Adult and child fly bite

Dipterology, which studies flies, has described almost 120 thousand species of these insects, and some of them can bite a person. In most cases, a fly bite causes only a slight skin irritation, but some species carry pathogens, including dangerous ones. It all depends on what kind of fly bit you.

Although it is difficult to determine the type of insect, especially if you have not seen it. And then complaints about the bite of a triangle fly or striped…

Which flies can bite humans and which cannot, and why?

Flies belong to the suborder Brachycera (short-whiskered) of the order Diptera (two-winged), which includes more than a hundred families. Some of its representatives are parasites in the larval stage, but adult individuals - carrion flies and blowflies of the families Calliphora and Coprosarcophaga (or Sarcophagidae) - are not parasites, but can be mechanical carriers of various pathogenic organisms. At the same time, the mechanical transmission of microbes by flies, whose diet does not include the blood of warm-blooded animals, is not associated with bites.

Thus, the housefly (Musca domestica) does not bite humans; bites from the raspberry fly (the long-horned stem gall midge, Drosophila suzukii of the suborder Sophophora or the fruit fly belonging to the family Tephritidae) are impossible. [ 1 ], [ 2 ], [ 3 ] The bite of the hoverfly (Episyrphus balteatus, Syrphus ribesii, Syrphus blandus or Musca ribesii L.), which has some external resemblance to wasps, is also entomological nonsense, since these insects simply have nothing to bite with, and the adult insect obtains its food - flower nectar and pollen - with the help of its proboscis. [ 4 ], [ 5 ]

The reasons why a bite from a grey fly (Sarcophaga carnaria of the Sarcophagidae family) [ 6 ] and a bite from a green fly (Lucilia sericata or Phaenicia sericata of the Calliphoridae family) are impossible are similar: they are necrophages, that is, they feed on decaying organic matter, for which the insects have quite sufficient spongy mouth appendages. Their “diet” also includes food waste and excrement. [ 7 ], [ 8 ], [ 9 ]

This also includes the bite of the Wohlfahrtia magnifica or Sarcophila Wolfartii, which, feeding on plant juices, is not capable of biting anyone. But its larvae, which emerge from eggs laid by females on mucous membranes or damaged skin, can cause deep myiasis of the skin and muscle tissue. [ 10 ], [ 11 ], [ 12 ]

No bites have been recorded from the earthworm fly (Pollenia rudis or Musca familiaris of the family Callflyhoridae), which parasitizes earthworms and lays eggs in the soil. [ 13 ]

Of course, among the species of Diptera Brachycera there are predators (for other insects) and bloodsuckers (hematophages). [ 14 ], [ 15 ] The reasons that make flies of the superfamily Hippoboscoidea – the families Glossinidae (tsetse fly), Tabanidae, Haematopota, Chrysops, Rhagionidae, the genus Stomoxys (autumn stingers) – hunt and bite warm-blooded animals or a person who has come into their field of vision, are the peculiarities of their reproduction. [ 16 ]

Epidemiology

According to statistics, there are more than 200 million insects per person on Earth, including 17 million flies. Of course, no one counts the number of their bites.

For example, in the summer of 2018, all British publications reported on the invasion of horse flies in the country - due to significant warming, but there was no information on the number of Englishmen bitten by flies.

As for the tsetse fly, which carries the pathogens of sleeping sickness, it is found in rural areas of 37 countries in sub-Saharan Africa. Thanks to the efforts of local authorities, supported by special programs of the World Health Organization, from 2005 to 2015 it was possible to reduce the incidence of sleeping sickness from 15.6 thousand registered cases per year to 2.8 thousand. [ 17 ]

However, today 70-80 million people in 20 African countries are at varying levels of risk of developing the disease, and only 3-4 million people living in endemic areas are subject to surveillance. [ 18 ]

Symptoms fly bite

Experts emphasize that in most of these species, only female flies feed on blood, having sharp chitinous outgrowths (stylets) with which they pierce the skin. Moreover, many hematophagous flies have a need for blood periodically - before laying eggs (to ensure their maturation and development).

Biting flies detect a suitable target (animals or humans) by sensing exhaled carbon dioxide and moisture, sweat, and body heat. After piercing the victim's skin, the insect releases saliva containing an anticoagulant into the wound.

Tsetse fly bite

Since we are talking about the tsetse fly, let's start with it. The blood-sucking tsetse fly - Glossina morsitans, Glossina palpalis, Glossina tachinoides of the Glossinidae family - can be up to 1.5 cm in length. It reproduces larvally, and females need blood to support the development of the larva in their body. [ 19 ]

It is considered an intermediate host of Trypanosoma brucei or Trypanosoma gambiense.

