This article is more than 5 years old. Information may no longer be current.
Chikungunya threatens to spread in Americas
Researchers warn that chikungunya virus has great potential to become a severe epidemic in the Americas — including in the United States — based on new data published in the Journal of Virology.
“Until recently, the Americas have never reported chikungunya autochthonous transmission despite its global expansion beginning in 2004 …” Ricardo Lourenço-de-Oliveira, PhD, of the Institut Pasteur in France, and colleagues wrote. “The risk of [chikungunya] spreading throughout the tropical, subtropical and even temperate regions of the Americas is more than ever a reality. In light of our results, local authorities should immediately pursue and reinforce epidemiological and entomological surveillance to avoid a severe epidemic.”
Lourenço-de-Oliveira and colleagues assessed the vector competence of 35 populations of Aedes aegypti (n=22) and A. albopictus (n=13), collected from 10 countries across the Americas, from Buenos Aires to as far north as Tyson, Mo. The species A. aegypti are common in the Caribbean, Central and South America and in warmer areas of the United States, and A. albopictus mosquitos infest numerous US states.
The researchers fed the mosquitos blood meal infected with three chikungunya genotypes belonging to two distinct lineages (Asian and East-Central-South African), assessing the vectors’ ability to disseminate and transmit the virus to humans at 7 and 10 days post-infection.
Although there was some variation in the mosquitos’ ability to transmit infection — even among members of the same species — all 35 populations of both mosquito species were susceptible to all three genotypes, suggesting that even temperate regions of the Americas are at risk. Rates of efficiency to transmit the virus reached as high as 83.3% in A. aegypti and 96.7% in A. albopictus.
Furthermore, the researchers found 56.7% of A. albopictus from Tyson, Mo., and 83.3% of A. aegypti from Salto, Uruguay, were able to effectively transmit the virus.
“Therefore, the establishment of [chikungunya] in temperate American countries is not simply a fiction even if less than 30% of both mosquito species collected in the south of United States were able to transmit” infection, according to the researchers.
In November, indigenous cases of chikungunya were identified on the French side of the Caribbean island of St. Martin. Since then, thousands of cases have been reported from numerous other Caribbean locations, including the Dutch side of St. Maarten, Martinique, Guadeloupe, St. Barthélemy, British Virgin Islands, Dominica and Anguilla. In December, cases also emerged in French Guiana, the first time the disease was reported in South America.
“Thus, the risk of [chikungunya] spread and establishment is real and should concern all areas in the Americas where the vector mosquitoes are present,” the researchers said.
Disclosure: The researchers report no relevant financial disclosures.
Perspective
Back to Top
It is no surprise that our Western Hemisphere mosquitoes are competent just like their Eastern Hemisphere cousins in transmitting the chikungunya virus. Chikungunya virus is well established in many of the Caribbean islands. As a result of the distribution of Aedes aegypti and A. albopictus mosquito vectors, chikungunya virus infection will probably spread to areas of South America (other than French Guiana, where it has already spread), Central America and, perhaps, North America. Dengue fever carried by the same mosquitoes occurs throughout Central and South America and has caused outbreaks in recent years in Florida and Texas.
It is important to note that while dengue fever can cause severe life-threatening disease in a proportion of patients in the form of dengue hemorrhagic fever, chikungunya is more of a nuisance disease and almost never causes life-threatening illness.