title: Strain theory of malaria: the first 50 years.
abstract: From the 1920s to the 1970s, a large body of principles and evidence accumulated about the existence and character of 'strains' among the Plasmodium species responsible for human malaria. An extensive research literature examined the degree to which strains were autonomous, stable biological entities, distinguishable by clinical, epidemiological or other features, and how this knowledge could be used to benefit medical and public health practice. Strain theory in this era was based largely on parasite phenotypes related to clinical virulence, reactions to anti-malarial drugs, infectivity to mosquitoes, antigenic properties and host immunity, latency and relapse. Here we review the search for a definition of 'strain', suggest how the data and discussion shaped current understandings of many aspects of malaria and sketch a number of specific connections with perspectives from the past 30 years.
authors.affiliation: Fogarty International Center, Building 16, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: F Ellis
authors.initials: FE
authors.lastname: McKenzie
authors.forename: David L
authors.initials: DL
authors.lastname: Smith
authors.forename: Wendy P
authors.initials: WP
authors.lastname: O'Meara
authors.forename: Eleanor M
authors.initials: EM
authors.lastname: Riley
mesh_terms: D000818:Animals; D000852:Anopheles; D000953:Antigens, Protozoan; D000962:Antimalarials / Q000627:therapeutic use; D006801:Humans; D008288:Malaria / Q000188:drug therapy / Q000469:parasitology* / Q000503:physiopathology* / Q000635:transmission; D010961:Plasmodium / Q000145:classification* / Q000235:genetics / Q000276:immunology / Q000472:pathogenicity*; D013045:Species Specificity; D014774:Virulence
chemical_list: D000953:Antigens, Protozoan; D000962:Antimalarials