Image caption Dr Campbell now works at Drew University in the US

The active ingredient, avermectin, went on to become a drug known as ivermectin which is now used to treat river blindness and lymphatic filariasis.

River blindness is an eye and skin disease that ultimately leads to blindness. Lymphatic filariasis, also known as elephantiasis, causes painful swelling of the limbs. Both affect people living in some of the poorest countries in the world.

'Out of the blue'

Dr Colin Sutherland, of the London School of Hygiene and Tropical Medicine, said it was immensely gratifying that the achievements in tackling these important diseases had been recognised.

"It's come out of the blue but we are very excited that the committee recognised the importance of parasitic diseases."

The Nobel committee said: "The two discoveries haveSo begins a new book by John Browne, former CEO of the energy giant BP. But that sentence could easily have read: "It was time to leave the closet."

During his 12 years as CEO, he never discussed his sexuality in the workplace. That changed in 2007, when his relationship with a male escort was exposed and Browne resigned amid an ensuing scandal. At the time, he said in a statement, "I have always regarded my sexuality as a personal matter, to be kept private."

The presumption in the business world "is that everyone is straight," Browne tells NPR's Audie Cornish. "The presumption is that a man will have photographs on his desk of his wife and children."

But looking back today, he says "it would have been better to come