Chapter 1: Overview of Multisystem Inflammatory Syndrome

As a pediatrician, I am relieved that COVID-19 generally spares children. However, an unusual trend has emerged: a notable rise in a rare condition known as Kawasaki Disease, along with similar syndromes. These are categorized under Pediatric Inflammatory Multisystem Syndrome (PIMS) or Multisystem Inflammatory Syndrome in Children (MIS-C).

Kawasaki Disease primarily impacts children under five, yet we are witnessing its occurrence across all age groups. Key symptoms include a prolonged high fever lasting five days or more, accompanied by:

• A rash
• Swollen glands in the neck
• Dry, cracked lips
• Red fingers or toes
• Red eyes

While the exact cause of Kawasaki Disease remains unclear, there is evidence suggesting that an infection or an inappropriate immune response to an infection could trigger this condition. This trigger may stem from any bacterial or viral infection. Experts hypothesize that an exaggerated immune response leads to white blood cells infiltrating blood vessel walls, causing inflammation (vasculitis) and subsequent cardiovascular damage.

The heightened immune response can result in inflammatory damage to vital organs such as the heart, kidneys, lungs, and even the brain.

The diagnosis of Kawasaki Disease can be difficult early on, as several illnesses exhibit similar symptoms, ranging from common viral infections to other inflammatory conditions like Toxic Shock Syndrome (TSS). TSS, while rare, is a life-threatening condition resulting from bacteria entering the body and releasing harmful toxins.

Recent analyses of pediatric cases admitted to Intensive Care Units (ICUs) in London and across the UK indicate a significant uptick in children diagnosed with either TSS or Kawasaki Disease. Anecdotally, one children's ICU in London has reported seeing 1-2 cases of TSS or Kawasaki Disease daily, compared to the typical 1-2 cases per month.

This trend is also being noted in various centers throughout Europe and the United States.

Chapter 2: Clinical Observations and Warning Signs

Pediatric intensive care specialists worldwide are collaborating to analyze cases and uncover potential links. The clinical features observed in these children, who tested positive for COVID-19 or had contact with a positive case, include:

• Prolonged high fever lasting 5-7 days
• Blood tests indicating elevated inflammatory markers
• Symptoms of mucositis (such as conjunctivitis)
• Rashes
• Severe abdominal pain that sometimes necessitated appendectomy
• A trend toward worsening health requiring increased intensive care support

Notably, Kawasaki Disease may manifest even after a child appears to have fully recovered from the initial COVID-19 infection. The prevailing hypothesis is that the immune response remains active post-infection.

Warning Signs to Monitor

Pediatricians, pediatric intensivists, and emergency department physicians should be vigilant for Kawasaki Disease in children presenting with high fevers and appearing unwell. Blood tests showing elevated inflammatory markers should heighten suspicion for this syndrome. Some children may also exhibit severe abdominal pain that resembles appendicitis.

Recognizing this rare complication is critical; with appropriate treatment (such as immunoglobulins and steroids), children often experience rapid improvement with minimal long-term consequences.

In general, most children with COVID-19 tend to have uncomplicated recoveries. For those who appear significantly unwell, early medical intervention is crucial. During the lockdown, many children have benefited from reduced exposure to other infections, allowing for adjustments in their treatment regimens without the disruptions typically caused by nurseries and schools.

In a more positive light, I explore some of the health benefits for children during the lockdown in this article, highlighting the need for a silver lining amidst challenging times.

The first video titled "Mayo Clinic Q&A podcast: Children, COVID-19 and multisystem inflammatory syndrome" provides valuable insights into the impact of COVID-19 on children's health and the rise of related syndromes.

The second video, "COVID-19 Update: Multisystem Inflammatory Syndrome in Children (MIS-C)," discusses the latest findings and implications regarding this serious condition in children.