Strictly in confidence.

As reported in the Australian Cellestis CEO Tony Radford said that

Qiagen dropped by (but only to say hello) a few months ago

What he failed to mention was that the "hello" involved signing this;

The effect of this confidentiality deed was to give Qiagen full access to company information not normally accessible to shareholders. It also indicates that prior negotiations had taken place, possibly before the 2010 AGM.

It also has the effect that any meaningful communication with shareholders from that date is virtually denied. 

You would wonder why Qiagen is interested in CST as it's diagnostics platforms do not appear to be harmonious. Investment firm William Blair analyst Brian Weinstein urgued caution saying Qiagen's dominance in the HPV market will be challenged by Roche and Gen-Probe.

Sharing those concerns are Goldman Sachs,

who in a report issued in February said that Gen-Probe's advantages in automation and Roche's sizeable sales force could consume part of Qiagen's HPV market share.

Also of concern to Weinstein was

Qiagen's success, or lack thereof, with the US Food and Drug Administration is a red flag, calling the company's record "unproven." Despite dozens of platforms and thousands of products, Qiagen has only a "handful" of FDA approvals that it has sponsored itself, he said, noting this is "particularly important given our belief that product launches are one of the three key things that will move a stock."....

....Questions around the deal exist, however. Qiagen said that Cellestis' QuantiFeron tests for TB and cytomegalovirus would be moved onto its QIAensemble, QIAsymphony, and ESE point-of-care platforms. Weinstein, however, said it is unclear what regulatory pathway there may be for getting the two tests approved for Qiagen's instruments.

"Also, we are not sure whether currently installed instruments will require retrofitting to accommodate the assays," he said.

It would appear that Qiagen need CST more than CST needs Qiagen.