Why do health experts fear the West Texas measles outbreak may be much larger than reported? For some, it’s a question of simple math.

An unvaccinated New Mexico adult who tested positive for measles has died, the second death in a growing outbreak centered along the Texas-New Mexico border, officials said Thursday. The individual did not seek medical care before death,

There has been one confirmed measles death while officials in New Mexico determine if a recent death in the state was caused by measles.