Talk about an industry that's in serious need of a doctor. The past week has been rough for health-care insurers, but intriguingly, the companies seem to suffer from different ailments.

WellPoint (NYSE: WLP) kicked things off by complaining about high health-care costs and decreased demand for its services. Miscalculating the price it set for its Medicare prescription plan caused Humana's (NYSE: HUM) ailment. And yesterday, Coventry Health Care (NYSE: CVH) became the latest company to check itself into the sick ward.

Conventry lowered its guidance to $4.39 to $4.50 per share, from its prior forecast of $4.42 to $4.58 per share. The health insurer blamed higher costs from a strong flu season, and lower investment income because the Fed lowered interest rates. Even with the reduced guidance, Conventry expects at least a 10% increase in earnings-per-share growth over last year.

The whole industry has languished over the last week, amid earnings announcements that seem to have displeased Wall Street. Even Aetna (NYSE: AET) and Cigna (NYSE: CI), which reaffirmed their guidance for the quarter, seem to be suffering in sympathy. It didn't help the sector much when the largest health insurer, UnitedHealth (NYSE: UNH), issued somewhat wishy-washy first-quarter guidance.

Only time will tell if the health insurance industry is headed for an extended bed rest, or if this is just a freak occurrence of multiple ailments happening simultaneously; I'd argue for the latter. While a recession might make it difficult for insurers to gain members as quickly as in an economic boom, I'm not sure the companies deserve the drastic share-price cuts they've suffered at investors' hands.

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Fool contributor Brian Orelli, Ph.D., doesn't own shares of any company mentioned in this article. The Fool's disclosure policy is well.