A measles outbreak in Manhattan and the Bronx has spread to Brooklyn and grown by three more cases to a total of 19 confirmed patients with the highly contagious virus, officials said Tuesday.

The new cases are all adults, for a total of 10 adults and nine children, the Health Department said.

The previous cases were in Inwood and Washington Heights in Manhattan, and in High Bridge, Morrisania and the Central Bronx, health officials say. The Health Department said Tuesday that cases had also been confirmed in Brooklyn.

The Health Department refused to say where in Brooklyn the cases were confirmed, but stressed that the outbreak is concentrated in northern Manhattan.

Authorities are working to identify the source of the outbreak, and are urging vaccinations for those who haven't had them. The first case was reported in February.

Four of the affected children were too young to have been vaccinated; three who had been vaccinated were 13 to 15 months old and two others had not been vaccinated by parental choice, the Health Department said. The affected adults range in age from 22 to 63 years.

Measles is a viral infection characterized by a generalized rash and high fever, accompanied by cough, red eyes and runny nose, lasting five to six days. The illness typically begins with a rash on the face and then moves down the body, and may include the palms of the hands and soles of the feet.

People who contract the measles virus can spread the infection for four days before developing a rash, and for four days after that. Measles can spread easily through the air to unprotected individuals, and the Health Department is urging all New Yorkers to make sure they and their families are vaccinated.

The Health Department said it is working with city hospitals to prevent additional exposure to the virus in emergency departments. It's also asking pediatric facilities to vaccinate any children who haven't already been vaccinated. Children should normally get a second dose of the vaccine between the ages of 4 and 6, but the Health Department says those who live in the affected communities should get their second dose immediately, regardless of whether they fall within that age range.

As many as one in three people with measles develop complications, which can be serious and may include pneumonia, miscarriage, brain inflammation, hospitalization and death. Infants, people who have a weakened immune system and non-immune pregnant women are at highest risk of severe illness and complications.