Pennsylvania has confirmed 1,222 measles cases and six measles-associated deaths, an increase from 86 cases the previous week. In response, the Centers for Disease Control and Prevention (CDC) announced on Thursday it would send a scientist from its epidemic intelligence service, described as a "disease detective", to assist with the growing outbreak.
The CDC is also releasing nearly $4m to aid measles response efforts in Pennsylvania. A CDC spokesperson told NBC News on Thursday that the agency would continue to work closely with Pennsylvania health officials to provide expertise and support.
Lancaster county, which accounts for more than 415 confirmed cases as of 9 October, is at the centre of the outbreak and is the largest county in the state without its own health department. Local officials state this puts the county at a disadvantage in managing the outbreak.
Nationwide, the CDC reported 4,410 measles cases as of Friday, an increase of 330 from the previous week's update.