Ordinarily when a fly touches a liquid food it infects the liquid with its pathogens, so it must be dipped in order to release also the antidote for those pathogens to act as a counter balance to the pathogens.
Kwa kawaida nzi anapogusa kimiminika kinachotumika kama chakula huathiri kimiminika kwa vijidudu vyake vinavyosababisha magonjwa, kwa hiyo ni lazima kumchovya ili kutoa pia kiuasumu cha vijidudu vyenye kusababisha magonjwa ili vipambane na vijidudu hivyo.