Chikungunya, a mosquito-borne viral illness found for the first time in the Americas in December last year, has been spreading throughout Caribbean territories and continues to be reported in new countries and territories in the Americas. The Ministry of Health of El Salvador reported 1200 cases of chikungunya on June 14—the first reported cases in the nation. The CDC has reported 57 imported cases in the U.S., but no locally transmitted cases have been discovered within the continental U.S. thus far. However, the U.S. Virgin Islands confirmed its first locally transmitted case of chikungunya on June 11, after Puerto Rico reported the first non-imported case in U.S. territory on May 29. The CDC currently reports 23 locally transmitted cases in Puerto Rico. Meanwhile, the virus continues to spread rapidly in other territories such as Guadeloupe (an overseas territory of France), where 5190 new cases were reported between May 26 and June 1. That amounts to 1 new case every 2 minutes.
The first locally contracted cases of chikungunya in the Americas were found on the French side of St. Martin in December. Previously, the virus had been most common in Africa and Asia. In an update on June 13, the Pan American Health Organization (PAHO) reported 165,990 suspected and confirmed cases in the Americas since the beginning of the outbreak. Countries and territories with especially high incidence rates include St. Martin (French side), Martinique, St. Barthelemy, Guadeloupe, and Dominica. The autochthonous (non-imported) cases in Puerto Rico pose a greater threat to the U.S. than cases elsewhere in the Americas because of the frequency of travel between the mainland U.S. and Puerto Rico.
The emergence of locally transmitted chikungunya cases in Puerto Rico is a cause of public health concern because of the interconnectedness between Puerto Rico and the continental U.S. The virus threatens to become introduced to the U.S. via frequent air travel between Puerto Rico and the mainland. To illustrate this frequency, consider the number of Puerto Ricans immigrating to New York City alone: the Puerto Rican population in NYC experienced an increase of 24,420 people between 2010 and 2012—an average of 235 people per week! The most vulnerable region of the U.S., however, is the southeast, due to its proximity to the Caribbean and the prevalence of Aedes aegypti mosquitoes, which have been spreading the disease throughout the Caribbean. Other regions of the U.S. that have reported imported cases are not at such a high risk for local transmission because of the absence of Aedes aegypti mosquitoes in more northern regions.
Chikungunya causes fever and severe joint pain, which explains the meaning of the name in the Kimakonde language: “to become contorted [with pain].” The disease also often causes muscle pain, headache, nausea, fatigue, and rash. Although serious complications are not common, debilitating joint pain can last for days, weeks, or even months. In older individuals, the disease may lead to death. There is no cure or vaccine for chikungunya, but treatment aims to ameliorate the symptoms. Because the disease is mosquito-borne, like dengue and malaria, communities can lessen the likelihood of an outbreak by removing any possible mosquito breeding grounds, such as plant pots and old tires filled with stagnant water.