The recall, which affected the company's Armour Lunch Makers kits produced between 18-23 November and distributed nationwide, was prompted by ConAgra's own microbiological tests on ham, turkey and bologna used in the kits, said the USDA.
Listeria monocytogenes can cause serious and sometimes fatal infections in young children, frail or elderly people, and others with weakened immune systems. It is mainly carried in raw and ready-to-eat meat, poultry, seafood and dairy products, and has prompted numerous product recalls, which have led to large financial losses for the food industry and numerous health scares.
According to a ConAgra spokesperson, the latest recall has not resulted in any reports of illness.
"We discovered listeria on some of the products during a routine quality food and safety check," said the spokesperson.
"As a precaution we recalled all the kits containing components produced using the same equipment on that day. We do not yet know what the cause is, but we are conducting tests and will take corrective action," she told FoodNavigator-USA.com.
Each year in the US alone about 2,500 people are infected, of which one-fifth die. Pasteurisation and cooking kill the bacterium.
Because of its high case fatality rate, listeriosis ranks among the most frequent causes of death due to foodborne illness. It ranks as the second leading cause of fatalities from foodborne diseases after salmonellosis in the US and France, and fourth in England and Wales.
Tougher regulatory standards and the increased reporting of food contamination in restaurants, supermarkets and processing plants has pushed companies to put a higher priority on safety, shelf life and cleanliness. The trend has fueled the demand for more stringent and rapid testing and tracing systems for food products along the supply chain to the consumer.
Effective prevention and control measures have worked to bring down the rate of the illness. Programs in France have reduced the incident rate to about a third of what it used to be, and in the US by half. The reduction was attributed to increased regulatory activity, the implementation of Hazard Analysis and Critical Control Points (HACCP) programs throughout the food industry, and specific recommendations to high-risk groups.
Further instances of potential contamination with Listeria monocytogenes that have resulted in recent product recalls include Oklahoma-based Allison's Gourmet Kitchens' BBQ Beans and Latin Food Group of Miami's Queso Seco Cheese.
According to the UN-backed World Health Organisation (WHO) changes in farm practices, more extensive food distribution systems and the increasing preference for meat and poultry in developing countries all have the potential to increase the incidence of foodborne illness.