Shaaybaar; laga helay dhiiga bukaanka maadada loo yaqaano difaac-jir (antibody) ee difaacda jirka.
Waxay ka dhigan tahay in baaritaanka dhiigga uu muujiyey jiritaanka unugyada difaaca ee gaar ah, taasoo tilmaamaysa in qofku hore ama hadda ula kulmay jeermis, cudur, ama uu leeyahay talaal.