Health officials have identified an uptick of hepatitis A cases in Marion County, Ohio, amid outbreaks elsewhere in the state and country in recent months.

The county has investigated 24 cases of the highly contagious liver infection since January 2018, with 14 cases in the last seven weeks alone. Hepatitis A is a vaccine-preventable illness spread through person-to-person contact, and recent outbreaks have occurred mostly among drug users and those who are homeless.

Across Ohio, health officials have identified 1,531 cases of hepatitis A since the beginning of 2018, with more than 100 cases each in Butler, Franklin, Hamilton and Montgomery counties. Nearly 960 people have been hospitalized and five people have died.

The state's epidemiologist, Sietske de Fijter, told the Dayton Daily News the number of cases is still rising in parts of the state that weren't as initially hard-hit and were slow to begin prevention efforts. Those efforts include vaccinating at-risk populations.

Across the U.S., reported cases of acute hepatitis A fell by about 96 percent between 1996 and 2011, according to the Centers for Disease Control and Prevention. But cases have picked up in recent years, and the consequences of outbreaks hitting the homeless and drug-using populations have been more dire than usual, health officials say.

"The numbers of hospitalizations and deaths during these hepatitis A outbreaks have been higher than what is normally reported through national surveillance of hepatitis A," the CDC said . Routine childhood vaccinations since 1996 have effectively curbed infections among younger people, but older adults who haven't been immunized remain susceptible to illness.

Hepatitis A can spread through sex, sharing contaminated food or drink, or other close contact with an infected person. Its symptoms are wide-ranging and can include nausea and vomiting, abdominal pain, fever, fatigue, loss of appetite, yellowing of the skin and eyes, dark urine, pale-colored feces and joint pain. Some people, however, do not show symptoms .

The illness can be more severe if an infected person has another health problem – such as chronic liver disease or hepatitis B or C – and can lead to "serious outcomes, including death," the CDC said.

The outbreaks have sparked responses. A California lawmaker, for example, recently introduced legislation to clarify the roles of local agencies that combat communicable disease outbreaks, after 20 people died and nearly 600 were infected with hepatitis A in San Diego County in an outbreak detected in March 2017.

A state audit found the county was slow to declare the outbreak an emergency, and that it lacked an adequate plan to prevent and respond to hepatitis A that may have curbed the outbreak sooner.

In Indiana, meanwhile, which has seen 935 cases of hepatitis A since an investigation began in November 2017, health officials expanded the state's adult vaccination program to include those who were uninsured or underinsured in an effort to combat spread of the infection. More than 112,000 people have been vaccinated for hepatitis A since the outbreak was identified.

The CDC says state and local health departments should work with community partners to vaccinate those who are homeless or use drugs and their close contacts, although these groups can be challenging to reach.