PHILADELPHIA (WPVI) -- It's an alarming spike in the number of Hepatitis A cases in Philadelphia.
The city typically sees two to six per year. This year so far, there have been 154 cases reported.
The center of the public health emergency is Kensington, an area hit hard by the opioid crisis and with a large homeless population.
Doctor Ron Goren is an infectious disease specialist at Nazareth Hospital.
He says in unsanitary conditions, the virus can spread quickly.
"When people are close to one another and maybe stool contamination of the water you're drinking, other things like that," said Doctor Goren.
And what makes it difficult to control is people can be contagious one to two weeks before noticing telltale signs, such as yellowing eyes and skin.
"Which is why vaccines are so important because you can't wait for someone to get sick and say I don't want you to come near me," added Doctor Goren.
The city has already administered more than 1700 vaccines to people to risk.
Doctor Goren says if someone was exposed, then gets the first dose of the vaccine within two weeks, it could prevent the illness.
Hepatitis A is a virus that causes fatigue, nausea and vomiting, loss of appetite, abdominal pain and yellowing eyes and skin.
Most people recover after several weeks, but some suffer complications.
"About 10 percent of people can get very sick with hepatitis, needing to be in the hospital and supported. It is not a pleasant disease to have," said Doctor Goren.
It can be fatal in rare cases for vulnerable patients such as someone with a comprised immune system.
The best way to prevent Hepatitis A is with the vaccine and by practicing good hygiene.
Hepatitis A cases spike in Philadelphia