When it comes to how susceptible a mosquito is to becoming infected with, and transmitting, chikungunya virus, not all mosquitos are the same. The interactions between mosquitos and the virus vary not only based on species and strain, but where the mosquitos come from, researchers report in PLOS Neglected Tropical Diseases.
Chikungunya virus (CHIKV), which causes fever and severe joint pain, occurs mostly in Africa, Asia and India. But between 2014 and 2016, more than 3,800 cases were diagnosed in Florida—mostly in individuals who had traveled to South and Central America and the Caribbean. Scientists have speculated that local transmission of CHIKV could occur within the US, particularly in Florida and Texas.
In the new work, Barry Alto, of the University of Florida, USA, and colleagues studied the susceptibility of mosquitos local to Florida and the Dominican Republic to catching and spreading CHIKV. They used local populations of both Aedes aegypti and Aedes albopictus mosquitos and two lineages of CHIKV—the Indian Ocean (IOC) and Asian (AC) genotypes. Mosquitos ingested infected blood and the researchers tracked the dissemination of the infection throughout the mosquitos’ bodies and saliva.
All the examined populations of Ae. aegypti and Ae. albopictus were susceptible to infection of both CHIKV lineages and could transmit the viruses through their saliva. However, differences were seen between populations of mosquitos—for instance, Ae. albopictus had higher disseminated infection and transmission of IOC soon after ingesting the virus, but Ae. aegypti had more infection and transmission of AC later in infection. In addition, both species of mosquitos from the Dominican Republic had lower viral dissemination and transmission rates than the mosquitos from Florida, and rates varied even between mosquitos from different areas of Florida.
“In the current study, we have identified variation in vector competence on a smaller scale than previously recognized,” the researchers say. “As similar variation may occur in other mosquito species, our results highlight the need for detailed investigations of vector competence across species and populations in different regions.”
Image Credit: University of Florida / IFAS-FMEL / Jim Newman
Reference: Alto BW, Wiggins K, Eastmond B, Velez D, Lounibos LP, Lord CC (2017) Transmission risk of two chikungunya lineages by invasive mosquito vectors from Florida and the Dominican Republic. PLoS Negl Trop Dis 11(7): e0005724. https://doi.org/10.1371/journal.pntd.0005724