State illness work group reports 2024 HAB‑associated cases: dozens of human, animal and wildlife events

Shannon (surname not given), speaking for the multi‑agency HAB illness work group, summarized 2024 morbidity and wildlife impacts reported to CDC’s OHABs system.

She reported 25 individual freshwater human cases associated with water contact or proximity, a single dog gastrointestinal report, 15 fish‑kill group events representing more than 49,000 fish, and one wildlife bird event of four waterfowl mortalities. On the marine side, the work group logged 49 marine mammal events involving 392 animals — the majority California sea lions — linked to domoic acid; the speaker said strandings and care‑center admissions showed neurological and gastrointestinal signs and that the season was substantial though not at the catastrophic scale observed in the previous year.

Shannon said the bulk of reported freshwater cases in 2024 were from two regions (reported in the meeting as Region 5 and Region 6). She cautioned that absence of a reported OHABs case in a region does not mean a region had no bloom events. The work group said some suspected illness reports could not be linked to HABs after follow‑up and that in other instances reporting parties lacked contact information, limiting follow up.

The illness work group also summarized outreach and training: it updated web materials and fact sheets in English and Spanish, supported local public‑health requests in Los Angeles and Lake counties, and participated in the CDC OHABs community‑of‑practice calls.

The work group urged ongoing cooperation among regional coordinators and partners to keep the public informed and to support timely incident responses.