This is one of the scariest graphs I've seen in a long time.

This plot, from the CDC, shows probable and confirmed cases of pertussis - whooping cough - in the state of Washington from 2011 through June 2012. Last year's numbers are the short, light-blue-grey rectangles, and this year's are the dark blue. The plot is by week, so you can see the 2011 numbers slowly growing across the year; then this year's numbers suddenly taking a huge leap upward. They are reporting the new rate as 13 times larger than last year. Note that 83% of these cases have been confirmed as being pertussis, while 17% are probable. The drop in recent weeks is due to a lag in complete reporting of cases. Got that? There are 13 times as many people - more than 2500 in total so far - getting pertussis right now as there were last year at this time in Washington. Some of this increase may be attributable to the pertussis bacterium growing a resistance to the vaccine and booster. However, it's curious that Washington state has seen such a large jump; the incidence of pertussis overall in that state is nine times higher than the national average. Why would this be? Well, it so happens that the antivax movement is quite strong in Washington state, and it also so happens that parents are choosing not to vaccinate their children in higher numbers there than the rest of the nation. There may be other factors, but it's clear that people who don't vaccinate are at least partially to blame for this. Maybe it's due to religious reasons, or the large number of antivaxxers who still blame autism on vaccines, when we know for sure that's not the case. Either way, when vaccine rates get too low, herd immunity is compromised, and we see more pertussis cases, even among those who are vaccinated. Pertussis is a terrible, terrible disease. It puts infants at grave risk of dying, and eight infants so far this year have been killed by pertussis in the US. Even if it doesn't kill them, it's a horrible thing to put them through. Vaccines save lives. Talk to your board-certified doctor and find out if you need one, or a booster. I did, and my whole family is up-to-date with their vaccinations. I refuse to be a part of spreading a disease that can kill anyone, let alone babies, and I refuse to be silent about it.

Tip o' the needle to Steven Saltzberg at Genomics, Evolution, and Pseudoscience and mims on Twitter.

Related Posts: - Not vaccinated? No kisses! - Whooping cough outbreak in Boulder - Pertussis can kill, and you can help stop it - Pertussis and measles are coming back