CHICAGO (WLS) -- The Chicago Department of Public Health has issued an alert about a dramatic spike in chickenpox cases this year.
CDPH said nearly 400 cases have been identified since January 1, the largest increase since 2005. CDPH has reported a median of 53 chickenpox cases per year from 2005 to 2022.
The organization now says 81 percent of the cases reported this year were detected in newly arrived migrants from the southern border who are living shelters. CDPH said 90 percent of the cases detected in new arrivals were in unvaccinated individuals.
"It presents as a fever, and a rash that are fluid filled bumps. Usually you have several hundred of these fluid filled bumps," said Dr. Larry Kociolek of Lurie Children's Hospital.
Kociolek said the chickenpox vaccine is very effective against the disease, but without it the virus is extremely contagious.
"If you're living or residing in an area where there's a large amount of people that are living in close quarters, or sharing big open rooms and those people do not have any immunity to chickenpox from vaccination or prior disease it can spread very, very quickly," he said.
CDPH said it's not aware of any spread of the chickenpox from new arrivals to city residents. CDPH also said most Chicagoans are already vaccinated against chickenpox and say there's no cause for alarm at this time.
CDPH Commissioner Dr. SImbo Ige said the new arrivals are coming from countries where getting a chickenpox vaccine just isn't routine.
"So when we see cases we investigate to know who's been in contact with them, and sure that as many people who may be vulnerable are vaccinated to contain it," she said.