Many schools aren't making the grade when it comes to receiving the mandatory inspections of their lunch programs, according to a recent USA Today article — part of a series investigating school lunch safety in the U.S.

The investigation uncovered that more than 8,500 schools failed to have their kitchens inspected at all last year, and another 18,000 fell short of a requirement in the Child Nutrition Act that calls for cafeteria inspections at least twice a year.

The requirement falls under the National School Lunch Program, which provides food for 31 million schoolchildren in almost every school across the United States. 

The purpose of the inspection requirement is to ensure that the facilities and workers comply with safety and sanitary requirements — from checking food temperatures to wearing gloves, according to the article.

A lack of inspections may be contributing to food-borne illness outbreaks in schools. According to the Centers for Disease Control and Prevention or CDC, there were 23,000 food-borne illness cases reported in schools from 1998 through 2007. At least one-third of the cases were caused by the norovirus, a food-borne illness that has similar symptoms to the stomach flu.

According to the investigation, no food-borne illness has sickened more schoolchildren in the past decade than the norovirus, and no other illness is linked as consistently to improper food handling in cafeterias.

The article highlights one case at Trinity High School in Dickinson, N.D., in which an employee who was sick with the virus over the weekend unknowingly spread the disease to school children after returning to work on the following Monday. Not long after consuming lettuce that the worker had chopped with bare hands, 52 students and eight faculty members fell ill with the same symptoms the sick worker had suffered.

Since then, head cook Diane Jilek said that the worker, who has made food at the school for more than two decades, has been "very conscientious" about wearing gloves.

"We needed to do things to prevent it from happening again," she said. "One of the key things is, if you're ill, call someone. The second thing is, we wear plastic gloves all the time."

This most recent case of food poisoning highlights the need for tougher inspection enforcement. The USDA, which is responsible for overseeing the school lunch program, admits that the rule is almost impossible to enforce, especially because the agency only requires that states provide the number of schools that have been inspected, but not the schools’ names.

In addition, the law does not say what will happen to schools that do not get inspected.

As a result, some are trying to beef up the laws in the name of children's safety. This summer, Agriculture Secretary Tom Vilsack told officials to "aggressively push state and local health agencies to conduct the two required annual inspections, so that schools are in compliance."

In addition, Illinois Democratic Sen. Dick Durbin, who put in the provision to require two inspections per year, agrees that more needs to be done.

"Fines or lawsuits or penalties ... may be the only way to move some of these districts," said Durbin.

Check out USA Today’s entire investigative series on school lunch safety.