Kawasaki disease-like symptoms linked to coronavirus in children is an entirely new condition, say experts

The condition appears to affect older children than Kawasaki disease and presents more often with abdominal pains and diarrhea

                            Kawasaki disease-like symptoms linked to coronavirus in children is an entirely new condition, say experts
(Getty Images)

Some countries have been grappling with a mysterious illness in children potentially related to Covid-19, with symptoms similar to Kawasaki disease. Researchers now say that children who develop dangerous inflammatory symptoms are suffering from an entirely new condition, which is distinct from Kawasaki disease.

In April, researchers in the UK and several European countries with high numbers of Covid-19 cases reported a new inflammatory syndrome in children that was similar to Kawasaki disease, a rare syndrome known to affect young children. The New York State Department of Health is also investigating 204 reported cases and three deaths in children — predominantly school-aged — experiencing symptoms similar to Kawasaki disease and toxic shock-like syndrome, possibly due to coronavirus.

Kawasaki disease, which usually affects children five years and younger, is the presence of a high fever, rash on back, chest, and abdomen, swollen red hands and feet, and bloodshot eyes, among others. Now, in a new study, researchers have identified the main symptoms and clinical markers of the new syndrome. This will help clinicians diagnose and treat the condition and researchers to understand it further and find new treatments, says the team led by Imperial College London.

The study involved clinicians and academic partners in hospitals across England, including Great Ormond Street Hospital (GOSH), Evelina London Children’s Hospital, and Kawasaki Disease Research Center at the University of California San Diego. The condition, which the researchers have named Paediatric Inflammatory Multisystem Syndrome Temporally associated with SARS-CoV-2 (PIMS-TS), was studied in 58 children.

They were admitted to eight hospitals in England between March 23 and May 16, 2020, and the final date of follow-up was May 22. Clinical and laboratory characteristics were abstracted by medical record review and were compared with clinical characteristics of patients with Kawasaki disease, who had been admitted to hospitals in Europe and the US from 2002 to 2019. 

According to the research team, the new condition is believed to be extremely rare, but it can make a child very ill, and there are concerns about long-lasting coronary damage. "Our analysis has shown that this is indeed a new condition. Untreated, there is a risk of severe complications in very unwell children, but with early identification and treatment, the outcome is excellent, with the children we are reviewing after discharge completely well. For clinicians, it's important that we build collaborative research to quickly improve our understanding of the condition and provide the best evidence-based treatment for our patients," said Dr Julia Kenny, consultant in pediatric infectious diseases and immunology at Evelina London, in the report published in JAMA.

According to the research team, the condition is believed to be extremely rare, but it can make a child very ill, and there are concerns about long-lasting coronary damage (Getty Images)

The condition appears to be more likely to affect older children than Kawasaki disease (average nine years old versus four years old respectively) and presents more often with abdominal pains and diarrhea alongside the common features such as persistent fever. It also appears to affect a higher proportion of Black and Asian patients, shows analysis. Blood tests show different results, with PIMS-TS patients showing more markers of inflammation and cardiac enzymes, which suggest the heart is under strain.

Kawasaki disease is known to damage the coronary artery in such a way that as the child grows the artery does not, leading to a reduction in the amount of blood that can reach the heart. Immune therapy is known to help alleviate these problems, so it has been used on patients with PIMS-TS as well, but the team says differences in the two diseases mean this needs to be investigated further and treatment should be carefully monitored.

While the team cannot say for certain that the new condition is caused by Covid-19, 45 of the 58 children had evidence of current or past coronavirus infection, and the researchers say the emergence of a new inflammatory condition during a pandemic is unlikely to be a coincidence. The majority of children with indications of infection had antibodies for the new coronavirus, suggesting PIMS-TS happens after infection, potentially as a result of an immune system overreaction, they explain.

Accordingly, the researchers say understanding more about the new condition could help a more general understanding of Covid-19 and its effects, even in adults. Because PIMS-TS is so distinct, it is easy to study individuals with high inflammation, which may be harder to identify in the general population, they add. 

"Results from SARS-CoV-2 polymerase chain reaction tests were positive in 15 of 58 patients (26%) and SARS-CoV-2 IgG test results were positive in 40 of 46 (87%). In total, 45 of 58 patients (78%) had evidence of current or prior SARS-CoV-2 infection," says the study. It adds, "In this case series of hospitalized children, there was a wide spectrum of presenting signs and symptoms and disease severity, ranging from fever and inflammation to myocardial injury, shock, and development of coronary artery aneurysms. The comparison with patients with Kawasaki disease (KD) and KD shock syndrome provides insights into this syndrome, and suggests this disorder differs from other pediatric inflammatory entities."

The research team says that an important next step will be to review the current data in the context of other studies being published globally. This will help inform management guidelines and to further refine the case definition, they say. 

In New York, among children displaying Kawasaki disease-like symptoms, 94% tested positive for Covid-19, shows analysis. Healthcare providers, including hospitals, are required to report to the Department of Health all cases -- being referred to as pediatric multisystem inflammatory syndrome potentially associated with Covid-19 -- in those under 21 years of age.

"Though most children who get Covid-19 experience only mild symptoms, this inflammatory syndrome has features that overlap with Kawasaki disease and toxic shock syndrome and may occur days to weeks after acute Covid-19 illness. Early recognition by pediatricians and referral to a specialist including to critical care is essential," says the New York State Health Department. 

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