The violent, gasping cough of a child with pertussis is one of most frightening noises a parent can ever hear.
It rattles the small lungs and overwhelms the frail rib cage. It reddens the little face and takes over the body.
Sometimes the paroxysms last so long that the child vomits, and when breath finally comes, it is with a desperate, sucking noise that sounds like no other thing in nature.
The whooping cough, for which the disease is popularly named, can go on for months — "the cough of 100 days," they call it in China. Its victims do not always survive.
Pertussis was sickening some 200,000 American children a year and claiming some 9,000 lives annually by the 1940s, when public health researchers Pearl Kendrick and Grace Eldering developed a standardized vaccine.
By the 1970s, the disease was all but eradicated in this country. Then in the 1980s and 1990s, concerns about side effects led to a new vaccine that caused fewer reactions but was less long-lasting.
Since then, pertussis has been making a gradual comeback, and California is in the midst of the second full-blown epidemic here in four years.
As they were last time, the numbers are both chilling and enraging. Already, the state has had more cases in six months than in all of last year.
Eighty-four percent of the nearly 3,500 cases reported statewide by June 10 were infants and children. Two babies have died, one each in Placer and Riverside counties.
Though the worst of the epidemic this time is in Marin, Napa and Sonoma counties, the spread has been rapid, with spikes all over California:
Fresno County has gone from 41 cases last year to at least 220 so far, with an infection rate that has more than quintupled.
In Madera County, numbers and infection rates have more than doubled, with 22 cases by mid-month.
The temptation is to get out the pitchforks and blame the anti-vaxxers — parents who choose not to vaccinate their children, either out of religious belief, misgivings or mere ignorance.
Health authorities say the resurgence has more to do with the fact that modern pertussis vaccines begin to wane within a few years; without boosters for older children, teens and adults, people can become infected.
But intentionally unimmunized children certainly aren't helping the situation. An unvaccinated child is not only in personal danger, but, because of waning immunization generally, can quickly become the epicenter of an entire cluster.
So if you haven't already, vaccinate your children. If they're vaccinated already, ask about boosters. If you're pregnant, get vaccinated for the sake of your unborn child.
And if you know someone who's not vaccinating their kids, suggest they rethink it. They may not want to hear it, but the voice of reason is far less unnerving than the sound of a lethal disease, threatening once again to run wild.