Transcript for Mexico Border Crisis Raises Serious Health Concerns

Now to the ongoing immigration crisis on our southern border, thousands of unaccompanied children making their way here from central America. Many of them not getting adequate medical screening and that is raising some serious health concerns. ABC's Jim Avila has the story. Reporter: This morning, the flood of immigrant children streaming across the southern U.S. Border is so overwhelming federal agencies admit they cannot medically screen all of them properly. According to a government memo reviewed exclusively by ABC news some children are leaving border patrol processing centers with high fever, flu-like symptoms and other contagious diseases. The memo says the director of refugee health at HHS has identified a breakdown in the medical screening processes at the border patrol facility in Nogales, Arizona. Some children flown to a Navy base in Ventura were sick, fevers and coughing. Others had chicken pox and coxsackie virus. Two suffering from pneumonia. It's very concerning that children who had pneumonia were allowed on a plane risking their health and other refugee children. The lack of screening according to government sources may jeopardize the health of workers and other children at the facilities. In fact, ABC news has confirmed that just a week after the unscreened kids arrived there appeared to be a pneumonia and influenza outbreak spreading through the Ventura facility. In Texas ABC news learned of one confirmed case and two probable cases of the h1n1 influenza strain known as swine flu linked to the unaccompanied children. It's important to note none of these diseases have spread into the communities around the facilities and sources tell ABC news the government is now adding a fit to travel screening for the children. They must pass it before being put on a plane and sent to facilities away from the border.

This transcript has been automatically generated and may not be 100% accurate.