Ectoparasites of animals and humans

Ectoparasites are organisms that feed on other organisms but do not penetrate the body but live outside the body (from Greek ektos - outside, outside), i.e. On the skin or in the upper layers of the skin. Infection by such organisms is called ectoparasitosis or infestation.

Classification of ectoparasites

Taxonomically diverse group of organisms parasitizing on the surface of the skin - ectoparasites of humans and animals, divided into insects (six-legged arthropods) and spiders (eight-legged arthropods), i.e. Mites (Acari).

The most common insects are ectoparasites:

• household ectoparasites - insects of the Hemiptera order - bedbugs;
• Wingless insect bloodsuckers of the order Anoplura, family Phthiraptera (down-eaters) - lice;
• wingless bloodsuckers of the family Pulicidae - fleas (Siphonaptera);
• insects of the Diptera (two-winged species) - gadflies, horseflies, flies, small flies (midges) of the family Simuliidae, mosquitoes (insects of the subfamily Phlebotominae).

Arthropod ectoparasites (invertebrate arthropods with a chitinous external skeleton) represent the same lice, bedbugs, fleas; mites are separately distinguished: Acariform mites of the families Trombidiformes (trombidiformes) and Sarcoptiformes (sarcoptiformes), and parasitiform mites of the order Ixodida (hard-bodied ixodid mites) and the family Argasidae (soft-bodied Argas mites). All these arthropods are hematophagous, i.e. Blood-sucking ectoparasites.

Ectoparasitic worms are some nematodes or roundworms (ankylostomes of the suborder Strongylida) and also the water-dwelling ringworms of the class Clitellata, the leeches (Hirudinea).

A separate group - crustaceans ectoparasites, for example, representatives of the parasitic crustaceans of the class Maxillopoda (sac-breasts), parasitizing on coral polyps and invertebrate marine animals. Some crustaceans of the order Isopoda, such as the crustaceans of the suborders Cymothoa and Livoneca, parasitize fish.

In addition, ectoparasites are divided into obligate and facultative (permanent and temporary), as well as imaginal (when parasites are sexually mature organisms) and larval (when only their larvae are parasites).

An obligate ectoparasite or permanent ectoparasite without the use of a suitable host organism cannot continue its life cycle. And the simplest example is lice or Demodex folliculorum mites.

Facultative or temporary ectoparasites are not completely dependent on any host to complete their life cycle and may exist freely for a certain period of time. The insect Culex pipiens of the two-winged family, the common mosquito mosquito.

Human ectoparasites

Human ectoparasites include:

• The head louse (Pediculus humanus capitis), pubic louse (Phthirus pubis), and hair louse (Pediculus humanus corporis);
• of the bed bug Cimex lectularius of the Hemiptera;
• Triatomine bugs ("kissing bugs") of the family Reduviidae;
• the human flea Pulex irritans;
• the sand flea Tunga penetrans;
• acariform scabies mite (Sarcoptes scabiei). [1]
• Trombidiform subcutaneous mite Demodex follicullorum and Demodex brevis; [2]
• ixodal ticks of the genus Dermacentor (subfamily Rhipicephalinae) and others.

In addition, bloodsucking flies of various families, such as Wohlfahrtia magnifici (Wolfart's fly), flies of the genus Stomoxys (autumn flies), flies of the Glossinidae family (tsetse fly); gadflies (Dermatobia hominis and others); midges, mosquitoes, some mosquitoes are involved in ectoparasitosis of humans.

More information in the articles:

• Tick bites in humans
• Bites from ticks that cause dermatitis
• Bedbug bites
• Flea bites
• Fly bite
• Human gadfly bite
• Consequences and complications after a gnat bite

Ectoparasites in animals

Everyone knows that pigs like to wallow in mud, but not everyone knows that this is how they clean their skin of ectoparasites. Pigs are especially bothered by mites and the pig louse Haematopinus suis, a blood-sucking ectoparasite whose females attach their eggs to the base of the hair shaft of pig bristles. It is an obligate parasite, as it spends its entire life cycle on the animal.

There's a reason we started our animal ectoparasites review with pigs, because 98% of their DNA is similar to human...

Dog ectoparasites are more numerous, including:

• Ctenocephalus canis is a dog flea;
• Trichodectes canis is a dog midge;
• lice Linognathus setosus and Haematopinus piliferus (dog's bloodwort);
• brown or brown dog tick (Rhipicephalus sanguineus) and the Ixodes ricinus tick of the ixodid family;
• acariform mites Sarcoptes canis or Detodex canis (with the development of sarcoptosis - canine scabies);
• the prostigmatic mite Cheiletiella uscuria, which causes acarodermatitis in the form of cheiletiellosis ("walking dandruff");
• The subcutaneous mite Demadex canis is the cause of demodecosis in dogs. [3]

The most common ectoparasites of cats and felines:

• cat fleas (Ctenocephalides felis);
• cat louse (Felicola subrostrata);
• ixodes ticks Ixodes ricinus and Dermacentor reticulatus;
• Cheyletiella blakei trombidiform mites (causing cheyletiellosis);
• Demodex cati or Demodex gatoi mites, which spend their entire life on their host, are the causative agents of feline demodecosis.

