The detention camps run by Customs and Border Protection (CBP) suffer from "dangerous overcrowding," according to the Department of Homeland Security's Office of the Inspector General. In a July report, DHS investigators said that the conditions in the camps were so dire that detainees started damaging cells, sometimes stuffing socks and blankets down toilets, just to be outside during repairs. One facility manager called the situation "a ticking time bomb." At one of the five sites that the OIG toured, a cell meant for 40 people held 88. At three of those facilities, children had no access to showers.

The result of massive overcrowding and extremely unhygienic conditions was that the camps become a breeding ground for disease. Three children have already died in CBP custody from flu-related causes. Yet, the agency announced that it will not be vaccinating detainees ahead of the upcoming flu season. In a statement sent to CNBC, a CBP spokesperson wrote, "In general, due to the short-term nature of CBP holding and the complexities of operating vaccination programs, neither CBP nor its medical contractors administer vaccinations to those in our custody."

A group of doctors sent a letter to Democratic congresswomen Rosa DeLauro of Connecticut and Lucille Roybal-Allard of California, asking them to investigate the health conditions of CBP camps. "I can tell you from personal experience that child deaths are rare events," Dr. Jonathan Winickoff, a Harvard pediatrics professor and one of the doctors who sent the letter, told CNBC. "When I learned that multiple children had died in detention from potentially preventable causes, it truly disturbed me. The country needs urgent answers to that question so that children stop dying in detention." Winickoff added that the disease weakens the immune system in children, making them more susceptible to a range of other illnesses. And that intense overcrowding greatly increases the chances of infection.

According to the Outbreak Observatory, a project of Johns Hopkins University's Center for Health Security, at least six children have died in CBP detention from not just the flu, but also pneumonia and Staphylococcus infection. In one post, it reported: "It has been clearly defined in the literature that factors such as overcrowding, improper use of quarantine, poor sanitation, and poor access to health care contribute to disease spread. It is imperative that any solution pursued to improve conditions at detention facilities also includes plans to address contributing factors to infectious disease outbreaks."

Andrea Pitzer, author of One Long Night: A Global History of Concentration Camps wrote for GQ that disease outbreaks are a common feature of concentration camps, like ones run by the British in southern Africa where "unsanitary camp conditions and inadequate food triggered medical crises." She adds, "Today’s U.S.-Mexico border camps are the heirs of these concentration camps. Putting people in similar conditions will unleash illness and death. The more people who are detained, the larger these crises will become."

Just a week ago, a federal court ruled that despite the Justice Department's protests, the Trump administration is required to supply soap, toothbrushes, and blankets to children held in detention camps. The administration has been arguing that none of those basic amenities fell under its obligation to provide "safe and sanitary" conditions for the adults and children it was detaining in camps. It required a federal court to force the administration to provide soap in the detention camps.

In May, the Washington Post reported that Border Patrol agents had quarantined 32 people infected with influenza at the agency's main processing facility in McAllen, Texas. According to the New York Times, at the Border Patrol facility in Clint, Texas, children were kept in flu quarantine rooms that often had no toilets. ABC News reports that at the McAllen facility, teens weren't even able to wash their hands.

The Centers for Disease Control recommends flu vaccinations for every person over six months old. According to CNBC, prior to the recent spate of child deaths, the U.S. had gone a decade without any children dying in CBP custody.