When is an epidemic really an epidemic? Or not? Just let the media tell you

My search for evidence to support the claim began with this tweet sent 9 minutes after midnight:

CBS Radio News ‏@CBSRadioNews

US appears headed for its worst year for whooping cough in 50 years with the number of cases rising at an epidemic rate http://bit.ly/cbsnewscast

Step 1: Click on the provided link. It led to the current newscast. All Aurora shootings; nothing on whooping cough.

Step 2: Google “whooping cough.” Story number one from Reuters:

SEATTLE (Reuters) – The number of U.S. whooping cough cases has risen to around 18,000 in an outbreak that is on track to become the most severe in over a half century and could in part stem from possible waning vaccine protection, health officials said on Thursday.

Quoting a federal government source, Reuters reports that Washington state declared an epidemic in April and Wisconsin was “particularly hard hit” with each state reporting about 3,ooo cases.

Two key facts from Reuters: “Nine people have died overall and the number of cases was already more than double than at the same time last year.” [emphasis added]

Story number two from The Associated Press:

ATLANTA — The U.S. appears headed for its worst year for whooping cough in more than five decades, with the number of cases rising at an epidemic rate that experts say may reflect a problem with the effectiveness of the vaccine.

Nearly 18,000 cases have been reported so far — more than twice the number seen at this point last year, the Centers for Disease Control and Prevention said Thursday. At this pace, the number for the entire year will be the highest since 1959, when 40,000 illnesses were reported.

In 1959, the population of the United States stood at just under 178 million people. Today, the American population is closing in on 315 million people.

If 40,000 Americans were afflicted by whooping cough in 1959 (about 0.0225 percent), that would be a higher percentage of the population than 40,000 in 2012 (about 0.0127 percent). For the “epidemic” of whooping cough in 2012 to reach the same percentage of the population as in 1959, the 2012 total would have to hit about 71,000 cases. The U.S. total will be well short of that.

During World War II, about 150 cases per 100,000 Americans were reported annually. After introduction of a vaccine, that rate dropped to 1 case per 100,000. But the number of cases reported has climbed since 1980. (Better recognition of disease? Better state-by-state epidemiological accounting? Reflection of population growth?)

The AP story reports five states — only five — out of 50 have exceeded typical rates of disease onset this year — Washington, Wisconsin, New York, Minnesota, and Arizona. Reuters reports only two — Washington and Wisconsin. Reuters referred to California — “where a 2010 epidemic counted more than 9,000 cases, including 10 infant deaths” — but did not report that California reported no — zero — infant deaths in 2011 with total cases falling to 2,795.

That’s hardly support for “The U.S. appears headed for its worst year …” And how is “worst” defined? Number of cases? Rate of incidence in the population? Rate of incidence in the young? Number of deaths overall? Number of deaths per 100,000 compared with past years?

The claim of epidemic is tied to less-than-evidentiary wording — appears (AP and CBS Radio News) and is on track (Reuters). And there’s the occasional could and may.

Should Americans be concerned about rising rates of incidence of whooping cough? Of course. The CDC website reports 37 states with higher incidence rates thus far in 2012. But overall, the U.S. incidence of the disease, says the CDC, is 5.24 per 100,000. Which of these facts represents “epidemic” and which doesn’t?

Both the AP and Reuters report officials are concerned the vaccine used to prevent whooping cough may be more short-lived than previously. No doubt officials at the National Center for Immunization and Respiratory Diseases at the Centers for Disease Control are on the case, studying whether booster shots are necessary. State epidemiological authorities surely are watching this. (Are they? Reuters and the AP only quoted officials of the health department in Washington state.)

The AP used epidemic rate and Reuters most severe carelessly, linking them to weak verbs and failing to provide adequate historical context for the claims. CBS Radio News chose, in true rip ‘n’ read fashion, to tweet about an epidemic rate.

Could the stories have provided more named sources? AP: two in its 17-graf story. Reuters: three in its 14-graf story.

And now other newsies are chiming in. The hed on a USA Today story in the Detroit Free Press: Whooping cough could reach highest levels since 1959.

The hed from the Los Angeles Times story: U.S. suffering worst whooping cough outbreak since 1959, CDC says — which, I’d argue, is not what the CDC said.

The lede in the Star-Tribune‘s HealthCheck blog: Health officials say the nation is on track to have the worst year for whooping cough in more than five decades.

This poorly worded hed claims an epidemic in fact already exists and may be worse than ’59: US whooping cough epidemic may be the worst since 1959.

And then the fear angle in the LATimes:

With the nation’s attention focused on dire news about whooping cough, parents’ inclination may be to hustle their children — or themselves — in for a booster shot.

Will there be a run on the whooping cough vaccine?

With the nation’s attention focused on dire news … Really? This is journalism today?

Would it have required any of these news organizations more than 15 minutes to provide better context about the rising incidence of whooping cough? Reporting on epidemiological concerns with appropriate context is demanding. News organizations should take a little more time to get it right.

h/t Joel Best

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