State health officials are investigating how five patients may have been exposed to hepatitis B at a Boston hospital, the Massachusetts Department of Public Health said Sunday.
During treatments, the five were potentially exposed to the virus at Boston Medical Center and are being monitored, the hospital said.
How the patients may have come into contact with the virus has not been made public because of patient privacy and confidentiality rights, hospital officials said.
Hepatitis B is a virus that is spread through bodily fluids, such as blood, and attacks the liver, according to the US Centers for Disease Control and Prevention. There are two types of the disease: acute, which lasts a few weeks and is short-term; and chronic, which is a long-term and sometimes life-threatening illness, the CDC said.
Boston Medical Center informed the Boston Public Health Commission about the incident on Friday, according to Nick Martin, director of communications for the city agency.
“The hospital properly fulfilled its reporting requirement with regard to the case, and we will continue to work with officials there to make sure all affected patients receive the appropriate follow-up care,” said Martin.
BMC officials said they have taken steps to prevent further exposure to the virus.
“We have communicated with these patients and are monitoring them closely,” BMC spokeswoman Jennifer Watson said Saturday. “Additional measures have been put in place to avoid the possibility of a similar exposure in the future.”
Among those affected, Joan Cooper, 64, of Weymouth, said she received a call from BMC alerting her that she may have been exposed to the virus through a recent dialysis treatment.
“Thursday I received a phone call from Boston Medical Center that because one of the [dialysis] machines had not been cleaned properly after a patient with hepatitis B had used it, I was exposed along with other people to hepatitis B,” Cooper said.
The hospital sent someone to her home to administer a shot of gamma globulin, an injection full of antibodies to fight the virus and block potential infection, she said.
The best way to prevent hepatitis B is to get vaccinated, according to the CDC.
“In the United States, 804,000-1.4 million persons are estimated to be infected with the virus, most of whom are unaware of their infection status,” the agency said on its website. An estimated 2,000 and 4,000 people die every year from liver disease related to hepatitis B, and it is the leading cause for liver transplants in the United States.
Cooper has since spoken with doctors and said she feels confident that if she has been infected, it will be caught early.
She recently had a blood test and should have results in about a week, she said.
Chronic hepatitis B can be treated with several antiviral drugs and those infected must be regularly monitored and evaluated, according to the CDC.
Globe correspondent Zachary T. Sampson
contributed to this report.
Derek J. Anderson can be reached