With 75 more measles cases reported in United States over the past week, the number of infections topped 800, putting this year on pace to pass the total for 1994, the US Centers for Disease Control and Prevention (CDC) said today in its weekly update.

In other measles developments, Toronto health officials announced two travel-related measles cases and said investigations are underway into both.

Maryland added to outbreak list, earlier outbreaks add more cases

The new cases boost the current US total to 839 from 23 states, with many of the cases linked to 10 outbreaks in seven different states: New York, Michigan, New Jersey, California, Georgia, Maryland, and Pennsylvania.

The modern record of 963 cases occurred in 1994, the year the federally funded Vaccines for Children program began, an event that stabilized the number people vaccinated against the disease and set the stage for measles elimination in 2000.

Added to the outbreak list this week is Maryland. The Maryland Department of Health (MDH) said five cases have been confirmed this year as of May 9. It said cases have been localized to a small geographic area involving three zip codes. Two are centered in Baltimore and one is in Pikesville, a suburb just northwest of the city

Of the 75 new cases, more than half appear to be linked to large outbreaks in New York City and New York's Rockland County, both centered in Orthodox Jewish communities.

In its most recent update, NYC Health said as of May 6, 466 cases have been confirmed in Brooklyn and Queens since September, an increase of 43 from the last report. Roughly half of the illnesses are in children ages 1 to 4 years old.

The hardest hit area are the city's Williamsburg and Borough Park neighborhoods, and as of May 6, 22,833 doses of measles, mumps, and rubella (MMR) vaccine have been administered to people younger than 18 years old.

Meanwhile, New York's Rockland County said as of May 10 tests had confirmed 225 cases, an increase of 10 since its last report. Among infected people, 79.9% had not received any MMR vaccine doses and 4.9% had received one. Vaccination status was unknown for 12.1%. Children make up just over 80% of cases, with those ages 1 to 3 and ages 7 to 18 in the most-affected groups.

In California, where four outbreaks have been reported this year, 44 cases have been confirmed as of May 8, including 30 that are part of outbreaks in Butte County, Los Angeles County, and Sacramento County.

Toronto probes two travel-linked cases

In developments elsewhere, Toronto health officials are investigating two lab-confirmed cases in adults that are both travel related, according to a statement from Toronto Public Health.

The department said the public may have been exposed at several locations, including Pearson International Airport on May 5 and May 8, the former involving a flight that departed for the United Kingdom and the latter an incoming flight from the UK. Other locations included a restaurant and the Toronto Zoo.

See also:

May 13 CDC update

May 9 MDH update

May 6 NYC Health update

May 10 Rockland County update

May 8 California Department of Public Health update

May 13 TPH press release