Head lice!

The mere thought of these tiny critters crawling around a child’s scalp is enough to generate shudders of disgust. Judging from the drastic measures some parents take to get rid of them  from mayonnaise and vinegar to overdoses of potentially toxic chemicals  you’d think they were the worst scourge on earth.

Yet aside from the ick factor and a sometimes itchy scalp caused by an allergic reaction to their saliva, head lice cause no physical distress and transmit no diseases. In a clinical report issued in July by the American Academy of Pediatrics, the organization noted that head lice cause “a high level of anxiety among parents of school-aged children.”

A bigger problem than the lice themselves is that infestations are commonly misdiagnosed. By some estimates, at least half of the young children treated for head lice  even forbidden to attend school, in some cities and states with “no nit” policies  no longer have them or were never infested in the first place.

Schools that check children for lice often rely on nurses and parents ill equipped to detect an active lice infestation. In one study of more than 600 samples of presumed lice or eggs submitted by teachers, parents, nurses and physicians, about two-thirds turned out to be dandruff, scabs, dirt, plugs of skin cells, hair spray droplets, other insects or eggs that were no longer viable or already hatched.