Another 71 cases of the mysterious hepatitis are under investigation in the United States, the Centers for Disease Control and Prevention revealed on Wednesday.

No other deaths have been reported in the past two weeks, but earlier the CDC revealed it was investigating five deaths in the outbreak – including one in Wisconsin.

One more child required a liver transplant, bringing the national number of patients requiring the procedure to 16.

A total of 180 cases of the mysterious hepatitis have now been linked to the outbreak in 35 states, with patients all under the age of 10.

It is the highest number of countries in the world with the United Kingdom, which was the first to detect the outbreak, with the second highest total at 163 cases.

The CDC said the “vast majority” of these patients were retrospective and came to hospitals before May, but had only just been diagnosed with the mystery disease.

Scientists are puzzled as to the cause of the outbreak, but CDC officials say adenoviruses – which can cause the common cold – remain a “strong lead” with nearly half of patients testing positive for them.

Other theories suggest that a previous Covid infection, adenovirus mutation or even exposure to pet dogs could trigger the disease.

All normal causes of the disease – hepatitis A, B, C, D and E viruses – were ruled out.

At least 12 children have now died from the mysterious hepatitis worldwide, with five deaths also reported in Indonesia and one in Ireland and Palestine.

Today’s announcement from the United States brings the global tally to at least 520 cases in 21 countries, mostly in children under the age of 10.

CDC officials said they are continuing to probe all possible causes of the mysterious hepatitis outbreak.

They revealed that 11 other states had detected cases of mystery hepatitis in the past two weeks.

These were: Arkansas, Hawaii, Kentucky, Maryland, Massachusetts, Nevada, New Jersey, Oklahoma, Rhode Island, South Dakota and Virginia.

Previously, a total of 24 states had detected the virus, namely: Alabama, Arizona, California, Colorado, Delaware, Florida, Georgia, Idaho, Illinois, Indiana, Louisiana, Michigan, Minnesota, Missouri, North Carolina, North Dakota , Nebraska, New York, Ohio, Pennsylvania, Tennessee, Texas, Washington and Wisconsin.

Puerto Rico was also reported at the time to have at least one case of the disease.

The CDC added, “It is important to note that severe hepatitis in children remains rare.

“However, we encourage parents and caregivers to be aware of the symptoms of hepatitis – especially jaundice, which is yellowing of the skin or eyes – and to contact their child’s healthcare provider if of problem”.

The US outbreak of the mysterious hepatitis began in October last year, when nine cases were reported in Alabama.

CDC officials initially dismissed them as isolated incidents, but took another look after the UK sounded the alarm about an outbreak on its shores.

Since then, US health authorities have issued two alerts urging doctors and nurses to monitor patients with the disease.

Last week, a top scientist warned the outbreak would continue “throughout the summer” with many cases going undiagnosed.

Dr Matthew Binnicker, director of clinical virology at the Mayo Clinic in Minnesota, told DailyMail.com that cases will continue to appear because transmission of adenoviruses – the prime suspect – tends to “not be seasonal”.

He warned that schools and daycare centers – where children mix – were major hubs for the spread of the virus.

Adenoviruses can be transmitted by touching surfaces contaminated with feces.

Speaking exclusively to DailyMail.com, Dr Binnicker said: ‘I wouldn’t be comfortable saying this outbreak has peaked.

“I would say that cases will continue to emerge throughout the summer period as we will continue to see children in daycare where transmission is higher.

“This type of adenovirus that we don’t tend to think of as seasonal, we will continue to see cases throughout the year.”

Adenovirus children with mystery hepatitis are most likely to have tested positive for the scientifically named type 41.

This infects the gastric system, causing symptoms such as diarrhea and vomiting.

It is spread through the fecal-oral route, or when someone touches a surface contaminated with feces and then touches their own mouth.

Asked if many more cases would be spotted in the United States in the past week, Binnicker warned that many still needed to be diagnosed because they were milder.

“Hepatitis can occur on a sliding scale resulting in an individual being hospitalized at the other end, where it is much milder,” he said.

‘In [the mild] In some cases, this may not encourage parents to take their child for examination or to the hospital.

“Many of these children will show symptoms of gastroenteritis such as vomiting, diarrhea and nausea, with some also facing upper respiratory disease, so a cough or sore throat which precedes hepatitis.

“Those who then develop hepatitis will see changes in skin color, so some develop symptoms of jaundice or yellowing of the skin … ranging from very very noticeable to very very subtle changes.

“A yellowing white of the eye is also something very apparent and sometimes parents are very shocked, but other times it’s very, very subtle and may not be noticed.”