Rains OK but what comes after probably won't be
Drenching downpours soaking the region likely have killed the drought for the foreseeable future, but they're giving birth to hatching swarms of mosquitoes that experts say could usher in a record year for the mosquito-borne West Nile virus.
And all the signs are there.
In the last three weeks, Harris County has confirmed three cases of this potentially deadly disease in humans. Meanwhile, officials are finding the virus in more and more birds, and infected mosquitoes are spreading quickly, despite preventive spraying. The number of Harris County ZIP codes where mosquitoes tested positive for West Nile skyrocketed from six in early June to 71 as of Tuesday.
While the number of cases of West Nile in humans is just average so far this year, Harris County's mosquito control director Dr. Rudy Bueno is concerned by an unusual spike in bird deaths from the same virus.
"We're finding more dead birds, in particular blue jays," he said. "They're the sentinels. Once they start to die, it's a red flag. That means the virus activity is pretty high."
Bird deaths recently were recorded in six Harris County ZIP codes: 77040, 77055, 77065, 77345, 77449 and 77493.
When this virus, which originated in the West Nile valley of Uganda, was introduced into this area about 10 years ago, it killed many birds that had not yet built up immunities. But since then, Bueno said, bird deaths have been declining.
"Yet this year, the numbers are increasing again," Bueno said. West Nile initially infects birds, which then are bitten by mosquitoes that in turn infect humans.
22 deaths over decade
In the last decade, the virus has been linked to 22 deaths and 367 confirmed cases in Harris County alone.
This year's unidentified victims, who were hospitalized in serious condition and are now recovering at home, include a northwest Harris County man, age 15 to 24; a west Harris County woman, age 45 to 55; and a northeast Houston woman, age 55 to 74.
Infected mosquitoes also have been found in Fort Bend, Brazoria and Montgomery counties but no human cases. The state health department reports tests have confirmed 19 individuals have contracted the virus in North Texas.
"We're definitely seeing an uptick in activity," Bueno said. "When there's more water, that equals more mosquitoes."
The Culex mosquito - one of 56 species in the Houston area - is the primary carrier of the virus and needs stagnant water to hatch its eggs.
"The dirtier the better," said Sandy Kachur, Harris County public health spokeswoman, noting the insect can find water to reproduce in anything from a clogged gutter to a saucer under a flowerpot.
In the last week, Harris County has had plenty of standing water for breeding, especially on the northwest side, which was hit with 15 inches of rain and saw 50 to 100 homes flooded, said Kim Jackson, Harris County Flood Control spokeswoman.
Bueno said about 95 percent of the mosquitoes being caught in his traps are Culex and as many as a quarter of them can test positive for the virus.
So when outdoors, especially during twilight hours when mosquitoes are most active, wear repellent, authorities say.
Luckily, only about 1 percent of those infected with the virus have serious health effects; many experience only mild flu-like symptoms or no symptoms at all. A severe reaction can result in brain inflammation, coma and sometimes death.
Meanwhile, every Sunday through Thursday, if it's not raining, Kachur said, spray trucks are being dispatched to target hot spots where the virus has been detected.
To see where the West Nile virus is being found in mosquitoes in Harris County, visit http://hcphes.org/mc and click on "current disease activity."