Miases are diseases caused by the penetration of the larvae of some flies into the human and animal body. According to the localization of the larvae, myiases are tissue, cavitary and mixed, according to their lifestyle - random, facultative and obligate.

Random myases

Intestinal myases. They occur when small newborn fly larvae are accidentally swallowed, which, in cases of low acidity of gastric juice, penetrate alive into the intestines, where they can even develop somewhat. It is assumed that the latter is possible in individuals prone to aerophagia, since oxygen is necessary for the development of larvae. With intestinal myiasis, irritation and inflammation of the mucous membrane of the gastrointestinal tract is observed. Patients complain of abdominal pain, nausea, vomiting, and frequent stools. Larvae are excreted with feces, less often with vomiting. The causative agents of intestinal myiasis are the larvae of room, brownie, gray, green and blue meat flies, as well as fruit flies and cheese flies.

Urinary myases. House flies and other flies sometimes lay their eggs on linen that has been soaked in urine or soiled with feces. The larvae hatched from the eggs penetrate the urethra and bladder, causing pain during urination, and sometimes urinary retention.

Prevention. It is necessary to fight flies, protect food products from them, and observe measures of public and personal hygiene. Water from open reservoirs should be drunk only after boiling and filtering.

Facultative myases

Green and blue blowflies usually lay their eggs in animal corpses and meat waste, house and house flies in human excrement, rotting plant matter, manure, gray blowfly in feces, sometimes in human food. Flies can also lay eggs and larvae in human wounds, noses and festering ears. Usually, the larvae do no harm and even promote wound healing by eating pus and releasing bactericidal substances. At one time, the so-called surgical fly larvae (Calliphora and others) were used in the treatment of wounds and osteomyelitis. However, with larvae taken from their natural habitat, pathogens of tetanus and gas gangrene are sometimes introduced into wounds. Subsequently, sterile larvae of blue blowflies began to be obtained. Nowadays, these methods of treatment are not used in surgical practice, and the larvae that have entered the human body are removed with tweezers or by washing.

Obligate myases

Malignant myiasis are caused mainly by larvae of the Wolfart fly (Wohlfahrtia magnibica), common in southern Europe, the Arab Republic of Egypt, Mongolia, China, the Caucasus, Central Asia, Kazakhstan, and central and southern zones of Russia.

The fly lays 120-160 very mobile larvae about 1 mm long on the skin of humans and animals. They quickly penetrate the skin into the depths of the tissues, flesh to the bones, move into the eyes, nose, ears and even the brain, exerting a mechanical, allergoic and enzymatic effect on the tissues. A person infested with Wolfart fly larvae develops necrosis and suppuration, extensive destruction of tissues and organs. Cases of complete destruction of the eyeball by the larvae, the destruction of the integument of the head, the occurrence of osteomyelitis, encephalitis, and severe damage to the female genital organs under their influence are described. Known deaths. The disease progresses with extraordinary rapidity.

Wolfart fly larvae develop very quickly: after 3-5 days they become mature, leave the host and pupate in the soil.

Treatment of malignant myiasis consists in washing wounds with chloroform water or irrigation with a solution of chloroform in vegetable oil, removing euthanized larvae with tweezers, removing necrotic tissues, opening abscesses, using antibacterial drugs, and administering tetanus toxoid.

Wolfart fly lays larvae mainly on ungulates. Of great importance for the prevention of malignant myiasis and the fight against it are periodic inspections of farm animals (sheep, etc.), removal of fly larvae from them.

Benign myiasis caused by larvae that develop singly and slowly. There are African and South American miases.

african myiasis

At the site of introduction of the larva, an infiltrate appears in the skin, similar to a boil and covered with a crust, under which there is a cavity with a larva. After 12-15 days, the larva reaches a length of 12-17 mm, leaves the skin, falls on the soil and pupates here.

Treatment is carried out by irrigating the infiltrate with water or pouring it with vaseline oil. Due to the lack of air, the larvae stick out the back of the body. This makes it possible to remove them with tweezers, after which recovery quickly occurs.

