Last year, 407 people in Cambodia died from dengue fever out of 40,000 people infected; most were children. This was the highest number of deaths since 1998 when 474 people died. Cambodia constantly faces cases from dengue fever. The outbreak last year was linked to an early rainy season. This is a good illustration of how environmental factors can affect diseases. To try to prevent further deaths, residents were told to keep still water away from mosquitoes. Last year there were also significant outbreaks in other parts of Southeast Asia. The WHO states that 50 million people a year contract the virus.