A doctor monitoring the plight of 75,000 Syrians stranded on the sealed border with Jordan says she's been told infectious diseases are spreading among them.

Natalie Thurtle of the international aid group Doctors Without Borders said Monday that refugees with some medical training have told her they see about 30 cases a day of jaundice, likely a symptom of hepatitis.

Thurtle says that's an increase from one a week before Jordan closed the border in June. She says diarrhea and respiratory problems are also common.

The closure, a response to a cross-border attack by Islamic State extremists, cut off two desert camps from medical and other aid, except for a one-off food delivery last week and occasional water shipments.

It's unclear how aid will reach the camps in the future.