia, encephalitis or corneal damage”. ““Immunocompromised people, pregnant women and young children would be at greater risk of developing a severe form of the disease.”specifies for his part the French Ministry of Health.

With the new variant, the head of the WHO is alarmed: clade 1b “causes more severe disease than clade 2”. It leads to “rash all over body”explains Trudi Lang, professor at the University of Oxford (United Kingdom), in an interview published on the site of the Gavi (Global Alliance for Vaccines and Immunization) organization. According to her, the symptoms also tend to last “for a long time”. In the same interview, Leandre Murhula Masirika, who is leading research in the DRC, spoke of side effects linked to the infection, with patients complaining of “problems with the eyes, skin or genitals”.

7 Are there any treatments or vaccines?

Initially designed for the treatment of smallpox, an antiviral agent, administered in cases of severe infection, has been approved for the treatment of MPOX, recalls the Pasteur Institute. For lighter infections, no treatment exists, the symptoms disappear spontaneously, underlines l’OMS.

To prevent infection, two vaccines exist, but few doses are available in the most affected African countries. Patients vaccinated against smallpox when young have less severe symptoms, but the campaigns ended in 1980, after the disease was eradicated. “Therefore, at present, people under 40-50 years of age (depending on the country) may be more susceptible”specifies the WHO. Moreover, we do not know the degree of effectiveness of these vaccines against the new variant of the virus. It is therefore necessary to focus on prevention by raising awareness and informing the population.

The Ministry of Health reminds that since July 2022, a specific listening device for the mpox virus, responsible in particular for informing, advising and directing towards care systems, has been available. Monkeypox info service is accessible 7 days a week, from 8 a.m. to 11 p.m., on the toll-free number 0 801 90 80 69.