Covid, MIS-C, or Kawasaki disease? Similar symptoms in kids have made correct diagnoses challenging

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  • Very few children experience severe Covid-19 disease and develop complications such as MIS-C
  • Diagnosing MIS-C can be difficult, as symptoms may be similar to those of Kawasaki disease
  • In a new paper, researchers provide insight into how doctors can accurately diagnose Covid, MIS-C, and Kawasaki disease

The new coronavirus has turned the world upside down and claimed the lives of more than 2.6 million people worldwide, although children have been largely spared.

However, doctors have been warned to look out for an inflammatory condition, called multisystem inflammatory syndrome in children (MIS-C) in otherwise healthy children and adolescents.

This rare but potentially life-threatening condition has been linked to Covid-19 disease, and can affect several organs and systems in the body, including the heart, brain, lungs, kidneys and gastrointestinal system.

Comparing clinical and lab results

In the early stages of the pandemic, it was described as an “atypical Kawasaki-like condition” since the condition had similar symptoms and behaviour to Kawasaki disease (KD). Typical KD is a rare disorder that causes inflammation in the blood vessels.

Unfortunately, diagnosing and treating MIS-C is difficult as its respiratory and gastrointestinal symptoms can be similar to severe Covid-19. And with other features of MIS-C being very similar to Kawasaki disease, it could make correct diagnosis quite challenging.

Attempting to solve this problem, assistant professor of paediatrics, Steven Horwitz (from Rutgers Robert Wood Johnson Medical School in New Jersey) and colleagues studied these conditions in 1 116 young patients (under 21 years old) hospitalised from March through October 2020.

All patients displayed symptoms that could have been caused by any of these disorders. They then compared clinical and laboratory results to determine how to more accurately diagnose MIS-C.

Their paper, published in JAMA Network, provides important insights.

About the three conditions

The first case of MIS-C was reported in a child in Europe on 28 April 2020. According to Horwitz’s paper, it has affected 2 600 children since May 2020 and is known to occur in children who have tested positive for SARS-CoV-2 (the virus that causes Covid disease), or have been exposed to someone with Covid-19.

It is an entirely new phenomenon in paediatrics and was initially termed paediatric multisystem inflammatory syndrome (PMIS). Although it occurs in association with SARS-CoV-2 infection, Horwitz explained in a news release that the symptoms can be delayed for several weeks in children who have Covid disease but who are asymptomatic (displaying no symptoms).

“Complicating the diagnosis, MIS-C symptoms also are similar to those of Kawasaki disease, the leading cause of acquired heart disease in children. Although the symptoms are similar, the potential complications, treatments and outcomes can be different. If we can distinguish these conditions better, it will improve treatment and follow-up care,” wrote Horwitz.

MIS-C, Kawasaki, or Covid?

In general, children with MIS-C tend to get sicker than those with acute Covid, explained Horwitz, as more organs are involved.

But the key factor to bear in mind is: “While children with acute Covid-19 can have respiratory and gastrointestinal symptoms directly related to the virus, MIS-C seems to be an inflammatory response to the infection that occurs several weeks later, and that can resemble Covid-19,” he explained.

In their study, 80% of the children with MIS-C and Covid each had severe respiratory symptoms, but more children with MIS-C had multiple organ involvement, including cardiac problems and mucus membrane conditions, such as rashes or redness in the eyes. These symptoms presented similarly to what is seen in patients with Kawasaki disease.

MIS-C vs Kawasaki

Compared with Covid and Kawasaki disease, MIS-C is more likely to affect Hispanic/Latino or Black children, said Horwitz.

MIS-C is also more likely to affect children who have no underlying medical conditions, as well as those aged between six and 12 years. Moreover, it is more likely to cause gastrointestinal symptoms than Kawasaki disease.

Horwitz also stated that both Kawasaki disease and MIS-C affect more boys than girls, but that Kawasaki disease affects primarily those of East Asian descent and appears in younger children, around the ages of two to three years.

In a separate article published in the South African Medical Journal (SAMJ), four researchers explained that "children are seldom infected with severe Covid-19 and are a highly unlikely source of spread of the virus. If they do develop an exaggerated immune response, it may present as an atypical Kawasaki-like condition now referred to as [MIS-C]."

Study will assist with identifying correct treatment

“What we learned will help refine how MIS-C is diagnosed and treated,” said Horwitz. “For example, while children with Covid-19 or MIS-C could benefit from anti-inflammatory treatments like steroids, children with MIS-C could further benefit from other treatment options such as intravenous immune globulin.”

He advised that these paediatric patients should also follow up with a cardiologist to check for changes in heart function, cardiac arrhythmia or coronary artery disease.

Tip for parents

Being a parent himself, Horwitz empathised with other parents whose children have MIS-C.

“I have children, so I understand how nervous parents are about this new syndrome,” he said, and advised: “If your child develops a multitude of symptoms such as persistent fevers, rash or seem unusually tired, have your child assessed by a medical professional to rule out MIS-C.”

According to the authors of the SAMJ article, cases have also been observed in SA. "If a child is suspected of having this condition, he or she must be referred for specialist care in a setting with high-care or intensive care facilities for prompt initiation of treatment in order to avoid the morbidity and mortality related to this disease," they wrote.

While MIS-C is a serious condition, Horwitz concluded on a comforting note, saying that most children, including those with severe cardiac symptoms, usually recover within 30 days.

READ | Do children and teens need to be vaccinated to get the Covid-19 pandemic under control?

READ | Two more J&J trials underway to test vaccine in pregnant women and adolescents, and two-dose effect

READ | Coronavirus transmission happens in the air, too much focus on cleaning surfaces, evidence shows

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