When refrigerator fare turns foul.

Think back to the last time you cleaned out your refrigertor. If you're like many people, it's not a pretty sight.

Two new studies now implicate bacteria-contaminated food as the source of many cases of listeriosis, a rare, but potentially lethal, illness that can strike pregnant women, the elderly and people with damaged immune systems, Listeria monocytogenes can cause flu-like symptoms, blood poisoning, complications of pregnancy and stillbirths. In severe cases,it can lead to meningitis, an infection of the membranes surrounding the brain and spinal cord.

During the last decade, scientific teams traced several listeriosis epidemics to widespread ingestion of foods fouled with the bacterium, found in soil, animals and vegetation. While epidemiologists blamed these large outbreaks on soft cheeses, pasteurized milk (SN: 3/2/85, p.141) and the cabbage in coleslaw, the cause of sporadic listeriosis cases remained mysterious.

Anne Schuchat and Robert W. Pinner of the Atlanta-based Centers for Disease Control (CDC) and their colleagues took a closer look at these infrequent cases. In the first study, the team identified listeriosis patients in parts of California, Tennessee and Georgia, and in the entire state of Oklahoma.

With those reports, as well as population estimates from the U.S. Bureau of the Census, the team calculated the annual incidence of listeriosis in the regions studied as 7.4 cases per million persons. Nationwide, the statistics translate to about 1,850 infections and 425 deaths every year, the researchers estimate.

Next, the team focused on 165 listeriosis patients and 376 healthy controls. A statistical analysis revealed that compared with controls, patients were 2.6 times more likely to have eaten a soft cheese, such as feta or some types of Mexican cheese, and 1.6 times as likely to have bought foods from a delicatessen counter. Eating such foods accounted for 32 percent of the listeriosis cases, the team reports in the April 15 JOURNAL OF THE AMERICAN MEDICAL ASSOCIATION.

In the second study, reported in the same journal, the team collected food from the refrigerators of 123 listeriosis patients. Foods such as lunch meat, cheese and leftovers were packed in sterile bags and shipped on ice to CDC headquarters.

Although they can't prove that any individual food caused a patient's illness, L. monocytogenes grew from at least one edible item taken from 79 (64 percent) of the refrigerators sampled. Furthermore, 26 of the 79 refrigerators (33 percent) had food samples that contained the same strain of L. monocytogenes that had infected the patient.

Most people with a healthy immune system don't have to worry about listeriosis, Schuchat says. However, she suggests that pregnant women, the elderly and people with damaged immune systems might want to avoid deli-counter foods and certain soft cheeses. In addition, she says, all Americans should adopt safe food-handling practices, such as washing raw vegetables; fully cooking beef, poultry and pork; and reheating leftovers until they are steaming hot.