Prevention. Deratization, wearing shoes, extermination of flies, sanitary improvement of beaches. It is not recommended to lie on the sand without bedding.

South American myiasis

South American myiasis is found in Mexico, Argentina and other countries of Central and South America. The causative agent is the larva of the fly Dermatobia hominis. The female fly lays eggs on the body of mosquitoes, Stinger flies and some mites. After 6 days, larvae are formed in the eggs, but they leave the shells of the eggs only when the insects and ticks on which they are located are planted on a person or animals (cattle, pigs, etc.). The larvae quickly penetrate the skin, where they slowly grow and develop. After 5-10 weeks, they reach 25 mm in length, fall on the soil and pupate.

Near the infiltrated larvae, an infiltrate appears with a hole from which a serous-purulent fluid flows. Lesions are located mainly on the limbs, back, abdomen, armpits. A case of death of a 1.5-year-old child with multiple infestation by the larvae of this fly is described.

Treatment is carried out by extracting the larvae with tweezers.

Prevention is carried out through a planned examination of domestic ungulates and treatment of patients, the fight against blood-sucking insects and ticks through repellents.

Myiasis caused by gadfly larvae

There are abdominal and skin myiasis.

cavity myiasis caused by larvae of the Russian sheep gadfly (Rhinoestrum purpureus and Oestrus ovis). The females of these gadflies on the fly throw their larvae into the nostrils of a horse and a sheep, less often into the eyes and even more rarely into the nose of a person. There are external ophthalmomyiasis, when the larvae penetrate only into the eyelids, lacrimal sac and conjunctiva, and internal - when they are introduced into the internal environment of the eye. There are conjunctivitis, dacryocystitis. Possible blindness. The larvae in the eye are very mobile, so the eye is first anesthetized and only then the larvae are removed with tweezers or by washing with water. With the penetration of the larvae of the Russian and sheep gadflies into the nose, rhinitis occurs with copious secretions, a constant headache is noted. Treatment consists in extracting the larvae.

Skin myiasis is caused by larvae of the gastric horse gadfly (Gastrophilus intestinalis) and skin gadflies of cattle (Hypoderma bovis, H. lineata).

Skin gadflies of cattle (N. bovis and N. lineata) stick eggs one at a time to animal hair or human hair. The larvae hatched from them penetrate the skin and migrate there. A few months later, a “tumor” forms around them under the skin with a hole through which the larva comes out. The larvae of the first stage of H. bovis in the host body necessarily migrate through the spinal canal, penetrating into it along the course of the nerves. From here, through the intervertebral foramina, they move under the skin. Cases of penetration of skin gadfly larvae into the anterior chamber of the eye and eyelid are described.

Skin myiasis is treated by surgical removal of the larvae.

The disease begins to develop after the larvae of certain types of flies and some other insects are introduced into the human and animal body. So, an adult lays eggs under the skin, in the eyes, ears, nose or open wounds. In rare cases, the lesion begins after swallowing the fly. For larvae, the subcutaneous environment is fertile, in which they actively develop and grow, feeding on the tissues of the host. The development of myiasis is quite fast, and if left untreated, the disease can lead to disability and even death.

Basically, the carrier is the tumbu fly - as a rule, it lays larvae only under the skin

Insect larvae have a unique adaptability. They tolerate exposure to many mild acids, alcohol, alkali and formalin.

It is because of this that some individuals are able to live quietly for several months in the human stomach.

Types of myiasis

An insect can lay eggs in various places. Depending on the localization on the body, myiasis is usually divided into several groups.

subcutaneous myiasis

The causative agents of surface myiasis are the larvae of meat, carrion, cheese, house flies

Skin myiasis in humans in the early stages is the easiest to cure. In addition, ulcers and severe scarring can be avoided.

Intestinal

Infection with the intestinal form is always accompanied by nausea, vomiting, and severe pain in the abdomen. At advanced stages, internal bleeding occurs, associated with the movements of the larvae in the body cavity.

