Ana iya rarraba ƙwayoyin cuta gwargwadon kwayar da suke kamuwa da ita: ƙwayoyin cuta na dabbobi, ƙwayoyin cuta na tsire-tsire, ƙwayoyin cuta na fungi, da ƙwayoyin cuta (ƙwayoyin cuta da ke kamuwa da ƙwayoyin cuta, waɗanda suka haɗa da ƙwayoyin cuta mafi rikitarwa). Wani rarrabuwa yana amfani da sifar geometrical na capsid ɗin su (sau da yawa helix ko icosahedron) ko tsarin kwayar cutar (misali kasancewar ko babu labulen lipid). Girman ƙwayoyin cuta daga kimanin 30 nm zuwa kimanin 450 nm, wanda ke nufin cewa yawancin su ba za a iya gani da microscopes mai haske ba. An yi nazarin siffar da tsarin ƙwayoyin cuta ta hanyar microscopy na lantarki, NMR spectroscopy, da X-ray crystallography. Tambaya: Waɗanne siffofi biyu na geometrical ne capsid?
helix ko wani icosahedron