Mystery Hepatitis Strain Outbreak in Children: What We Know So Far

The UK was followed by Spain (13), Israel (12), the US (9), Denmark (6), Ireland (<5), Netherlands (4), Italy (4), Norway (2), France (2), Romania (1) and Belgium (1).

Around 10% of these 169 kids, aged between 1 month and 16 years, have undergone liver transplantation, said the WHO.

Aetiology Inconclusive

After observing several cases of abdominal pain, diarrhoea and vomiting among children, the WHO identified the condition as acute hepatitis. However, after clinical examination, the international health body and laboratories ruled out all the hepatitis causing viruses (A,B,C,D,E). Instead, they detected adenovirus, a respiratory virus in about 74 cases.

The UK, which has the majority of cases, had recently seen a spike in adenovirus cases in the community (particularly detected in faecal samples in children), according to the WHO.

A study published by researchers in Scotland on April 14, 2022 stated that adenovirus infection is "the leading hypothesis". "While adenovirus is currently one hypothesis as the underlying cause, it does not fully explain the severity of the clinical picture," said the WHO. This is mainly because this particular adenovirus type 41, has not previously been linked to such a clinical presentation.

Adenoviruses are common pathogens that spread from person to person and most commonly cause respiratory illness, but depending on the type, can also cause other illnesses such as gastroenteritis (inflammation of the stomach or intestines), conjunctivitis (pink eye), and cystitis (bladder infection).

Further, the laboratories also found that SARS-CoV-2 was identified in 20 cases and 19 were detected with a SARS-CoV-2 and adenovirus co-infection.

To get to the root cause of the outbreak, clinical investigations are being undertaken for detailed exposure histories of the children including their environmental and food toxicity tests. Kirstin Norlund, a spokeswoman for the Centers of Disease Control and Prevention (CDC), said, "The CDC is working with state health departments to see if there are additional US cases, and what may be causing these cases. At this time adenovirus may be the cause for these, but investigators are still learning more—including ruling out the more common causes of hepatitis."

Hepatitis: Types & Symptoms

Hepatitis is inflammation of the liver and inflammation defends the immune system against harmful agents but it also leads to swelling when the liver is injured, resulting in liver dysfunction.

While Hepatitis is often caused by a virus – such as Hepatitis A,B,C,D,E (viral hepatitis), heavy alcohol use, certain medications, toxins, genetic disorders, etc can also cause this condition. An overactive immune system that mistakenly attacks the liver can cause it.

Hepatitis can be either acute (short term and rapid) or chronic (long term). Apart from the five main types of viruses, Hepatitis in children can be caused by several others including, cytomegalovirus (part of the herpes virus family), herpes simplex virus (affects the face, the skin above the waist, or the genitals), rubella (mild disease that causes a rash), adenovirus (group of viruses that causes colds, tonsillitis, diarrhoea and ear infections), etc.

Symptoms of acute hepatitis (in the current scenario) can manifest in the form of malaise, flu-like symptoms, jaundice, nausea, loss of appetite, dark urine or light stool colour, joint pain, Diarrhoea and so on. However, chronic hepatitis may have mild to no symptoms and may last up to six months.

How Does Hepatitis Spread?

Hepatitis A & E are passed through faecal-oral contact and account for 20%-25% of hepatitis in developed countries, according to Johns Hopkins Medicine. It can be spread to children if they consume food made by an infected person who did not wash their hands well after using the washroom. Drinking water contaminated by infected faeces, international travel to areas where hepatitis A is common, blood transfusions, etc. Hepatitis E is most commonly seen in developing countries.

Hepatitis B & C are spread when blood from an infected person enters a healthy person's body. Hepatitis C can also pass through sexual contact and can spread via needles/syringes or by sharing sharp instruments such as razors, etc. Children born to mothers with Hepatitis are at higher risk of developing the condition. Notably, Hepatitis D can only develop if someone already has been diagnosed with Hepatitis B. However, unlike Hepatitis B, Hepatitis D cannot be spread from mother to the foetus during pregnancy.

While vaccinations exist for Hepatitis A and B, there are no vaccines for Hepatitis C, D and E. Antiviral medications treat both acute and chronic types of Hepatitis C.