Work by a Chinese scientist, who shared this year's Nobel Prize for medicine for her work with Vietnamese soldiers during the American War towards finding a cure for malaria has come under attack by the son of a leading local scientist.

Dang Van Ngu and Dang Nhat Minh

Dang Nhat Minh, the son of Dang Van Ngu, who was well-known in Vietnam for his researches against malaria, has challenged that Vietnamese troops were cured by drugs developed by Chinese scientist Youyou Tu.

International media, including the BBC and the British newspaper The Telegraph, acclaimed Tu's discovery of a therapy against malaria.

Tu was allegedly part of a secret project set up by the late Mao Zedong, in 1969. The project reportedly aimed to find a cure for malaria, which was killing thousands of Vietnamese troops fighting the US-backed regime in southern Vietnam.

The British newspaper, The Guardian, said Mao's project began in 1967 to help Vietnamese troops, and Tu joined the research team two years later. When Tu went to Hainan Island, troop losses to malaria were greater than military engagements.

Ngu, who died in 1967, spent his lifetime's work on researching a vaccine for malaria, which still eludes scientists today.

When Minh read of Tu's Novel Prize, he sought out other scientists who had worked with his father, notably Nguyen Tien Buu, who had accompanied him to the Tri-Thien battlefield in 1967 to study the impact of malaria on troops there. Buu surprise at the news that implied Tu's medicine had cured Vietnamese troops.

Buu worked at the Vietnamese Institute of Malaria-Bacteriology and Insects from 1957 to 1992, but had heard nothing of Mao's "secret" project to cure Vietnamese troops.

Malaria is endemic to Vietnam, and many scientists have battled to fight the debilitating and sometimes fatal disease, which is transmitted by infected mosquitos for more than a century, among them, French epidemiologist Alexandre Yersin, who discovered the cause of bubonic plague in 1897 and devoted his life to Viet Nam, working for the Institute Pasteur, based in Na Drang.

The team at Vietnamese Institute of Malaria-Bacteriology and Insects studied malaria from 1957 to 1962 across northern Vietnam and, by the end of 1962, the government approved a programme to end malaria in the north within three years. The chairman of the committee against malaria was former Prime Minister Pham Van Dong. Ngu was in charge.

They set up committees against malaria at all levels of provinces and communes. This programme also received support from the former Soviet Union.

When the programme ended in 1964, the rate of malaria was reduced to 20%, a dramatic drop from 90-100% in rural and mountainous areas.

Dang Van Ngu (middle) and Ho Chi Minh (right) on November 14, 1955

But the US escalation of the war opened a pathway for malaria to spread from southern Vietnam to the north.

In March 1967, Ngu and 12 co-workers joined Tri-Thien Campaign to research a vaccine against malaria for the military and to prevent malaria from spreading. Ngu was killed in a bombing raid the next month.

A week later, bombing destroyed the research office and documents at the Institute of Malaria in Hanoi. The work was halted and the team was ordered to return to the north.

Buu said, "If Tu's drug, 'Artemisinin', had ever been used in Vietnam, the institute would have been informed, so it could be reviewed before going into mass distribution."

By 1980, it was worked out that Artemisinin could be produced by using the sweet wormwood (artemisia annua) found along the northern borders.

On October 11, Minh received a letter from a friend, Vu Duc Duong, then living in San Francisco, urging him to dig into the problem.

The letter read:

"The news that a Chinese scientist was given A Nobel prize reminds me of your father who also researched a vaccine for the military. I thought a lot about this news ... And saw another one today, this time, Youyou Tu said the project against malaria was started in 1969.

"You know about Ngu's works more than anyone else and have documents so I want to ask you to clear this issue.

"Not only it will help the world understand more about Ngu's work and relationship between China and Vietnam, but also provide truth for future generations."

Dang Van Ngu was born in Hue on April 4, 1910. He graduated from the Indochina Medical University in 1937 and became an assistant to the French physician and professor Henry Galliard, dean of the Department of Bacteriology at the university.