True or False: If the feces of a one month old mammal are examined for Baylisascaris procyonis, the test will be negative if the animal is not a raccoon.

True or False: If the feces of a one month old mammal are examined for Baylisascaris procyonis, the test will be negative if the animal is not a raccoon.

• A. False
• B. True
• C. Not determinable
• D. Always positive

Answer: (B)

Baylisascaris procyonis is the raccoon roundworm, and its eggs are shed in the feces of raccoons, which are the definitive hosts. Non-raccoon mammals don’t produce adult worms in their intestines, so they don’t shed these eggs. If you test the feces of a mammal that isn’t a raccoon, you would not find Baylisascaris procyonis eggs, making the result negative. This is why the statement is true. (Note: a raccoon or contamination with raccoon feces could yield a positive result, and paratenic hosts may carry larvae without shedding eggs.)

Baylisascaris procyonis is the raccoon roundworm, and its eggs are shed in the feces of raccoons, which are the definitive hosts. Non-raccoon mammals don’t produce adult worms in their intestines, so they don’t shed these eggs. If you test the feces of a mammal that isn’t a raccoon, you would not find Baylisascaris procyonis eggs, making the result negative. This is why the statement is true. (Note: a raccoon or contamination with raccoon feces could yield a positive result, and paratenic hosts may carry larvae without shedding eggs.)