KAMPALA, Uganda (AP) — Authorities are having trouble figuring out how many more people are getting Ebola in Liberia and Sierra Leone and where the hot spots are in those countries, harming efforts to get control of the raging, deadly outbreak, the U.N.'s top Ebola official in West Africa said Tuesday.

"The challenge is good information, because information helps tell us where the disease is, how it's spreading and where we need to target our resources," Anthony Banbury told The Associated Press by phone from the Ghanaian capital of Accra, where the U.N. Mission for Ebola Emergency Response, or UNMEER, is based.

Health experts say the key to stopping Ebola is breaking the chain of transmission by tracing and isolating those who have had contact with Ebola patients or victims. Health care workers can't do that if they don't know where new cases are emerging.

"And unfortunately, we don't have good data from a lot of areas. We don't know exactly what is happening," said Banbury, the chief of UNMEER.

Banbury, who visited the three most affected countries last week, said it was "heartbreaking" to see families torn apart by Ebola as they struggle to care for sick loves ones while also hoping to avoid infection. He said he is hoping for a new approach in Liberia as the U.N. and its partners work to improve the capacity of communities to safely bury victims.

Over the past week, Banbury met with the presidents of Guinea, Sierra Leone and Liberia, where Ebola has infected at least 10,000 people and killed roughly half of them, as he focuses on adapting an operational framework for international anti-Ebola efforts, the U.N. said.

The president of the World Bank, Jim Yong Kim, meanwhile, said the three countries need at least 5,000 more health workers to effectively fight the epidemic.

Kim said Tuesday that he is worried about where those health workers can be found given the widespread fear of Ebola. Quarantining health workers returning to their home countries could also hurt recruitment efforts. The World Bank president spoke alongside U.N. Secretary-General Ban Ki-moon and African Union Chairwoman Nkosazana Dlamini-Zuma in Addis Ababa, Ethiopia, where the AU is headquartered.

Although Western governments and aid groups have stepped up Ebola aid in recent months, the U.N. says more support is needed. The U.N.'s target is to have 70 percent of Ebola cases getting access to a treatment center and to achieve a similar percentage for safe Ebola burials.

"They are extremely ambitious (goals), given the geographical spread of the disease, the numbers of people infected, the very poor information on exactly where those infected are and what the transmission patterns are," Banbury said. "The three things we need the most are people, supplies and money. The most critical right now are people, health workers in particular, trained health care workers . but also people who can manage these Ebola treatment facilities."

Ban said the transmission of the virus continues to outpace the international community's response. He appealed to the AU's 54 member states not to impose Ebola-related travel restrictions or close their borders. Some already have.

Dlamini-Zuma said African Union states have pledged to send more than 2,000 health care workers to West Africa. She did not say when the workers would arrive.

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Associated Press reporter Elias Meseret in Addis Ababa, Ethiopia contributed to this report.