A chikungunya outbreak in China has infected more than 7,000 people. Chikungunya causes fever and joint pain, but in some cases can be fatal. There is no vaccine or real treatment. Epidemiologist Jason Rasgon, from Penn State University, explains how the disease is transmitted, and why it seems to be spreading to new areas. The chikungunya virus is not currently endemic in Australia. There have been no locally acquired cases, though mosquitoes capable of spreading the virus are present in some areas of Queensland, and travellers can become infected with the chikungunya virus if travelling to a region of the world where chikungunya is found.