More bad news on the Zika front is leaking out of Brazil. A single study of vector competence in Brazil has determined that Culex quinquefasciatus, the Southern House Mosquito may be capable of transmitting the Zika virus. Culex quinquefasciatus was fed Zika virus and the virus was observed in the salivary glands. To be an efficient vector, a virus must be able to migrate from the mosquito gut to its salivary glands and reproduce in the mosquito. People become infected when feeding mosquitoes inject saliva containing virus into the bite. This is bad news on multiple fronts. Culex quinquefasciatus has a range that extends from the tropics north to Virginia in the US. Indiana does not have Culex quinquefasciatus but we do have other Culex species. The recent report raises a new question, “Are species of Culex other than quinquefasciatus competent vectors of Zika.”
Indiana has over 20 species of Culex, some of which vector West Nile Virus. Many Culex species feed on both humans and birds. Could Zika spread to our Culex population and from there infect some bird species and create a new reservoir?
We still do not understand why Zika was confined to Africa for a long time without causing epidemics, and then became a large problem in Pacific Islands and later Brazil. One possibility is that Zika in its new geographical location has encountered new mosquito species that are better vectors. The summer mosquito season in the US threatens to get a lot more interesting.