New cases of children with inflammatory syndromes similar to Kawasaki disease have been reported in France since this fall. 62% of cases were positive for Covid-19. What are the symptoms ? The after-effects? How many (fatal) cases in France?

[Mise à jour le vendredi 20 novembre à 10h44] At the end of April 2020, doctors alerted the authorities to cases of pediatric multisystem inflammatory syndrome (PIMS) observed in young children with some symptoms close to the Kawasaki disease and for the most part with a infection Covid-19 recent. In Italy, United Kingdom, Belgium, but also in France, learned pediatric societies and health authorities have set up active surveillance of these atypical clinical pictures. In its epidemiological update of November 19, Public Health France indicates that “from new cases of PIMS have been reported since this fall, bringing to 254 the number of cases observed between March 1 and November 15, 2020 “. Do these cases remain rares ? What are the symptoms ? The sequelae and the treatments? Explanations.

Kawasaki disease or “Lympho-cutaneous-mucous syndrome“was described by Tomisaku Kawasaki in 1967. It is a vascularite that is, a disease characterized by inflammation of the blood vessels which, in the absence of treatment, may becoming complicated with coronary aneurysms which can be fatal. Although this disease has been reported worldwide, it is very more common in Asian populations, in particular at Japan. In the vast majority of cases, it affects infants and young children before puberty. This disease is rare in adolescents and adults.

The alert in France was given in April by the Necker hospital which reported the cases of 25 children hospitalized in intensive care in the Paris region with inflammatory syndrome. “This inflammatory syndrome involves heart, lungs or the digestive system, explained Doctor Damien Bonnet, coordinator of the M3C Necker network in Paris to the daily Midi Libre. The clinical condition of some patients recalls the Kawasaki disease. Some children had recently had a Covid-19 infection. In order to better identify these atypical clinical pictures, hospital pediatricians have been invited, since April 30, to report each new case possibly related to Covid-19 to Public Health France, as well as retrospectively since March 1, 2020 . New cases of PIMS have been reported since this fall, bringing to 254 the number of cases observed between March 1 and November 15, 2020, indicates the latest Public Health France bulletin of November 19:

128 cases of “pediatric multisystem inflammatory syndromes” (50%) concerned girls.

→ The median age of cases was 7 years (25% of cases were ≤ 3 years old and 75% ≤ 11 years old).

→ A stay in intensive care was needed for 118 children (46%) and in critical care unit for 44 children (17%). The other children were hospitalized in the pediatric ward.

→ Only one child, aged 9, is deceased, in a picture of systemic inflammation with myocarditis.

62% of cases had a positive PCR er / or serological test for the Sars-CoV-2 virus responsible for the Covid-19 disease.

→ Almost half of the cases (122) were reported in the region Ile-de-France, and between 10 and 27 cases in Auvergne-Rhône-Alpes, Grand Est, Normandy, New Aquitaine and Provence-Alpes-Côte d’Azur.

Weekly distribution of hospitalizations for PIMS, according to the link with COVID-19, and COVID-19 hospitalizations for all ages, France, from March 2 to November 15, 2020 (data as of November 17, 2020)

Weekly distribution of hospitalizations for PIMS, depending on the link with COVID-19, and COVID-19 hospitalizations for all ages, France, from March 2 to November 15, 2020 © Public health France

What is the link with Covid-19?

The alert first came from UK where the National Health Service (NHS) reported in April cases of dozen children hospitalized in serious condition with fever, inflammation of the arteries (associated with “pediatric multisystem inflammatory syndromes” (PIMS) similar to Kawasaki disease) and for most positive for Covid-19. According to a study carried out at the‘Robert-Debré hospital (Paris) the incidence of cases similar to Kawasaki disease has increased by 500% in April 2020 in the establishment, compared to the last 15 years.

“the data collected confirm the existence of a rare pluri-systemic inflammatory syndrome in children with frequent cardiac involvement, linked to the Covid-19 epidemic

For Professor Albert Faye, head of the pediatrics department at Robert-Debré hospital interviewed by Francetvinfo, the link between Covid-19 and Kawasaki disease in children appears quite clearly since at that time, the SARS-Cov-2 was “the only” respiratory virus that was circulating. ” A mean time to onset cases of PIMS 4 to 5 weeks after infection with SARS-CoV-2 was observed during the first wave, reports Santé Publique France. After a peak observed in week 18 (hospitalization week), the number of reported cases decreased significantly during the summer, before a moderate increase at the end of September As of week 39: 46 confirmed cases were reported between September 21 and November 15.

