Earlier this month, the first two cases of locally-transmitted chikungunya virus in the contiguous United States were reported in Florida.1 Chikungunya virus has been previously identified in people in the US (on average, 26 individuals per year are diagnosed with the disease), but all were in travelers who had contracted the it outside the country. These two new cases of people who had not left the country signal chikungunya virus’s official arrival in the US.
Chikungunya virus has moved swiftly across the Americas once introduced. The virus is endemic to Africa and Asia and was first described during an outbreak in Tanzania in 1952. The first report of circulating chikungunya virus in the Western hemisphere was just this past December (2013) on the French side of St. Martin in the Caribbean.2 Seven short months later, the virus is circulating in South and Central America,3 the US territories of Puerto Rico (193 confirmed cases of locally-transmitted disease) and the Virgin Islands (2 cases), and now Florida.4
Chikungunya virus5 is a member of the family Togaviridae and is a type of alphavirus. These small, enveloped RNA viruses are transmitted to humans via infected mosquitoes; uninfected mosquitoes then acquire the virus when they bite an infected human (mosquito -> human -> mosquito infection cycle). Symptoms of the disease appear 2-12 days after being bitten, and include fever, muscle aches, tiredness, joint pain (typically in the hands and feet, which may become swollen), a rash of red, raised spots across the body and limbs, and arthritis. Arthritis pain may last weeks, months, and even years. The virus name ‘chikungunya’ derives from a word in the Kimakonde language meaning “to become contorted” and describes the appearance of those suffering from the debilitating joint pain of this disease. Almost all people infected with chikungunya experience symptoms of the disease.6 Infection with chikungunya virus rarely leads to death although it can occur among the elderly, newborns, and the immuno-compromised. There is currently no vaccine and no anti-viral drugs to combat the disease. Rest, fluids, and pain medicine is the current treatment.
How concerned should we be of chikungunya? Dengue is another mosquito-borne virus that has been flirting with the US over the past ten years, but, outside of some local outbreaks in Hawaii and Texas, has yet to gain a foothold here.7 Hopefully, chikungunya will behave the same way. The best prevention for this disease is mosquito control: empty standing water, keep windows and doors closed or screened to prevent mosquitoes from entering the home, and use insect repellent to avoid bites.8 (Author’s note: if chikungunya ever makes it to Pennsylvania, I will be the first to know as mosquitoes LOVE me. I will keep you all posted!)
References/ Further Reading:
6. Morens, DM and AS Fauci. 2014. Chikungunya at the door – déjà vu all over again? N Engl J Med. Epub ahead of print. PMID:25029435.