The mosquito used to be thought of as a mere nuisance until, in Victorian times, it was revealed that they were the ultimate killing machine, spreading the sometimes fatal disease of malaria. A century on, Horizon traces the astonishing war on the insect that this discovery unleashed, and how the mosquito and malaria have returned, increasingly immune to man's chemical weapons and spreading once more. Determined and seemingly unstoppable, together mosquitos and malaria are nature's deadliest partnership.

Because of Economy class syndrome, a bride-to-be from Newport in South Wales collapsed and died from a blood clot moments after walking off a long haul flight from Melbourne, Australia. Emma Christoffersen was diagnosed as having suffered a pulmonary embolus brought on by the immobility associated with long hyaul travel or flight-related Deep Vein Thrombosis. The airlines argue that this condition is rare and certainly not exclusive to air travel. But leading vascular surgeon, John Scurr, announced to the medical world that roughly one in 100 air passengers probably develop blood clots while flying long haul. Reporter Andy Davies investiges how the issue of DVT has been handled by the aviation industry.