Mosquito bites may be a nuisance, but fortunately, in the U.S., they tend to amount to nothing more than that. Upon being bitten, most Americans experience a bit of swelling and itchiness, and nothing more. However, there are exceptions to this, including stronger allergic reactions to bites and cases of mosquito-borne illness.
Insect and arachnid bites, including ticks, account for approximately 2,000 cases of malaria and 30,000 cases of Lyme disease in the U.S. annually. In addition, millions of people worldwide die of malaria each year. It is helpful to protect yourself against insect bites, not only to avoid pesky welts but also to prevent potential illness.
It may sound surprising that both male and female mosquitoes obtain the majority of their nutrition from plant nectar. It is the pregnant females that require blood from a mammal in order to synthesize the protein they need to help their eggs mature. These eggs are then laid on the surface of still water, such as ponds or birdbaths, as they wait to hatch.
Itchy, Bumpy Bites
Infants and children are bitten by mosquitoes more than by any other insect. In fact, mosquitoes tend to prefer children over adults if they have the choice. When a mosquito lands and prepares to feed, the sharp, needle-like components of its mouth pierce the skin, first injecting digestive enzymes and anticoagulants before drawing blood.
Often, the first mosquito bites a child receives produce no reaction at all. Experiencing more bites over time causes an increase in sensitivity. While nothing may appear on the skin at the time of the bite, small, itchy red bumps generally appear about 24 hours later. With time, older children and teens will likely find a pale, swollen hive or wheal immediately after being bitten, followed by the appearance of requisite red bumps within 24 hours.
Symptoms of Allergy
Sensitivity to mosquito bites either increases or decreases with age. For those with more severe reactions to mosquito bites, an allergy is a result of increased exposure. Blistering, bruising, and major inflammatory responses are rare but can happen. Such children may start to develop these symptoms between ages 2-4 but typically outgrow them within a few years. Children living farther north, in places such as Alaska, Canada and Scandinavia may take a few extra years to outgrow the allergy, as summer, and therefore mosquito, seasons are shorter in those locations. While we discuss ways to prevent and treat mosquito bites below, the best treatment for children with severe allergic responses is to avoid being bitten altogether.
Mosquito Bite Protection and Prevention
Mosquitoes are attracted to things that remind them either of nectar or mammal flesh. It is helpful to wear lightweight clothing that covers most of the body, keeping skin and hair covered as much as is practical. Avoiding bright, floral colors and instead opting for a neutral palette helps as well. Mosquitoes are less attracted to muted colors such as khaki, beige, and olive.
They also tend to prefer the body odor of some people over others. Avoiding perfumes and fragrances in soaps, shampoo and lotion will lessen your similarity to tasty flowers nearby.
Most, but not all, species of mosquitoes are more active at night, with the hours around dawn and dusk accounting for the highest rate of activity. They also appear more often in seasons of heat and humidity, near still water and in large, grassy areas. It’s best to stay inside when they’re most active to avoid being bitten. Individuals who are highly allergic should take a non-sedating antihistamine (such as loratadine, or Claritin) before potential exposure, and avoid vacationing in areas like the Everglades.
In addition, keep an eye out for anywhere around your property that may hold standing water, and do your best to keep it drained. Such areas may include:
- Outdoor pet dishes
- Flowerpot saucers
- Wheelbarrows and buckets
- Old tires
- Wading pools and swimming pools
- Trashcans, recycling bins, and trash lids
- Puddles and ditches in your yard or driveway
Treat and Prevent Mosquito Bites
Physical barriers, such as well maintained window screens can help reduce mosquito exposure. The use of bed netting may be necessary when traveling to areas with high mosquito populations. Mosquito netting is also helpful over strollers and beds when sleeping outdoors.
Bugs, Be Gone: Insect Repellents
Mosquito repellents are commonly used to prevent bites and subsequent itching. In addition, the Center for Disease Control (CDC) endorses the use of insect repellent in order to minimize the spread of illness. For children 10 years of age and below, it’s best to apply lotions and sprays for them so they are less likely to get it into their eyes and mouths. Apply the repellent to your hands, then rub it onto their skin, being sensitive around the face. Don’t apply insect repellent to a child’s hands if they frequently put their hands in their mouths. Citronella candles are also beneficial when placed outside around the home in the evening, helping to keep mosquitoes at bay.
Studies have shown that topical insect repellents containing DEET (N,N-diethyl-meta-toluamide), picaridin, or essential oil of lemon eucalyptus to be the most effective in warding off mosquitoes for the greatest period of time. The following are some things to consider when choosing the best repellent for your family.
