THURSDAY, Feb. 19 (HealthDay News) -- U.S. health officials issued a public health advisory Thursday for the psoriasis drug Raptiva after confirming that three people using the medication have died.

Two of three people with confirmed cases of a rare brain infection called progressive multifocal leukoencephalopathy (PML) are among the dead, according to the U.S. Food and Drug Administration advisory. The third death was a person believed to have contracted the brain infection, according to the advisory.

All four had been treated with Raptiva (efalizumab) for at least three years, and none was taking other immune suppressants.

In its advisory, the FDA said it would study the issue carefully and "strongly recommends that health care professionals carefully monitor patients on Raptiva, as well as those who have discontinued the drug, for any signs or symptoms of neurologic disease, and that they periodically reassess the benefits of continued treatment."

"Patients should be aware of the symptoms of PML and contact their health care professionals immediately if they experience any such symptoms," the advisory recommended.

Outside experts, however, said that, though the news was serious, there was no reason to panic.

"Patients should talk to their doctors and carefully weigh the risks and benefits of Raptiva, taking into account the most recent bit of information," said Bruce Bebo Jr., director of research for the National Psoriasis Foundation in Portland, Ore. "The risk to folks in the grand scheme of things is still not very high. For some patients, this [and similar drugs] have very profound efficacy. Psoriasis is a life-changing disease for many people, and a lot of people are willing to accept that degree of risk."

Srikanth Kolluru, an assistant professor of pharmaceutical sciences at Texas A&M Health Science Center, said that people "who are on this medication currently should be made aware that it might cause brain infection [PML] or any other infections and possible symptoms so that they can contact their physician immediately."

People using the drug "need to be well-informed about the symptoms for PML infection and need to be monitored closely," he said.