Eighth Infant Diagnosed With Measles at Illinois KinderCare

— -- Another infant has been diagnosed with measles at the Illinois daycare center where five babies were diagnosed with the virus last week, health officials told ABC News today.

In all, eight babies and one adult at the KinderCare daycare center in Palatine, Illinois, have been diagnosed with measles, said Illinois Department of Public Health spokeswoman Melaney Arnold. Another adult was diagnosed with measles on Jan. 27 before this cluster of cases, but it's unclear whether it was related, she said, adding that they are still investigating.

The measles patients were unvaccinated, the Cook County Department of Public Health said Monday. The latest baby to be diagnosed was likely too young to be vaccinated.

The measles cases prompted KinderCare, a daycare chain with 1,900 locations nationwide, to change its policy on Friday, requiring all employees working with infants to be vaccinated against the measles.

The first dose of the MMR vaccine, which protects against measles, mumps and rubella, is not administered until a child is a year old, and KinderCare said in a statement that it hopes to protect its children who are too young to be vaccinated by also limiting access to infant rooms.

Measles is one of the most contagious viruses in existence and can infect 9 out of 10 exposed people if they are not immunized. The virus can cause rash, fever, conjunctivitis and runny nose. In severe cases the virus has caused swelling of the brain, pneumonia or even death.