Dr. Benjamin Chan

Dr. BENJAMIN CHAN, state’s epidemiologist

The state’s Division of Public Health has identified a significant increase in Hepatitis A cases in southern New Hampshire over the past three months and is urging residents to get vaccinated to prevent the outbreak from spreading.

New Hampshire averages about seven new cases of Hepatitis A each year, but since November public health officials have tallied 13 cases. Seven of those were diagnosed in January alone.

“We’re worried that these few cases over the last few months are just the tip of the iceberg, and that once this virus gets into our communities it will spread very rapidly,” said Dr. Benjamin Chan, the state’s epidemiologist.

Infection generally happens when a person ingests food or liquid that has been contaminated with a tiny, undetectable amount of Hepatitis A-positive fecal matter. The virus, which affects the liver, is carried in stool and can survive for weeks or months on some surfaces.

Five of the cases involved Hillsborough County residents. Rockingham and Strafford counties each had three new cases since November, while Cheshire and Merrimack counties each had one.

“A majority of these individuals are people experiencing homelessness, people with a substance use disorder,” Chan said, but the risk extends beyond those most vulnerable communities.

Other states have recently experienced outbreaks of Hepatitis C and HIV directly linked to needle sharing among opioid users. But while Hepatitis A can be passed through intravenous drug use, that is not its most common path of transmission.

So far, New Hampshire hasn’t seen a spike in HIV cases like the ones documented in Boston and Lowell, Mass. over the past year.

Wendy LeBlanc, director of the Southern New Hampshire HIV/AIDS Task Force said her team is monitoring the spread of the disease and is hoping to expand its needle-exchange program, which helps ensure drug users don’t share contaminated needles.

Because there is a vaccine for Hepatitis A, which has proven highly effective, public health officials are hoping they can contain the spread of the disease.

Since the vaccine was introduced in 1995, the rate of infection has declined by more than 95 percent, to an estimated 4,000 Americans in 2016, according to the U.S. Centers for Disease Control and Prevention.

Surveys show that about 65 percent of children in New Hampshire have received the two-shot vaccine series, Chan said. That’s far less than the 95 percent of children inoculated against Hepatitis B, likely because that vaccination is required to enter school or child care.

“This is a very effective vaccine,” Chan said. “We’re encouraging people in the community to talk to their health care providers about obtaining the vaccine ... we’re still in the early stages of an outbreak but part of our concern, given what we’ve seen in other states around the country, is that this could grow rapidly.”

The Manchester and Nashua health departments offer Hepatitis A vaccinations, as do many community health centers around the state.