The Piraka were influenced by Teridax telepathically. The Voya Nui Matoran weren't infected by a virus, they were infected with Antidermis, the essence of Makuta, which is not a virus. The only way the Antidermis influenced Brutaka was that it made him stronger, essentially he was addicted to it. The Rahi were controlled through infected masks infected by the essence of Makuta using Shadow Kraata.
The viruses refer to, in canon, the substances used to create Rahi, aswell as what was used to modify the Skakdi and shut down the Great Spirit Robot. We've also seen weaponized viruses that consumes armor and flesh, such as the virus that killed Kojol and Tridax, and a virus that gave Takanuva the ability to fly in 2008.
Tl;dr: Antidermis is not the same thing as a virus far as we know.