A hepatitis A outbreak linked to a New Jersey golf and tennis club has sickened nearly two dozen people, health officials said.

At least 23 people — including one person who is “seriously ill,” according to the New Jersey Department of Health — have contracted hepatitis A from a food handler at the Mendham Golf & Tennis Club. Those sickened were likely exposed between June 9 and June 30 but were not notified of a possible exposure until July 5.

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“The food handler was excluded from work and a review of other food handlers for vaccination and proof of immunity was conducted. Close contacts of the food handler were identified and given prophylaxis (vaccine or medication to prevent illness after exposure),” according to a statement from the New Jersey Department of Health.

The outbreak was contained to the members-only club.

When members were notified, they were asked to inform any guests who may have dined at the club with them.

“This notification also advised that those who dined at the club when the food-handler was potentially infectious should receive post-exposure prophylaxis,” health officials added.

The “highly contagious” liver infection is caused by the hepatitis A virus, according to the Centers for Disease Control and Prevention. The virus typically spreads when a person eats or drinks something “contaminated by small, undetected amounts of stool from an infected person,” the health agency said.

Those who contract hepatitis A — not to be confused with hepatitis B or C, which are caused by different viruses — may be sick for “several weeks" and usually fully recover, according to the CDC. It is rare to die from the illness, though hepatitis A can cause liver failure and death, typically in those who are 50 years of age or older.

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Symptoms include fever, fatigue, dark urine, vomiting, joint pain, and jaundice, among other signs.

While hepatitis A infections do happen in the U.S., they're more common in developing countries where sanitation and hygiene are poor, the CDC says.

The disease is preventable with a vaccine.