Can algae cause disease?

Yes. Certain blooms produce toxins that harm humans and animals.

How illness happens

• Toxins: Some algae/cyanobacteria release potent poisons.
• Blooms (HABs): Rapid growth concentrates toxins.
• Exposure:
  • Ingestion: Drinking/swimming in tainted water; eating contaminated seafood.
  • Inhalation: Breathing spray from contaminated water.
  • Skin/eye contact: Direct exposure.

Culprits and toxins

• Cyanobacteria (blue-green algae): Hepatotoxins, neurotoxins, dermatotoxins.
• Dinoflagellates: Red tides; can cause paralytic shellfish poisoning.

Symptoms

• Mild–moderate: Rash, itching, watery eyes, nose irritation, headache, stomach pain, vomiting.
• Severe: Liver injury, neurologic effects, paralysis, respiratory failure.

Who’s at risk

• Humans: Swimmers, those drinking untreated water, shellfish consumers.
• Pets (esp. dogs): Highly vulnerable; exposures can be fatal.

Prevention

• Avoid discolored/scummy/smelly water.
• Obey swimming, fishing, and shellfish advisories.
• Keep pets out of suspect water.
• If exposed or symptomatic, contact a clinician or poison control.