As the monsoon season makes its annual return, so, too, will mosquitoes — particularly the ones carrying West Nile virus. In fact, the Arizona Department of Health Services announced today that a Maricopa County man in his late 50s already has contracted the disease this year. And though he has recovered, health officials warn that this is just the start of the season, and many more people are likely to be infected.
“We never know how bad a season is going to be at the beginning,” says Dr. Rebecca Sunenshine, medical director for the Disease Control Division at the Maricopa County Department of Public Health, “but when we see one case, we can assume there are more out there.”
The number of cases “has gone up and down in the last few years, and a lot depends on the amount of rain and standing water,” says Sunenshine. 2010 was worst season for the county in recent years, with 115 reported cases and 12 deaths (166 cases and 14 fatalities were reported across the state).
Most of Arizona’s cases occur in Maricopa County because more than half of the state's population resides here, and diseases spread more easily in high-density areas. (West Nile can’t be transmitted from person-to-person, by the way.)
Before you panic, you should know that flu-like symptoms — fever, headache, body aches, joint pains, vomiting, diarrhea, or rash — occur in only 20 percent of infected people, and according to the Centers for Disease Control and Prevention, “most people with this type of West Nile virus disease recover completely, but fatigue and weakness can last for weeks or months.”
So while 80 percent of people who get bitten by an infected mosquito won’t know it, an unlucky one percent will develop what’s known as a severe case of West Nile virus. This group, which disproportionately comprises the elderly, develops serious neurologic problems like paralysis and meningitis. According to the CDC, “recovery from severe disease may take several weeks or months. Some of the neurologic effects may be permanent. About 10 percent of people who develop neurologic infection due to West Nile virus will die.”
Aside from the traditional preventative methods like bug repellent, citronella candles, and wearing long sleeves, Sunenshine cautions people to be on the lookout for standing water. “Dog dishes, empty containers, used tires,” anything that collects and holds water for at least a week “is where they like to lay eggs.”
Rain puddles and irrigation water shouldn’t be a problem, she says, because they dry within a day or two, but an un-chlorinated backyard pool is prime West Nile mosquito real estate.
The ADHS also warns citizens that they’re susceptible to other mosquito-spread diseases when they leave the state: dengue, chikungunya, yellow fever, and malaria. So while dengue has yet to be detected in Arizona mosquitoes, the ones just south of the border carry it. Sunsenshine and other health officials say it’s probably only a matter of time before it spreads north.
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In a press release from the ADHS, Director Dr. Cara Christ says that “taking a few extra precautions will not only help you protect your own health, but also the health of our entire state."
Mosquito bites are bad enough without potentially deadly viruses. So on behalf of everyone else in the state of Arizona, we ask you to take their advice and check for standing water after every rainstorm. Thanks.