May 13 (UPI) -- Researchers in Italy announced Wednesday that they have identified 10 cases of young children with COVID-19 symptoms that resemble Kawasaki disease, a rare inflammatory disorder.
Their findings, which were published by the Lancet, are similar to reports from New York, where more than 70 children have developed symptoms similar to the rare disease that can cause heart problems after becoming infected with the new coronavirus, SARS-CoV-2.
Three of the children in New York who experienced these "Kawasaki-like" symptoms, as the Italian researchers described them, died.
"We noticed an increase in the number of children being referred to our hospital with an inflammatory condition similar to Kawasaki disease around the time the SARS-CoV-2 outbreak was taking hold in our region," Dr. Lucio Verdoni, a pediatrician at the Papa Giovanni XXIII Hospital in Bergamo, Italy, said in a press release. He co-authored the Lancet report.
"Although this complication remains very rare, our study provides further evidence on how the virus may be affecting children," he said.
Symptoms of Kawasaki disease include abdominal pain, fever, nausea and vomiting and severe rash. These can be managed with anti-inflammatory drugs, but if left untreated, those afflicted and develop heart problems.
Kawasaki disease, however, is rare. Roughly 4,000 children 5 years old and younger in the United States have been diagnosed with the condition, according to the Centers for Disease Control and Prevention.
In the Lombardy region of Italy, where Verdoni and his colleagues are based, only 19 children had been diagnosed with Kawasaki disease in the five years before February, when the COVID-19 outbreak began, they said.
The 10 cases between February and April could represent a 30-fold increase, although the researchers caution that it is difficult to draw firm conclusions with such small numbers.
Verdoni and his colleagues performed a retrospective review of patient notes from all 29 children admitted to their pediatric unit with symptoms of Kawasaki disease between January 2015 and April 20. Before the COVID-19 outbreak, the hospital treated roughly one case of the disease every three months, they found.
The increase could not be attributed to an increase in hospital admissions, as the number of patients admitted during that time period actually was six-fold lower than before COVID-19 was first reported in the area, they said.
The children admitted to the hospital with Kawasaki-like symptoms since the start of the outbreak -- with a mean age of 7 1/2 -- were up to three years older than those in pre-outbreak cases, and all but two tested positive for SARS-CoV-2.
They also appeared to experience more severe symptoms than past cases, with more than half suffering heart complications, compared with just two of the 19 treated before the pandemic.
In all, half of the children had signs of toxic shock syndrome, while none of those treated before February 2020 had the complication. Toxic shock syndrome -- a release of toxins in the body often caused by a bacterial infection, rather than a viral one, like SARS-CoV-2 -- produces initial symptoms similar to Kawasaki and can lead to multiple organ failure.
Eight of the COVID-19 cases also required additional treatment with steroids, compared with just four of the 19 in the pre-outbreak group.
Although two of the patients treated for Kawasaki-like illness after the start of the outbreak tested negative for SARS-CoV-2 on an antibody test, the researchers noted that the test used is not 100 percent accurate, suggesting these could be false negative results.
In addition, one of the children recently had been treated with a high dose of immunoglobulin, a standard regimen for Kawasaki disease, which could have masked any antibodies to the virus.
Taken together, the authors said their findings represent an association between an outbreak of SARS-CoV-2 virus and an inflammatory condition similar to Kawasaki disease.
"In our experience, only a very small proportion of children infected with SARS-CoV-2 develop symptoms of Kawasaki disease," said study co-author Dr. Annalisa Gervasoni, a pediatric specialist at the Papa Giovanni XXIII Hospital.
"However, it is important to understand the consequences of the virus in children, particularly as countries around the world grapple with plans to start relaxing social distancing policies," she said.