An immigration detention facility in Aurora, Colorado, has just one in-house physician treating its 1,500-plus detainees amid a chicken pox outbreak and a confirmed case of mumps, according to a U.S. congressman. And when the legislator tried to visit the facility Wednesday, he was turned away.

Colorado Rep. Jason Crow, a freshman Democrat, said the Denver Contract Detention Facility is in the midst of its fourth chicken pox outbreak since October and has experienced a new case of mumps. The illnesses often lead to quarantine, which bars some detainees from meeting with their lawyers or attending hearings. Both viruses are highly contagious but preventable with vaccines.

Concerned about the availability of healthcare at the facility, Crow tried to drop by Wednesday but was denied entry because he hadn’t made an appointment in advance.

“There’s an urgency to this, a public health urgency,” Crow said during a press conference outside the facility, where he announced he had delivered a letter to Homeland Security Secretary Kirstjen Nielsen asking why the facility had so few in-house doctors, considering the frequent disease outbreaks. He also inquired why the facility added 432 beds to the facility’s annex in January without talking to local authorities first, according to the Denver Post.

“With the recent influx of migrants coming from the southern border, U.S. Immigration and Customs Enforcement (ICE) has confirmed one new case of parotitis, mumps, at our Denver Contract Detention Facility,” Jeffrey Lynch, field office director for ICE, said in a statement. “Medical personnel are credited with reducing the further infection of detainees by their quick reaction to quarantine everyone who may have been inadvertently exposed to stop the spread of the disease.”

For-profit prison giant GEO Group, which operates the ICE facility, did not immediately respond to a VICE News request for comment.

In a separate statement, issued Feb. 1, an ICE spokesperson said the agency had confirmed two new cases of chickenpox at the facility.

“The expansion of the facility comes on the heels of two varicella (chicken pox) outbreaks within months of one another, subjecting dozens of inmates to lengthy quarantines,” Crow wrote in the letter to Nielsen on Wednesday. “Of note, it is my understanding that the facility only has one physician for the entire population, even after the recent increase in detainees.”

The facility was also the subject of a complaint filed by the American Immigration Council and the American Immigration Lawyers Association in June. The groups allege that the Aurora center failed to provide detainees with proper health care.

“Medical and mental health care in immigration detention facilities — including Aurora — repeatedly has been flagged as grossly substandard, even though substantial evidence indicates that facility staff, and ICE, are aware of the grave risks to detainees’ health,” the attorneys wrote in a letter to the Department of Homeland Security. They referenced December 2017 reports regarding a 64-year-old Iranian man who was arrested on a 12-year-old cocaine conviction and sent to the Aurora facility. The man died 15 days later of cardiac arrest.

This isn’t the first time a politician has been turned away from visiting an ICE facility, either. In January 2018, Democratic Sen. Jeff Merkley was blocked from entering a detention center in south Texas, although he was eventually allowed to look around the facility.