Another 36 cases of mysterious pediatric hepatitis in children aged 10 or younger, health chiefs revealed on Wednesday – after six deaths were reported in the outbreak.
That brings the number of children affected by hepatitis to 216 in 37 states, with Mississippi and Utah adding last to the growing list.
No new deaths or liver transplants were reported in the past week, the Centers for Disease Control and Prevention (CDC) said in its weekly update, with the total remaining at 14 and six, respectively.
The agency has declined to disclose where the deaths occurred to sift through “confidentiality issues,” but at least one was recorded in Wisconsin, the state’s health chiefs say.
Globally, the US has recorded the most deaths and suspected cases of any nation – although that may be due to heavy surveillance.
Indonesia has reported five deaths in the outbreak, while both Palestine and Israel have recorded one each.
Scientists say it will be weeks before the cause of the cases is uncovered, although the CDC continues to consider adenoviruses – which can trigger the common cold – to be the most likely cause of the disease.
The outbreak may also be the result of weakened immunity due to lockdowns that damaged people’s immunity, some experts warn.
The CDC now releases weekly breakouts on the numbers of suspected cases reported, liver transplants, and deaths.
Many of the cases are “historic” as they have emerged in the seven months since October 2021 but are only now coming to light as doctors examine samples collected from sick children in the mail.
The CDC said last week there was no sign that cases had increased in recent months.
A total of 37 states have now reported cases of the hepatitis outbreak. These are: Arkansas, Alabama, Arizona, California, Colorado, Delaware, Florida, Georgia, Hawaii, Idaho, Illinois, Indiana, Kentucky, Louisiana, Maryland, Massachusetts, Michigan, Minnesota, Nebraska, Nevada, New Jersey, North Carolina, North Dakota, New York, Ohio, Oklahoma, Pennsylvania, Rhode Island, South Dakota, Tennessee, Texas and Virginia, Washington and Wisconsin.
The Territory of Puerto Rico has also recorded at least one case of mysterious hepatitis.
Experts warn lockdowns mean the US could now be heading for a time when it’s difficult to know what to expect from infectious diseases.
dr Marion Koopmans, head of the Virosciences department at Erasmus Medical Center in Rotterdam, the Netherlands, warned STAT News, saying it was due to less recent immunity.
She said blood tests on children showed they were on a sort of “infection honeymoon” where there were few antibodies to normal diseases.
She added: “You really see that in the second year of the pandemic, children have far fewer antibodies to a number of common respiratory viruses.
“They just got less exposed.”
The CDC said last week that adenovirus infection – which can cause the common cold – is their leading hypothesis for the cause of the disease, although they are also still investigating whether Covid infections played a role.
They have all but ruled out theories that suggest a mutation in the virus could be causing the disease, or that it could be due to exposure to pet dogs. There is no evidence that the Covid vaccine causes hepatitis.
The usual causes – hepatitis viruses A, B, C, D and E – have all been ruled out.
Questions and Answers: What is the mysterious global hepatitis outbreak and what is behind it?
What is hepatitis?
Hepatitis is inflammation of the liver, usually caused by a viral infection or liver damage from alcohol consumption.
Some cases resolve on their own with no lingering problems, but a fraction can be fatal, forcing patients to require liver transplants to survive.
What are the symptoms?
People with hepatitis generally experience fatigue, loss of appetite, nausea, vomiting, abdominal pain, dark urine, light-colored stools, and joint pain.
You can also suffer from jaundice – when the skin and whites of the eyes turn yellow.
Why are experts concerned?
Hepatitis is usually rare in children, but experts have already detected more cases in the current outbreak than they would normally expect in a year.
The cases are “of unknown origin” and also serious, according to the World Health Organization.
What are the top theories?
co-infection
Experts say the cases may be linked to the adenovirus, which is commonly associated with the common cold, but more research is ongoing.
In combination with Covid infections, this could lead to an increase in some cases.
Around three quarters of UK cases have tested positive for the virus.
weakened immunity
British experts tasked with investigating the wave of the disease believe the endless cycle of lockdowns may have played a role.
Restrictions may have weakened children’s immunity due to less social mixing, putting them at increased risk of adenovirus.
This means that even “regular” adenoviruses can cause the severe consequences as children no longer respond to them as they did in the past.
adenovirus mutation
Other scientists said it could have been the adenovirus that acquired “unusual mutations”.
This would mean that it is more transmissible or better able to bypass children’s natural immunity.
New Covid variant
UKHSA officials included “a new variant of SARS-CoV-2” in their working hypotheses.
Covid has caused liver inflammation in very rare cases during the pandemic, although this has occurred in all age groups and not in isolation in children.
environmental triggers
The CDC has noted that environmental triggers are still being studied as possible causes of the diseases.
These can include pollution or exposure to certain drugs or toxins.