Clostridium botulinum is an anaerobic, spore-forming bacillus that produces the toxin responsible for causing botulism. Seven distinct types of toxin exist, labeled as Type A through G. Type A, C and E toxins are the types that most frequently affect domestic poultry. C. botulinum live in decaying organic matter and soil. The bacteria form spores which allow them to survive in a dormant state until exposed to conditions that can support their growth. It can also develop in spoiled animal feed. The toxin is extremely potent, and can survive in the soil for years and is resistant to heat and most chemical disinfectants.
Temperature is a critical factor in the multiplication of C. botulinum in the environment, and outbreaks are more likely to take place during the summer and fall seasons, when ambient temperature is high. Anywhere where there has been raw sewage discharge and deaths of terresteial and aquatic invertebrates and fish posses an increased risk of botulism. Maggots can also pose a risk because they are able to harbor the toxin in their bodies.