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Arachnoentomoses of humans and animals
Last reviewed: 05.07.2025
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An innumerable number of insect and arthropod species (arthropods), comprising more than 80% of all known representatives of the planet's fauna, live near us. Some of them can cause invasive parasitic diseases of humans and animals - arachnoentomoses.
Epidemiology
In general, statistics on arachnoentomoses are unknown, although some data are available on individual species.
Thus, according to WHO information, at least 200 million people suffer from scabies worldwide, and up to 10% of them are children. This disease is most common in hot countries and in areas with high population density, such as South and Southeast Asia, the tropics of Latin America, the Caribbean, and Africa (below the Sahara). [ 1 ]
Infestation with head lice is estimated at 0.62% of the entire population. In Asian countries, the incidence rate varies between 0.7-60%, in South America – 3.6-61%, in Europe – 1-20%.
Causes arachnoentomoses
In the etiology of human arachnoentomoses, the main place is occupied by parasitiform mites (arachnoid arthropods), wingless arthropod insects (lice, bugs of the Cimicidae family, fleas Pulex irritans, etc.) and insects of the order Diptera - gadflies and flies.
Thus, the causes of the development of arachnoentomoses in humans or animals in most cases are associated with inoculative lesions of the skin, that is, with bites of ticks, flies or lice as a result of their infestation (attack) and parasitic infection (invasion).
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Bed bugs (Cimex lectularius) and some other representatives of the Hemiptera order, insects of the genus Pediculus – lice, as well as fleas (arthropods of the family Aphaniptera) – parasitic hematophagous insects (feeding on the blood of warm-blooded mammals), cause superficial arachnoentomoses.
Head lice (Pediculus humanus capitus) cause pediculosis (diagnosis code B85 in the infectious and parasitic diseases section of ICD-10), [ 2 ] and infestation with pubic lice (Phthirus pubis) causes phthiriasis.
But when bitten by a tropical sand flea (Tunga penetrans), which penetrates the skin, sucks blood and lays eggs, tungiasis develops (code B88.1 according to ICD-10).
Infestation with the mite Demodex folliculorum, which is a histophage (tissue-feeding) is the cause of another type of arachnoentomosis, and this is demodicosis of the skin, head, eyes and eyelids (ICD-10 code B88.0). [ 3 ]
In case of skin damage by the scabies mite (Sarcoptes scabei), a type of acariasis known as scabies develops (the disease has the code B86 according to ICD-10). [ 4 ], [ 5 ]
Thyroglyphosis (flour scabies) is caused by infestation of the acariform flour mite Tyroglyphus farinae, and grain scabies (called pyemotic dermatitis) is caused by bites of mites of the subfamily Pyemotes. Acariasis, caused by chigger mites of the Trombiculidae family (or rather, their larvae), is called trombidiasis. [ 6 ]
In addition, allergic arachnoentomoses are observed: entering the body with inhaled air, barn and flour mites - Glycyphagus destructor, Aleuroglyphus ovatus, Gohieria fusca, Acarus siro, etc. - and their secretions can lead to the development of an allergy to mites in the form of respiratory allergosis. [ 7 ]
House dust also contains mites (including those of the Dermatophagoides family) that can cause dust mite allergies. [ 8 ]
Entomoses include myiasis (cutaneous or intestinal), associated with infection by larvae of detritivorous flies or gadflies, which enter wounds, intact skin, the nasal cavity, ear canals, and when swallowed with food - into the gastrointestinal tract. In this case, the larvae, feeding on the host's tissues, continue to grow. [ 9 ]
The causative agents of myiasis are recognized as the larvae of gadflies (Dermatobia hominis, Hypoderma tarandi, etc.), blue and green meat (carrion) flies - Calliphora uralensis, Lucilia sericata, etc., flies of the genus Wohlfahrtia and the family Drosophilidae.
Risk factors
Anyone who is in their habitat is at potential risk of being bitten by insects or arachnids that cause arachnoentomoses: forests and parks, pastures and garden plots, grain storage facilities and livestock enterprises, as well as contact with agricultural products affected by ticks. And specialists associate additional risk factors for the development of an allergic form of arachnoentomoses with the sensitization of the human body (a tendency to allergic reactions).
Myiasis may be more common in people with open wounds.
As for pediculosis, phthiriasis, scabies and the same myiasis, the risk of infection with their pathogens increases with non-compliance with sanitary and hygienic standards in everyday life and/or poor living conditions.
Pathogenesis
The pathogenesis of arachnoentomoses is determined by the saliva of blood-sucking arthropods, which contains antihemostatic protein substances that prevent platelet aggregation and blood clotting during a bite, and immunogenic compounds of various protein enzymes (proteases) and excrement.
The result of damage to the epidermis and dermis and the penetration of foreign proteins into the skin is the immediate onset of acute inflammation and the formation of a local immune response: activation of leukocytes, mast cells, neutrophils and other protective cells; release of proinflammatory cytokines and chemotactic factors (histamine, leukotrienes, inflammatory macrophage protein MIP-1α, etc.); production of antibodies by dendritic cells and T-lymphocytes.
The mechanism of development of allergic respiratory arachnoentomosis is identical. And with myiasis, tissue damage occurs by larvae, which leads to inflammation and focal necrosis.
Symptoms arachnoentomoses
Most often, symptoms are manifested by acrodermatitis: erythema, local swelling and tissue compaction, hyperemic spots, urticaria, hemorrhagic papules and vesicles (blistering rashes), skin itching and local pain of varying intensity.
More information:
- Bedbug bites: symptoms and how to get rid of them
- Tick Bites: Symptoms and Treatment
- What do flea bites on human skin look like and how to treat them?
