According to estimates released in December 2014, there were about 198 million cases of malaria in 2013 and an estimated 584,000 deaths.1 It is estimated that 3.4 billion people (approximately half of the world’s population) and 106 countries and territories are at risk of malaria transmission. Hundreds of millions of people live in areas where malaria is prevalent (principally in Africa, Latin America, and Asia).
Malaria is transmitted when infected female anopheline mosquitoes inject sporozoites while taking a blood meal, or when infected erythrocytes are injected intravenously. Within minutes of entering the circulation, sporozoites invade hepatocyles, where they develop as hepatic exoerythrocytic forms. There are numerous Plasmodium species but only four are important human pathogens:
- Plasmodium falciparum
- Plasmodium vivax
- Plasmodium malariae
- Plasmodium ovale
Symptoms of malaria include fever, headache, and vomiting, and usually appear between 10 and 15 days after the mosquito bite. If not treated, malaria can quickly become life-threatening by disrupting the blood supply to vital organs.
Key interventions to control malaria include prevention (i.e. use of insecticidal nets by people at risk; and indoor residual spraying with insecticide to control the vector mosquitoes), and prompt and effective treatment for those infected.2
1 The World Health Organization, malaria facts (http://www.who.int/mediacentre/factsheets/fs094/en/ accessed July 8, 2015).
2 The World Health Organization, health topics – malaria, (http://www.who.int/topics/malaria/en/ accessed July 8, 2015).