Following the child's first discharge from the hospital, both he and the father were put into a temporary holding facility where agents were aware of the child's illness and provided the child with his medication.
After an agent noticed Felipe coughing, father and son were taken to an Alamogordo hospital, where Felipe was diagnosed with a common cold and found to have a fever of 103 degrees Fahrenheit, CBP has said.
The child had seizures and a fever, and was flown to the hospital, where she went into cardiac arrest and died. The boy was given prescriptions for amoxicillin, an antibiotic, and the painkiller ibuprofen.
McAleenan announced the agency was "conducting secondary medical checks upon all children in CBP care and custody", and "reviewing its policies with particular focus upon care and custody of children under 10, a day after the death of 8-year-old Felipe Alonzo-Gomez".
The Guatemalan government was notified and is in contact with the boy's father and family, the statement added.
House Democratic Whip Steny Hoyer of Maryland said in a statement Wednesday that the Democrats would hold hearings in the new Congress over Felipe and Jakelin's deaths, "as well as the conditions under which thousands of children are being held".
"I'm not going to die, papa, " she said Felipe told him. He died around midnight. That could include support from the Coast Guard as well as possibly more aid from the Defense Department, the Federal Emergency Management Agency, Health and Human Services, and the Centers for Disease Control and Prevention.
Oil prices surge as U.S. equities soar
On London-based ICE Futures, the price of Brent crude oil to be delivered in February advanced by $4.86, to $55.29 a barrel. It prior tumbled to $49.93, the least since July 2017, and posted a 6.2 percent slide in the past session.
As with Jakelin's family, Felipe's relatives now must deal with the death of a child, a debt and their continued worry about the fate of Agustin Gomez.
The unnamed boy is the second youngster to die in detention this month.
The announcement comes the same week that eight-year-old Felipe Gomez Alonzo died at a hospital in the state of New Mexico.
While 89 percent of asylum-seekers from Central America pass an initial credible-fear screening at the border, only 9 percent are subsequently granted asylum by an immigration judge, according to the U.S. Department of Justice.
"While this result indicates that the child had influenza, determining an accurate cause of death requires further evaluation", the statement said.
Neighbours and relatives attend the wake of Jakelin Caal, the immigrant girl who died earlier this month in the custody of the US Border Patrol, at her home in the village of San Antonio Secortez, in Guatemala.
"Children in the custody of the Trump administration are dying, and the best the secretary of Homeland Security can do is blame those who seek open borders" and "parents". She died in the hospital on December 8.