It’s been more than a week since a detainee at Victorville — a prison complex in California being used by Immigration and Naturalization Service (INS) — was diagnosed with chickenpox.

About 1,000 immigrants were moved here as part of the Trump administration’s crackdown on asylum seekers; authorities claim that they were medically screened on entry to the prison.

{mosads}The diagnosis of chickenpox — highly contagious, passed by touching or breathing virus particles — came days after protesting prison workers there — who considered the situation dangerous – urged the federal government to add more staff to the medical unit.

Victorville puts into stark relief our government’s responsibility toward those whom they detain or deport and all those with whom they interact. It also raises questions about how screening and treatment decisions are being made for our detainees, and what exactly is being done to protect public health.

Running an operation like Victorville with little transparency, conflicting aims (holding detainees/caring for them/prohibiting access to them), and a lack of systematic approaches to health screening can — in the hectic situation that exists — cause problems. These can have adverse health effects on new entrants into the U.S., but also the much wider circle of their contacts.

The crowding of 800 Victorville workers with 1,000 detainees creates perfect conditions for the transmission of communicable diseases. Stress and poor nutrition further increase that risk.

Honduras, Guatemala, El Salvador and Mexico — the nations from where most of these detainees are fleeing — all have vaccination programs against infectious diseases like Varicella (chickenpox), Influenza, Hepatitis B and Diphtheria.

Their reported vaccination coverage rates are high overall. Mexico’s is between 93 and 99 percent, El Salvador’s varies from 90 to 93 percent, 93 to 98 percent in Guatemala, and 88 to 93 percent in Honduras — depending on vaccine.

However, many entrants from these countries come from rural areas where coverage is spotty and reporting less reliable. Of even greater concern are more consequential diseases common in Central America such as Dengue fever, Malaria, Chikungunya and Zika, which are not vaccine preventable. Local Dengue and Zika outbreaks within our borders have been attributed to infections in those crossing the border; however the contribution of detainees to these outbreaks is unknown.

There’s another issue: while examinations of immigrants – with visas and paperwork for legal entry — are thorough, examinations of refugees — who arrive undocumented and without permission — are variable, depending on local conditions of detention, staffing and information systems.

The Centers for Disease Control and Prevention (CDC) publishes screening guidelines for physicians administering pre-departure examinations in immigrants’ home countries, which are to occur several weeks prior to departure for the US.

These exams include appropriate vaccinations and treatments for malaria and intestinal parasites. Upon entry, further examinations are conducted for physical or mental disorders — including communicable diseases of public health significance or drug addiction, which render applicants ineligible for admission.

But, refugees are only examined on arrival. Specificity regarding what is being done, where and with what results is lacking. Are the exams consistent? Are they thorough? Once an asylum seeker has made a formal application, the law requires their examination by a physician and vaccination; but, according to the CDC, there is very little data on the health problems of asylees after they migrate to the U.S.

Examining and caring for refugees is a gargantuan task. ICE Health Service Corps (IHSC) currently cares for about 13,500 ICE detainees in 21 U.S. facilities, and an additional 15,000 in 120 non-IHSC-staffed detention centers.

In 2015, ICE conducted nearly 200,000 intake screenings; 87,078 physical exams; 126,486 sick calls; 21,245 urgent care visits; 90,276 mental health interventions and filled 234,001 prescriptions. In 2016, 1.49 million foreign-born individuals moved to the United States, a 7 percent increase from the 1.38 million coming in 2015.

Refugee screenings in California give us a glimpse of what public health officials face. From 2014-2017, approximately 70,000-85,000 refugees resettled in the United States annually; California receives 15 to 17 percent.

California’s screening results show that nine percent of refugees were infected with tuberculosis, 18.6 percent suffered from dental caries, and nearly 28 percent of refugees from African nations suffered from schistosomiasis.

{mosads}In addition, 27.7 percent of refugee children suffered from elevated lead levels. There is insufficient information on how these problems were treated, with the possible exception of tuberculosis.

Increasingly, detainees report that they are fleeing violence in Honduras, Guatemala, El Salvador and Mexico, and these refugees can apply for asylum once on U.S. soil. The president’s order on refugees may limit the number that will be accepted, but not the numbers seeking entry into the U.S.: the United Nations Refugee Agency reports refugees filing asylum applications from Mexico alone jumped from 2,000 in 2014 to 14,000 in 2017. Until stability is restored in Central America, we can expect more refugees who come despite knowing our “zero-tolerance” policies.

Interning asylum seekers on our southern border creates challenges to addressing the health of thousands of detainees, as well as guards and support workers detailed to serve in our internment facilities, and others in these communities.

Holding thousands of detainees from cities and rural areas together puts those with diseases and others with little immunity to them in close contact. Infectious diseases like chickenpox are only one indication of the dual challenges we face in trying to identify and treat health care problems of detainees while protecting our collective public health.

Jonathan Fielding, M.D., is a professor of public health and pediatrics at University of California, Los Angeles.