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  • About HABs
    Harmful Algal Bloom (HAB) can occur when certain types of microscopic algae grow quickly in water, forming visible patches that may harm the health of the environment, plants, or animals. ...more
  • CDC Activities
    CDC works with public health agencies, universities, and federal partners to investigate how algae which can cause HABs may affect public health ...more
  • Data
    Harmful Algal Bloom-related databases from federal and non-federal resources ...more
  • Focus Areas
    • Cyanobacteria
      Cyanobacteria are single-celled organisms that live in fresh, brackish, and marine water and can use up the oxygen and block the sunlight that other organisms need to live and can produce powerful toxins that affect the brain and liver of animals and humans ...more
    • Harmful Marine Algae
      • Ciguatera
        Ciguatera fish poisoning is an illness caused by eating fish that contain toxins produced by a marine microalgae ...more
      • Red Tide
        Overgrowth of the microscopic marine algae called Karenia brevis can create blooms that can make the ocean appear red or brown. People often call these blooms “red tide” ...more
    • Pfiesteria piscicida
      Pfiesteria piscicida is a microscopic alga that lives in estuaries—where freshwater streams or rivers mix with salt water—along the Atlantic and Gulf coasts ...more
  • Publications
    Related studies on harmful algal blooms from various scientific publications ...more
  • Resources
    Useful information about harmful algal blooms from federal, state, non-profit organizations as well as universities and others ...more
  • Surveillance
    NCEH has developed the Harmful Algal Bloom-related Illness Surveillance System (HABISS) to support public health decision-making ...more

Other Environmental Hazards & Health Effects Topics