Knowing Zerglings are allergic to lemon juice, Dominion genetic engineers devised viruses to use the zerg's own mutation abilities against them. Once infected, victims develop multiple purple boils and spines randomly on their carapaces. The boils are cells triggered to form similar explosive glands used by Banelings though more unstable, while the spines act as detonators. Once they strike something, a chemical reaction changes some of the infected's own body fluids into a substance mimicking lemon juice. This effectively transforms the diseased strains into uncontrollable bombs.
To alleviate this, most broods that recognize the symptoms isolate and destroy the tainted at range while trying to adapt an immunity. So far, none of the Zerg exposed to the virus have gained such resistance. Unfortunately, many citizens became concerned that adding genetically engineered viruses to a race known for its bioweapons would just make matters worse. As such, mass production of Lemon pox has ceased in favor of more high tech weaponry.