The past week brought news that two more residents of Missouri and Kansas — one from Johnson County — have the Zika virus.
That brings to 11 the number of travelers who have returned to the two states with Zika, but that hasn’t overly alarmed state health officials.
The alarms will sound when someone actually contracts Zika from being bitten by a local mosquito.
Health officials have been monitoring Zika’s progress north, but the danger of contracting the virus has remained much lower in the U.S. than in places such as Brazil or Puerto Rico.
Area health agencies have continued to prepare for a confirmed local Zika transmission — a mosquito biting a sick person, becoming infected with Zika and spreading the disease to another person.
With the case in Johnson County announced Saturday, Kansas has now counted four people who have contracted Zika, said Cassie Sparks, spokeswoman for the Kansas Department of Health and Environment.
Last week, a Missouri woman became the seventh in the state to be diagnosed with Zika, according to the Missouri Department of Health and Senior Services.
Lougene Marsh, director of the Johnson County Department of Health and Environment, emphasized the importance of people returning from Zika-affected areas “to exercise extreme caution to avoid being bitten by a mosquito. (A bite is) the only way we’ll begin to see local transmission.”
So far, Zika has only been found in the U.S. in people who brought back the virus after contracting it on their travels.
“That does put the risk not at zero, but very, very low,” Marsh said.
The Centers for Disease Control and Prevention has outlined a draft response to Zika with five different levels of risk.
There’s a Mosquito Season phase that includes infections from travel or sex, which is where Missouri and Kansas would be, near the lower end of the scale. The risk level would go up once there’s a confirmed local transmission, and it would further elevate if Zika started to continuously spread across the country.
The CDC has taken the lead on publishing preparedness measures. That doesn’t mean area agencies have been idle.
The CDC has encouraged states to come up with their own plans, and Sparks said the Kansas health department was developing one, along with monitoring for instances of local transmission.
The Johnson County health department has enlisted zoologist Christopher Rogers to perform mosquito surveillance for the Aedes mosquito, the type known to carry Zika, Marsh said. Marsh said she expected to know in about a month to what extent the Zika-carrying mosquitoes are present in the county.
The range of potential Zika carriers has been estimated by the CDC to include Kansas City and parts of eastern Kansas and western Missouri.
Ellen Dorshow-Gordon, an epidemiologist with the Jackson County Health Department, said larvicide application was planned for public property in parts of eastern Jackson County. Larvicide targets young mosquitos, which hatch in standing water.
“Offense is a good defense to try to prevent mosquitoes from breeding,” Dorshow-Gordon said.
She said health agencies in the area were getting the same information from the CDC, which has assembled a wealth of Zika-related data and information.
“We are on the alert,” Dorshow-Gordon said. “If I got a case that looked like local transmission, I have a system where I can contact other health departments in the region to let them know that I think I have a case.”
A vaccine for Zika has not been developed — although a vaccine trial with human volunteers has been approved — and there is no medicine to treat it. To complicate matters, most people with the virus don’t show symptoms.
The best way to avoid the virus is by avoiding being bitten by a mosquito — a tough task in muggy summer weather.
Health officials recommend using bug spray and wearing long-sleeved shirts and long pants, and they urge the purging of standing water by emptying buckets, birdbaths, flower pots and the like to eliminate potential mosquito breeding grounds.
While not as common as transmission through bug bites, Zika also can spread through sex and from pregnant mother to fetus, usually in the first trimester, Dorshow-Gordon said.
Marsh said that any man who returns to a partner of child-bearing age after traveling in a Zika zone should either wear a condom or practice abstinence.
The virus is believed to cause microcephaly, a neurological disorder that causes a baby’s head to be abnormally small and can lead to mental disabilities. Women who have traveled to Zika-threatened regions of the world have been cautioned to avoid pregnancy until they are tested for the virus.