BEIJING, China (CNN) -- China's Health Ministry strengthened surveillance and dispatched specialists to the eastern Anhui province as the death toll from a virulent virus climbed to 22, the Xinhua News Agency reported.

A girl suffering from an Enterovirus 71 infection receives treatment this week in a Fuyang, China, hospital.

The number of reported cases of the virus in children rose to 3,736 early Saturday in the hardest-hit city of Fuyang, according to the state-run news agency. There were 3,321 reported cases Friday in Fuyang.

Xinhua reported that 4,529 children have been sickened in 15 cities in Anhui province.

The virus -- called Enterovirus 71, or EV71 -- can cause hand, foot and mouth disease. It's often confused with foot-and-mouth disease in livestock, but the diseases aren't the same, according to the U.S. Centers for Disease Control and Prevention.

An Anhui province official, Wang Yan, told Xinhua that 978 children are hospitalized, including 48 in critical condition.

"Authorities in Anhui ... are doing the utmost to treat the children and strengthen disease control," he said.

The virus is another concern for Chinese officials as the nation prepares to host the Summer Olympics, which open August 8 in Beijing.

Anhui province is south of the Chinese capital.

The Health Ministry issued a pamphlet Saturday urging local health bureaus to step up prevention and control of infectious diseases as the Olympics approach, Xinhua reported.

In milder cases, EV71 can cause coldlike symptoms, diarrhea and sores on the hands, feet and mouth, according to the journal Genetic Vaccines and Therapy.

But more severe cases can cause fluid to accumulate on the brain, resulting in polio-like paralysis and death, according to the journal.

There is no effective antiviral treatment for severe EV71 infections, and no vaccine is available.

Adults' well-developed immune systems usually can fend off the virus, but children are vulnerable to it, according to the CDC.

There was a large outbreak of the virus in Taiwan in 1998 with 78 deaths, and smaller outbreaks recurred in 2000 and 2001, the CDC said.

Wang Jinshan, secretary of the Provincial Committee of the Communist Party of China, visited hospitals in Fuyang on Friday and called for a long-term system to prevent such outbreaks, Xinhua said. In addition, 45 medical specialists have arrived in the city.

Anhui has upgraded its public health emergency status from Class 3 to Class 2, meaning the provincial government can quarantine patients and control movement in to and out of Fuyang.

In a statement Friday, the World Health Organization noted that the number of hospitalized cases has gradually risen since late March, with a sharp increase in the number of cases since April 19.

Public health officials expect the number of cases to peak in June or July, the WHO said.

"Chinese health authorities have put in place targeted prevention and control measures in Fuyang city and Anhui province, including enhanced surveillance, training of health care workers at all levels in treatment, prevention and control, strengthening of environmental health management and the supervision and monitoring of drinking water quality," the WHO statement said.

"A public awareness campaign is ongoing, stressing the need for good personal hygiene, mostly by hand washing." E-mail to a friend

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