With pyemotosis dermatitis (grain scabies) - in addition to papular-pustular rashes, hyperemia and itching of the skin - general malaise, fever, headaches and joint pain, asthma attacks may be observed.
The symptoms of myiasis are related to its form: cutaneous (superficial or deep), linear migratory, furuncular, ophthalmological, ear or intestinal.
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Intestinal myiasis is usually asymptomatic, and accidentally swallowed larvae or eggs of flies present in water or food are excreted with feces. But in some cases there may be discomfort and pain in the abdominal area, nausea, intestinal disorders, etc.
Complications and consequences
Common complications of arachnoentomoses include damage to the skin and local inflammation from scratching, as well as the addition of a secondary (bacterial) infection - often with the formation of skin ulcers and the development of pyoderma or abscess.
Respiratory mite allergy can be complicated by bronchial asthma and angioedema.
The consequences of ophthalmomyiasis may be inflammation of the vascular membrane of the eye (uveitis) and retinal detachment. And in cases of myiasis affecting the nasal cavity and auditory canals, the penetration of larvae into the base of the brain may lead to inflammation of its membranes (meningitis).
Diagnostics arachnoentomoses
Only at first glance does the diagnosis of arachnoentomoses not present any particular difficulties. In fact, it is quite difficult to diagnose an insect bite correctly, since the symptoms may differ in different people due to individual characteristics of immune reactions.
Therefore, specialists determine the cause of the symptoms not only by their appearance - by conducting a thorough examination of the patient, but also find out the circumstances of the alleged bite.
Blood tests for eosinophils, immunoglobulin E (IgE), etc., and skin scrapings at the bite site help in diagnosis. See also:
Instrumental diagnostics may be limited to dermatoscopy, but other hardware studies are also carried out if necessary.
However, differential diagnosis can be a difficult task in many cases, since it is not always possible to identify the specific tick or fly that bit the patient.
Treatment arachnoentomoses
Treatment of diseases caused by inoculum of the skin by insects and arachnids usually involves cleaning the affected area and using topical agents (particularly glucocorticoids and NSAIDs). Systemic antihistamines or anti-itch ointment are used to reduce itching and prevent excoriation of the skin at the bite site.
Antibiotics are used in cases of secondary infections.
More information in the materials:
- Ointments for scabies
- Fast and effective treatment for scabies at home
- Drugs for the treatment of demodicosis
- Lice and Nits Sprays
Arachnoentomoses of animals and birds
No less numerous and varied are arachnoentomoses of animals, which are caused by the bites of ticks and gadflies or the ingestion of gadfly larvae and flies, and are manifested by both skin and gastrointestinal symptoms.
Acariasis in cattle, domestic animals and birds is the result of bites from parasitic argasid ticks (Alveonasus lahorensis, Alveonasus саnestrini, Otobius megnini, etc.), as well as gamasid ticks of the Phytoseiidae, Laelapidae and other families. In rabbits, scabies with skin inflammation and hair loss is caused by parasitic mites of the genus Psoroptes.
Bites from the bullfly Hypoderma bovis cause cutaneous myiasis in cattle. Intestinal myiasis in horses, mules and donkeys is caused by the horsefly Gasterophilus intestinalis, and in sheep and goats by flies of the genus Oestrus. Oestrinae and Hypodermatinae gadflies can lay eggs in the nostrils and ear canals of livestock (from which larvae emerge and penetrate the skin).
Arachnoentomoses of birds include skin-eating scabies - epidermoptosis of poultry, caused by mites parasitizing on the skin (at the base of the feathers) Epidermoptes bilobatus; knemidokoptosis (the causative agents of which are acariform mites of the genus of the family Knemidokoptes) - with damage not only to the skin, but also to the joints of the limbs.
Bites from the gamasid mite Dermanyssus gallinae cause dermanissiosis in chickens. And the mites Ornithonyssus spp. of the Macronyssidae family affect wild birds, but some subspecies are also common on poultry farms.
Mites of the subfamilies Rhinonyssidae, Ptilonyssus, Mesonyssus can penetrate the respiratory organs of birds, which leads to inflammation of the lungs and mucous membrane of the air sac (aerocystitis) in birds.
In most cases, arachnoentomoses in dogs are caused by bites of the Ixodes ricinus dog tick and ticks of the Cheyletiella and Trombiculidae families. And the Demodex folliculorum tick, as in humans, is the cause of demodicosis in dogs.
In addition, dogs can be bothered by dog fleas (Ctenocephalides canis), and cats by Ctenocephalides felis, whose bites cause focal inflammation of the skin, accompanied by severe itching and scratching - flea dermatitis.
Dogs also suffer from trichodectes, a skin disease associated with infestation by lice Trichodectes canis of the suborder Mallophaga (called lice-eating lice); the infestation is manifested by itching and thickening of the skin, the formation of wounds due to scratching, and hair loss in the affected areas.
The main method of combating parasitiform mites and parasitic insects is veterinary treatment of animals against arachnoentomoses, which consists of external application of acaricidal agents (with permethrin or amitrazine) and appropriate insecticides.
More details in the publications:
Prevention
A preventive measure against arachnoentomoses is the prevention of bites of ticks, flies and other insects. Repellents are used to scare them away: when going out into nature, you can use them to protect exposed areas of skin. And disinfestations are carried out to destroy them.
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Forecast
Cutaneous arachnoentomoses in the form of scabies and other acarodermatitis are curable and have a good prognosis regarding health.
But we must not forget that it is precisely through the inoculation route – through the bites of insects and arthropods – that many transmissible diseases are transmitted: bacterial, viral, protozoan.
Thus, lice can be carriers of typhus, and the consequences of a tick bite include tick-borne borreliosis (Lyme disease), tick-borne encephalitis, and babesiosis.