The two mosquitoes that can carry the Zika virus have been found in more Kansas counties, and Missouri needs to step up its mosquito surveillance, according to a new study by researchers from the Centers for Disease Control.
Six researchers examined all of the available county-level mosquito surveillance data to follow up on a study they published last year on the range of the Aedes aegypti and Aedes albopictus mosquitoes.
They found that Crawford County in southeast Kansas had to be added to the list of counties in which Aedes aegypti had been found and the Aedes albopictus had been found in another 38 Kansas counties.
“I think what this paper is telling us is how important it is state and local jurisdictions have in place these surveillance networks to detect the presence of these mosquitoes,” CDC spokesman Tom Skinner said.
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The Kansas Biological Survey stepped up its surveillance efforts last year with the help of federal grant money, expanding the number of counties it set traps in. Based in part on those results, the CDC researchers said Missouri is among the states that should be doing more, especially when it comes to the Aedes albopictus.
“Additional areas for enhanced Ae. albopictus surveillance include states such as Missouri, Georgia, and Florida that have fewer surveillance records than expected based on reported mosquito presence in surrounding states,” the study says.
“That means the conditions are probably right (in those states) for the mosquitoes and if we were looking harder for them we likely would find them,” CDC spokesman Tom Skinner said.
Larger counties with more resources are more likely to have their own mosquito surveillance programs. Aedes aegypti mosquitoes have been found in Wyandotte, Johnson, Douglas and Shawnee counties in Kansas and Aedes albopictus mosquitoes have been found throughout all of eastern Kansas and in Jackson and Clay counties in Missouri.
“If you’re finding them in one county there’s a good chance they’re in the counties next door as well,” Skinner said.
The amount of federal grant money for Zika prevention allocated to both Kansas and Missouri has been small compared to most states. That could change based on the Kansas results because the funding is based partly on risk.
The researchers emphasized that the presence of the mosquito in a certain county does not mean it’s abundant in that county and that mosquito-borne transmission of Zika has so far been extremely rare in the continental United States.
The 22 cases of Zika reported in Kansas and 37 cases in Missouri have all been travel-related. The only documented instances of mosquito-borne Zika in the continental U.S. were in Florida and Texas.
Zika is a relatively mild illness except when it occurs during pregnancy, when it can cause the birth defect microcephaly. A study of almost 1,500 pregnant women with Zika in the continental United States found that it caused birth defects in about 5 percent of cases.
Of the mosquito-borne illnesses, West Nile virus is considered much more of a threat in this region. The Kansas Department of Health and Environment is now reporting a high risk of West Nile transmission throughout the state and the virus is suspected in the death of a Jackson County boy last month.
The Missouri Department of Health and Senior Services is investigating the case and has yet to confirm whether it was West Nile-related.