Urogenital

With this form, the lesion occurs in the human reproductive system. In the early stages, the process of suppuration always occurs due to the penetration of larvae into the body. In addition, there is always a strong itching, urinary retention. In the genitourinary form, there is a high risk of myiasis becoming malignant, in which soft tissue cells are destroyed.

Infection in this case always occurs through linen. Therefore, simple prevention and hygiene is the best way to avoid illness.

Ophthalmic (ophthalmomyiasis)

Surgical removal of the larva, one of the most difficult forms for humans

Nasal or nasal

Myases in the oral cavity

Ear (otomiasis)

This species is characterized by the location of fly larvae in the ear canal and on the surface of the shell. Infection occurs in a dream both actively and through contaminated linen. Otomiasis is dangerous with complications - larvae are ways to make moves from the ear to the human brain, which significantly reduces hearing, and can also lead to meningitis. With this form, surgery is necessary to remove absolutely all the larvae.

The laying of fly eggs in the ear is very dangerous - the larvae are ways to make moves from the ear to the human brain

List of diseases

• Hypodermatosis. Pathogens - eggs of some species of gadflies. Most often, the disease affects people living in rural areas and livestock;
• Cordylobiosis. The defeat is caused by flies of the species Cordylobia anthropophaga. In the initial stages, myiasis looks like a boil or small ulcers;
• Wolfarthiosis. This is the damage to body tissues by the larvae of the Wolfart fly. Eggs are localized most often on the skin and mucous membranes, which often leads to necrosis;
• Gastrophilia. Infection occurs with the larvae of the gadfly of the species Gastrophilus equi. The disease is localized mainly in the internal organs. Fatalities have been reported in the medical literature.

Diagnosis and treatment

After identifying and analyzing the larvae, complex treatment is prescribed.

• Surgical treatment is prescribed in almost all cases. This is necessary in order to completely remove eggs and insect larvae from the body;
• The affected area is treated with an antiseptic solution for a long time to eliminate inflammatory processes;
• After removing the larvae and treating the wound, a bandage with a restorative solution is applied to the infected area. If the internal organs are affected, then all the necessary doctor's prescriptions are observed;
• In addition, a course of strong antibiotics is needed to eliminate inflammatory processes and avoid complications.

Only timely treatment will help to avoid the consequences of myiasis, because insect eggs develop very quickly, over time affecting an increasing area and causing significant harm to the body.

Fortunately, in the vast majority of cases, with timely treatment, these diseases quickly regress and pass without complications for the patient.

In the vast majority of cases (about 90%), flies of the following groups become pathogens in humans:

1. family calliphoridae ( lat. calliphoridae).
2. Superfamily Oestroidea, predominantly the family of gadflies ( lat. Gasterophilidae).
3. Family of gray blowflies ( lat. Sarcophagidae).

In more rare cases, the causative agents of myiasis in humans are flies of the following groups:

• family of grasshoppers (lat. Anisopodidae);
• family of cheese flies (lat. Piophilidae);
• the family of lions (lat. Stratiomyidae);
• hoverfly family (lat. Syrphidae).

Methods of human infection

Female flies lay eggs in large numbers in the eyes, ears, nose and wound openings of a person. Direct subcutaneous injection of egg clutch is also possible, and in rare cases, visceral infection by accidental ingestion of fly larvae is possible.

The method of infection depends on the type of flies. Namely:

• flies of the genus Gasterophilus, Hypoderma, Dermatobia and Cordylobia inject eggs subcutaneously;
• infection with eggs of the Fannia genus is possible through the gastrointestinal tract or urinary system;
• flies of the genus Phonnia and Wohlfahrtia lay their eggs in open wounds and ulcerative lesions;
• flies of the genus Oestrus lay their eggs in the eyes;
• flies of the genus Cochliomyia enter the nasal passages and lay their eggs there.

Also, fly larvae can enter the human body with soil, through mosquito bites, from bed linen, and so on.

This is possible in the presence of larvae on food, linen or in the soil. The gastrointestinal tract (intestinal myiasis) and the genitourinary system (urogenital myiasis with urethral involvement) are most commonly affected. In casuistic cases, larvae may enter the brain or heart.

