The Centers for Disease Control in Atlanta is looking into a mumps outbreak among Orthodox Jews in New York and New Jersey that has now surpassed 1,500 cases and shows no sign of ending soon.
In November, the CDC called the spike in mumps cases, "the largest U.S. mumps outbreak since 2006, when the United States experienced a resurgence of mumps with 6,584 reported cases." Then, only 179 people were sickened in New York and New Jersey.
The outbreak began last summer at a boys camp in the Catskills. Authorities have linked the outbreak to an 11-year-old camper who had just come from Britain where a mumps outbreak had sickened more than 4,000 people.
Since the summer, there have been almost 500 cases reported in Orange Country, N.Y, and more than 300 in neighboring Rockland Country. It also has spread to Lakewood , N.J., where about 150 are affected and to the New York City borough of Brooklyn, where some 50 cases have been reported.
Nearly all the cases are in the insular Orthodox Jewish community. Health officials said most had a mumps vaccination, but the shots are not completely effective.
The Centers for Disease Control and Prevention on Thursday said the count has now reached 1,521. Nineteen people have been hospitalized but no deaths have been reported.
Mumps is a contagious disease caused by a virus, according to the CDC. Initial symptoms appear 12 to 25 days after infection and include fever, headache, muscle aches, loss of appetite and swelling of the jaw and cheeks.
Complications can lead to deafness, painful swelling of the testicles or ovaries, and, rarely, death.
© 2010 CBS Interactive Inc. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report.