Epidemiology - Clostridium perfringens

Epidemiology

◗ Geographical distribution

C. perfringens is distributed world wide. C. perfringens typeA is responsible for most human diseases including food poisoning, soft tissue infections, gas gangrene, and primary septicemia. C. perfringens type C is responsible for enteritis necroticans.

◗ Habitat

C. perfringens type A is part of the normal flora of the intestinaltract of humans and animals. These bacteria are excreted in the feces and hence contaminate the skin of the perianal region, buttocks, and thighs. C. perfringens type A spores are ubiquitous. They are found in the soil, dust, and air. They remain viable for a very long period even in adverse environmental conditions. C. perfringenstypes B, C, D, and F colonize the intestinal tractsof animals and occasionally humans. Their spores usually do not survive in soil.

◗ Reservoir, source, and transmission of infection

Gas gangrene occurs following road traffic accidents or any other injuries (like during war) involving crushing trauma of large muscle mass contaminated with pathogenic clostridia. Rarely, the condition may occur following surgical operations. The condition is caused by:

·           Contamination of wound with soil, such as manure soil or cultivated soil, road dusts, or bits of clothing heav-ily contaminated with C. perfringens and other pathogenic clostridia (exogenous infection).

·           Clostridium species that are present on the normal skin, espe-cially on the perineum and thighs, which invade through a wound and cause the infection (endogenous infection).

Clostridial food poisoning occurs following ingestion of cold or warmed up meat dishes contaminated with spores of  perfringenstype A. Spores are responsible for the infection.

    Foods contaminated with large number of bacteria are the sources of exogenous infection in case of necrotizing enteritis. The conditions that facilitate exposure of the food to a large number of C. perfringens spores and malnutrition are the risk factors for the disease.