Harmful algal blooms can cause human and animal illnesses, environmental damage, and socioeconomic impacts. We analyzed data from the first nationally representative survey to estimate public awareness and concerns about the health impacts of harmful algal blooms. Porter Novelli's Fall 2020 ConsumerStyles survey was sent to 4,548 U.S. adults between September 24 and October 10, 2020, with an overall response of 3,625 adults (80%). Weighted descriptive analyses found that over half (59%) of respondents were aware that harmful algal blooms can be a health threat, while almost a third (32%) were concerned about health or economic impacts. Awareness and concern varied by demographic characteristics. Those who reported awareness of at least one health impact were more likely to be older, White, non-Hispanic, have higher income and education levels, and not have a child in the household. Concern about harmful algal bloom impacts was lowest among males, Mountain region and inland state residents, those with higher income and education levels, and those who identify as White and non-Hispanic. Public health practitioners can improve outreach about harmful algal blooms by using information about public awareness and concerns to tailor messages for different audiences.

INTRODUCTION: Illnesses caused by harmful algal blooms can vary in clinical presentation and severity depending on the types of algae, cyanobacteria, or toxins involved as well as the route and extent of exposure. These illnesses are primarily diagnoses of exclusion owing to lack of access to clinical testing for harmful algal bloom toxins. We used a national survey of healthcare providers to explore self-reported confidence and perceived barriers to diagnosing harmful algal bloom-associated illnesses. METHODS: We conducted a descriptive analysis (SAS 9.4) of 2 questions from a national survey of healthcare providers administered September 14-October 26, 2020 (N=1,503). Chi-square tests were used to assess differences between groups, with statistical significance defined as p<0.05. RESULTS: Most (68%) providers reported little to no confidence in their ability to identify illnesses caused by harmful algal blooms, 17% were confident or very confident, and 15% reported not seeing patients with these illnesses. Responses differed by specialization, work setting, sex, experience, whether pediatric patients were seen, and number of patients seen. Respondents regularly using resources such as newspapers (31%), professional societies (29%), and government health agencies (26%) reported increased confidence. Of 1,283 (85%) respondents who were asked about barriers to accurately diagnosing patients with these illnesses, 71% selected lack of knowledge about harmful algal bloom-associated illnesses as a barrier. CONCLUSIONS: Provider confidence in identifying harmful algal bloom-associated illnesses was low, and lack of knowledge was identified as a primary barrier, suggesting that more outreach and education are needed. Tailoring information for specific provider audiences and providing it through highly frequented channels could increase providers' confidence in identifying and diagnosing harmful algal bloom-associated illnesses.