Thursday, 7 June 2012
How to tell the biting insects to bug off
The good news first: "For the most part, mosquitoes...are more of an annoyance than a serious problem," says Gary Simon, director of the Division of Infectious Diseases at the George Washington University School of Medicine. "Most of the infections they transmit here are serious but fortunately quite rare, like encephalitis and West Nile virus," he adds, pointing out that dengue fever, malaria and several other mosquito-borne ailments are an issue only in far-flung tropics.
Nonetheless, to counter this year's expected oversupply of blood-sucking bugs, he recommends such standard precautions as eliminating standing water around your yard that can serve as a breeding ground and regularly using DEET or proven natural repellents such as the oil of lemon eucalyptus.
The bigger concern is ticks, which pose considerable health risks, says Thomas Mather, a professor of public health entomology and director of the University of Rhode Island's Center for Vector-Borne Disease.
Feeding the problem is that more of these ticks appear to carry more disease-causing agents than in the past. That includes those that lead to Lyme disease but also lesser-known, equally serious conditions such as the malarialike babesiosis, and ehrlichiosis and anaplasmosis, both acute infections that are generally mild but can be fatal if left untreated.
Human cases of Lyme and these less common diseases have risen sharply in the past decade, as they have spread across the country, according to CDC statistics.
"Today's nymphal-stage ticks carry a range of pathogens, and they are like little stealth bombers ready to deliver their payloads of disease," says Mather. "With deer ticks, for example, current research shows that one in four or five are infected with Lyme, and most are also contaminated with more than one disease." He and other experts stress that if you see deer in or near your neighborhood, you have reason to be concerned.
Paul Beals, a physician who specializes in diagnosing and treating Lyme disease at National Integrated Health Associates in the District of Columbia, says, "We're finding that the vast majority of our patients who are getting tick bites causing Lyme are also getting other co-infections at the same time," including such febrile illnesses as bartonella, which can be transmitted by ticks and mosquitoes, as well as babesiosis and ehrlichiosis.
Mather suggests that it's time for more people to get "tick smart," particularly since the symptoms of Lyme disease and other tick-borne infections are often subtle and hard to diagnose.
"The initial bite may or may not be known, and only 10 to 20 percent of people see the bull's-eye rash for Lyme, for example," says Beals. Watch for sudden onset of symptoms such as fever, chills, chronic fatigue, joint pain and headaches that typically get worse over time.
Another complicating factor is that the lab tests used to diagnose these ailments are notoriously unreliable. "Seventy percent of the time, for people with documented Lyme disease, routine tests don't show it," Beals says.
As a result, the prevention of bites -- which starts with knowing your enemy -- is key.
"This is not a great big tick that's going to crawl to the top of your head. This is something the size of a poppy seed that crawls to your...nether regions -- and who looks there?" says Mather, who also heads the University of Rhode Island's TickEncounter Resource Center.
He suggests a daily tick check. Pay special attention to the back of your knee, your armpit area, around waistbands and underwear, and belt and bra lines.
It's essential to treat pets frequently with a reputable tick repellent.
Mather advises carefully following instructions for bug repellents. He adds that products containing DEET, which merely repel insects for a relatively short period, appear to be less effective than clothing or gear treated with permethrin, a chemical that can kill ticks and mosquitoes even after repeated laundering.
Mather co-authored a study that found that summer-weight clothing treated with permethrin greatly reduced the risk of tick bites: Overall, participants who donned tick-repellent garments were bitten about one-third less often as those wearing untreated clothes.
Mather coats his family's shoes with permethrin once a month: "It makes protecting yourself against tick bites -- and also mosquitoes, to some degree as well -- as easy as getting dressed in the morning."