Harmful Algal Bloom Surveillance: Defining an Emerging Environmental Health Concern

Freshwater harmful algal blooms (HABs) are of increasing concern in recreational and drinking waters due to their potential public health risk. In order to assess the scope and magnitude of this problem, the Wisconsin Department of Health Services (DHS), the Wisconsin Department of Natural Resources (DNR) and the Wisconsin State Laboratory of Hygiene (WI SLH) undertook a five-year surveillance effort to evaluate the public health burden of HABs.

With funding from the Centers for Disease Control and Prevention, the interagency team developed case reporting pathways, including automated call notifications from the Wisconsin Poison Center, a web-based illness survey, direct contact with ill individuals, and referrals from partner agencies. Illness reports were reviewed by program staff to ensure they fit the case definition of a HAB-related illness and follow-up water sampling was conducted to determine environmental conditions at the time of the exposure.

Between 2009 and 2013, DHS received 144 health complaints associated with exposure to HABs. The most common illnesses were gastrointestinal distress, rash, respiratory irritation and cold-like symptoms. Cyanotoxins were detected in over 56% of the environmental samples analyzed.

Expanded outreach efforts to health-care professionals, veterinarians and local lake associations helped increase reporting of HAB-related illnesses and awareness of the potential hazard associated with algal blooms. The information gathered in this surveillance effort has helped the interagency team prioritize surveillance and outreach activities to address the public health burden of HABs and implement interventions to reduce exposures to harmful algal blooms.