The Department of Homeland Security (DHS) is requesting that the Centers for Disease Control and Prevention (CDC) investigate the cause of the growing number of sick migrants illegally crossing the U.S.-Mexico border, officials revealed to reporters Wednesday morning.

A DHS official told reporters that “literally dozens” of sick migrants are being transported to hospitals across the border each day and that growing numbers of children showing illness are present in border patrol custody.

“We’re doing dozens of hospital trips every single day with children that have fevers or manifest other medical conditions,” CBP Commissioner Kevin McAleenan told CBSNews Wednesday morning.

An official also told reporters that DHS Secretary Kirstjen Nielsen is requesting that Mexican authorities also investigate the living conditions of migrant holding camps across the border to see if that is the source of illness.

DHS officials revealed their concern during a phone call to discuss the plight of an 8-year-old Guatemalan child who died in border patrol custody Monday. The child’s death came just days after DHS also announced the death of a 7-year-old girl who died in mid-December. (RELATED: Fact Check: Was A 7-Year-Old Girl In Border Patrol Custody For A Week Before Dying Of Dehydration?)

The children’s deaths have brought intense scrutiny on the holding conditions and procedures of DHS, which says they are simply overburdened by thousands of daily illegal border crossings. A DHS official noted that, prior to these two incidents, border patrol had not lost a child in custody in over a decade. This was remarkable, they claimed, given the hundreds of thousands who have passed through its holding facilities in the interim period.