About 25 miles northwest of New York City, local authorities have been waging a losing battle to curb the coronavirus outbreak: Rockland County has the highest per capita rate of infection in the state, and among the highest in the nation.

The source of the problem lies in small pockets of the county that are home to a large number of Orthodox Jewish residents, some of whom, according to authorities, have refused to adhere to social distancing requirements.

Spring Valley and Monsey — two adjacent communities with large Orthodox Jewish populations — each have more than 1,000 confirmed cases, accounting for more than a third of the county’s entire caseload, according to statistics compiled by the county health department.

With Passover beginning Wednesday, county officials are increasingly worried that the disease could spread among large Orthodox families, leading to a spike in cases similar to the one seen last year during a measles outbreak.