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Is the monkeypox virus a new virus? Nothis virus, which belongs to the Poxvirus family (like smallpox and its historic vaccine vaccinia) was first discovered in Denmark in imported monkeys in 1957 and the first human case described in 1970… English (Pocket or Pustule) emphasizes that these viruses are precisely prone to pustules… but not only.
Is the monkey the usual host of this virus? No, is a zoonosis that affects several species. Although the disease was initially described in monkeys, the Monkeypox reservoir is likely to be small African rodents. It is for this reason that the first human cases were described in Africa.
Were there outbreaks reported outside of Africa prior to this outbreak? Yeanotably in the United States, 2003: Importation of infected Gambian rats from Ghana contaminated American prairie dogs in the breeders who housed them, then humans who bought the prairie dogs as pets.
We often read that this disease is more serious in children, is this true? Probably not. The first series of cases actually studied in Africa included a majority of children with a relatively serious prognosis (15% mortality or even more), but their conditions of access to care and hygiene were not the same as in developed countries. This notion of severity is not found among the cases described in children in developed countries before this epidemic, then during this epidemic. However, the very small number of current cases in children does not allow us to be formal.
What are the characteristics of the current epidemic? There are several:
- Its magnitude: Between April and early October 2022, more than 70,000 cases were reported worldwide.
- This is the first time that human-to-human transmission has played an essential role in the spread of the virus.
- The primarily affected population is men (>97%), predominantly those who have sex with men and multiple partners. Women represent approximately 2% of infected individuals and children less than 0.5% of cases.
How is the virus transmitted during this epidemic? Essentially by close, repeated and/or prolonged contact of the skin and mucous membranes. Indirect transmission through surfaces or “fomites” (contaminated by the skin and mucous membranes of patients) is possible, where live viruses are found. Respiratory transmission is possible in theory, but marginal in this epidemic.
What do we know about pediatric cases during this outbreak? A Spanish series of 16 cases under the age of 18 was reported. There were 12 adolescents (9 infected in a tattoo and piercing parlor, 3 through sexual contact) and 4 children (3 cases of family contact and one child whose mode of contamination is unknown). Ten pediatric cases are listed in France by Santé Publique France; for half of the cases, a contact is known. A (serious) case has just been reported in England in a 9-day-old newborn whose father was sick.
What is the evolution of the epidemic in France? A Santé Publique France document dated October 4, 2022 provides an update on the Monkeypox epidemic in our country. Just over 4,000 cases, over 97% men, 10 children and for half of them, a known contact with an infected adult, over 100,000 doses of vaccine administered. The trend is rapidly decreasing (as in all western countries) and most of the epidemic seems to be behind us. This drop is probably a result of behavioral changes in the population at risk and the vaccination campaign. However, the disease should not yet be considered to disappear.
Should contact children be vaccinated? ? Not for now For different reasons. 1) The risk of intrafamilial transmission is low if hygienic conditions are maintained 2) No studies on vaccine tolerance in children have been published. However, the nature of the vaccine (non-replicating vaccine) and some previous clinical experience with this type of vaccine are reassuring. The British also offer it in their support algorithm. In France, it would be better for this vaccination to be done as part of a clinical trial.
Does the Monkeypox vaccine correspond to the smallpox vaccine whose use was discontinued forty years ago due to low tolerance? Nois a smallpox vaccine that is said to be 3º generation, developed after the eradication of this disease, in particular for fear of bioterrorism (Vaccine Modified Ankara or VMA). It is a non-replicating vaccine. It enters cells, expresses its antigens and induces immunity without being able to multiply in human cells. As a result, it is much better tolerated than the historic smallpox vaccine and is theoretically administerable to immunocompromised people, infants, and pregnant and lactating women. Its effectiveness against the Monkeypox virus is estimated at 85%.
What are the clinical conditions? I noticed ? The classic picture is a febrile vesicular eruption with fever for 1 to 3 days, headaches, then in a single attack, centimeter-sized, deep, “embedded” blisters, affecting the face, arms, palms, soles of the feet and progressing to crusts. . In this epidemic, the number of lesions is highly variable, predominating in the genital, oral and rectal regions in adults due to the mode of contamination. There are atypical forms, not very symptomatic. Cutaneous elements can be non-vesicular, sometimes of different ages, but often itchy and painful.
In case of predominantly mucosal contact, painful mucosal involvement and voluminous cervical lymphadenopathy are observed. Complications are not uncommon: skin superinfections, pneumonia, dehydration, etc.
In practice, in children, two situations can be foreseen:
- The child is in contact with a sick subject (figure 1). After having put in place, for the contact subject, the hygiene measures imposed by the disease (isolation, mask, hand washing, etc.), monitoring for 3 weeks and collection of samples regardless of the mucosal or general skin symptoms (the pretest being relatively high).
- The child is not in contact and has a pustular eruption (Figure 2). Monkeypox risk (pre-test probability) is very low. When evoking the usual diagnoses of pustular eruptions and asking for advice and additional tests useful for the diagnosis, a sample looking for Monkeypox may be needed.
How is the biological diagnosis of a Monkeypox infection made? By a PCR after smearing crusts or fluid from blisters, or from the throat in case of mucosal involvement. To prevent the spread of the disease, particularly among caregivers, samples must be collected under stringent conditions. For the time being, it is recommended to take the sample in a “P3” type laboratory. As viremia is very short, blood CRP is rarely positive and therefore useless. The first PCR usually targets orthopoxviruses as a whole and, if positive, specific Monkeypox PCR is performed. Specific RDTs are under development that allow a diagnosis within minutes.
Robert Cohen, Philippe Minodier, Yves Gillet
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