DEET – DEET was developed in 1944 for use by the U.S. Army, then made its way into agriculture as a pesticide. The EPA rates DEET as Category III, or “slightly toxic” to acute oral and dermal exposure. Indeed, it is recommended that DEET-containing products be washed off the skin once inside, or after the threat of insect bites has subsided. It is considered “slightly toxic” to birds, fish, and aquatic invertebrates.
If you choose to use products that contain DEET, do not apply it to babies less than two months old. It should also not be applied underneath clothing in order to minimize absorption. A 30% solution is the maximum amount of DEET that is considered safe for children and babies, but lower concentrations have not been shown to be any safer. In fact, the EPA states that the child safety claims made on some DEET products are misleading, as lower concentrations are not known to be any less harmful. The concentration of DEET refers to how long it will last, not how effective it will be when applied.
DEET is irritating to eyes and mucous membranes. It may also cause a rash on the skin. Serious but rare adverse reactions include seizures and encephalopathy, or damage to the brain. It is not safe for newborns. If you choose to use DEET products, be sure to use a separate sunscreen so that sunscreen can be reapplied as necessary. This is often at shorter intervals than is recommended to reapply DEET.
Picaridin – Picaridin, found in products such as Natrapel 8 Hour, is a synthetic product that mimics components found in black pepper. Similarly to DEET, it is a Category III, “slightly toxic” substance in acute oral and dermal exposure. In animal studies, it caused slight to minimal liver hypertrophy, individual necrotic liver cells, chronic kidney inflammation, and slight kidney degeneration when large amounts were applied to the skin on an ongoing basis. Studies found no evidence of picaridin to be an endocrine disruptor or carcinogen. It is non-toxic to birds and moderately toxic to fish.
Like DEET, if you choose to use a product containing picaridin, only apply it to exposed areas of skin and not under clothing to minimize absorption. It is also best to keep it out of the eyes and mouth, and off of the hands of small children if they frequently put their hands in their mouths.
Lemon Eucalyptus – The essential oil of lemon eucalyptus, or Eucalyptus citriodora, smells surprisingly similar to citronella. While a dilution of it may need to be reapplied more frequently than the options above, lemon eucalyptus is considered the safest option according to the EPA. It is considered Category IV, or “practically nontoxic” for acute oral and dermal exposure. There is minimum to no risk for wildlife and the environment, and it is not believed to pose a health risk to humans, including children, those who are pregnant, or other sensitive populations.
Products containing lemon eucalyptus work just as well as DEET in preventing mosquito bites, but need to be applied every 2-5 hours. It has not yet been tested on children under 3 years of age. It is best to avoid getting any type of essential oil in the eyes. An easy preparation can be made at home by placing 25-35 drops of organic lemon eucalyptus essential oil in a 2-ounce spray bottle, filling it nearly to the top with water, and topping it off with rubbing alcohol, witch hazel or vodka to preserve it. Because it is extremely effective and virtually nontoxic, lemon eucalyptus oil is one of the best options for mosquito repellent.
Other repellents – Studies have been done on other plant oils, as well as synthetic compound IR3535, and while they prevented mosquito bites to a degree, they did not perform as well as the options listed above.
Supplements – A study was done in which subjects took 25-50mg of thiamine, or B1, three times a day. The study showed that after two weeks on this regimen, the incidents of mosquito bites dropped significantly. It is believed that the thiamine subtly changed the odor of the skin over time, making it less enticing to mosquitoes. It was especially effective for those subjects who suffered more severe reactions to bites. In contrast, subsequent studies have stated that this method has no effect on rates of mosquito bites. Studies done on the relationship between garlic intake and frequency of bites has been similarly inconclusive.
Mosquito Bite Treatment
The best treatments for mosquito bites include things that are cooling and calming to the skin. A cold compress made from an ice pack wrapped in a towel, or a cool, damp washcloth can feel very soothing to children. In addition, antihistamines may be helpful to reduce itching and swelling. Ask your pharmacist for the best antihistamine options for your child, keeping in mind that some may be available by prescription only. Another thing to consider is that some antihistamines can make children drowsy. It may be a matter of balancing the strength of the antihistamine versus its potential side effects. Zyrtec and Claritin tend to work well without causing sleepiness.
It is important to treat the bite’s itchiness as continued scratching may create an opening on the skin which can introduce bacteria and increase the risk of a secondary bacterial infection. To treat itchiness, a simple paste of baking soda and water can be applied to red, swollen bites to relieve discomfort. This may be applied several times a day. Calamine lotion also works to reduce itching, in addition to menthol lotions such as Sarna. Topical anesthetics that contain pramoxine, such as prescription PrameGel or over-the-counter Caladryl work to reduce both itching and any pain associated with the inflammation of the bite. Hydrocortisone is also considered to have a good benefit-to-risk ratio, as well as oral Benadryl.
