The current issue of the Lancet carries a study of 10 Italian children diagnosed with a Kawasaki-like syndrome, recently reclassified by the World Health Organization as Multisystem Inflammatory Syndrome—Children (MIS-C). The study compares the Covid-19 related syndrome to that observed for 19 children with Kawasaki Syndrome in the same hospital over the past five years.
Here are some of the take-home messages about MIS-C compared to previous, non-Covid-19 related Kawasaki cases:
1. MIS-C is a consequence of infection with SARS-CoV-2.
2. The average of of children with MIS-C is 8 years old as compared to 3 three years old for Kawasaki. The WHO definition of children includes all those between 0-20 years old.
3. MIS-C is more serious that Kawasaki Syndrome and frequently involves damage to the heart and lungs.
4. The disease is effectively treated with a combination of intravenous gamma globulin and high dose methylprednisone (10 of 10 positive responses). Methyl prednisone is usually not needed for the treatment of non Covid-19 related Kawasaki.
What does this mean for parents? Here are the take home messages for those caring for young kids:
1. MIS-C is a rare life-threatening disease for your child. It can be treated but you must take your child to the hospital immediately at the first signs of the disease.
2. Be alert for signs and symptoms of MIS-C if anyone in your community is diagnosed as either SARS-CoV-2 infected or is ill with Covid symptoms.
3. Be on high alert if anyone in your family or your child’s school is diagnosed with Covid-19, is SARS-CoV-2 infected or is ill with Covid-like symptoms.
4. Be aware that MIS-C occurs several weeks after exposure. The time to be on highest on alert is 2-4 weeks post-diagnosis of a close contact.
5. Symptoms include fever, rashes, reddened toes, diarrhea, fainting. A child may appear to be entirely normal one moment and faint the next.
Kawasaki seems to be a mild form of MIS-C. MIS-C children display all the clinical and laboratory characteristics of Kawasaki and many more.
Kawasaki is described as a general inflammation of the medium-sized blood vessels. Kawasaki patients have a constellation of blood abnormalities that have been designated as Kawasaki Disease Shock Syndrome (KDSS) and Macrophage Activation Syndrome (MAS). All are typical of children MIS-C. Both KDSS and MAS are characteristic of MIS-C.
Clinical differences in case presentation:
1. Children with MIS-C are typically older than those with Kawasaki
2. MIS-C children often are in respiratory distress—low oxygen saturation
3. MIS-C children more often present with diarrhea
4. MIS-C children often have signs typical of encephalitis, meningeal symptoms—painful neck flex, and leg extension.
Clinically, the presentations of the two diseases also vary:
1. Lung X-ray abnormalities
2. Cardiac aneurysms (ballooning of the arteries reflecting weakened blood vessel walls.)
3. Low levels of leucocytes and lymphocytes
4. Thrombocytopenia (low platelet levels)
5. Increased levels of ferritin (typical of abnormal inflammation)
6. High troponin levels (indicates cardiac damage, in the case of MIS-C myocarditis-inflammation of the heart).
All of these abnormalities are typical of adult Covid-19.
Five of the ten children were known to be exposed to Covid-19 in the weeks before hospitalization.
SARS-CoV-2 RNA was detected in two of the 10 children by nasal swabs. Three of the children tested positive for anti-SARS-CoV-2 IgA or and eight for IgG indicating that they had been infected at least two weeks or more before infection.
The authors speculated that Kawasaki Syndrome is also the late consequence of infection with a coronavirus and suggests that, like MIS-C, it is a late consequence of infection, accounting for the difficultly in isolating the causal agent. Like MIS-C, the virus may be long gone before the symptoms appear. If so, this paper provides the clues to unravel this longstanding mystery.