The United States remains committed to fighting Ebola in Africa, American health officials said on Monday, but the scope of the current outbreak in the Democratic Republic of Congo has become somewhat unclear.

There were rumors that Ebola had reached Tanzania, the officials noted. And the arrest of Congo’s former health minister, who until recently led his country’s response to the outbreak, has raised doubts about how effective that effort ever was .

The American delegation included Alex M. Azar, the secretary of Health and Human Services; Dr. Robert R. Redfield, the director of the Centers for Disease Control and Prevention; Dr. Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases; and Tim Ziemer, a retired admiral who is a senior deputy assistant administrator at USAID.

The group toured Ebola response operations in Congo, Rwanda and Uganda. In a telephone news conference as the trip neared its end , Mr. Azar said that, to date, the United States has spent $158 million in direct aid on the fight and another $238 million in technical assistance, including research on vaccines and treatments.