The study, however, said the disease had not resulted in co-infections that could be fatal. The virus that caused the fever was the 'African strain,' similar to the one that spread chikungunya in other parts of the country.

Releasing the findings of the study, Sreejith N Kumar, Convenor, IMA Epidemic Cell, said the outbreak in the state was "non-fatal". Most of the deaths in Cherthala in Alappuzha district -- the region worst-hit by the disease -- "were not due to chikungunya, but other ailments", he said.

Sreejith said the study report was being released so that people stop panicking. The controversy regarding the cause of deaths should have been avoided, he said, adding more efforts have to be made to check the spread of the disease.

Sreekumar, scientist with the Rajiv Gandhi Biotechnology Centre, said of the 13 samples, nine tested positive for Chikungunya.

The polymerised chain reaction tests conducted by the centre's team did not find any mutation in the virus that could make it more virulent.

He said viral tests also ruled out incidence of Dengue or other co-infections. The IMA requested the people to concentrate more on mosquito-eradication and sanitation programmes.