Image description: Child's room with a boy standing in front of a bed covered with a long-lasting insecticide-treated net (LLIN). On his bedside table sits a packet of antimalarial drugs. Several mosquitos, alive and dead, are visible around the room. Outside the window are fields and other potential mosquito habitats with several people, including a community health worker, working and talking. On the wall of the room is a depiction of the malaria parasite lifecycle in the mosquito vector and in the human host.

Audiotour: At any moment, malaria parasites are coursing through the blood of millions of people across vast stretches of Africa, Southeast Asia, and South America. In some people, about 438,000 in 2015, parasites will find their way to the brain or to the placenta or will lead to catastrophic destruction of red blood cells and they will die. Overwhelmingly, these malaria victims will be children under 5. Yet, at the same time, governments, private industry, academia, philanthropic, and non-governmental organizations will spend billions of dollars on malaria control, interventions and treatments, and research and development. Celebrities will lend their names to awareness campaigns. 

Why then does malaria remain such a difficult and deadly problem? There is no single answer. Malaria is a complex disease caused by an organism with an impressive ability to adapt and evolve. Unlike a virus with 50 or 100 genes, malaria parasites have 5,000. 

And despite years of research on malaria, major gaps in our knowledge of the parasite and its transmission remain. Questions as seemingly straightforward as who in this area has malaria can be extremely difficult to answer. Yet the last 10 years have seen great success in prevention of this disease, which used to kill nearly 2 million people each year. Interventions like long-lasting insecticide-treated nets have protected millions from being bitten by infected mosquitos as they sleep. 

Indoor residual spraying of insecticides has provided further protection. In fact, many successes in reducing the malaria burden have come from successful control of the Anopheles mosquitos that transmit the infection. But just as the parasites have become resistant to drug after drug, mosquitos are becoming resistant to insecticides. 

Night biting mosquitos are being replaced by those that bite during the day when nets can't offer protection. Environmental management can sometimes eliminate breeding sites for mosquitos, but only when governments and society work together. New drugs, vaccines, diagnostics, and vector control tools can be developed if the basic biology of the parasite and its passage through the mosquitos can be better understood. 

Controlling malaria will not be easy. But if it is accomplished, it will be because leaders and people across the world begin to understand the many interconnected elements of this deadly disease. This course is our first step to that understanding.