Malaria is caused by a single-celled parasite of the genus Plasmodium. The parasite is transmitted to humans most commonly through mosquito bites. The malaria parasites enter the bloodstream and travel to the liver. When the parasites mature, they leave the liver and infect red blood cells.
Because the parasites that cause malaria affect red blood cells, people also can be infected by exposure to infected blood, including from mother to unborn child, through blood transfusions and by sharing needles used to inject drugs.
Signs and symptoms of malaria typically begin within a few weeks after being bitten by an infected mosquito. However, some types of malaria parasites can lie dormant in your body for up to a year. Some people who have malaria experience cycles of malaria "attacks." An attack usually starts with shivering and chills, followed by a high fever, then sweating, and finally a return to normal temperature.
The greatest risk factor for developing malaria is to live in or visit areas where the disease is common. These areas include tropical and subtropical regions of sub-Saharan Africa, South and Southeast Asia, the Pacific Islands, Central America and northern South America. The degree of risk depends on local malaria control, seasonal changes in malaria rates and the precautions you take to prevent mosquito bites.
Last year the World Health Organization (WHO) recommended widespread use of a new malaria vaccine for children. WHO Director-General Dr. Tedros Adhanom Ghebreyesus called the long-awaited vaccine a "breakthrough for science, child health and malaria control," and said when combined with existing tools to prevent malaria, tens of thousands of children could be saved each year.
