When the People's Republic of China under Deng Xiaoping battled against Vietnam with mixed results in the Sino-Vietnamese War of 1979 (with border skirmishes continuing until 1990), some Chinese who are more knowledgeable than others on the topic of history must have felt a tinge of deja vu.
Lucky for them and their Vietnamese enemies, however, they were now both more likely to die in battle than in some makeshift hospital while suffering from the effects of that most dreaded tropical disease: malaria. That's because a decade before this Chinese invasion of Vietnam, North Vietnam's leader Ho Chih Minh actually requested of the Chinese premier Zhou Enlai that research should be funded for a cure to this deadly disease that was ravaging his army (in 1967, at the height of the Vietnam War). Luckily for them and the Chinese who were dying of malaria in southern provinces like Guangdong and Yunnan, a Chinese female pharmaceutical chemist named Tu Youyou (who at age 85 just recently won the Nobel Prize in Medicine, 2015) discovered artemisinin, a drug which has arguably saved the lives of millions these past few decades.
For Chinese and Vietnamese people of centuries past, however, the luxury of avoiding this awful disease was one they simply couldn't afford (aside from those privy enough to have Ge Hong's 4th-century medicinal book handy, an ancient Chinese text that Tu Youyou used in order to discover the correct level of heat that should be applied to sweet wormwood, or artemisia annua). The Chinese were successful in controlling the northern half of Vietnam for over a thousand years until the 10th century, with largely unsuccessful invasions coming afterward. From what I understand, it is well documented in Chinese historical sources how Chinese troops contracted malaria and died in droves, sabotaging more than one invasion of Vietnam. That includes the Chinese Sui Dynasty's invasion of Champa (i.e. southern Vietnam) from 602-605 AD (Ebrey, Walthall, & Palais, 2009) and the Chinese Song Dynasty's invasion of Dai Viet under the Ly Dynasty from 1075-1077 AD (Anderson, 2008).
However, I'm not so sure about the impact of malaria and its consequences for other Sino-Vietnamese conflicts, and whether or not this gave the Vietnamese the edge they needed in order to drive Chinese forces out of the country. That includes the:
1) initial conquest of northern Vietnam (i.e. Nam Viet, Nanyue) under the Triệu dynasty by the Chinese Han Dynasty under Emperor Wu in 111 BC (Han Chinese victory)
2) the Trung sisters' rebellion from 40-43 AD (Han Chinese victory)
3) the Sui-Former Ly War of 602 AD (Sui Chinese victory)
4) the Battle of Bach Dang, 938 AD (Southern Han Chinese defeat, independence of the Vietnamese Ngô Dynasty)
5) the Mongol invasions of Vietnam, 1258, 1285, 1287-1288 AD (Yuan Mongol-Chinese defeat, yet with tributary status imposed on Dai Viet and Champa)
6) the Yongle Emperor's invasion of northern Vietnam in the Ming–Hồ War of 1406-1407 AD, and occupation until 1427 (eventual Ming Chinese defeat)
I've read a bit about each of these conflicts, but I haven't found any solid references to malaria being a contributing factor to any Chinese defeat beyond the first two conflicts mentioned above (i.e. Sui invasion of Champa and Song invasion of Dai Viet). Does anyone know more or have access to sources which reveal the role malaria played if any in these other conflicts?
On a side note, the Sino-Soviet War of 1979 began after Vietnam invaded and occupied Cambodia. The Vietnamese sided with Russia in the Sino-Soviet Split by toppling the regime of the Khmer Rouge that was backed by China. Funnily enough, a thousand years before this the Chinese Song Dynasty called on the Khmer Empire based in Angkor Wat, plus the Champa Kingdom of southern Vietnam, to aid them in their fight against the common enemy of the Ly Dynasty in Dai Viet (i.e. northern Vietnam). The more things change, the more they stay the same.