STAFFORD, Va. — An analysis of sewage in one Virginia county indicates that it has 10 times as many people walking around with the coronavirus than test results suggest.

The Free Lance-Star reported Friday that Stafford County has been conducting experimental testing at two wastewater plants since April.

Sewage can provide an early indicator of a disease spreading before people start seeking health care.

Sampling of households hooked up to the county sewer system showed that up to 18 percent of North Stafford’s population may have the virus.

County officials said the sewage data doesn’t necessarily mean there are that many cases.

But they said the sewage data can indicate whether cases are increasing.