The illness that struck about 50 people following a high school basketball game in Pierre, SD was the result of Clostridium perfringens food poisoning, possibly linked to tacos, according to the state Department of Health.

The health department used an electronic questionnaire to high school and middle school staff and students, as well as others who attended the Jan. 31 game, to try to pin down the food source of the illnesses.

Clostridium perfringens is a spore-forming bacterium commonly found on raw meat and poultry. It produces a toxin that causes illness.

According to the Centers for Disease Control and Prevention, C. perfringens infection often occurs when foods are prepared in large quantities and kept warm (68°C-140°F) for a long time before serving. Outbreaks often happen in institutions or at events with catered food.

Foods such as beef, poultry, gravies and other foods commonly associated with C. perfringens infections should be cooked thoroughly to an internal temperature of at least 145°F-165°F, and then kept at a temperature that is either warmer than 140°F or cooler than 41°Fafter cooking.

Leftovers should be reheated to at least 165°F (74°C) before serving. Leftover foods should be refrigerated as soon they are removed from heating devices and serving tables.