Something is clearly wrong with Don Draper.

If you caught the latest episode of “Mad Men” on Sunday night, you saw a feverish Don coughing and spluttering around Sterling Cooper Draper Pryce before leaving the office early to take to bed.

So what’s ailing Don?

Viewers aren’t given any definite answers in this episode, but Michael Ginsburg, the agency’s new copywriter, has a theory: “Maybe you have TB.”

Not necessarily a bad guess.

Though tuberculosis is at an all-time low in the United States, it was more common in 1966 — when the episode is set. In fact, according to the Center for Disease Control and Prevention, TB killed 7,625 of the nearly 48,000 people who contracted the disease that year.

In 2009, there were significantly fewer deaths (542), and the following year, 11,000 people were infected with TB. Globally, TB is second only to HIV/AIDS as the greatest killer worldwide (due to a single infectious agent.) According to the World Health Organization, in 2010, 8.8 million people fell ill with TB and 1.4 million died from it. Over 95% of these deaths occured in low-and middle-income countries.

Back to New York City, 1966: In addition to the wheezing and coughing, Don suffers from such a high fever (spoiler alert ahead) that he ends up on the verge of hallucination. And according to his wife Megan, he was babbling in his sleep.

“It certainly is possible that Don has TB,” says Scott Teesdale, who has a masters in public health epidemiology and works on malaria intervention projects. “Smoking is a risk factor, and New York City had a significant segment of the population with known cases in the 1960s.”

Many of the TB patients in the 60s were given drugs to prevent the spread of the disease, however, Teesdale says. “In the 60s, it was a treatable disease with available antibiotics,” he says. “So it wouldn’t have been a death sentence.”

Even though Don’s persistent cough and high fever are consistent with a TB diagnosis, Teesdale — who hadn’t yet watched the episode, but graciously offered his opinion based on my observations — says there may be one problem with this hypothesis.

“It would be unusual that Don would be fairly healthy and then rapidly deteriorate in a day or two. TB normally manifests over the course of several weeks, and would need time to get to a point with extreme symptoms,” he says.

“Most likely, he had some other type of respiratory disease like the flu, cold, strep throat, or general bronchitis, where it could present faster.”