The most dangerous in this regard is intestinal myiasis, which in some cases can result in the death of the patient.

Types by affected organs

There are several types of myiasis, differing from each other in localization. So it is possible that the following organs of humans and animals can be affected by myiasis:

1. Skin and subcutaneous tissue (subcutaneous type).
2. Genitourinary system (genitourinary or urinary type).
3. Gastrointestinal system (intestinal type).
4. Nasal cavity (nasal or nasal type).
5. Ears (ear type or otomiasis).
6. Eyes (ocular type or ophthalmomyiasis).

In addition, fly larvae can damage the internal structure of the eye so much that surgery to remove it (enucleation) may be required.

intestinal myiasis

This is one of the most severe types of myiasis, leading to a whole range of disorders of the gastrointestinal system. Intestinal myiasis can cause about 50 different types of flies, including common houseflies.

Symptoms of intestinal myiasis:

• nausea and vomiting;
• severe pain in the abdomen;
• the presence of blood in vomit and feces.

This form of the disease is dangerous due to the formation of numerous ulcers and perforations along the intestine, which often leads to the death of the patient.

With this type of disease, the fly larva settles in the urethra, clogging it and leading to local inflammation and sometimes allergic reactions. In this case, the patient experiences pain in the urethra, often very strong ("dagger").

Symptoms of urogenital myiasis:

• pain in the urethra;
• urinary retention;
• burning and feeling of heaviness in the urethra.

The prognosis for this type of disease is favorable, the risk of serious complications is minimal.

Treatment: washing the urethra with saline to remove fly larvae from it.

Skin myiasis

With this type of disease, both the surface layer of the skin (epidermis) and the connective tissue layers are affected. Often the disease proceeds as a boil, differing only in migration from one area on the body to another.

Symptoms of cutaneous (subcutaneous) myiasis:

• the appearance of a moving subcutaneous swelling;
• itching and burning in the area of ​​swelling;
• the occurrence at the site of swelling of the ulcer;
• allergic reaction in the area of ​​swelling.

With timely treatment, the prognosis is favorable, but in its absence, severe and deep ulcers, as well as severe allergic reactions, may occur.

Treatment: surgical removal of the larvae from the skin, followed by treatment of the wound with antiseptics.

Eye myiasis (ophthalmomyiasis)

Symptoms of ocular myiasis (ophthalmomyiasis):

• pain in the eyeball;
• visual disturbances (its decrease in the affected eye, the appearance of flies, double vision);
• lacrimation, redness of the affected eye.

An extremely dangerous form of the disease, often leading to loss of vision or even death.

A relatively rare form of the disease, usually found in people without a fixed place of residence or in animals.

Symptoms of nasal (nasal) myiasis:

• pain (including bursting) in the nasal passage;
• copious secretion of nasal mucus;
• sneezing
• redness of the skin of the nose.

Due to its proximity to the eyes and brain, this form of the disease is considered dangerous, so treatment should be started immediately.

Infection with ear myiasis in the vast majority of cases occurs with the passive participation of a person, usually in a dream. Drug therapy and washing with this form of the disease are meaningless, the only method of treatment is surgery.

Symptoms of ear myiasis (otomias):

• bursting pain in the ear canal;
• congestion of the affected ear, hearing loss;
• inflammation of the affected ear (normal touching causes pain).

This form of the disease is dangerous because the larvae can drill passages from the affected ear to the brain, which can result in meningitis, thrombosis of the venous sinuses and, accordingly, the death of the patient.

Myiasis refers to all diseases caused by the larvae of many species of flies. Simply put, myiasis is a general term that includes many diseases. But what specific diseases are caused by fly larvae?

