Blowfly larvae in humans

Myases – parasitic diseases caused by fly larvae found in the tissues and cavities of humans or animals.

What types of myiases occur and how infection occurs in humans or animals is given in the table.

What to do in such a situation? To get started, we recommend reading this article. This article describes in detail methods of controlling parasites. We also recommend that you consult a specialist. Read the article >>>

Kinds	Infection
Random.	Through dirty bed, clothes, food.
Obligate (cannot live outside the human body).	Wohlfarth fly.
Facultative (they live freely, but once in the human body, they switch to parasitic life).	Flesh flies.

What is myiasis in humans

The causative agents of myiasis are fly larvae. As a rule, their habitat is tropical latitudes. Found in Africa, South America. Often tourists returning from these places bring this disease with them.

Tropical fly that causes myiasis

The larvae enter the human body with untreated water. They penetrate not only the damaged surface of the body, but also healthy skin. They can get into the eyes, sinuses, and ears, causing a disease called myiasis.

Depending on the location of the larvae in the human body, myiasis has different names:

• cutaneous;
• subcutaneous;
• intestinal;
• urogenital;
• oral;
• African tropical myiasis.

Stages of larval development

The larval stage of the gadfly usually lasts 6-10 weeks. After entering the host’s body, the parasite begins to intensively feed on blood, drawing out useful substances. In a few weeks it increases in size tens of times, and the mature larva reaches 2 cm.

The photo shows a small gadfly larva extracted from a human body.

Having collected the necessary supply of nutrients from the host, the parasite breaks through the skin and crawls out. After this, a new stage of development of the gadfly begins - the pupa. In this phase, the insect arrives for 2-4 weeks, after which it turns into an adult, the life cycle of which is 20 days, the main task of the fly is reproduction.

Cutaneous myiasis: symptoms and treatment

Skin or tissue myiasis is a disease in which the larvae of flies (or gadflies) live and reproduce in the skin, epidermis. They do not emerge from the epidermis to the surface.

Symptoms

Once in the subcutaneous tissue, the larvae spread throughout the body, breaking through passages and thereby causing unbearable itching and pain. Sometimes you can see subcutaneous migration of these parasites. The larvae move quite quickly; they can move 24 cm in a day.

Cutaneous myiasis

In appearance, these passages are similar to scratches that are in the healing stage. As the larva grows and begins to molt, it develops a capsule. This capsule causes infiltration.

The infiltrating area grows and ruptures after a few days. From this gap the larva emerges to the surface. The rupture site dries out without causing deep wounds.

Treatment

1. Wash the wound with an antiseptic (furacilin, potassium permanganate).
2. Drop any oil (camphor, vaseline, etc.) into the infiltrate hole.
3. Use tweezers to pull out the parasite that has crawled out.
4. Treat the wound with a disinfectant solution and apply a bandage.

The larva must be pulled out very carefully, without allowing it to rupture. Otherwise, the site where the larva emerges becomes infected, and suppuration develops, which leads to a large abscess.

Consequences

Infection with the subcutaneous botfly leads to the following consequences:

• Cows have a decrease in milk yield by approximately 7%.
• Young animals have growth retardation.
• For the leather industry - the skin of animals that have suffered from hypodermatosis has holes, which spoils the raw hides.
• For the meat industry, the capsules in which the larvae developed require removal, due to which a fairly large amount of meat is lost; sometimes, with severe contamination, about 10% of the raw materials have to be cut out.

We suggest you read: How many children does a cockroach have at a time?

If signs of infection are detected, animals are slaughtered exclusively in sanitary slaughterhouses.

Subcutaneous myiasis: symptoms and treatment

With subcutaneous myiasis, the larva penetrates from the epidermis into the connective tissue. Re-invasion through the skin is possible.

The disease has an acute form. For its development and transformation into a sexually mature individual, the larva actively feeds on connective tissue. Its penetration is also possible into deeper layers of tissue. When colonized extensively, the tissues are eaten down to the bones.

