Key findings
Blood samples were available for 14 of the 16 children with acute hepatitis of unknown origin. Among this study group, AAV2 was found in 13 (93%). No other adeno-associated viruses were found. HAdV was detected in all 14 children: HAdV-41 in 11 children and HAdV-40, HAdV-2, and an untypeable strain in one child each. This finding was not intuitive because HAdVs are not commonly associated with hepatitis, according to the study.
AAV2 was much less common in the control group. For example, it was found in none of the children with hepatitis of known origin and in only four children (3.5%) with acute gastroenteritis and HAdV-positive stool. Of note, neither AAV2 nor HAdV-41 was detected among the 30 pediatric controls with acute hepatitis of defined etiology nor 42 of the hospitalized children without hepatitis, the researchers wrote.
In the search for other viruses in the study group, metagenomic sequencing detected EBV, also known as human herpesvirus (HHV)–4, in two children, cytomegalovirus (CMV) in one child, and HAdV type C in one child.
Analysis of whole blood revealed enterovirus A71 in one patient. HAdV type C also was detected in one child on the basis of a nasopharyngeal swab, and picobirnavirus was found in a stool sample from another patient.
Researchers conducted virus-specific PCR tests on both patient groups to identify additional viruses that may be associated with the unexplained acute hepatitis. EBV/HHV-4 was detected in 11 children (79%) in the study group vs. in 1 child (0.88%) in the control group. HHV-6 was detected in seven children (50%) in the study group, compared with one case in the control group. CMV was not detected in any of the children in the study group versus vs. two children (1.8%) in the control group.
“Although we found significant differences in the relative proportions of EBV and HHV-6 in cases compared to controls, we do not believe that these viruses are the primary cause of acute severe hepatitis,” the researchers wrote. The viral load of the two herpes viruses were very low, so the positive results could represent integrated proviral DNA rather than bona fide low-level herpesvirus. In addition, herpesvirus can be reactivated by an inflammatory condition.
“Nevertheless, it is striking that among the 16 cases (in the study group), dual, triple, or quadruple infections with AAV2, adenovirus, and one or both herpesviruses were detected in whole blood from at least 12 cases (75%),” the researchers wrote.
Management of suspected hepatitis
The study’s key messages for parents and health care providers “are awareness and reassurance,” Dr. Balistreri said in an interview.
Vigilance also is warranted if a child develops prodromal symptoms including respiratory and/or gastrointestinal signs such as nausea, vomiting, diarrhea, and abdomen pain, he said. If jaundice or scleral icterus is noted, then hepatitis should be suspected.
Some patients need hospitalization and quickly recover. In very rare instances, the inflammation may progress to liver failure and transplantation, Dr. Balistreri said.
“Reassurance is based on the good news that most children with acute hepatitis get better. If a case arises, it is good practice to keep the child well hydrated, offer a normal diet, and avoid medications that may be cleared by the liver,” Dr. Balistreri added.
“Of course, COVID-19 vaccination is strongly suggested,” he said.
Some existing treatments could help against unexplained acute hepatitis, Dr. Chiu said. “The findings suggest that antiviral therapy might be effective in these cases.”
Cidofovir can be effective against adenovirus, according to a report in The Lancet . Similarly, ganciclovir or valganciclovir may have activity against EBV/HHV-4 or HHV-6, Dr. Chiu said. “However, antiviral therapy is not available for AAV2.”
The three studies published in Nature “offer compelling evidence, from disparate centers, of a linkage of outbreak cases to infection by AAV2,” Dr. Balistreri said. The studies also suggest that liver injury was related to abnormal immune responses. This is an important clinical distinction, indicating a potential therapeutic approach to future cases – immunosuppression rather than anti-adenoviral agents, he said.
“We await further studies of this important concept,” Dr. Balistreri said.
Many unanswered questions remain about the condition’s etiology, he added. Is there a synergy or shared susceptibility related to SARS-CoV-2? Is the COVID-19 virus helping to trigger these infections, or does it increase the risk once infected? Also, are other epigenetic factors or viruses involved?