Canada detects severe hepatitis of ‘unknown origin’ cases in kids. What is it?

Canadian health officials are investigating cases of severe acute hepatitis of “unknown origin” found in children across the country.

The Public Health Agency of Canada (PHAC) told Global News on Wednesday it is aware of reports of this illness as other regions in the world report cases of liver disease in kids with an unknown cause.

“These are being investigated further to determine if they are related to cases in the United Kingdom and the United States,” PHAC said. “As the investigation evolves, we will keep the public updated accordingly.”

Here’s what we know so far.

So far, 190 children worldwide have developed sudden liver disease for reasons unknown. At least one child died and several others needed to have liver transplants, the WHO said.

Otherwise healthy children are developing hepatitis, or liver inflammation often caused by viruses. Children impacted so far range in age from one month to 16 years.

Most cases have occurred in Europe. The first U.K. cases were recorded in January, while the U.S. detected its first cases in October in Alabama. The Centers for Disease Control and Prevention made that announcement last week.

PHAC did not indicate how many cases have been reported in Canada, or when they first emerged.

“These are in multiple countries all over the world; mostly high-income countries have been reporting this,” said Dr. Isaac Bogoch, an infectious disease specialist at Toronto General Hospital.

“We haven’t heard much from low- and middle-income countries just yet. It’s likely an underreported issue; there’s probably more cases out there.”

Hepatitis is usually caused by one of several contagious hepatitis viruses, like A and B, which have not been found in the affected children.

Sometimes the disease is mild and requires no specific treatment, but severe cases require hospitalization and can lead to liver failure.

Authorities around the world are not sure what is causing the cases.

Nine children in the Alabama cluster tested positive for adenovirus – a family of viruses that can cause a range of illnesses like colds, fever and sore throat, according to the CDC.

Andrea Ammon, director of the European Centre for Disease Prevention and Control, told reporters at a virtual briefing this week that scientists are also investigating whether the adenovirus involved has mutated, or is acting in tandem with another infection, possibly COVID-19.

“Obviously, we’re in the middle of a pandemic and there’s a lot of COVID out there, so that’s one avenue that obviously warrants significant investigation, be it infection or recovery from infection and some immune process,” Bogoch said.

“But again, we don’t want to have what we call an anchoring bias and just focus on COVID because you might miss other causes of this.”

A toxin could also be responsible, but it is less likely due to the geographical spread of the cases to date, Reuters reported on Tuesday. Any link with COVID-19 vaccination has been ruled out.

“From our cohort of nine cases, all of them all of them tested positive for adenovirus,” said Dr. Helena Gutierrez, medical director of the pediatric liver transplant program at the University of Alabama at Birmingham.

“The majority of these adenovirus cases have been a specific type of adenovirus.”

That specific type can cause digestive problems in children, Gutierrez said. It is unknown whether that virus is a cause or is somehow contributing to the illnesses.

Symptoms of adenovirus linked to the reported cases in Alabama include vomiting and diarrhea, Gutierrez said.

“Very few have fever and very few of them have respiratory symptoms,” she said.

A few days or a few weeks later, they start to develop jaundice – a condition in which the skin and whites of the eyes become yellow, Gutierrez added.

Those symptoms require medical attention, she added.

Because it’s unknown what exactly is causing the liver disease, it’s hard to pinpoint exact symptoms right now, Bogoch said.

“It’s premature to put a stamp on that and say that this is the ultimate cause,” he said. “There need to be more investigations.”

While scientists are in the early stages of understanding the outbreak, it’s unclear why only children have been getting sick, Gutierrez said.

One theory going around is COVID-19 lockdowns may have weakened children’s immunity, because they were less exposed to common pathogens while in isolation.

“We’re still gathering information, but that’s why that hypothesis is something that people have voiced because adults throughout our lives have been exposed to adenovirus potentially multiple times,” Gutierrez said.

“This is a virus that causes cold symptoms, so maybe potentially these kids have never been exposed to it before and then their body is just having an overdrive response to it.”

It’s important for parents to understand that children routinely get sick, Gutierrez said.

That doesn’t mean they’re going to develop acute liver failure or severe hepatitis, but it’s important for parents to understand if their child’s condition doesn’t improve, they may have to seek medical attention.

Practicing some of the public health measures taught for COVID-19 –like keeping your distance from someone showing signs of illness – can be helpful, as well as good hand washing, Gutierrez added.

“This is how adenovirus gets transmitted, just by close contact,” she said.

“If you go outside and your kid is going to touch all surfaces, make sure that before they put their hands on their face or in their mouth that you wash very well.”

— with files from Global News’ Jamie Mauracher, the Associated Press and Reuters