SHANGHAI—Chinese authorities have launched a nationwide public hygiene campaign in an effort to combat the spread of hand, foot and mouth disease (HFMD), which has killed 42 children and infected at least 30,000 youngsters throughout Asia since the end of April. The disease, caused by an unusually virulent strain of the intestinal flu known as enterovirus 71 (EV71), so far has spread from Mongolia to Vietnam, including most parts of eastern China, and health officials warn that the situation could get worse as the disease usually peaks during the summer heat of June and July. Already, Mongolia has shut all kindergartens and primary schools as a result of the spreading outbreak.

The hardest hit areas in eastern China have been in Anhui Province, especially the city Fuyang, where 23 died, and even Beijing was not spared: two children, one a resident and one a visitor, died from the disease last week, whose symptoms include a mild fever, rash on the hands and feet and open sores in the mouth. In the most severe cases it can lead to a heart and lung infection (pulmonary edema) as well as inflammation of the brain lining (meningitis) or of the brain itself (encephalitis)—conditions that can result in paralysis or death.

Health officials here have ordered residents, schools and business to take steps designed to prevent the disease's spread, including sterilizing furniture and toys with alcohol wipes as well as keeping symptomatic children at home. The national government also ordered kindergarten and primary schools to check kids twice daily for signs of the illness. In fact, health officials have ordered schools to close for two or three weeks if any child attending becomes severely sick or if more than two cases occur in one class.

Shanghai has had nearly 2,000 cases of the disease so far this year. "Until now, the number of deaths caused by hand, foot [and] mouth disease in Shanghai [had been] zero," Fang Weimin, director of the Health Supervision Agency of the Pudong New District of Shanghai, told me through my translator. "The education department should do the educational work to enhance the awareness and alertness of related people" to make sure that parents know precautions to take to prevent the disease and how to recognize symptoms in affected kids.

The disease is typically allowed to run its course and does not usually kill those infected, according to the U.S. Centers for Disease Control (CDC). Those afflicted are most commonly the poorest of the population, such as workers who have emigrated to the booming cities and then must pay hundreds of dollars (thousands of yuan) for treatment or, in the worst cases, funerals.

The English-language newspaper Shanghai Daily reported, for instance, that 31-year-old migrant worker Chen Weiming in Guangzhou, who earns just $145 (1,000 yuan) a month, had to borrow money from his family to scrape up $245 (1,700 yuan) for his four-year-old daughter's funeral. He also cannot afford the $720 (5,000-yuan) treatment that saved his seven-year-old and 18-month-old daughters, Shanghai Daily reported and therefore cannot take custody of them from the hospital until he can pay the fee.

The World Health Organization and the U.S. Department of Health and Human Services are helping the Chinese track the source of this year's unusually deadly outbreak and map its spread. The U.S. was the first country to identify the EV71 virus as one of the culprits behind this disease in 1969. But this outbreak is also being caused, in some cases, by another enterovirus—coxsackievirus A16, according to Shanghai authorities. The CDC considers the A16 virus the most common cause of HFMD.

Chinese authorities are also working on developing a vaccine against it, but do not expect to have one ready anytime soon. "This infectious disease usually starts in May and reaches its peak in July," Sun Shuguang, a mouth disease specialist, or stomatologist, at the Medical Center of Jingan District in Shanghai said through my translator. In lieu of a vaccine, he recommends that people take extra care to eat right to keep their immune systems strong, wash their hands regularly, and make sure their surroundings are sanitized.