Biological Agents Information

HARMFUL ALGAL BLOOMS (HABs) “Blue-green algae”

Tiny Plants with a Toxic Punch. Harmful algal blooms, or HABs, occur when colonies of algae—simple plants that live in the sea and freshwater—grow out of control while producing toxic or harmful effects on people, fish, shellfish, marine mammals, and birds. For more information about Harmful Algal Blooms Click Here.


Anthrax is a disease caused by the bacteria Bacillus anthracis. It can affect animals and humans. Humans can be affected by anthrax in three ways: skin (cutaneous), digestive tract (gastrointestinal), and the most serious, lung or inhalation anthrax. Anthrax spores can enter the body through cuts or sores, eating improperly cooked meat, or inhaled. Anthrax is not usually spread from person to person. Symptoms usually appear 1 to 7 days after exposure.

Symptoms vary by the type of anthrax. If diagnosed early enough, anthrax can be treated.


Smallpox is a deadly and very contagious disease caused by the variola virus. Smallpox is mainly spread person to person through direct contact with respiratory secretions or skin lesions. Incubation is about 12 days but ranges from 7 to 17 days. Symptoms begin with a high fever, body aches, and fatigue. A rash appears beginning in the mouth and spreading to the face and rest of the body. The sores then become pus filled and begin to crust. Death occurs in 30% of infected people. Vaccination within 3 days after exposure can help prevent or lessen the severity of smallpox.


Plague is caused by the bacteria Yersinia pestis and is found in rodents and fleas throughout the world. There are three types of plague: bubonic plague, septicemic plague, and pneumonic plague. With Bubonic plague, patients develop swollen, painful lymph nodes or buboes near the area where they were bitten by the infected organism.

Patients with Septicemic plague (bloodstream infection) develop bleeding into the skin and often shock. Pneumonic plague is a lung infection, which causes the patient to cough and have difficulty breathing. Symptoms appear from 1 to 8 days after exposure. If diagnosed early, the plague can be treated with antibiotics, otherwise, death is usually inevitable.


Botulism is a disease that paralyzes the muscles and is caused by a toxin made by the bacteria Clostridium botulinum. There are three main types of botulism: foodborne, infant, and wound. Foodborne botulism occurs when a person eats food contaminated with the toxin. Symptoms occur from 6 hours to 2 weeks after exposure, and may include double or blurred vision, slurred speech, difficulty in swallowing, and muscle paralysis. Infant botulism occurs in a small number of infants who have certain intestinal conditions and occurs from eating honey or corn syrup. Wound botulism can occur when wounds are infected by contaminated soil or gravel. Botulism is not spread from person to person. Hospitalization may be necessary and patients recover after many weeks of supportive care.

Partner with Southwestern District Health Unit to protect our community!
Click here for more information about becoming a PHEVR volunteer.