Umalaleveva isifo esithelelanayo esithwalwa omasikido esiphatha abantu kanye nezinye izilwane esibangelwa ukucinzwa umasikido protozoans (uhlobo lwesicubu esisodwa i-microorganism) sohlobo lwe-Plasmodium. Umalaleveva ubanga izimpawu ezibandakanya umkhuhlane, ukutubeka, ukuphalaza kanye nokuphathwa yikhanda. Uma kukubi kakhulu kungabangela isikhumba esiphuzi, ukuxhuzula, i-coma noma ukufa. Lezi zimpawu zivamise ukuqala ezinsukwini ezilishumi kuya kwezilishumi nanhlanu emva kokuncinzwa umasikido.Kulabo abangalashwanga kahle isifo singaphinde sibuye emva kwezinyanga. Kulabo abasindile ekuthelelekeni, uma uphinda utheleleka kuvamise ukuba nezimpawu ezincane. Lokhu kuvimbeleka kwesikhashana kuyaphela emva kwezinyanga noma iminyaka uma ungaphindanga waba sendaweni engaba nomalaleveva. Imvamisa, isifo sihanjiswa ukuncizwa umasikido wesifazane onesifo owaziwa nge-Anopheles. Lokhu kuncizwa kungenisa izilwane eziphila ngegazi ezisuka ematheni kamasikido ziye kumuntuegazini. Izilwane eziphila ngegazi zibe seziya esibindini lapho ezifike zikhule khona zizalane zande. Izinhlobo ezinhlanu ze-Plasmodium zingathelela abantu baphinde bazisabalalise. Ukufa imvamisa kubangelwa P. falciparum ne P. vivax, P. ovale, kanye P. malariae okujwayele ukubangela umalaleveva ongenawo amandla kakhulu. Lezi zilwanyana P. knowlesi azivamisile ukubanga isifo kubantu. Umalaleveva uvamise ukuxilongwa ngokuhlola ngezipopolo kwegazi kusetshenziswa amafilimu egazi, noma nge-antigen- ukuhlola okusheshayo. izindlela ezisebenzisa i-polymerase chain reaction ukuze kutholakale izilwanyana eziphila ngegazi DNA isisunguliwe, kodwa azikasetshenziswa ezindaweni ezinomalaleveva ojwayele ngenxa yezindleko zayo kanye nokuba nzima kwayo.