CDC, WHO note latest kids' unexplained hepatitis cases

Sick child hooked up to IV fluids
Sick child hooked up to IV fluids

kan2d / iStock

Simultaneous investigations are under way in the United States and other countries into unexplained hepatitis cases in young children, and a few days ago, the US Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) both posted updates that detail new cases.

The main hypothesis is an adenovirus link, but scientists are still weighing several other possibilities, such as a cofactor like SARS-CoV-2 infection or a toxicologic exposure.

US cases are similar to global profile

Researchers from the CDC and their state and territorial health partners detailed their interim findings in a Jun 24 early online edition Morbidity and Mortality Weekly Report (MMWR). They include 296 patients who were diagnosed as having unexplained hepatitis between Oct 1, 2021, and Jun 14, with a detailed analysis of 123 patients.

Of the total, 18 kids needed liver transplant and 11 died. In a separate weekly case-count update, the CDC said as of Jun 22, 305 cases have been reported from 42 states or territories.

In an earlier report, CDC researchers had said neither unexplained hepatitis nor adenovirus type 40 and 41 infections seem to have risen above the prepandemic baseline levels.

In the investigation into the current cases, most involved children younger than 5, and adenovirus was found in 45%. From a subset of 13 patients with available typing data, adenovirus type 41 was predominant.

Officials said no cause is found in nearly a third of kids who have acute liver failure, and that the current cases might reflect different etiologies. Though adenovirus isn't a known cause, its identification in several specimens raises questions about a new disease pattern, an under-recognized cause, or a cofactor.

Regarding SARS-CoV-2, 10.2% of those who were tested for acute infection were positive, and 26% had a history of SARS-CoV-2 infection. Only five kids had received one or more doses of COVID-19 vaccine.

No epidemiologic links were found among the cases, and 56.1% had never attended a childcare facility or school in the month before illness.

Alongside possible roles for adenovirus and SARS-CoV-2, another possibility is adeno-associated virus-2, found in a high proportion of United Kingdom kids, changes in exposure to adenovirus, and immune naivety, the group wrote.

They noted that global investigations are turning up some similarities, including the young age—mainly kids age 5 and younger—as well as frequent adenovirus detection and identification of adenovirus type 41.

WHO: Global count climbs to 920 cases

In its update on the outbreaks investigations, the WHO said as of Jun 22, it had received reports of 920 probable cases from 33 countries across five of its regions, mostly from Europe and the Americas. If the global total, 45 kids needed transplants and 18 patients died.

The WHO said adenovirus continues to be the most frequently detected pathogen among cases with available data. It was detected at a similar but higher level in Europe (55%) than in preliminary reports from the United States (45%).

Similarly, acute SARS-CoV-2 infection was detected in 15% of European patients with available data, similar to 10% of cases from preliminary US findings.

Most cases don't appear to be epidemiologically linked, but a few were reported from the Netherlands and Scotland.

The WHO said a little less than half (48%) were male, and 78% were kids younger than 6. The most common symptoms were nausea or vomiting, jaundice, weakness, and abdominal pain. The median number of days between symptom onset and hospitalization was 4.

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