The number of people dying from malaria in the country doubled, despite the gradual decline of malaria cases as a whole, an official said.

According to the Chinese Center for Disease Control and Prevention, malaria killed 30 people in China last year, an increase of 100 percent from 15 cases in 2010. That comes as the total number of malaria cases in 2011 declined 44 percent to 4,158.

"Over the past decades, the country has indeed made some achievements in controlling malaria. Now the incidence of malaria has entered historically low levels," said Yang Weizhong, deputy director of the center.

"But at the same time, another problem is being seen in recent years as more and more imported malaria cases have been reported," Yang said at a seminar about imported malaria prevention in Shanghai on Thursday, the country's fifth Malaria Day.

According to the center, 1,398 cases of pernicious malaria or falciparum malaria, the most deadly form of the disease, were reported in the country last year, an increase of 19.8 percent over 2010. Among them, 97.7 percent were caused by people infected in other countries and returning to China.

Those patients are generally adult males who had been in Africa and Southeast Asia, the center said.

Malaria is a mosquito-borne disease, with parasites transmitted through the mosquito's saliva, and often causes symptoms of fever and headache. The disease, widespread in tropical and subtropical regions, including Africa and Southeast Asia, can lead to hallucinations, coma and death.

Many laborers from China are working in shabby environments in other countries and are often exposed to mosquitoes. They bring back the disease as they return home for reunions, said Zhou Xiaonong, deputy director of the National Institute of Parasitic Diseases under the Chinese Center for Disease Control and Prevention.

According to the center, provinces where more laborers have gone to work in other countries, such as Anhui, Jiangsu and Liaoning provinces, often see more pernicious cases.

East China's Jiangsu province has seen a sharp increase of malaria cases for seven years running, and reported 350 cases in 2011, the highest in the country.

In response to the steep rise of imported malaria cases, the province established a system of weekly reporting and analysis by experts. By the end of March, the province had reported 180 cases of imported malaria cases, 91 percent of them pernicious malaria.

"Our research found that 97 percent of the cases come from 25 countries in Africa, mainly concentrated in Nigeria, Equatorial Guinea and Angola," said Gao Qi, director of the Jiangsu Province Parasitic Diseases Institute.

More than 83 percent of those patients, almost all males between the ages of 30 and 50, are workers, Gao said.

"And 90 percent of them were dispatched abroad through companies, such as construction companies," he said.

"Malaria can actually be cured as long as it is discovered early and given proper treatment. However, many deaths happen due to late diagnosis," Gao said, noting that it is important to improve doctors' awareness of the disease in small and lower-level hospitals.

"Local disease control and prevention departments and medical bodies should improve their ability to discover and diagnose malaria," he said.

In a bid to control imported malaria cases, China has laid out a plan to wipe out the disease by 2020.

Contact the writer at wanghongyi@chinadaily.com