Two Mosquito Species Can Transmit New Chikungunya Virus in the Americas

Yellow fever and Asian tiger mosquitoes from Florida and Brazil can transmit an Asian strain of chikungunya virus that’s emerging in North, South and Central America, a University of Florida scientist says.

The Asian strain of the virus is not currently circulating in Florida, and Barry Alto, associate professor of entomology at the UF Institute of Food and Agricultural Sciences, said that he can’t predict whether it will cause local transmission in the Sunshine State this year.

“Chikungunya is an epidemic disease in Brazil and a potential risk in Florida,” Alto said. “Our study measuring the mosquito’s ability to pass along the disease contributes to our understanding of the epidemiology of chikungunya.” 

Researchers are evaluating the ability of Florida and Brazilian mosquitoes to transmit chikungunya because the virus was transmitted in Florida as part of an outbreak throughout the Americas in 2014. That year, scientists confirmed the first case of chikungunya in Florida. Between 2014 and 2016, more than 3,800 imported human cases of chikungunya fever in Florida highlighted the risk of contracting the illness, according to a UF/IFAS study published last year.

People can get the chikungunya virus if they’re bitten by an infected yellow fever mosquito, also known as Aedes aegypti or the Asian tiger mosquito, known as Aedes albopictus, said Alto, a faculty member at the UF/IFAS Florida Medical Entomology Laboratory in Vero Beach, Florida.

Symptoms of virus infection are usually mild, including fever, rash, headache and pain and swelling in the joints. Serious, chronic musculoskeletal diseases occur in a very small percentage of cases, according to clinical studies. Those cases may last for months to years and lead to rheumatoid arthritis-like symptoms. 

In a newly published study led by Brazilian scientist Nildimar Honório of the Oswaldo Cruz Institute, Alto helped assess the ability of the two mosquito species to transmit chikungunya. Because yellow fever and Asian tiger mosquitoes are abundant in Florida and Brazil, scientists tested those species from the two areas.

In the study, researchers from Oswaldo Cruz Institute in Rio de Janeiro and UF/IFAS compared the abilities of yellow fever and Asian tiger mosquitoes from Brazil and Florida to transmit an emergent Asian strain of chikungunya virus present in North, South and Central America, Alto said.

Scientists conducted a laboratory experiment that let groups of mosquitoes eat chikungunya virus- infected blood. They later tested mosquitoes several days apart to determine how mosquito species and geographic origin may influence infection and how well the mosquitoes may be able to transmit the virus by biting a person. They did this by testing mosquito saliva for the presence of chikungunya virus. 

“Our findings suggest that mosquito-virus interactions of both these mosquito species may vary by geographic population – whether that’s in Brazil or Florida — which may impact public health measures and should be considered during outbreaks of this mosquito-borne disease,” said Honório.

The new research is published online in the journal PLOS Neglected Tropical Diseases.

Written by: Brad Buck