Ebola may have the nation on high alert, but the deadly virus hasn't yet made its way to Arizona. With the late summer's heavy flooding, locals should be more concerned about mosquito-borne diseases, officials say, especially the West Nile virus.
"West Nile virus is here; we know it's here, and so it's a much bigger risk," says Jessica Rigler, chief of the state Department of Health Services' Bureau of Epidemiology and Disease Control.
As of Friday, Arizona has seen 75 reported cases of West Nile virus in 2014, nine of them resulting in death, Rigler says. The majority came from Maricopa County. Those numbers already are higher than last year's, which totaled 62 reported cases and six deaths.
And the potential for more cases is high.
Not all mosquitoes carry the disease. The mosquitoes that have been bugging Valley residents lately--called flood mosquitoes--typically lay eggs before flooding ever hits a region. Once water is present, their eggs quickly hatch. Flood mosquitoes have a short life cycle, so they are opportunistic pests, sucking blood during the day and night. Fortunately, they don't carry West Nile.
But the mosquitoes that do carry the virus--the Culex species--wait until flood waters have immersed a region, and then lay their eggs. Recent flooding means that the Culex mosquitoes in the Valley have only started hatching lately.
"We're going to see an uptick in coming days and weeks," Rigler says. And that could mean an uptick in West Nile infections.
West Nile spreads through the blood of an infected person or animal. When a Culex mosquito bites an infected human, bird, or other carrier, it can later transmit the virus to its next victim.
The best way to prevent infection is to prevent mosquito bites. Culex mosquitoes are small--you may not notice them until after they've taken a bite--but they prefer to feed at dusk and dawn. Rigler acknowledges that it's a tough time of year to ask Arizonans to stay inside, but she suggests at least avoiding the great outdoors during these times of day. If you can't, she suggests wearing sleeves and long pants and using DEET-containing bug repellent.
It's also important to try to keep mosquitoes where they belong: outside. If your doors and windows aren't screened, keep them shut, Rigler says.
Last, cutting off mosquitoes' access to their favorite breeding spots can help reduce their numbers. "Remove any standing water," Rigler says, including outdoor dog bowls you don't empty regularly, flowerpots that flood when it rains, or any backyard junk that might collect water. "That's where mosquitoes are laying eggs and breeding," she says.
Such preventative measures are the best defense against bites, and thus against the virus.
Interestingly, the vast majority of people carrying West Nile virus don't even know it--"80 percent of cases are asymptomatic," Rigler says--but extreme cases can lead to brain inflammation in the form of encephalitis or meningitis, and with it, death. The disease can affect anyone, but the elderly, the very young, and those with immunedeficiencies are the most susceptible.
Symptoms of infection include fever, headaches, muscle aches, body aches, and difficulty moving. Because the spectrum of symptoms is broad, it's hard to dictate exactly when a person should seek medical help. Rigler suggests consulting a doctor any time you aren't feeling yourself, and especially if you are showing any of the more serious symptoms, like aches or difficulty moving.
Unfortunately, the West Nile virus has no treatment. Healthcare providers can only offer relief for symptoms, ranging from fever- or pain-reducing medications for minor symptoms to hospitalization for more serious ones.
Because of its deadly potential, national and regional health agencies have their eye on the virus. They coordinate with local health departments, which assess how prevalent the virus is by trapping mosquito pools and testing them. "It gives an indicator of what's going on in the state," Rigler says.
This year, 282 Arizona pools were positive for the virus, an increase from years past. Last year only 213 pools were positive. And in 2012, an outbreak year, only 190 pools were positive. The science behind this testing isn't perfect--numbers can vary depending on how much testing is done and where--but the monitoring is still considered a crucial preventative measure. Coupled with surveillance of human infection rates, mosquito trapping allows local health departments to identify hot spots and warn the public about dangerous areas.
Such public messaging --"fighting the bite", they call it--is the health department's biggest work around West Nile Virus.
And public messaging is important, as West Nile virus is a relatively new phenomenon. It first appeared in the United States in 1999, and didn't make its way to Arizona until 2003. The state's largest outbreak was in 2004, which saw 391 reported cases. The state saw a second, smaller outbreak in 2012, with 135 cases and 7 deaths. The majority of cases take place in Maricopa County, largely because of its population size.
Simply put, it's a lot more likely that you'll come into contact with West Nile virus than Ebola here in the Valley. So instead of having another Ebola freak-out, avoid being outside at dusk and dawn, put on some bug spray, and get to cleaning out the backyard.
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