France's Francoise Barre-Sinoussi and Luc Montagnier, who shared one half of the award, discovered the human immunodeficiency virus (HIV) that causes
AIDS by destroying immune cells, one of the biggest scourges of modern times.
Harald zur Hausen of Germany went against current dogma and claimed that human papilloma virus (HPV) causes cervical cancer, the second most common cancer among women, the jury said.
The French pairs HIV discovery was "one prerequisite for the current understanding of the biology of the disease and its antiretroviral treatment," the Nobel citation said.
Their work "led to development of methods to diagnose infected patients and to screen blood products, which has limited the spread of the pandemic," it said.
"The combination of prevention and treatment has substantially decreased spread of the disease and dramatically increased life expectancy among treated patients."
AIDS -- acquired immune deficiency syndrome -- first came to public notice in 1981, when
It has since killed at least 25 million people, and 33 million others are living with the disease or harboring HIV.
In May 1983, in a paper published in the
Their groundbreaking discovery was also helped by
Both Montagnier and Gallo are co-credited with discovering that HIV causes AIDS, although for several years they staked rival claims that led to a legal and even diplomatic dispute between
The Nobel jury made no mention of Gallo in its citation.
Barre-Sinoussi, born in 1947, is a professor at the Institut Pasteur in
Meanwhile, Zur Hausen was rewarded for his work against cervical cancer, which is sometimes called "the silent killer" of women because it is so often tragically undetected until it is too late.
"His discovery has led to characterization of the natural history of human papilloma virus (HPV) infection, and understanding of mechanisms of HPV-induced carcinogenesis and the development and the development of prophylactic vaccines against HPV acquisition," the jury said.
"The global public health burden attributable to human papilloma viruses is considerable," it said, pointing out that five percent of cancers worldwide were caused by the virus.
Fifty to 80 percent of the population is infected with the virus, though not all infections are cancerous.
"Human papilloma virus can be detected in 99.7 percent of women with histologically confirmed cervical cancer, affecting some 500,000 women per year," it said.
In the 1970s and 80s, Zur Hausen demonstrated that a form of cancer called Burkitts lymphoma was linked to Epstein-Barr virus.
It was the first step towards showing that HPV is a cause of cervical cancer.
Today, there is not only a simple smear test that can detect HPV, there are also two effective vaccines against it.
Zur Hausen, 72, is a professor emeritus and former chairman and scientific director of the German Cancer Research Centre in
The Medicine Prize is the first award to be announced in this years Nobel season.
The Physics Prize is to be announced on Tuesday followed by the Chemistry Prize on Wednesday. The Literature Prize will be announced on Thursday and the Peace Prize on Friday.
The Economics Prize will wrap up the awards on October 13.
Laureates receive a gold medal, a diploma and 10 million Swedish kronor (1.42 million dollars, 1.02 million euros) which can be split between up to three winners per prize.
The formal awarding of the prizes will take place in