Lifesaving treatment and prevention programs for tuberculosis, malaria, H.I.V. and other diseases cannot access funds to continue work.

Patients and health care advocates said the abrupt decision to halt U.S. funding for a lifesaving H.I.V. program led to widespread confusion. The backtracking didn’t help.

Many of the frozen programs are aimed at alleviating disease and malnutrition, but even security programs with U.S. funding are shutting down.

PEPFAR’s computer systems also are being taken offline, a sign that the program may not return, as Republican critics had hoped.

Pepfar, which is estimated to have delivered lifesaving treatment to as many as 25 million people in 54 countries, faces a funding delay of as long as 180 days.