More than 1,000 people have died in two provinces of Congo in the second-worst outbreak of the Ebola virus recorded in modern times.

The Congolese health ministry said Friday that 1,529 people had been infected in the outbreak, which is concentrated in two trading cities in North Kivu Province. Of those, 1,008 people have died, a mortality rate of nearly 66 percent.

In just the last week, 132 new Ebola cases have been confirmed, the health ministry said.

ADVERTISEMENT The latest outbreak — the 10th recorded in Congo in modern history — began last summer in the town of Beni, which has a population of about 250,000. It has since migrated south, to the cities of Butembo and Katwa, where hundreds of new cases have been reported in recent months.

Public health officials are scrambling to respond to the outbreak in a region where ethnic strife is endemic. The World Health Organization (WHO) said Friday they had recorded more than 100 attacks against health care workers or facilities dedicated to treating Ebola patients.

Eighty-five health care workers have been injured or killed since the outbreak began. Last month, an attack on Butembo University Hospital killed Richard Valery Mouzoko Kiboung, a WHO epidemiologist from Cameroon who had been assigned to lead a local response team there.

“The operating environment has become increasingly insecure and socio-politically complex. Insecurity remains a major impediment to ensuring timely response interventions in the affected communities,” the WHO said in a statement Friday.

Public health officials have worried for months that a deep and lasting distrust between residents of North Kivu and virtually anyone from the outside — including the far-off federal government in Kinshasa — would hamper response efforts. Those efforts are exercises in gaining community acceptance, which requires anthropology as much as any hard science.

“Anything that comes from the outside is really not welcome. That combination of a population that’s traumatized by 30 years of conflict, the conflict itself and the mistrust makes everything more difficult,” said Carlos Navarro Colorado, who heads the Ebola response for UNICEF.

About 44 percent of the total number of Ebola cases have been identified in Butembo and Katwa. The mortality rate in those cities, where public acceptance of efforts to combat the virus has been slower to take hold than in other cities, has been far higher. The virus has spread from Butembo and Katwa to five neighboring villages, where health officials thought they had stamped out previous outbreaks.

Mike Ryan, WHO’s assistant director general for emergencies, said in a press conference Friday that the recent spike in cases has followed previous patterns, when response operations were delayed or halted because of the risk of violence.

And there are worrying signs that the case count could rise further. Health officials are tracking 12,000 people who have come into contact with someone who has contracted the Ebola virus. As of Thursday, the health ministry was tracking 286 potential cases across the region.

Ryan said public health officials would embark on a more aggressive vaccination campaign to halt the virus’s progress. So far, more than 110,000 people have received a vaccine, manufactured by Merck, that appears to be working. Ryan said the goal would be to administer up to 1,000 doses of the vaccine every day in the coming weeks.