Mosquito Season and West Nile Virus, Are You Protected?

As I was driving across the state to Easter dinner with my family, I was surprised to see how many bugs were plastered to my  windshield.  With the unseasonably warm weather we can see an early start to mosquito season.  In the southern states they are already beginning mosquito control measures in preparation for a particularly nasty year.  We should also be prepared for a nasty year and protect ourselves and loved ones from mosquito transmitted infection most notably West Nile virus.  Some people infected will show no symptoms, others can develop mild flu-like symptoms.  The more severe cases can result in swelling of  the brain (encephalitis) and meningitis (swelling around the brain and spinal cord) both of which can have deadly results.  Because this is a virus, our armament of antibiotics will not have any treatment value and currently we have no antivirals to treat West Nile so only supportive measures are used. 

When we can't treat an illness effectively, prevention is going to be the most important measure.  There were 33 reported cases in Michigan in 2011 which  resulted in 2 deaths. There were no reported cases in Washtenaw county but were several in the surrounding counties. 

A couple questions that come up each season are “What is the most effective repellent?” and “which repellent is safe for children?”

The gold standard for repellent is DEET  (N,N-diethyl-m-toluamide).  This chemical can be found in many products and in various concentrations.  The higher the concentration the longer the product will be effective though the effect will plateau near 50%.  Based on a 2002 study 4.75% DEET would be effective for 1 & ½ hours and 20% would afford 4 hours of protection.  This will help you select an appropriate product.  If you only plan to be outdoors for a couple hours 10% and lower would be a good choice.  For extended outdoor activity perhaps a 25% product.  This chemical has been used for over 50 years with very few adverse events reported even in children.  The American Academy of Pediatrics (AAP) recommends that DEET can be used in children over 2 months old and that 30% seems to be as safe as 10% in this group.  

Picaridin (KBR 3023) is another chemical that has demonstrated high degree of efficacy as a repellent.  This chemical is similar  in concentrations to time of protection to that of DEET.  This is sometimes preferred by some because it is less greasy and less of an odor.  The AAP does not have an official opinion on the chemical at this time but there doesn't seem to be any realistic danger to using these products in children.

Oil of Lemon of Eucalyptus is a good alternative to the above as it has similar protective effects to DEET in low concentrations. 

I would expect around 1 & ½ hours of protection so you may want to stick to 
DEET for extended outdoor activities.  Again AAP does not have an opinion on this product however the labeling suggests not for use under 3 years old. 

Permethrin is a good choice to spray on clothes for additional protection but do not apply directly to skin. 

Of course many other choices exist but how effective are they?  Many other products out there on the internet make claims which are not supported  by any peer-reviewed journal articles and are not regulated by the EPA.  I have seen various bracelets infused with citronella for sale.  The good news is the bracelet most likely will not be bitten by a mosquito but I can't say the same thing about the people wearing them. 

Citronella candles do not seem to be any more effective than regular candles unless you are completely enveloped in the smoke.  Citronella oil may be effective but for very short periods of time probably around 20 to 30 minutes. 

Other essential oils do not seem to be efficacious in most studies.  Also don't waste your money on sonic mosquito deterrents as this is just wishful thinking.

Eating cloves of garlic is sometimes recommended but is not going to repel mosquitoes. 

Additional tips:

• Apply repellent only to exposed areas of skin. 
• Wear long sleeves and pants when possible to minimize potential mosquito targets and use permethrin on clothing for additional protection particularly on thin fabrics.
• Avoid combination sunscreen/repellent products as you usually have to apply sunscreen more often.  First apply sunscreen to allow binding to skin then apply repellent if necessary.
• Young infants can be protected using proper clothing and mosquito nets.
• Apply  repellents to face by spraying on hands and rubbing on. Seems sensible but I am sure someone out there has sprayed repellent directly in their eyes.
• When returning indoors, you will want to wash off the repellent with soap and water.

I am hoping that the recent frosts will kill some of the early mosquitoes so I can enjoy a nice Mojito in peace this summer but I will be prepared for the mosquito apocalypse in any case.  


Cheers

Dr. Steven Jensen PharmD. owns Jensen's Community Pharmacy located in The Oaks plaza, where traditional and compounded prescriptions are dispensed along with a variety of over the counter products.