If your child’s symptoms warrant it, anti-inflammatory medications such as ibuprofen (Motrin or Advil) or naproxen (Aleve) work to reduce redness, pain, itching, swelling, and fever. Evening primrose oil taken orally is a natural option with anti-inflammatory benefits, easily found in health food stores.
In some cases, topical steroidal cream may be appropriate, or even a systemic steroid treatment. Stronger experimental treatments include thymic hormones, recombinant gamma interferon, ultraviolet radiation, various chemotherapeutic agents, and immunotherapy with mosquito extract Cases that require such drastic measures are quite rare.
West Nile Virus
West Nile virus (WNV) was first discovered in the U.S. in 1999 in New York state. By 2002 it had spread to 39 states. Currently, 47 states have reported detection of the virus in birds, people, or mosquitoes. 958 cases of humans with West Nile virus have been reported in total to the CDC.
Symptoms of WNV include a fever, headache, body aches, skin rash, and swollen lymph glands. It is not a severe disease and is not necessarily dangerous to children or babies, other than potential temporary discomfort. In addition to mosquito bites, WNV can be passed through blood transfusions and breast milk, but again, it is not a major threat to babies.
First discovered in the Zika Forest in Uganda in 1947, Zika virus is still a threat in 2020. Zika is spread by the Aedes aegypti mosquito, the same type of mosquito that carries dengue fever and chikungunya. This type of mosquito is active in the daytime. It is spread when an infected mosquito bites a person, and subsequently, an uninfected mosquito bites a person carrying the virus.
Zika virus itself is a rather mild illness, with symptoms that may include fever, rash, conjunctivitis, muscle and joint pain, malaise or headache lasting 2-7 days. However, only 20% of carriers exhibit any symptoms at all. Blood tests are available if you think you may be infected with Zika virus. If you do experience symptoms, it’s best to get plenty of rest, drink fluids, and take over-the-counter pain medication if need be. It is also best to stay indoors during the first week of illness in order to prevent the spread of disease. While symptoms of the virus are not severe, the greater concern is the effect that it sometimes has on the babies of women who become infected during pregnancy.
In rare cases, Zika can be passed from an infected man to a woman during sex, but more often infection is the result of a mosquito bite. Zika infection in pregnant mothers can be passed to the child during pregnancy or at birth. In some instances, Zika infection causes babies to be born with microcephaly, causing them to have a smaller head than normal. In some cases having a smaller head is the extent of the condition, however, microcephaly can cause other complications, including hearing or vision problems, intellectual disability, and difficulties in brain development. It has also been linked to Guillain-Barré syndrome, which causes muscle weakness and temporary paralysis in more severe cases.
Zika has been detected in breast milk but appears to be deactivated by the acid present in the baby’s stomach. It is not considered dangerous to continue breastfeeding if you have the virus; this has not been known to cause infection in babies. If a baby gets Zika virus by way of a mosquito bite, they may experience mild symptoms similar to what anyone else might experience, but there is no danger of microcephaly or related complications.
If you are pregnant or planning to become pregnant, avoid all travel in areas affected by the virus. If you’ve already traveled in those areas, or you have a male partner who has, consult a doctor, especially if either of you develop a rash or other symptoms within 2 weeks of travel. It is best for both men and women to wait 6 months after traveling in Zika-affected areas to try for pregnancy, even with a blood test that reports negative for Zika. While there are currently no reports of Zika transmission within the continental U.S., it may be helpful to use a bug spray labeled safe by the EPA for pregnancy and breastfeeding.
It is possible for mosquito bites to become infected, but usually, the only way to tell is if the bite is not healing on schedule, typically 3-10 days, or if there are other symptoms such as a fever or drainage from the site. Typically infections in mosquito bites are not severe and do not require antibiotics.
A Vital Place on the Food Chain
While it may be tempting to complain that mosquitoes are nothing more than blood-sucking pests, they do, in fact, occupy a vital place in the food chain, as all animals and insects do. Certain species of fish in the Everglades require mosquito eggs for their diet, and in turn, larger animals eat those fish. Even the most seemingly insignificant creatures play a vital role in maintaining environmental equilibrium.
As parents, our role is to effectively treat and prevent mosquito bites so our little ones can safely play outdoors.
References and Resources
Clinical Pediatric Dermatology. Saunders; 1993.
Nguyen QD et al. Insect repellents: An updated review for the clinician. J Am Acad Dermatol S0190-2018;9622(18)32824-X.
Environmental Protection Agency: Mosquito Control
Photo credit: Parinya Binsuk