Thousands of Missouri restaurant patrons unknowingly ate at a restaurant where an employee had a possibly contagious case of hepatitis A. After the popular food chain Red Robin announced the dangerous possibility of exposure at its Springfield, Miss., location in mid-May, county health officials warned customers to be on the lookout for any symptoms.

The employee in question last worked on May 16 and has since, along with all workers at the Red Robin, been inoculated with an immune globulin prophylaxis shot, which offers three-month maximum protection if taken within two weeks. The restaurant has been deemed safe after the health department conducted a procedural inspection. However, because the employee was in the restaurant, there is still cause for concern. Hepatitis A is a viral liver disease that is transmitted through ingestion of contaminated food, water, or through direct contact with an infectious person, according to Mayo Clinic.

Thousands more customers could have been exposed because the infected employee worked there for several months. The county health officials warned the nearly 5,000 customers, who made their way through Red Robin’s doors most recently last week to be on the lookout for symptoms including fever, nausea, abdominal pain, and dark urine.

"It scared me because my husband has been sick," Andrea Hall, a Red Robin customer, told CNN affiliate KOLR. "And a lot of his symptoms of his matched. A red flag just went off and I was like what do I do from here."

The incubation period of hepatitis A usually lasts between 14 to 28 days and puts anyone who hasn’t been vaccinated or who was previously infected, at risk. It’s a highly contagious infection that inflames the liver and limits its ability to function. Even though mild cases don’t require treatment, most people who are infected never completely recover. Severe cases leads to liver failure and even death if it goes untreated. The Springfield-Greene County Health Department provided information for those who ate at the potential local health threat and outlined plans for those who may be infected.

According to their website, “While the Health Department considers this a significant health threat, an important thing to remember is that people are now commonly vaccinated for Hepatitis A.”

The local health department and medical clinic will be providing vaccinations for those who haven’t already received them, and has already had 4,000 doses of the vaccine shipped to them. The department has set up a hotline for people to call in with questions, especially for those who are experiencing the following symptoms that are characteristic of hepatitis A.

  • Fever
  • Fatigue
  • Loss of appetite
  • Nausea
  • Vomiting
  • Abdominal pain
  • Dark urine
  • Clay-colored bowel movements
  • Joint pain
  • Jaundice

The two-step vaccination has been widely available in the United States since 1995, which means many people are already vaccinated. Despite the availability, many do not vaccinate and in turn, 17,000 people contract hepatitis A each year, according to the Centers for Disease Control and Prevention.

The infection is much more threatening to those who live with poor sanitation, lack of safe water, are injecting drugs, living in a household with an infected person, being sexually active with an infected person, or traveling without a vaccination to areas with such disease prevalence. Currently, there are an estimated 1.4 million hepatitis A cases across the world, according to the World Health Organization.