October 31 (HealthDay News) -- Media coverage greatly influences how people perceive the threat of infectious diseases, Canadian researchers say.

For example, diseases that receive extensive coverage are likely to be regarded as especially dangerous by the public, even if that isn't the case.

"The media tend to focus on rare and dramatic events. When a certain disease receives repeated coverage in the press, people tend to focus on it and perceive it as a real threat. This raises concerns regarding how people view their own health, how they truly understand diseases, and how they treat themselves," study co-author Meredith Young, a graduate student in the department of psychology, neurosciences and behavior at McMaster University in Hamilton, Ontario, said in a university news release about the research.

For this study, two groups of students (undergraduate and medical) were asked to rate 10 infectious diseases on how serious, prevalent, and "disease-like" they were. Five of the diseases have received recent high-profile media coverage -- anthrax, SARS, West Nile virus, Lyme disease and avian flu -- while the other five haven't received much attention -- Tularemia, human babesiosis, yellow fever, Lassa fever and hantavirus.

The researchers found "that a single incident reported in the media can cause great public concern if it is interpreted to mean that the potential risk is difficult to control, as with the possibility of a pandemic like in the case of avian flu, and bioterrorism, as in the case of anthrax infection," Young said.

But when the students read descriptions of the diseases, without their names, they rated the diseases that received little media attention as being the most dangerous.

"Another interesting aspect of the study is, when we presented factual information about the diseases along with the names of them, the media effect wasn't nearly as strong," study co-author Karin Humphreys, an assistant professor in the department of psychology, neurosciences and behavior, said in the news release. "This suggests that people can overcome the influence of the media when you give them the facts, and so objective reporting is really critical."

The researchers were surprised to find that medical students -- who have more factual knowledge about infectious diseases -- were just as influenced by media coverage as the other students.

The study was published online Oct. 29 in the journal PLoS One.

SOURCE: PLoS One, news release, Oct. 28, 2008