The ear flaps of cats can be affected by the mite Otodectes cynotis - with the development of otodectosis scabies.

In addition to Haematopinus asini lice and Bovisola equi lice, specialists call such ectoparasites of horses as: horseflies of various subfamilies; horse gadflies (Rhinoestrus purpureas), deer gadflies (Hypoderma tarandi), bovine gadfly (Hypoderma bovis). Larvae of the horse hook gadfly (Gasterophilus intestinalis), parasitizing on the skin, cause in animals linear migratory miasis.

Equine hematophagous fly Haematopota pluvialis (family Tabanidae), horse bloodsucker Hippobosca equina, lighter fly (Stomoxys calcitrans) pester horses no less. The list continues with sheep or deer tick Ixodes ricinus, elk or winter tick Dermacentor albipictus, swamp tick Dermacentor reticulatus, ear mite Otobius megnini.

By the way, lice, flea beetles, gadflies, flies and acariform mites of various families affect cattle and small horned cattle to no lesser extent.

Rabbits have their own ectoparasites: rabbit fleas (Spilopsyllus cuniculi), lice Haemodipsus ventricosus, fur mite Leporacarus gibbus. Even the ears of rabbits are affected by Psoroptes cuniculi mites. Blood-sucking insects and mites can lead to anemia in animals and can also be carriers of the virus of such an infectious disease as rabbit myxomatosis.

Main ectoparasites of rodents (rats and mice): fleas Xenopsilla cheopis and Ceratophyllus fasciatus, red mite Trombidium ferox and ticks Ixodes Scapularis.

Ticks (Trixacarus caviae and Chirodiscoides caviae) and lice of the suborder Mallophaga (Gliricola porcelli and Gyropus ovalis) are the most common ectoparasites of guinea pigs (rodents of the mumps family). These rodents may also have cat fleas.

And the flea family Ischnopsyllidae prefers hosts such as bats (which are not rodents, forming the order of man-eaters).

Ectoparasites of birds

Ectoparasites of birds are no less numerous and diverse. Thus, ectoparasites of chickens include chicken lice, or, more precisely, similar wingless insects of the Mallophaga series - puff-eaters (Menacanthus stramineus, Menopon gallinae, Goniocodes gallinae, Liperus caponis, Cuclotogaster heterographus), which do not feed on blood, but are permanent ectoparasites of domestic chickens.

Chickens and other poultry are also affected by the hamasic hematophagous mite Dermanyssus gallinae and feather mites (Trombicula fallalis, Megninia ginglymura). Keratin-feeding acariform mites of the family Epidermoptidae - Knemidocoptes mutans and Knemidocoptes - are the cause of knemidocoptotic dermatitis (knemidocoptosis) in birds.

Pigeons are also parasitized by pigeon fluff-eaters and various arthropod ectoparasites. The mites Knemidocoptes and Ornithonyssus bursa are the most frequent ectoparasites of parrots.

Ectoparasites of fish

Among the ectoparasites affecting the scales and skin of fish (freshwater and marine), the most common are:

• carp lice or carp-eaters (Branchiura) are crustaceans of the class Maxillopod, of the order Arguloida;
• crustaceans of the families Sphyriidae and Lernaeoceridae, and the family Aegidae (genus Aega), which parasitize marine fish;
• Planaria are flatworms of the Tricladida and Monogenea orders;
• flatworm suckers of the genus Dactylogyrus - Dactylogyrus, occupying not only the skin, but also the gills of freshwater and marine fish.

And parasitic crustaceans of the genus Ergasilus of the subclass Copepoda (paddlefish) - because of their favorite habitat on fish - are called gill lice.

Aquarium fish can also suffer from ectoparasites: Ichthyophthyrium - infusoria parasites, flatworms Monogenea, etc.

Ectoparasites of plants

Parasitic phytonematodes (almost microscopic roundworms called phytohelminthes) live in the soil and are considered the main ectoparasites of the root system of plants.

These are obligate ectoparasites of the family Paratylenchidae (Paratylenchus nanus, etc.), the phytohelminth Gracilacus audriellus and Macropostonia sp. Parasitizing the roots of more than two dozen species of deciduous trees.

Nematodes Tylenchorhynchus dubius parasitize the roots of many vegetable crops, maize and perennial cereal grasses, resulting in inhibited plant growth. Hemicycliophora parasitic worms may form root cecidia (galls).

Gall mites of the family Eriophyidae (Trombidiformes) also parasitize plants; the mites suck sap, resulting in deformation of plant tissues and abnormal formations.

About three dozen tetranychid mites of fruit crops, including the common spider mite Tetranychus urticae, are considered ectoparasites of plants.

