The Lipscomb Lowdown: Personal awareness helps lessen risk of West Nile virus
By Kim Chaudoin on 9/20/2012
As the hot, humid days of summer slowly fade into fall, one family of very small insects is causing quite a commotion.
In recent weeks, West Nile virus has made a resurgence in many parts of the U.S. and has been the focus of much media attention. At the center of this frenzy is a variety of mosquitos that carry and transmit the virus to humans.
As of last week, 48 states have reported West Nile virus infections in people, birds or mosquitos, according to the Center for Disease Control (CDC). Nearly 2,640 cases in people, including 118 deaths, have been reported to the CDC this year, which is the highest number of cases reported through this time period since 2003.
Although West Nile virus does not generally cause a fatal illness, it is one that concerns many communities.
Disease ecologist James English said recent weather patterns have likely led to this year’s increased West Nile virus presence.
“This time of year is the typical West Nile virus season,” said English, associate professor and academic director for Lipscomb University’s Institute for Sustainable Practice. “In the winter, the mosquito population usually decreases because of the cold weather. But, when you experience a mild winter as much of the country did earlier this year, the mosquito levels start out the season higher because they survived the winter at greater rates. Plus, if rain events allow standing water to occur at the right times of the year, and if temperatures are high during the summer, mosquitoes will breed in even greater numbers than usual. Weather events this year seem to have been just right for this outbreak.”
Increased outbreaks of the disease could persist as weather patterns continue to change throughout the country.
“As climates change, we can expect to see outbreaks of diseases where they haven’t occurred before, this is true for diseases in general, not just West Nile virus” he said. “For example, in a single location, you may have the same amount of rain from one year to the next, but if that rain comes in fewer rain events – but more at any one time, it could lead to the presence of more standing, stagnant water. As difficult as it is to understand how climates are changing, it’s even more difficult to predict how diseases will respond to those changes.”
Mosquitos need just a small amount of standing water to breed and can find ideal breeding areas in places such as clogged gutters, flower pots and children’s pools. Mosquitos typically live for about a month but may breed several times during their lifespans, he said.
English has studied West Nile virus since he developed and directed the United States Navy’s West Nile Virus Program in 2001-2002. After studying the ecology of West Nile virus, English developed a response plan for decreasing the risk of contracting the disease. He worked with military personnel as well as county and state-level public health officials to design and implement response plans.
English said there are several common misconceptions about the disease. Though West Nile virus can affect people of all age groups, only about 1% of those getting the virus will get seriously ill; people over the age of about 50, and those with already compromised immune systems seem to be more likely to become ill from the virus, he said. And, regardless of age, those with a large number of mosquito bites will have a greater chance to get the disease, just because they have more chance to get the virus, he said.
“It’s interesting, there is some percentage of the population already naturally inoculated to the disease because they have had it and don’t know it – they got the virus through a mosquito bite, maybe they felt a little run down for a day or so, but never even knew they had the virus and they’ll never get sick from it again. Spraying pesticides is also not as effective as we would like to think and you run the risk of killing harmless or beneficial insects in the process,” said English, who also directed the Navy’s medical informatics department and was office-in-charge of environmental issues such as disease ecology and control including acute and chronic air-soil-biological-chemical-nuclear hazards in Iraq during Operation Iraqi Freedom.
English said the best way to control the spread of the disease is for individuals to reduce the risk factors around them and to be proactive in protecting themselves. He encourages people to reduce the amount of standing water around their yards by emptying flower pots, buckets, pools, gutters or other common items where water collects, thus reducing the number of breeding options for mosquitoes.
“If you are getting attacked by mosquitoes, their breeding place is probably nearby. Look for standing water and get rid of it,” he said. “If you’re getting eaten up by mosquitoes in your yard, you or your neighbor probably have something in the yard that is a good breeding ground. Mosquitos only travel about a mile or so from where they are born. They don’t usually travel that far.”
English also suggests limiting outside activity at dusk and dawn, key times for mosquito activity, and wearing long sleeves, pants and insect repellant to reduce the risk of being bitten by mosquitoes.
Since the disease’s first appearance in the United States in 1999, more than 30,000 people in this country have been reported as getting sick from West Nile virus, according to the CDC. English said birds — particularly crows — are the main harbor of the disease in the U.S. A species of mosquito feeds on the birds, becoming a carrier of the virus. These mosquitos feed on other birds spreading it around in bird populations and then occasionally bite humans, spreading the virus to people.
According to the CDC, symptoms of West Nile virus vary from severe symptoms, such as high fever, disorientation and numbness, to milder symptoms such as fever, body aches, nausea and skin rash. Approximately 80 percent of those who are infected with West Nile virus will not exhibit any symptoms, and only a very few will become seriously ill.
English said that although West Nile virus can be serious in some cases, it is important to keep its impact in perspective.
“West Nile virus is not the most dangerous thing we face in our daily lives,” he said. “It’s true that this is an unusually bad year, but the odds of contracting the disease and dying from it are still much lower than dying in a traffic accident. And, there is a lot you can do to help keep areas free of mosquito breeding areas.”