Washington, Dec 31 : Global warming might lead to the spread of tick borne diseases in humans, warns a professor at the University of Marseille School of Medicine in France.

Didier Raoult, a professor at the University of Marseille School of Medicine in France suggests that as global climate warms, dog ticks might be more likely to bite people, and tick-transmitted diseases might become more common.

In the spring of 2007, three men in France became seriously ill after sustaining bites from disease-infected dog ticks. The bites occurred after the hottest April since 1950.

A 2004 outbreak of Rocky Mountain spotted fever in Arizona was also associated with dog ticks. During the extremely hot summer of
2003, a man died after 20 brown dog ticks bit him at once

These cases prompted the researchers to investigate if hot weather made dog ticks turn on humans.

For the study, Raoult and his two of his colleagues incubated 500 brown dog ticks at 77 degrees Fahrenheit (25 C) and 500 at 104 degrees Fahrenheit (40 C). Then, they placed the ticks on their own arms.

"They take a very long time to attach. It''s not like a mosquito. They don''t have time to bite you," Discovery News quoted him, as saying.

After an hour, the researchers found that almost 50 pct of the ticks incubated at 104 degrees tried to burrow in, while none of those incubated at 77 degrees did.

Raoult believes that thirst compels the ticks to seek human blood at higher temperatures.

However, Christopher Paddock, a pathologist with the Centres for Disease Control and Prevention in Atlanta said that the temperature is just one factor that affects tick behaviour.

Moreover, a sudden surge from 77 degrees to 104 degrees is too extreme to mimic a realistic global warming scenario, he added. (ANI)