1. HIV DOES NOT replicate in mosquitoes. Thus, mosquitoes cannot be a biological vector as they are for malaria, yellow fever, or dengue. In fact, mosquitoes digest the virus that causes AIDS.
2.There is no possibility of mechanical transmission (i.e., flying contaminated syringes); even though we all know that HIV can be transmitted by dirty needles. However, the amount of “blood” on a mosquitoes’ mouth parts is tiny compared to what is found on a “dirty” needle. Thus, the risk is proportionally smaller. Calculations based on the mechanical transmission of anthrax and Rift Valley fever virus, both of which produce very high titers in blood, unlike HIV, showed that it would take about 10,000,000 mosquitoes that first fed on a person with AIDS and then continued feeding on a susceptible person to get 1 transmission.
3.Mosquitoes are not flying hypodermic needles. Mosquitoes regurgitate saliva into the bite wound (the normal route for disease transmission) through a separate tube from that through which it imbibes blood.
DEET-based repellents have been around for more than 50 years but that hasn’t kept the folks who make these products from innovating with new fragrances, new formulations, new product types, and, best of all, products that feel nice when applied. The DEET-based repellent fragrances are pleasant to use and range from fruity to woodsy neutral scents. Unscented products have a slight alcohol odor (there’s alcohol in the formulation) until they dry on the skin. Folks who tend to be allergic to fragrances should try the unscented products.
Today’s products start out at a concentration of 5% (lasts 90 minutes or so) and range up to 100% (for approximately 10 hours of protection from bites). Pick one that matches your activity. For an outdoor family barbecue in the evenings, a 10% product is fine. It will help protect from bites for approximately 90 minutes to two hours. Products are available in aerosols, pump sprays, lotions, creams and even towelettes. These are individually packaged and are also sold in a handy plastic container that allows the towelettes to pop up one at a time. There are water resistant and water repellent products. One brand uses a microencapsulation process that helps the DEET release over time after you have applied it. Another goes on dry from an aerosol can, just as powder antiperspirants do.
For those who are in tick country, it’s important to use a product with at least a 20% concentration. Lower concentrations of all EPA-registered repellents are not effective at warding off ticks.
Most apparent repellency failures with DEET are due to misapplications, so care should be taken to apply it thoroughly (avoiding the eyes and mucous membranes) and to reapply when necessary. This is crucial to maintain the DEET vapor barrier above the skin. New polymerized 30% DEET cream formulations provide excellent protection not significantly exceeded by higher DEET concentrations. Physicians recommend that a formulation of no more than 10% DEET be used on children, but formulations of over 30% can be used in areas of high disease incidence if label directions are followed.
In April of 2005, the Centers for Disease Control and Prevention (CDC) began recommending two new active ingredients as safe, effective repellents.
The first of these is picaridin, a synthetic developed by Bayer Corporation in the 1980s. This repellent is the most widely used repellent in the world outside of the United States and is marketed as Cutter Advanced. Picaridin is odorless, has a pleasant feel and doesn’t plasticize like DEET. Studies have shown it to be as fully repellent to mosquitoes as DEET and can also be applied on infants as young as 2 months. The 15% picaridin formulation, Cutter Advanced Sport, is also an effective repellent for ticks.
The other repellent, often the choice of those wanting a natural product, is oil of lemon-eucalyptus, sold as Repel®. Repel is a 40% formulation of naturally-derived eucalyptus and has a pleasant scent and feel without any plasticizing properties. It is also effective at repelling ticks.
EPA has further registered 2 additional repellents, Metofluthrin, a spatial repellent, and a catnip formulation (not marketed as yet). Metofluthrin is currently sold as OFF! Clip-Ons, a battery-operated system that allows the metofluthrin to volatilize from a wicking substrate and utilizes the battery to blow the substance around the body, providing the protection. Efficacy studies are underway at present, so I can’t speak to its effectiveness yet in a field setting. In the laboratory, metofluthrin both repels and kills flying insects. Catnip has been noted for years as possessing repellency against mosquitoes. However, only recently has its efficacy been demonstrated to the extent it could be registered by the EPA. DuPont has engineered a catnip formulation that exhibits the traits of a commercially effective repellent and has registered the product with the EPA. A commercial version is not yet available, though. Catnip products currently available through internet suppliers do not possess an EPA registration that validates its efficacy.
Mosquito coils and Therma-cell devices can also provide some protection. Both utilize a synthetic pyrethroid insecticide that has repellent properties, but are most effective in situations of little wind, where the repellent mixture remains in place in the air column surrounding the body. The Therma-cell is a favorite among hunters.
Another option may be to obtain and wear clothing impregnated with permethrin. Marketed under the name of Insect Shield, these clothing articles employ a process of impregnating permethrin into fabric that will retain its repellency through 70 washings. The Department of Defense utilizes this process to impregnate battle dress uniforms for the operational forces in order to protect the troops from arthropod-borne diseases overseas. This method is extremely effective at repelling all flying insects in addition to ticks and mites. The EPA has registered permethrin for this use and this method of repellency is endorsed by the Centers for Disease Control and Prevention (CDC).