The key risk factors for being bitten by this fly are staying in endemic regions of the African continent. [ 20 ]

What does a tsetse fly bite look like? The bite is often painful and may cause a red, swollen area of skin or small red sores on the skin – marks from the barbs with which the insect’s mouth is “equipped”. Since the insect moves quietly, the first signs of a bite are noticed too late. After about a few weeks, the victim may show symptoms such as headaches, muscle pain, swollen lymph nodes, fever, loss of coordination, and convulsions. As the disease progresses, infected people feel constantly tired and sleepy, and personality changes may occur, indicating damage to the brain and central nervous system. Incidentally, an infected person may not have any symptoms, but he or she becomes a carrier of trypanosomiasis. [ 21 ]

Trypanosoma brucei gambiense can develop in the human body for several years, and T. brucei rhodesiense can lead to death after a few months. Sleeping sickness without treatment with antitrypanosomal drugs is usually fatal. Read more - African trypanosomiasis (sleeping sickness). [ 22 ]

Burnt fly bite

In autumn, throughout Europe and North America, cattle, rabbits, dogs, rats, and sometimes even people can be bitten by synanthropic stinging flies (Stomoxys calcitrans), and individuals of both sexes. These flies are obligate bloodsuckers, having chitinous outgrowths for piercing the skin of their victims, which, by the way, is quite painful. So, first of all, a stinging fly bite causes acute pain. And the most typical location of bites is the ankles. [ 23 ]

Through the resulting microscopic incision, the fly inserts its proboscis under the skin, simultaneously releasing saliva containing digestive enzymes (which help the insect obtain nutrients from the blood) and various isoforms of proteins that prevent blood clotting. So very quickly, swelling occurs on the skin after the fly bite, and the bite site begins to itch. [ 24 ]

It is clear that the pathogenesis of itching is caused by the release of histamine from mast cells of the damaged epidermis. And the development of an inflammatory reaction is the result of an increase in IgG antibodies in the blood. [ 25 ]

Fly bites in children, as well as in people with a weaker immune system or increased sensitization of the body, increase the risk of more serious symptoms: there may be a systemic allergy to a fly bite - with anaphylaxis, causing breathing problems, dizziness, swelling of the face. [ 26 ]

Moose fly bite

In everyday life, the bite of the moose fly Cephenemyia ulrichii (family Oestridae) or Haematobosca alcis (family Tabanidae), which resembles a bumblebee and is called the moose botfly by entomologists, is usually identified as a bite of the striped fly. [ 27 ]

But the first variety – cephenemia – in the wild mainly attacks the nostrils and pharyngeal cavity of elks (and also deer), but does not bite, but injects its larvae there. There are cases when flies of this species injected larvae into people's eyes, which without timely medical care can lead to the development of ophthalmomyosis. [ 28 ]

The deer bloodsucker (Lipoptena cervi or Hippoboscidae cervi), which feeds on the blood of ungulates, is also often called the moose fly, and it can also bite any warm-blooded animals, including humans. Its bites cause pain and itching of the skin with the formation of papules, which disappear in two to three weeks.

Black fly bite

Most often, a black fly bite is a bite from a female fly of the Simuliidae family (which includes about 1,800 species worldwide). [ 29 ]

Simulids are small species (4-5 mm in length), live near running water, like hilly terrain, swarm in late spring and early summer - in the morning or evening, and are guided by smell. [ 30 ]

Their bites are most often localized in the head, neck and ear area, and at the site of each bite a small red spot forms, causing severe itching. Headache, nausea and swelling of nearby lymph nodes are not excluded. [ 31 ]

Big fly bite

The largest flies are horseflies, the females of which attack warm-blooded animals. Read more - Horsefly bite

The bite of the large fly Haematopota pluvialis – a common horse fly-haematophagous of the Tabanidae family – is hard not to feel: it is quite painful; almost immediately the bite site turns red and swells, the skin becomes denser and hotter. [ 32 ]

In Europe, the large brown-yellow horse bloodsuckers Hippobosca equina (superfamily Hippoboscoidea) are called forest flies. The fly is really large – up to 1.5-1.8 cm; it is active throughout the day. During the mating season, the female insects attack horses and cattle. [ 33 ]

This type of forest fly bite causes pain, skin irritation in the form of redness and itching, and a rounded hardening in the form of a papule appears. The irritation and swelling from the bites usually disappear within one to two days. But some people have an allergic reaction to the bite of this fly. [ 34 ]

Yellow fly bite

A complaint about a yellow fly bite, although this description is suitable for a dozen different species of flies of this color, may concern Diachlorus ferrugatus of the Tabanidae family (or Chrysops ferrugatus), the size of which does not exceed 9-10 mm. Only females bite, the food of males is pollen and nectar.

