Cabell County has reported 74 cases since January 2018, primarily among drug users sharing contaminated needles. The recent surge in infections represents the convergence of two major health epidemics, HIV and opioids, the Trump administration has pledged to fight.

The fact that the uptick is happening in a rural county with an unusually robust public health system — which already does much of what the Trump administration wants to replicate nationwide as it seeks to eradicate HIV transmission within a decade — may be fortuitous for officials trying to prevent a broader outbreak. But the fact that the cases have occurred despite the county’s surveillance and prevention is also worrisome.

“The ground is fertile,” said Judith Feinberg, a professor of behavioral medicine and infectious diseases at West Virginia University. “This is the nightmare everyone is worried about.”