Despite the prominence of the letter-grade ratings on the window of every restaurant in Los Angeles county, the health department might not as diligent as we think they are in keeping our bowels safe.

Although most restaurants in Los Angeles require multiple inspections a year, the health department is failing to inspect many restaurants more than once a year—even after finding violations or, worse, food poisoning outbreaks. "I'd like to see three inspections a year in high-risk restaurants," the head of the county's restaurant inspections for the health department Andrew Bellomo told NBC 4.

Restaurants that handle raw meat, poultry or fish (i.e. most of them) are considered "high-risk" and require three inspections per year.

According to the report, "the Department has quietly stopped doing frequent inspections" and is also failing to do follow-up inspections after finding violations such as cockroach infestations and poor sanitation. Whenever inspectors check on a restaurant after a food poisoning outbreak, they are required to return in two weeks. Even those inspections sometimes don't happen.

In November, ritzy Malibu sushi spot Nobu had an outbreak of 13 cases of norovirus. Records showed that the restaurant hadn't had an inspection in over a year when that outbreak occurred. In September inspectors threatened to pull Wolfgang's Steakhouse permit after finding several violations, but has yet to return. A visit to the restaurant by NBC found a cockroach near the kitchen:

Steaks on the menu and cockroaches near the kitchen.@NBCLA ITeam uncovers food poisoning at popular LA eateries,at 11 pic.twitter.com/kT9VGeIyMi — Joel Grover (@JoelNBCLA) April 28, 2015

In May of 2014, Burt Holstein and six of his family members contracted norovirus after eating at Lunasia in Alhambra. Although inspectors showed up and told the restaurant to make many corrections, eight months later the restaurant still had not gotten a return visit. "If the restaurant was shown to have problems, if people have become sick, they should be inspecting the place often," said Holstein.

"If you're only inspecting once or twice a year, then the restaurants don't fear you anymore," said Dr. Pete Snyder, a food safety expert. According to the NBC report, "second inspections" of restaurants will be cut down on this fiscal year because of "low staffing levels."

"We thought those grades were meaningful," said Holstein's wife Pat. "But obviously there's more to the story."

NBC 4 put together the above interactive map that shows the confirmed food poisoning outbreaks at county restaurants in the past 18 months. The irony is that a handle of the places are glamorous spots: a country club in La Verne, a sushi restaurant in Malibu, and a Italian restaurant in Rancho Palos Verdes.

"We could be doing a better job in many areas," said the health department's Bellomo

Related: 21 Salmonella Cases Linked To Brent's Deli And Officials Said Nothing