Clinical Notes : Dermatology

191. Mosquito and midge bites

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What is the difference between mosquitos and midges ?

 

  • Midges don't have a biting needle (proboscis) and because of this they cannot transmit diseases. Mosquitoes do.

  • Midges fly in swarms that look like clouds. Mosquitoes don’t always fly in swarms because mosquitoes fly faster while midges fly more slowly, slower than an individual walks

  • Midges like most species of mosquitoes do not like direct sunlight; they prefer cool shady places such as front entry ways and covered back yard patios.  However, certain mosquitoes can be active in direct sun light

  • Midges and mosquitoes are both attracted to lights in the evening which draws them to homes and businesses

The commonest mosquito in Ireland is Culex pipiens. 

They can be seen hovering over water and marshy places in the late summer and early autumn, especially in the south and east of the country.

There are 29 species of midge in Ireland, including six that will bite people.

The most significant nipper is Culicodes impunctatus.

It is only the female midge that bites, doing so to extract protein from our blood, which will help develop their eggs.

 
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Culex pipiens female mosquito

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Culicoides Impunctatus midge

Culex pipiens female mosquito

Culex pipiens male mosquito 

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Culicoides Impunctatus midge

Culicoides Impunctatus midge

Culex pipiens mosquito

Culicoides Impunctatus midge

 

Mosquitos in Ireland

Mosquitoes tend to be more active around dawn and dusk, however this can vary between species.

A mosquito’s internal body clock actually kicks in at these times telling them it's feeding time.

At these times of the day, the atmosphere and wind speeds are calmer and temperatures are lower.

All in all this provides ideal conditions for mosquitoes, encouraging them to head out to find something… or someone to bite and feed on.

Irish mosquitoes have not been demonstrated to carry any human infections.

The reasons for this are:

  1. There are not enough mosquitoes in Ireland to carry infected blood. A large numbers of mosquitoes is required to sustain  spread of infection.

  2. The cold weather in winter kills off mosquitoes. At the beginning of each summer, the mosquito numbers are very small and will not grow quickly enough over the summer to produce the large numbers needed to sustain infection.

  3. In addition, there are not enough people or animals whose blood is infected. You need large numbers of infected animals or birds or people to ensure that mosquitoes, when they feed, are becoming infected and carrying the virus to infect others

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Mosquito life cycle

Midges in Ireland

 

Midges live most of their lives as worm-like larvae at the bottom of water sources but every spring, If the weather is warm and there is a lot of fresh water available, they will make the transition to adults.

The midge larvae drift slowly up from the bottom and rest on the water surface to pupate and prepare to take to the sky.

As pupae, they are an excellent food source for fish, frogs, newts, and even other insects.

 

When they become adults, they lose the ability to eat or drink and will live only 3 days before they starve to death.

To maximize the chance of finding a mate in that short time, the midges will rise together in huge numbers called “mating swarms” which may be blown into shore to rest on buildings, windows, or plants.

 

They are particularly attracted to light sources such as porches with lights.

The swarms will die out in just a few weeks and in the meantime, they’re a very good source of food for the babies of local birds.

 

Swarm of midges

Swarm of midges

Clinical presentation

Sensitivity to both mosquito and midge mosquito bites varies with individuals, most people have only a mild reaction but others can have severe symptoms from the saliva of mosquitoes.

 

Typical symptoms include swelling, redness and irritation at the puncture site.

 

If the bites are scratched or traumatized, they may become infected with bacteria and a secondary infection can be initiated,

especially on the lower limbs.

 
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Treatment 

Treatment advice for mosquito and midge bites includes :

  • Avoid scratching.

    • I know it’s a tough thing to do, but scratching provides only temporary relief and scratching too much can result in breaking the skin.

    • Once you break the skin you may start bleeding and you run the risk of an infection.

 

  • Use lotion.

    • There are a few anti-itch lotions on the market that might help alleviate the itching of the common mosquito bite.

    • The most effective lotions contain one or more of these ingredients: calamine, diphenhydramine (Benadryl), or hydro-cortisone.

 

  • Cold compresses.Ice packs may help alleviate itching.

    • The ice constricts blood vessels in the area, which blocks blood flow to and from the bite.

    • Whenever you use ice for anything, only keep the ice on for about 15 minutes and don’t put ice or bags containing ice directly on the skin.

    • Putting ice on the skin for too long can result in frostbite

  • Homemade paste.

    • You can make your own topical paste using meat tenderizer containing papain or using baking soda.

    • Mix the powdered tenderizer or the baking soda with water to make a paste.

    • Apply it liberally (meaning plenty of it) on your bite and re-apply often until the itching subsides.

 

  • Oral antihistamines.

    • If you have serious allergic reactions to mosquito bites or you have a lot of bites, you might try oral antihistamines containing diphenhydramine, chlorpheniramine maleate, loratadine or cetirizine.

    • Which of these works best for you will take a little trial and error to figure out.

  • Antibiotics

    • Antibiotics are not necessary for mosquito and midge bites, unless the skin has become infected.

    • Bites do not become infected unless scratched.

    • Signs of infection include

      • induration (the skin becomes tense and stiff)

      • heat (the rash is hot to touch)

      • you may feel unwell (malaise) or feverish (raised temperature)

    • see your GP if you suspect the bites have become infected

Prevention 

The risk of being bitten by mosquitos and/or midges can be reduced by :

  • Consider timing.

    • Dawn and dusk are when mosquitoes really are out in force and much more likely to bite.

    • If possible, avoid being out at those times.

  • Use repellents

    • There are several types of mosquito repellent available on the market, but DEET has been shown to be the most effective.

  • Wear proper clothing.

    • Wear long sleeves and treat the clothing with repellent as well.

    • Permethrin is a repellent made for clothing that should never be applied directly to the skin.

  • Get rid of standing water.

    • Mosquitoes breed in stagnant water, so getting rid of any buckets, puddles or untreated pools will help cut down on mosquitoes and midges in your area.

 

  • Install or fix your window screens.

    • This becomes more important if your house is located near water

 
 
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Mosquitos

Department of Medical Entomology, University of Westmead Hospital, Australia

Access

Mosquito Bites: Treat Itching and Recognize Infections

Nicola Leach

Alliance Work Partners

Online February 2020

Access

Mosquito Info

The American Mosquito Control Association

Online February 2020

Access

Mosquitoes Factsheet

Health Service Executive, Ireland

Health Protection Surveillance Centre

Online February 2020

Access

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