Fly larvae lead to the development of the following human and animal diseases:

1. Wolfarthiosis. The causative agent is the larva of the Wolfart fly. The disease affects humans and animals, leading to unbearable pain, tissue necrosis and often death.
2. Gastrophilia. The causative agent is the larva of the gadfly Gastrophilus equi. The disease affects mammals (including humans), leading to extensive damage to various organs.
3. Hypodermatosis. The causative agent is the larvae of the gadflies Hypoderma bovis and Hypoderma lineatum. The disease affects humans and cattle, leading to the formation of ulcerative diseases of the gastrointestinal mucosa.
4. Dermatobiasis. The causative agent is the larva of the gadfly Dermatobia hominis. The disease affects humans and animals, leading to the development of local inflammation and abscesses.
5. Cordylobiosis. The causative agent is the larva of the fly Cordylobia anthropophaga. The disease affects animals and humans, leading to the development of abscess nodes, ulcers and boils (especially in children).

Myiasis treatment

In the vast majority of cases, myiasis is treated with the help of medications aimed at destroying the larvae, reducing inflammation and destroying the secondary infection. For these purposes, such means as "Mebendazole", "Penicillin", "Difezil" and so on are used.

Surgical intervention is also very effective, in which fly larvae and necrotic (literally dead) body tissues are removed from the affected organs. In addition, during surgical intervention, purulent masses are drained from the site of introduction of the larvae.

Surgical treatment is used both as an analogue of drug treatment, if the use of the second is meaningless or difficult, and as a primary treatment to achieve a rapid subsidence of inflammatory and allergic phenomena.

For reference! When the larva passes to the next stage, it no longer poses any danger to humans.

Infection with cutaneous myiasis can occur in several ways:

Oral (dental) myiasis is diagnosed less frequently than cutaneous myiasis, but it can also cause problems for a person. The larva, along with food, enters the oral cavity. The disease is accompanied by symptoms such as:

• constant itching in the mouth;
• swelling of the gums;
• nasal congestion;
• long-lasting cough;
• general malaise;
• increased body temperature;
• fever;
• gum bleeding.

The disease is oral, caused by the larvae of the wolfarth fly. The risk group includes patients who do not follow the rules of personal hygiene, for example, do not brush their teeth at least once a day. Also, the disease can overtake people with purulent wounds in the oral cavity, alcoholics, the elderly.

Intestinal myiasis is diagnosed when the larva first enters the oral cavity, then moves into the gastrointestinal tract. When the intestine becomes infected, the patient feels severe pain in the abdomen.

Intracerebral infection is extremely rare. The symptoms of this disease are slightly different from the usual disease. The patient is worried about convulsive conditions, high body temperature, back pain, the appearance of boils.

Important! To cure intracerebral myiasis, surgery is necessary. The surgeon will mechanically remove all the larvae.

How to diagnose an infection?

Diagnostic measures are based on the detection of fly larvae in wound discharge, urine, vaginal swab, or vomit. It is extremely important to ensure that the material for analysis is selected in compliance with sanitary standards.

The doctor establishes the diagnosis of cutaneous myiasis after a thorough examination of the affected area with a magnifying glass and good lighting. These devices allow you to detect the movement of larvae inside the wound. To confirm the diagnosis of otomiasis, you will need to consult an otolaryngologist, and an ophthalmologist detects eye pathology.

As an additional treatment, folk recipes are used.

1. For effective treatment, sulfur and birch tar are required. Take 4 large spoons of tar liquid and mix with 6 grams of sulfur and 3 vaseline. Ready homemade ointment must be used for skin infection.
2. You can make healing tea from currants and fennel. Such a drink is useful to drink with intestinal myiasis. You can also add cumin and cinnamon as seasonings to the dish. Take garlic and onions regularly as a preventive measure.
3. With intestinal infection, they drink an infusion of celandine. For cooking, you need a large spoonful of chopped herbs. It should be poured with a glass of boiling water. The finished product is drunk in the morning and afternoon before meals.

Preventive measures

1. To prevent such types of diseases, it is important to comply with sanitary and hygienic requirements. And keep the food clean.
2. If you have pets in your house, it is important to monitor their health and treat wounds in time.
3. If a person has open wounds on the body, then the dressings should be changed regularly.
4. It is better to clean the room with disinfectants.

Timely measures will positively affect the cure of the disease. But it is better to take care of your health in advance!