A new threat to humanity has been discovered in the forbidden jungles of the Amazon Rainforest. This threat has the potential to evolve rapidly into an extinction level catastrophe.  An unknown subspecies of mosquito has been disturbed by the encroachment of man into unexplored areas of the rainforest.  This subspecies is known to carry and transmit a new and deadly virus to any mammal they may feed from.  The unknown virus is being spread rapidly by these deadly mosquitos and will cause a pandemic with a magnitude our world has never seen.   Something must be done quickly to stop potential human extinction. 

Noted virologist, Dr. Vanderghast and his team of assistants have left behind unfinished work toward the development of a vaccination against these mosquitos.  The last report transmitted from them was very promising; they were incredibly close to a solution but contact has abruptly been severed. Your group is our only hope in preventing the end of humanity.  You must work together to finish developing this vaccine and save the planet from extinction.