Chikungunya (pronounced chik-en-gun-ye) is an infectious disease with symptoms that typically include fever and severe joint pain. It is caused by the chikungunya virus, which is transmitted to people by mosquitoes. Chikungunya is transmitted by Aedes aegypti mosquitoes (also known as yellow fever mosquitoes) and by Aedes albopictus mosquitoes (also known as Asian tiger mosquitoes). These mosquitoes bite primarily during the day. They are not native to California; however, they have recently been detected in several counties. An Aedes mosquito can only transmit chikungunya virus after it bites a person who has this virus in their blood. Thus far in California, chikungunya infections have been documented only in persons who were infected while travelling outside the United States. A person with chikungunya is not contagious.