Before we answer that question, let's first define what giardiasis is.
What is giardisis?
Giardiasis is a parasytic infection that may affect cats due to the protozoan called giardia. When ingested, these microscopic protozoans would reproduce in a cat's intestines causing diarrhea.
What are the symptoms of giardiasis?
If your cat defecated soft, watery, or mucus-like stools, with an awful smell, then it is possible that your feline friend is suffering from giardiasis.
How do cats acquire giardiasis?
Cats acquire giardiasis when they ingest a contaminated fecal matter of other animals, or when they drink a giardia-infested water.
So based on how your pet cat acquires giardiasis, plastic food bowls are not the main culprits.
However, your vet would most probably advise you to get rid of your pet's plastic food bowls because plastic food bowls have the highest percentage to harbor bacteria which may then worsen your pet's diarrhea.
So, do cats acquire giardiasis from plastic food bowls?
The answer is no. Cats only do get giardiasis "from plastic food bowls" if you accidentally or unknowingly filled their plastic food bowl with a giardia-infested water, or if the bowl is unsanitary.