Robert Alvarez Genndy Tartakovsky Craig McCracken (art direction)
Germ Warfare is the third part of episode 10 of season 2, and the 63rd episode of Dexter's Laboratory that originally aired on September 17, 1997. In this episode, Mom, Dad, and Dee Dee all come down with the flu. Dexter tries to avoid getting the flu himself, but the mission is made harder when Dee Dee stumbles into his lab looking for her handkerchief.
Dexter has just put the finishing touches on his "greatest creation", which is a sphere that he claims will give him the power to rule the universe. Then, his Mom calls him down for breakfast. However, Mom is revealed to have the flu and sneezes all over his food where the germs crawled towards it. After Dexter runs out of the kitchen in disgust, he runs into his Dad who is also sick with the flu. When Dexter has ran up the stairs to avoid getting sneezed on by Dad, he runs into Dee Dee, who has the worst case of the flu. Dexter rushes to his lab for refuge from his sick family. Suddenly, Dee Dee comes into his laboratory looking for her "hanky", which is actually a tissue that she accidentally left in the lab, which leads Dexter to put himself in a bubble to avoid catching the flu. However, his plan soon goes awry when Dee Dee sneezes onto Dexter's latest invention seen at the beginning of the episode, which causes Dexter's bubble to explode. The episode ends with Dee Dee finding her tissue inside of the bubble, but Dexter, on the other hand, catches the flu that he was trying to avoid. A sick Dexter gives the viewer a sad look of defeat as Dee Dee offers him her tissue and the episode ends.
The three talking amoebas found under Dexter's microscope appear to reference Powerpuff Girls' Amoeba Boys (Craig McCracken was working on Whoopass Stew aka Powerpuff Girls at the time and the shorts were created and debuted the first appearance of the Amoeba Boys during the "What A Cartoon" run in 1992. However, their "official" appearance when PPG became an official series was on December 2, 1998 with the episode "Geshundfight".) During the timeline between the airing of this Dexter's Lab episode and the debut of The Amoeba Boys on PPG, both Craig McCracken and Genndy Tartakovsky were working on both series so the appearance is not coincidental.
This episode it's produced in the same year of 1997 according to the credits.