Ectoparasites: diseases

The first thing to list are the human diseases that are a direct consequence of ectoparasite infestation, and these are sporadic, endemic or epidemic parasitic skin diseases such as:

• pediculosis (caused by head lice); [4]
• phthyriasis (pubic pediculosis); [5]
• scabies is the result of skin infestation by the mite Sarcoptes scabiei; [6]
• Demodecosis, caused by the Demodex mite); [7]
• Chemipterosis, which develops after bed bug bites;
• Pulicosis with itching and rash in human flea ectoparasitosis;
• Tungiosis is a disease that is caused by a female sand flea parasitizing in the skin; [8]
• Phlebotoderma is a mosquito-borne dermatosis;
• skin larva migrans, which occurs when the larva of the nematode parasite Ancylostoma larva penetrates the skin; [9]
• larval dipterosis or superficial skin myiasis;
• Dermatobiasis is a skin myiasis provoked by the Dermatobia hominis gadfly larva parasitizing in the skin;
• thrombidiasis (caused by the larva of red-legged mites of the family Trombiculidae)
• Tyroglyphosis or mealybug scabies is a skin lesion caused by the mealybug mite Tyroglyphus farinae.

For more details, see:

• Acariasis
• Arachnoentomoses of humans and animals
• Skin lesions caused by arthropods

It should be noted that it is not the ectoparasites that are diagnosed, but the parasitic diseases they cause, for which various methods are used skin examination, for example, spectrophotometric intracutaneous analysis - SIascopy of the skin. [10] Laboratory tests are also performed, in particular, IgE levels are taken and scraping for ectoparasites - scraping for demodecosis.

What can ectoparasites infect with?

And now a little about those infectious diseases, the causative agents of which can be carried by blood-sucking arthropods and ectoparasitic insects.

Anopheles mosquitoes transmit malaria, while Haemagogus and Aedes mosquitoes transmit yellow fever. Lice bites can transmit to humans the intracellular proteobacterium Rickettsia prowazekii, which causes epidemic typhus, and fleas can transmit Yersinia pestis, the causative agent of plague.

Trypanosoma cruzi-infected triatomine bugs transmit this unicellular protista of the class Kinetoplastea, which causes American trypanosomiasis (Chagas disease), to humans when they bite them in the southern United States, Central America, and Latin America. [11]

As ectoparasites, mosquitoes of Phlebotomus papatasi species infected with Leishmania, when bitten by humans, become transmissible vectors of this intracellular parasite - with the development of cutaneous leishmaniasis. [12]

Infected Ixodes Scapularis and Ixodes ricinus ticks transmit the spirochete Borrelia burgdorferi - the cause of Lyme disease. [13] Also these arthropod ectoparasites can carry and transmit to humans the virus tick-borne encephalitis, [14] pathogens babesiosis [15] (protista Babesia microti) and human granulocytic anaplasmosis (intracellular bacterium Anaplasma phagocytophiluma). The dog tick Rhipicephalus sanguineus is a vector for the bacteria Rickettsia conorii, which causes Mediterranean spotted (or Marseille) fever.

And this is by no means a complete list of possible consequences after a tick bite.

Treatment

It is not the ectoparasites that are treated, but the parasitic diseases they cause, for which various drugs are used.

Ivermectin ectoparasite tablets are an effective preparation against ectoparasites. This ectoparasiticide in the form of 1% solution is administered subcutaneously to animals.

For pediculosis use thyme water, liquids Delacet and Pedex, insecticidal shampoo Pedilin with permethrin and others.

Comprehensive treatment of demodecosis. See - Drugs for the treatment of demodectosis

How to get rid of scabies, read in the publications:

• Fast and effective treatment of scabies
• Scabies ointment
• Scabies aerosol

Drops from ectoparasites are applied on the withers of animals:

• Flea drops
• Tick drops

Ectoparasite spray makes infestation control easier:

• anti-pediculosis aerosols Para-Plus and Spray-Pax
• lice and nits sprays
• flea sprays
• bug sprays

Insectal or Olkar (with synthetic pyrethroid deltamethrin), Ectosan (with insecticide alpha-cypermethrin), etc. Are used for treatment of animals.

Also read:

• Treatment and prevention of fleas in cats
• Ticks and fleas in cats: prevention, treatment and other issues

Prevention of the ectoparasites

Ectoparasitosis prevention and control measures depend on the extent and nature of the disease - sporadic, endemic or epidemic. The prevalence of ectoparasitoses in the general population, according to WHO, is relatively low, but can become high in economically disadvantaged regions and vulnerable populations.

In case of sporadic ectoparasite infestation, compliance with personal hygiene and treatment of the parasitic disease may be sufficient. The use of special preventive products in the form of shampoos, collars, sprays and drops will help in the fight against parasites.

In cases of endemic or epidemic ectoparasitosis, comprehensive sanitary and hygienic measures aimed at protecting the environment from pollution, neutralizing human and animal ectoparasites, controlling the sanitary situation and public health education are intended to prevent its spread.

Treatment against ectoparasites is carried out: from scabies mites use mite aerosols, solutions of sodium triosulfate and benzyl benzoate; insects ectoparasites are treated with repellents and insecticides.