Vietnam and Singapore also have seen a increase in cases linked to EV-71.
The outbreak in China comes as the country gears up for the Olympic Games. But Hans Troedsson, The World Health Organization's country representative for China, said the disease should not disrupt the Beijing games, which start Aug. 8.
"I don't see it at all as a threat to the Olympics or any upcoming events. ... This is a disease mainly affecting young children," he said.
The outbreak is centered around Fuyang city, where 22 deaths have occurred. On Sunday, the official Xinhua News Agency said the virus had claimed the lives of two more children in southern Guangdong province.
"That's an extraordinarily high case fatality rate, and that's what caught our attention," said Peter Cordingley, spokesman for WHO's regional Western Pacific office. "Otherwise, it would have passed under the radar."
Hand, foot and mouth disease is a childhood illness found worldwide that spreads through contact with saliva, feces, fluid secreted from blisters or mucus from the nose and throat. Symptoms typically include fever, skin rashes and sores inside the mouth and on fingers and toes.
There is no vaccine or specific treatment, but most children affected by the disease typically recover quickly without problems.
However, EV-71 can result in a more serious form of the illness that can lead to paralysis, brain swelling or death. Many of the severe cases in China did not exhibit typical symptoms, and the children eventually died from respiratory problems, which kept Chinese experts puzzled about the cause of the outbreak, Troedsson said.
He told reporters Sunday that while more cases are expected, he is confident the outbreak does not pose a serious threat.
The disease, which is not related to foot and mouth disease that affects livestock, is endemic across Asia and many countries experience annual flare-ups.
"On average, several children die from the disease each month at the hospital," said Dr. Nguyen Quang Vinh at Children's Hospital No. 1 in Vietnam's southern Ho Chi Minh City. "Those children die not because they are admitted to the hospital late, but because their disease develops fast and attacks the brain and heart."
The number of cases reported nationwide this year in Vietnam was not immediately available, but state-run media have reported that some children's hospitals have seen increases of up to seven times over last year.
Infections also continue to rise in Singapore, which has reported more than 9,000 cases this year, with EV-71 found in 25 percent of the samples tested. No deaths have been reported in the wealthy city-state, but the government has ordered 11 preschools and child-care centers closed, according to the Health Ministry's Web site.
WHO issued a warning last week predicting that the outbreak will likely continue in China for the next few months because the virus tends to thrive in hot weather. It advised disinfection and frequent hand washing to prevent its spread, along with closing schools and daycare centers in hard-hit areas.
Troedsson said it is important for China's Health Ministry to brief the public about such outbreaks early on, even if officials are unclear about the cause.
No official information on the virus was released to the public until last week, leading to widespread rumors and fear among parents, according to local media reports.
Suspicion continues to surround the Chinese government's handling of disease outbreaks following allegations of a cover-up during the 2003 emergence of severe acute respiratory syndrome, or SARS, which originated in southern China and eventually killed nearly 800 people worldwide.
The Health Ministry alerted WHO two weeks ago that it had been working to identify the disease, which began spreading in Anhui province in March.
The ministry has dispatched teams to the area to coordinate treatment and prevention measures. State-run television showed workers spraying disinfectant around houses in rural areas outside Fuyang and medical teams visiting families with small children.
A major enterovirus outbreak hit Taiwan in 1998, infecting up to 300,000 children with hand, foot and mouth disease and killing at least 55, according to WHO.