Dengue fever and chikungunya are transmitted by the same mosquitoes (Aedes aegypti and Aedes albopictus) and both vectors are found in the Western hemisphere, or the Americas. However, until Dec. 2013, only dengue fever flourished in this part of the world.
In December 2013, all that changed when the first autochthonous, or locally acquired chikungunya cases were reported on the Caribbean island of St. Martin. Local transmission means that mosquitoes in a particular area have been infected with chikungunya and are spreading it to people.
The arrival of locally acquired chikungunya came as no surprise to the experts at the Centers for Disease Control and Prevention (CDC) or the Pan American Health Organization (PAHO). Several years ago, the agencies collaborated to publish the Preparedness and Response for Chikungunya Virus Introduction in the Americas. The guidelines are designed to help countries in the Western Hemisphere improve their ability to detect the virus and be prepared to monitor, prevent, and control the disease, should it appear.
According to the authors of the guidelines, “The broad distribution of mosquitoes capable of spreading chikungunya virus, coupled with the fact that people in the Americas have not been exposed to chikungunya virus, places this region at risk for the introduction and spread of the virus.”
Chikungunya did in fact appear and more than one million locally acquired cases were reported in 2014. In the latest PAHO chikungunya tally dated Dec. 29, a total of 1,071,696 suspected and confirmed cases were seen in the Western hemisphere (There will likely be more cases added to the total as not all countries are completely up to date in their numbers).
Countries hit especially hard by the mosquito borne virus include the Dominican Republic (524,297 cases), El Salvador (135,226) and Colombia (74,150). 169 deaths from chikungunya were recorded with half from the island of Martinique.
In 2014, the number of dengue fever cases dropped from the previous year’s numbers; however, still more than 1.1 million cases were reported according to the latest PAHO data Dec. 29.
Brazil recorded by far the most cases with 575,000 suspected and confirmed dengue cases. Other countries reporting more than 100,000 cases include Colombia and Mexico. The number of dengue-related fatalities in the Americas were 641, roughly one-half the total deaths in 2013.
In the United States, more than 2,000 imported chikungunya cases were reported to the CDC as of Dec. 16. This compares to the eight year average prior to 2014 of 28 imported cases annually, mostly from Asia. There were 11 locally acquired chikungunya cases reported in the US, all in the state of Florida.
On the other hand, the number of dengue fever cases in the US dropped in 2014 to 389 cases. In 2013 there were 543 cases, all confirmed.
In the state of Florida, there was 80 imported dengue fever cases and 437 imported chikungunya cases, according to the Florida Department of Health as of Dec. 27.
Travelers from Cuba accounted for the most imported dengue cases, while travelers from Puerto Rico accounted for the most imported chikungunya cases.
There were six locally acquired dengue fever cases in Florida, all reported from Miami-Dade County.
Chikungunya is a viral disease transmitted by the bite of infected mosquitoes such as Aedes aegypti and Aedes albopictus. It can cause high fever, join and muscle pain, and headache. Chikungunya does not often result in death, but the joint pain may last for months or years and may become a cause of chronic pain and disability.
There is no specific treatment for chikungunya infection, nor any vaccine to prevent it. Pending the development of a new vaccine, the only effective means of prevention is to protect individuals against mosquito bites.
Dengue remains a public health problem in the Americas despite the efforts of the Member States to stop and mitigate the impact of epidemics. It is a dynamic systemic infectious disease. The infection can be asymptomatic or show with a broad clinical spectrum that includes serious and non-serious ways of expression.
After incubation, the disease begins abruptly and goes through three phases: The febrile, critical, and recovery stage. Dengue needs to be addressed as a single disease with different clinical presentations ranging from benign conditions to severe clinical courses and outcomes that may lead to death.