Credit CDC
# 8322
Earlier this week, in COCA Call On Chikungunya – Feb 18th, I blogged on the CDC’s efforts to inform clinicians of the recent arrival of the Chikungunya virus to the Americas. Those who missed it can find additional information on that webinar HERE.
Until a decade ago, Chikungunya (aka `Chik’) was only found in parts of central Africa, and then only occasionally sparked small outbreaks.
In 2005, however, it jumped to Reunion Island in the Indian Ocean, where it sparked a major epidemic. Since then it has spread rapidly to counties such as India, Thailand, Vietnam, Indonesia, Myanmar, Pakistan, and others in Asia and the Western Pacific.
Quite famously, Chik was carried by an international traveler from India to Northern Italy in 2007, where it sparked a local outbreak involving roughly 300 people (see It's A Smaller World After All).
While that outbreak was eventually contained, that introduction of the virus to Italy showed that Europe and the Americas were vulnerable to the importation of the virus, prompting the CDC & PAHO to publish a document in 2011 called Preparedness and Response for Chikungunya Virus Introduction in the Americas.
As predicted, the virus showed up last November (see WHO: Chikungunya In Caribbean – French Part of St. Martins), and since then has spread rapidly between the Leeward and Windward Islands, and has now appeared on the South American continent.
Today, the ECDC provides the following Epidemiological update, indicating nearly 6,000 suspected infections have been reported since the fall.
21 Feb 2014
An outbreak of chikungunya in the Caribbean region was reported from the French part of the island of Saint Martin on 6 December 2013. It is the first time that autochthonous transmission of the virus has been documented in the Americas.
An ECDC risk assessment of the outbreak published on 12 December 2013 concluded that the risk of the disease spreading to other islands in the Caribbean region was high. Since then, autochthonous transmission of chikungunya has been reported from several islands in the Caribbean and recently for the first time in South America (French Guiana).
As of 21 February 2014, more than 5 900 suspected cases have been reported in the following locations:
Caribbean:
- Saint Martin (FR): 1 780 suspect cases
- Sint Maarten (NL): 65 confirmed cases
- Saint Barthélemy: 350 suspect cases
- Martinique: 3 030 suspect cases
- Guadeloupe: 1 380 suspect cases
- British Virgin Islands, Jost Van Dyke islands: 5 confirmed cases;
- Dominica: 45 confirmed cases including one imported case
- Anguilla: 5 confirmed cases including one imported case;
- Island Aruba: one confirmed imported case
- Saint Kitts & Nevis: one confirmed case
South America:
- French Guiana: 7 confirmed/probable cases including 2 autochthonous cases and 5 imported cases.
This overview indicates that the chikungunya outbreak in the Caribbean is still ongoing and reaching now South America.
The chikungunya transmission was detected during a concomitant dengue outbreak in the Caribbean. Both arboviruses are transmitted by the same Aedes aegypti mosquito species. The naïve population, the presence of an effective vector in the region and the movement of people in and between islands and territories are factors that make it likely that the outbreak will continue to spread geographically and increase in numbers.
The conclusions and recommendations of the rapid risk assessment published on 12 December 2013 remain valid.
Clinicians and travel medicine clinics should remain vigilant regarding imported dengue and chikungunya cases from the Caribbean and French Guiana.
As with West Nile Virus, Malaria, and Dengue fever – the mosquito vectors for spreading Chikungunya are abundant across much of the United States.
Although we’ve seen sporadic cases of viremic CHKV infected travelers to the United States in the past (see 2011 CID Journal report Chikungunya Fever in the United States: A Fifteen Year Review of Cases), those numbers have been small (109 between 1995- 2009), and so far (unlike dengue and WNV), we haven’t seen any evidence of local transmission.
But with CHKV now in the Americas, the number of CHKV infected travelers to the United States may well increase, and any who are viremic (producing large quantities virus in their blood) while visiting regions where suitable mosquito vectors are present, could potentially introduce the virus to the local mosquito population.
