Arachnoentomoses of humans and animals
Last reviewed: 07.06.2024
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Countless species of insects and arthropods (arthropods), which make up more than 80% of all known representatives of the fauna of the planet, live near us. Some of them can cause invasive parasitic diseases of humans and animals - arachnoentomoses.
Epidemiology
In general, the statistics of arachnoentomoses are unknown, although some data are available for individual species.
According to WHO, 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, Africa (below the Sahara). [1]
Head lice infestation is estimated at 0.62% of the total population. However, the incidence rates in Asian countries range from 0.7-60%, in South America from 3.6-61%, and in Europe from 1-20%.
Causes of the arachnoentomoses
Parasitiform mites (spider arthropods), wingless arthropod insects (lice, bedbugs of the family Cimicidae, fleas Pulex irritans, etc.) and insects of the group of two-winged (Diptera) - gadflies and flies - occupy the main place in the etiology of human arachnoentomoses.
Thus, the causes of human or animal arachnoentomoses are in most cases associated with inoculative skin lesions, that is, when ticks, flies or lice bite as a result of their infestation (attack) and parasitic contamination (invasion).
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Bed bugs (Cimex lectularius) and some other representatives of the Hemiptera, insects of the genus Pediculus - lice, as well as fleas (arthropod insects of the family Aphaniptera) - parasitic insects-hematophagous (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 by pubic lice (Phthirus pubis) - phthiriasis.
But when bitten by the tropical sand flea (Tunga penetrans), which penetrates the skin, sucking blood and laying eggs, develops tungiosis (ICD-10 code B88.1).
Infestation by the mite Demodex folliculorum, which are histophagous (tissue-feeding), is the cause of another type of arachnoentomosis, and this is demodecosis of the skin, head, eyes and eyelids (ICD-10 code B88.0). [3]
In the case of skin lesions by the scabies mite (Sarcoptes scabei), a type of acariasis develops, such as scabies (the disease has the code B86 according to ICD-10). [4], [5]
Tyroglyphosis (flour scabies) is caused by infestation of the acariform flour mite Tyroglyphus farinae, and grain scabies (called pyemotous dermatitis) is caused by bites of mites of the subfamily Pyemotes. Acariasis caused by red-legged mites of the family Trombiculidae (or, more precisely, their larvae) is called thrombidiasis. [6]
In addition, allergic arachnoentomoses are observed: by entering the body with inhaled air, barn and flour mites - Glycyphagus destructor, Aleuroglyphus ovatus, Gohieria fusca, Acarus siro, etc. - and their excretions can lead to the development of mite allergy 5 as respiratory allergosis. - and their excretions can lead to the development of mite allergy in the form of respiratory allergosis. [7]
House dust also has mites (including those in the Dermatophagoides family) that can cause dust mite allergies. [8]
Entomoses include miasis (cutaneous or intestinal) associated with infection by larvae of detritophagous flies or gadflies that enter wounds, intact skin, the nasal cavity, ear canals and, if swallowed with food, the GI tract. The larvae continue to grow while feeding on host tissues. [9]
The larvae of gadflies (Dermatobia hominis, Hypoderma tarandi, etc.), blue and green meat flies (Calliphora uralensis, Lucilia sericata, etc.), flies of the genus Wohlfahrtia and the family Drosophilidae are recognized as the causative agents of myiasis.
Risk factors
The potential threat of being bitten by insects or spider arthropods that cause arachnoentomosis, are exposed to everyone who is in their habitat: these are forests and parks, pastures and homesteads, premises of granaries and livestock enterprises, as well as contact with agricultural products affected by ticks. And additional risk factors for the development of allergic form of arachnoentomosis experts associate with sensitization of the human body (tendency to allergic reactions).
Miasis may be more common in people with open wounds.
As for pediculosis, phthyriasis, scabies and the same miasms, the risk of infection with their pathogens is increased by lack of hygiene in everyday life and/or poor living conditions.
Pathogenesis
The pathogenesis of arachnoentomosis is caused by the saliva of blood-sucking arthropods, which contains anti-hemostatic protein substances that prevent platelet aggregation and blood clotting in the bite, and immunogenic compounds of various protein enzymes (proteases) and feces.
The result of damage to the epidermis and dermis and entry 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, macrophage inflammatory protein MIP-1α, etc.); production of antibodies by dendritic cells and T-lymphocytes.
The mechanism of development of allergic respiratory arachnoentomosis is identical. In myiasis, larvae damage tissues, leading to inflammation and focal necrosis.
Symptoms of the arachnoentomoses
The most frequent symptoms are acrodermatitis: erythema, localized edema and tissue thickening, hyperemic patches, urticaria, hemorrhagic papules and vesicles (vesicular rashes), skin itching and local soreness of varying intensity.
More information:
- Bed bug 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?
In piemotous dermatitis (grain scabies) - in addition to papular-pustular rashes, hyperemia and itching of the skin - there may be a general malaise, fever, headaches and joint pains, asthmatic attacks.
