The fight against Congo's Ebola outbreak could fail unless the overall living situation in affected areas is improved, a senior WHO official says.

In parallel to efforts to rein in the deadly virus, it is necessary to build up local infrastructure now instead of after the outbreak, the WHO's Ebola operations chief Michel Yao told dpa.

The Canadian's comments came in reaction to an analysis by the medical aid group Doctors Without Borders (MSF), which had declared the current Ebola strategy in Congo a failure.

In areas where armed groups have been fighting for decades, people suspect health workers of having political motives and too few patients are brought to clinics, according to the analysis.

There is also frustration about money being spent on this outbreak rather than on malaria.

"We want a contract of confidence with the local population," Yao said, calling for rapid development aid. "If we don't gain the heart of the population we will not succeed."

The WHO has started helping with small projects such as missing water pumps in health centres.

The UN health agency is also pushing other organisations such as the World Bank to implement bigger projects now rather than later.

Over the past seven months, more than 900 people have been infected and more than 570 of them have died from the virus that causes bleeding and fever, according to the Health Ministry.