Acute childhood hepatitis: how many cases have been detected in Latin America and what is known about the infection of unknown origin so far

the enigmatic acute hepatitis whose origin is unknown and that apparently attacks young children – mostly up to 5 years old – is already in Latin America.

Until Tuesday they were six Latin American countries that they had reported probable cases of acute childhood hepatitis of unknown origin, the adviser on Disease Prevention and Control of the Pan American Health Organization (PAHO), epidemiologist Enrique Pérez, informed BBC Mundo.

In those six countries – which Pérez preferred not to say which ones they are – 23 cases. Also, there are other 53 suspects being studied.

No deaths had been recorded in the region of confirmed cases or those due to receive a liver transplant as of Tuesday, May 17.

The first Latin American country to register a suspected case was Argentina, although it is still under investigation to confirm whether its origin is unknown.

It happened on May 5, when the Ministry of Health of that country reported that an 8-year-old boy was admitted to a hospital in the city of Rosario (300 kilometers northwest of Buenos Aires). He had to be transplanted and was evolving favorably.

Eight more cases were added to it.

Costa Rica reported the case of a 2-year-old girl with acute hepatitis who tested positive for adenovirus. Days later she was released.

The Central American country reported after a 4-year-old girl whose hepatitis was of unknown origin, although in that case the adenovirus test was negative, local media reported.

Brazil reported on Saturday the detection of 44 possible cases, of which three were discarded and 41 were under study.

Mexico said it had detected five possible cases, but two have already been dismissed, while in Panama, two cases were being studied.

Puerto Rico reported two suspected cases; one was a 2-year-old girl who died on Monday.

The first warning about the disease in children was given by the United Kingdom on April 5.

Until May 15, the World Health Organization (WHO) had received reports of 429 cases of acute childhood hepatitis of -for the moment- unknown origin in 22 countries, while it had another 40 cases under study.

75% were under 5 years of age, 15% had to be admitted to an intensive care unit and the majority occurred in Europe.

In the world there were six children who died from this cause and 26 required a transplant.

What is acute hepatitis?

Hepatitis is a inflammation of the liver. When it occurs abruptly it is called “acute hepatitis”.

Causes include infection (by a virus or bacteria), intoxication (alcoholic, substance, or drug), and the immune system.

In some cases, such as hepatitis B, C and D, the infection can become chronic.

“Acute hepatitis has different symptoms: gastrointestinal, such as diarrhea or vomiting, fever and muscle pain, but the most characteristic is jaundice, a yellow coloration of the skin and eyes,” said infectologist Leandro Soares Sereno, advisor for prevention and the control of viral hepatitis in PAHO.

What is known so far about the new hepatitis?

The European Center for Disease Prevention and Control (ECDC) said that acute hepatitis may take time to develop after the appearance of the first symptoms, so there may be a delay in the notification of cases.

He added that once a suspicion exists, confirming it through studies also takes time.

That the hepatitis is of unknown origin implies that cannot be attributed to the most frequent variants -A, B, C, D or E-all studied in the past, and neither to intoxication or an autoimmune effect.

“Common exposures to toxins, medications and vaccination against covid have not been identified as a cause,” Philippa Eastbrook, a specialist with the WHO’s global hepatitis program, told a news conference on Tuesday.

“The key in the hypothesis [del origen es sobre] the links between adenovirus and SARS-CoV-2 And what is more important, how these two infections may be working together as cofactorseither by increasing susceptibility or creating an abnormal response,” Eastbrook said.

The SARS-CoV-2 coronavirus is the cause of covid-19.

What is being studied in greater depth is “if a previous covid infection in children, perhaps some time ago, could have persisted and remained in the intestine, and then a subsequent adenovirus infection caused the immune system to activate and cause inflammation” in the liver, the hepatitis expert added.

70% of the cases tested until May 10 had tested positive for adenovirus, and of these the majority was for adenovirus type 41. 18% had tested positive for covid.

However, it is not yet clear whether all the cases identified after the alert are part of a true increase compared to the initial rate of hepatitis of unknown origin in children.

Experts are investigating a possible link to an increase in adenovirus infections, a common cause of childhood illness.

It is also being studied if it has any link with covid-19 – if a current or previous infection increases the risk of this disease in some children – or something in the environment.

The latest evaluation of the ECDC, published on May 13, also points out how main hypothesis to an adenovirus infection.

According to the European body, it would be mild under normal circumstances, but in these cases it triggers a more serious infection or liver damage mediated by the immune system.

Other possible causes were not excluded as hypotheses, but are considered less plausible.

The disease is rare and the evidence on person-to-person transmission remains unclear.

What is adenovirus 41?

Adenoviruses are a family of viruses that spread from person to person and most often cause respiratory diseases, but, depending on the type, can also cause other ailments such as gastroenteritis (inflammation of the stomach or intestines), conjunctivitis, and cystitis (bladder infection), according to the US Centers for Disease Control and Prevention (CDC).

Adenovirus type 41, also called F41, typically presents with symptoms such as diarrhoea, vomiting and fever, often accompanied by breathing problems.

Although there have been case reports of hepatitis in immunocompromised children with adenovirus infection, it is unknown whether adenovirus type 41 is a cause of hepatitis in otherwise healthy children.

The CDC believes that adenovirus may be the cause of these reported cases, but researchers are still learning about this infection. To do this they want to rule out other possible causes and identify factors that may have contributed.

“In general, the infection is of limited duration and does not progress to worrisome conditions, although rare cases of severe adenovirus infections causing hepatitis have been reported in immunocompromised patients or transplant recipients. However, these children do not fit this description, as they were previously healthy,” said Soares Sereno, from PAHO.