According to data transmitted by Public Health France on November 19, 2020, on the 254 cases of “pediatric multisystem inflammatory syndromes” (PIMS):

  • 62% had a positive PCR and / or serological test for the Covid-19 virus.
  • The link to the virus was “probable” in 7% of patients and considered “possible” in 8%. For 23%, the link could not be established.
  • Among the 196 patients for whom the link with Covid-19 was possible, probable or confirmed, PIMS was associated with myocarditis in 72% of cases. Among the 58 unrelated patients, myocarditis was found in only 5 of them.

In total, concludes Santé Publique France, “The data collected confirms the existence of a rare pluri-systemic inflammatory syndrome in children with frequent cardiac involvement, linked to the Covid-19 epidemic, also observed in other countries. In France, the incidence of PIMS linked to Covid-19 has been estimated at 13.5 cases per million inhabitants in the population under 18 years old ” (i.e. 14,511,544 inhabitants, INSEE 2019 data).

What are the symptoms ?

Children with Kawasaki disease are in poor general condition. Symptoms suggestive of Kawasaki disease:

  • a prolonged unexplained fever, above 38 ° C, which persists for at least 5 days and does not respond to antipyretics or antibiotics,
  • a rash;
  • conjunctivitis that appears with fever;
  • oropharyngeal damage (erythema of the lips, dryness, cracks and sometimes bleeding). The tongue is raspberry;
  • cervical lymphadenopathy (swollen glands);
  • damage to the feet and hands: erythema of the palms or soles as well as edema, peeling of the skin, that is to say a loss of the surface layer of the epidermis, mainly affecting the area towards the organs genitals, soles or palms of the hands.

In children positive for coronavirus : It’s about a form “more marked” of the Kawasaki maladie, with “an attack on the digestive level, abdominal pain, describes Professor Albert Faye. Inflammation is “a little more important than in the classic disease”, with a damage to the heart, inflammation of the heart muscle and inflammation in the pericardium, inflammations “more frequent than in Kawasaki disease” classic.

The severity of this disease is defined by the heart risks that it can generate, in the absence of treatment. “Cardiac complications occur in 25 to 30% of untreated patients, reports La Revue du Praticien. The most important complication is represented by coronary aneurysms, which usually occur between 10 and 30 days after the onset of the disease. ” Among the 196 patients for whom the link with Covid-19 was possible, probable or confirmed, PIMS was associated with myocarditis in 141 cases (72%), indicates Santé Publique France on November 19. Among the 58 unrelated patients, myocarditis was found in only 5 of them. A stay in intensive care was necessary for 118 children (46%) and in critical care unit for 44 children (17%). Only one child, aged 9, died, in a picture of systemic inflammation with myocarditis

The diagnosis of Kawasaki disease is difficult to ask at first, because many childhood illnesses have similar symptoms. It is before the association of the aforementioned signs, classically five of the six signs mentioned above, that the diagnosis is confirmed. A blood test is sometimes taken showing inflammation at its level, but if Kawasaki disease is confirmed, a Echocardiography should be practiced in search of a coronary aneurysm that is to say a malformation of an artery of the heart which is the seriousness of this childhood disease. Thrombosis, blood clots blocking a blood vessel, can also complicate this disease.

“Quickly, we can improve things, if necessary, by combining corticosteroids”

Kawasaki disease requires hospitalization. Pathology is treated with the help of a drug combination. Aspirin is used to prevent the formation of thrombosis, associated with a course of immunoglobulins passed through the veins. “There may be a little more resistance to immunoglobulins, notes Professor Faye. But quickly, we manage to improve things, if necessary, by combining corticosteroids “. In addition, the cardiac ultrasound should be repeated to monitor the occurrence of a possible aneurysm. “Kawasaki disease has become exceptionally serious since it was treated early and effectively with immunoglobulins” explains Dr Fanny Bajolle from the Center of Reference “Congenital Cardiac Malformations Complexes-M3C” of the hospital Necker Enfants Malades. Of relapses are possible but rare.

Sources :

COVID-19: epidemiological update of November 19, 2020, Public Health France, November 19, 2020.

Kawasaki disease in four tables. Dr Fanny Bajolle. Reference Center “Congenital Cardiac Malformations Complexes-M3C” of the Hospital Necker Enfants Malades. 2011.

Kawasaki disease; R. Cimaz *, J.-C. Lega; Lyon Civil Hospice, Claude-Bernard University, Lyon-1; 2007.

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