UPDATE: Hepatitis A clinic vaccinates 550 people, had to shut down early amid N.J. outbreak. It reopens today.

The number of hepatitis A cases in New Jersey continues to grow and the vast majority of patients have been linked to an outbreak that began in December.

As of the New Jersey Department of Health’s Nov. 2 update, there have been 541 confirmed cases of hepatitis A in New Jersey since Dec. 1, when state officials say the ongoing outbreak of the disease began.

There have been six deaths from hepatitis A in New Jersey during the outbreak. Of the 398 cases that have the appropriate data available, 337 have resulted in hospitalizations.

By comparison, there were just 67 confirmed hepatitis A cases in the Garden State between Dec. 1, 2017 and Nov. 2, 2018, according to the state. From 2013 to 2017, there were never more than 74 confirmed cases of the disease in New Jersey in a given year, according to the Centers for Disease Control and Prevention.

Anyone can get hepatitis A, but according to the state the highest risk is “among persons reporting homelessness, drug use, Men who have Sex with Men (MSM) and recent incarceration.”

According to the CDC, New Jersey is one of 28 states currently dealing with hepatitis A outbreaks. Kentucky has been hit the hardest, with 4,958 cases and 61 deaths as of Oct. 19. California and Utah also had recent outbreaks which have since been declared over.

It’s unclear when New Jersey’s outbreak may end, state officials said.

“It is difficult to predict exactly how long the outbreak will continue, but we are working with our public health partners to contain it,” said Donna Leusner, a spokeswoman for the DOH.

South Jersey has been hit hardest, according to the state’s numbers. Camden County has had by far the most confirmed cases, with 140 associated with the outbreak. Gloucester County has had the second most with 62.

Leusner said that New Jersey’s outbreak began in South Jersey, and noted that Philadelphia had its own outbreak of the disease in early 2019.

Most of the cases in Camden County have been people who are either dealing with homelessness or opioid abuse, according to county spokesman Dan Keashen.

“While the opioid epidemic continues to move through the community, it creates more opportunity for communicable diseases like this to thrive,” Keashen said.

Keashen said that cases in Camden County spiked in February, around the same time the Philadelphia outbreak began. Since then, Keashen said that the county has worked with shelter providers and social service providers to offer free hepatitis A vaccines and to educate at risk populations on disease prevention.

“We are working towards an end, and we have a good game plan in place,” Keashen said.

But cases of the disease have been confirmed in all 21 New Jersey counties. In June, exposure to hepatitis A at the Mendham Golf & Tennis Club in Morris County led to 27 confirmed cases and one death.

Recently in Somerset County, a deli worker at a ShopRite in Somerville was confirmed to have hepatitis A. People who ate food from the deli or used the store’s bathrooms and have not previously been vaccinated against the disease are advised to get a vaccine within two weeks of eating the food. For most people, that cutoff date would be Nov. 13.

Somerset County health officials are offering free hepatitis A vaccines Wednesday and Thursday in response to the ShopRite case. About 200 people stood in line outside the Somerset County Department of Health on Wednesday afternoon, waiting to be vaccinated.

The Somerset County clinic closed early at 4:30 p.m. on Wednesday afternoon due to “an overwhelming public demand,” according to a county press release. Nancy Weinman, an administrative assistant for the Somerset County Health Department, said that the county administered 550 vaccines before the clinic closed.

The clinic will still offer free vaccines on Thursday from noon to 8 p.m.

Over the summer, a worker at Stanhope’s Camp Somers in Sussex County was diagnosed with hepatitis A. And in January in Cape May County, an employee at a Dunkin’ Donuts in Ocean City was confirmed to have the disease.

Hepatitis A is an inflammation of the liver, according to the CDC. The virus that causes the infection is spread through stool; washing hands and practicing good hygiene is important to preventing the spread of the disease.

Symptoms may include fever, stomach problems, dark yellow urine, and yellow skin or eyes, according to the DOH. There is no specific treatment for hepatitis A and people with the disease typically recover on their own.

The DOH recommends vaccinations for people who are at risk of contracting the disease. Leusner said that local health departments around the state have administered 1,600 vaccines and are “providing education and awareness to countless more.” That number is in addition to vaccines administered by private physicians, emergency rooms and urgent cares.

This story was updated at 5:33 p.m. with additional information from Somerset County.

NJ Advance Media photographer Ed Murray contributed to this report.

Michael Sol Warren may be reached at mwarren@njadvancemedia.com. Follow him on Twitter @MSolDub. Find NJ.com on Facebook.

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