United States Customs and Border Protection has announced changes to its official guidance for care of migrant children under 10 years of age.

The move comes after two migrant children died of health problems while in U.S. custody.

Department of Homeland Security (DHS) and Border Patrol officials spoke with reporters on Wednesday about the deaths.

A woman and children stand amidst U.S. Border Patrol agents after crossing illegally over the border wall into San Diego, California, on December 9, 2018. Border security officials say there has been a sharp increase in people seeking to enter the country illegally.

The officials said that medical workers had carried out new medical exams of almost all the children in the care of the U.S. Border Patrol. They added that the exams are sometimes "conducted by individuals that are under contract support services to the Border Patrol."

At the U.S. southwestern border with Mexico, there are areas where no medical workers are available. In such places, migrant children are to be sent to medical centers or emergency medical crews for examination.

DHS officials did not say how many children are currently held by the Customs and Border Protection. But officials said they have asked the U.S. Coast Guard, Department of Defense and the Centers for Disease Control and Prevention for help.

The announcement comes the same week that eight-year-old Felipe Gomez Alonzo died at a hospital in the state of New Mexico.

Alonzo was taken to a hospital where he showed signs of "potential illness." Doctors said he was sick with a cold and a high body temperature. They gave the boy an order for medicines and released him. However, within a few hours he became very sick and was returned to the hospital, where he later died.

The cause of death has yet to be announced.

Border Patrol officials said they will carry out an "independent and thorough" investigation. They also said they informed the Guatemalan government and members of the U.S. Congress.

Funeral held for Guatemalan migrant girl

Also this week, a funeral for seven-year-old Jakelin Caal was held in a small Guatemalan village. She had traveled more than 3,200 kilometers with her father to the U.S. border.

But shortly after being detained by U.S. border agents, she developed a high fever and died of shock from sepsis on December 8. Sepsis happens when infecting organisms release deadly substances in the blood and tissue.

Customs and Border Protection is part of the Department of Homeland Security. The agency has struggled to deal with a sharp increase in the number of migrants seeking to enter the United States.

DHS Secretary Kristjen Nielsen released a statement Wednesday. It said that Border Patrol officials had detained nearly 140,000 people seeking to enter the country illegally in the last two months. That includes more than 68,000 families and 13,981 children who were not with their father, mother or family members.

Nielsen also said she had asked Mexican officials to investigate "the causes of these illnesses on their side of the border and to provide medical assistance in shelters as needed."

The DHS secretary defended Border Patrol officials, saying they had "assisted more than 4,300 people in distress along the border." She said that was a 20 percent increase in rescues from the year before.

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