The symptoms of miasis are related to its form: cutaneous (superficial or deep), linear migrating, furuncular, ophthalmic, auricular, or intestinal.
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Intestinal myiasis is usually asymptomatic and accidentally ingested fly larvae or eggs present in water or food are excreted in the feces. But in some cases there may be discomfort and pain in the abdominal region, nausea, intestinal disorders, etc.
Complications and consequences
Common complications of arachnoentomoses are skin lesions and localized inflammation from scratching, as well as secondary (bacterial) infection, often with the formation of skin ulcers and the development of pyoderma or abscess.
Respiratory tick allergy can be complicated by bronchial asthma and angioedema.
The consequences of ophthalmomyiasis may include inflammation of the vasculature of the eye (uveitis) and retinal detachment. In cases of myiasis affecting the nasal cavity and ear canals, penetration of larvae into the base of the brain may lead to inflammation of the brain membranes (meningitis).
Diagnostics of the arachnoentomoses
Only at first glance the diagnosis of arachnoentomosis does not present any particular difficulties. In fact, it is quite difficult to diagnose an insect bite correctly, as the symptomatology may differ from person to person due to individual immune reactions.
Therefore, specialists determine the cause of the symptoms not only by their appearance - conducting a thorough examination of the patient, but also clarifies the circumstances of the alleged bite.
Blood tests for eosinophils, immunoglobulin E (IgE), etc., and a skin scraping at the bite site can help in diagnosis. See also:
Instrumental diagnosis may be limited to dermatoscopy, but other instrumental studies are also performed if necessary.
But differential diagnosis in many cases can indeed be a challenge, as it is not always possible to identify the specific tick or fly that bit the patient.
Treatment of the arachnoentomoses
Treatment of diseases caused by inoculative skin lesions of insects and arthropod spiders usually involves cleaning the affected area and the use of topical agents (particularly glucocorticoids and NSAIDs). To reduce itching and prevent skin excoriation at the bite sites, systemic antihistamines or ointment for itching are used.
Antibiotics are used in cases of secondary infections.
More information in the materials:
- Ointments for scabies
- Quick and effective treatment of scabies at home
- Drugs for the treatment of demodecosis
- Lice and nits sprays
Arachnoentomoses of animals and birds
Equally numerous and diverse are arachnoentomoses of animals, which are caused by tick and gadfly bites or ingestion of gadfly larvae and flies, and manifest both cutaneous and gastrointestinal symptoms.
Acariasis of livestock, domestic animals and birds is the result of bites of argas mites (Alveonasus lahorensis, Alveonasus sapestrinii, Otobius megnini, etc.), as well as gamaze mites of the families Phytoseiidae, Laelapidae and others. In rabbits scabies with skin inflammation and hair loss is caused by mites of the genus Psoroptes parasitizing them.
Bites of the bovine gadfly Hypoderma bovis cause cutaneous myiasis in cattle. Intestinal myiasis of horses, mules and donkeys is caused by the horse gadfly Gasterophilus intestinalis, sheep and goats by flies of the genus Oestrus. In the nostrils and ear canals of livestock can lay eggs (from which larvae emerge, penetrating the skin) of the gadflies of the families Oestrinae and Hypodermatinae.
Arachnoentomoses of birds include skin scabies - epidermoptosis of poultry caused by Epidermoptes bilobatus mites parasitizing on the skin (at the bases of feathers); Knemidokoptosis (causative agents of which are acariform mites of the genus family Knemidokoptes) - affecting not only skin but also joints of limbs.
Bites of the gamaze mite Dermanyssus gallinae cause dermanyssiosis of chickens. Ornithonyssus spp. Of the family Macronyssidae affects 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 mucosa of the air sac (aerocystitis) in birds.
In most cases, canine arachnoentomoses are caused by bites of the canine ixodid tick Ixodes ricinus and ticks of the families Cheyletiella and Trombiculidae. And the mite Demodex folliculorum, as in humans, is the cause of demodecosis in dogs.
In addition, dogs may 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 can also get trichodectosis, a skin disease caused by the lice Trichodectes canis of the suborder Mallophaga (called wetflies); the infestation is manifested by itchy and thickened skin, wounds due to scratching, and hair loss in the affected areas.
The main method of controlling parasitiform mites and insect parasites is veterinary treatment of animals against arachnoentomosis, 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 arachnoentomosis is the prevention of bites from ticks, flies and other insects. To repel them, repellents are used: when going outdoors, you can use them to protect exposed skin. And for extermination, disinfections are carried out.
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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 should not forget that many vector-borne diseases, such as bacterial, viral and protozoal diseases, are transmitted by inoculation through the bites of insects and arthropods.
For example, lice can be carriers of typhus, and consequences after a tick bite include tick-borreliosis (Lyme disease), tick-borne encephalitis, and babesiosis.