The codes are possibly (also) related to incidents that CDC or other organizations would like statistics on.

Lemur's aren't common, ducks are, and "Chlamydia psittaci in ducks: a hidden health risk for poultry workers" is (via https://pubmed.ncbi.nlm.nih.gov/25854003/)

According to Google, it's: 2023 ICD-10-CM Diagnosis Code W55.81XA Bitten by other mammals, initial encounter