There could be a simple explanation as to why the joints are most affected in arthritis caused by mosquito borne viruses, Queensland researchers say.

QIMR Berghofer Inflammation Biology group leader Professor Andreas Suhrbier said the body’s first line of defence against viral infections caused by  Ross River virus and chikungunya virus were type 1 interferons.

But in their study in mice the research team discovered that interferons work optimally at body temperature (37C) and not so well at cooler temperatures.

“The bizarrely simple answer is, because these joints in the limbs are usually a few degrees cooler than the rest of the body,” he said.

Professor Suhrbier and his team found that when the limb temperature in the mice was warmer, the anti-viral defence system was more effective at fighting-off the virus. Mice housed at 30C also had less severe arthritis than the mice housed at 22C.

“This is the first time that ambient temperature has been shown to have such a dramatic effect on viral infections in warm-blooded animals,” Professor Suhrbier said.

According to Professor Suhrbier the findings vindicated the ‘Kenny method’ – a controversial limb-warming therapy used in the 1930s for children with polio.

“[Our findings] also beg the question: Can the Kenny method of warming the limbs also potentially treat arthritis caused by Ross River virus and chikungunya virus?”

Professor Suhrbier said heat treatment would need to be started very early in the infection and how this related to humans would need to be established in future trials.