These flies usually bother residents at the end of summer and the beginning of autumn, they avoid bright sun and swarm in shady places under bushes and trees or overhead - in cloudy weather or closer to evening. The insects are aggressive towards moving dark-colored objects.

The bite of these flies is painful, and in its place there is redness and an intensely itchy swelling.

Sand fly bites

Typically, bites from Phlebotominae sand flies of the Psychodinae subfamily, which are no more than 3.5 mm in size (and range in color from gray to yellow and brown), cause redness and swelling of the skin with the formation of a blister. In addition, severe itching occurs at the site of the bite. [ 35 ]

These insects are inhabitants of the subtropics and tropics, so bites are suffered by residents of these latitudes, as well as travelers traveling to hot countries. [ 36 ]

As entomologists note, the Phlebotominae family contains about 700 different species of sand flies, and two dozen of them, belonging to the genus Phlebotomus, Sergentomyia and Lutzomyia, carry pathogens. Thus, phlebotomines, the largest population of which is found in the Amazon basin, carry promastigotes of Leishmania sps, which cause parasitic leishmaniasis in humans. [ 37 ]

Sand flies are endemic in 90 countries on all continents except Australia. It should be borne in mind that, for example, in tropical regions of Asia, the number of sand flies increases significantly during the monsoon season, and their "hunting" time is twilight and night. [ 38 ]

Complications and consequences

The possible consequences of a tsetse fly bite (sleeping sickness) were mentioned at the beginning of the article; now you also know what sand fly bites can cause. But these are far from all the consequences and complications that fly bites can cause.

First, it is an allergic reaction: bites from black flies, horse flies and sting flies can cause anaphylaxis.

Secondly, intoxication and parasitic invasions, and in case of scratching – secondary bacterial infection.

Stinging flies can cause an invasion known as stomoxosis; they also transmit Francisella tularensis bacilli, the causative agent of tularemia, rickettsia (Anaplasma, Coxiella), West Nile and Rift Valley transmissible viral fevers, and the parasitic worms Onchocerca volvulus, which cause onchocerciasis. These nematodes can also be “delivered” to humans by black flies, and the causative agents of tularemia can be transmitted by deer and horse bloodsuckers.

In addition, deer flies carry the bacterium Bartonella schoenbuchensis, which can cause inflammatory skin lesions in humans.

Diagnostics fly bite

Diagnostics carried out in a regular clinic cannot accurately determine which fly has bitten a patient: fly bites are identified using a stereo microscope and taxonomic keys.

Therefore, it is important to examine the bite site and take a medical history that takes into account where, when and under what circumstances the person was bitten by the insect.

In cases of systemic allergic reaction, a test for specific antibodies, including insect venom, may be performed.

Differential diagnosis

Differential diagnostics are carried out to exclude the possible effects of exogenous toxins, the presence of infectious diseases with skin manifestations and false allergic reactions.

Treatment fly bite

First of all, the bite site should be washed with soap and water. Bites are treated with external agents.

What to apply to a fly bite? The simplest antiseptics are suitable for disinfection: an alcohol solution of iodine, a solution of hydrogen peroxide or fucorcin, ethyl alcohol, alcohol tinctures of calendula or St. John's wort.

To reduce swelling and itching, apply cold compresses or ice packs.

You can also use antiseptic ointments Betadine, Sanitas, Calendula. Redness and itching can be relieved by: hydrocortisone ointment, Polcortolone cream (with triamcinolone), Belogent or Diprogent (with betamethasone and gentamicin), Ultralan, etc. More information in the article - Ointment for itching and material - Ointment for skin irritation

For severe itching, use Crotamiton cream (not used for children under 12 years of age).

An allergic reaction requires a mandatory visit to a doctor, who will prescribe appropriate medications for oral administration - antihistamines.

Traditional treatment involves using a soda solution (in the form of lotions); lubricating the bite with aloe juice, propolis tincture, tea tree essential oil, a mixture of lemon juice with salt and turmeric powder. A thin slice of raw potato applied to the bite is very good at reducing swelling.

It is recommended to carry out treatment with herbs: plantain juice, lotions and compresses with water infusions of St. John's wort, yarrow, cinquefoil, sweet clover, calendula or chamomile flowers.

Prevention

Sticky paper "traps" are not effective because they are not as attractive to flies as warm-blooded animals. Smoking fumigators are more helpful.

The use of pesticides has limitations in the fight against flies, since these products act only upon contact and quickly decompose after application. But repellents containing diethyltoluamide are effective in repelling most biting flies, that is, in preventing their bites. These insects are also repelled by the smell of essential oils of geranium and citronella.

The better the body is protected by clothing – long trousers and a long-sleeved shirt – the less chance there is for flies flying in the forest, near a river, near a rural house or in a pasture to reach the skin and bite.