Exit of fly larvae

Externally, the skin in the area where the parasites live appears thickened and reddened. As the larvae move, you can see swelling that leads to boils. A larva crawls out of the opened boils and leaves the human body.

One larva parasitizes in the subcutaneous layer for up to 6 days, but the damage caused to it is significant.

Symptoms

In its acute form, the disease manifests itself by the following factors:

• rise in temperature;
• pain, burning in muscles;
• sensation of movement inside the skin;
• weakness;
• hives.

Treatment

Treatment is the same as for cutaneous myiasis.

Description of the disease

Myiasis refers to entomosis - diseases that are caused by various types of insects. The group of entomoses includes such common diseases as pediculosis (infestation with lice) and caterpillar dermatitis (skin irritation after contact with the hairs on the body of caterpillars).

The mechanism of development of myiasis is as follows: the female fly lays eggs or live larvae on the mucous membranes, skin, wounds and abrasions on the body of a person or animal. The larvae feed on the tissues of the victim and make passages in the muscles. The victim experiences severe pain, the damaged areas become inflamed, swollen, and rot.

Some fly larvae in humans can move at speeds of up to 30 cm per day, so the area affected by the body can be huge. Sometimes parasites reach the stomach and brain.

Fly larvae can be under the skin of a person
. Flies that lay larvae under the skin:

• Tumbu is a large insect that lives in Africa;
• Wohlfarth fly is found in the Middle East, the Asian part of Russia, China and North Africa;
• Gadflies - scientists count about 150 species of gadflies.

Fly eggs laid under the skin during a bite are practically undetectable, so at first myiasis develops unnoticed: the person thinks that he has an ordinary pimple on his body. Infection with larvae can occur not only through an insect bite: for example, a female tumbu fly lays eggs in the soil, on dirty clothes. If the larvae emerging from the eggs come into contact with human skin, they immediately invade it.

Intestinal, genitourinary and oral myiases

Intestinal

Intestinal myiases occur when a person swallows fly eggs. As a rule, these are eggs of blowflies or carrion flies.

Possible entry into the human body through ingestion of dust when transplanting flowers in which there were eggs in the soil. There have been cases of banana infestation with larvae.

Swallowed eggs and larvae move through the gastrointestinal tract and enter the large intestine. They do not parasitize the intestinal mucosa.

Often infection occurs asymptomatically. However, with intensive infestation, the number and type of parasites may show signs of disease.

Symptoms

• discomfort in the intestines;
• cramping pain;
• vomiting reflex;
• tenesmus;
• anal itching;
• loose stool streaked with blood.

In rare cases, parasites can enter the brain and heart through the blood circulation. In this case, death is possible.

Treatment

1. Prescribing laxatives.
2. Taking antinematode drugs.

Urogenital

With genitourinary myiasis, parasitism of the larvae occurs in the woman’s genital organs, in the urethra, in the penis, in the anus.

Symptoms

• pain when urinating;
• urinary retention;
• severe itching.

Treatment

1. Rinsing the genitourinary organs with an antiseptic solution.
2. Taking anthelmintic drugs.

Since flies are also carriers of worms, treatment is carried out comprehensively.

Oral

During oral infection, parasites penetrate the gums and oral tissues. In children, the course of the disease is severe. Possible death.

Symptoms

• itching and swelling of the gums;
• cough;
• nasal congestion;
• fistulas on the lips;
• fever;
• mouth ulcers;
• pain when chewing.

Larvae in the mouth

Treatment

1. Mechanical removal of parasites.
2. Taking anthelmintics.
3. Prescribing antibiotics.

Fortunately, oral myiasis is a fairly rare disease.

Larva: what does it look like and reproduce?

The white maggot in a person must go through 3 stages of development. Moreover, at each stage the larva acquires a certain shape.

At first these are legless and headless white worms. In one part of the body there is a thickening and three black stripes.

When the larva is in the second stage of development, it increases in size and takes on the shape of a bottle. In the third stage it becomes even larger. Moreover, at each stage, spines and small black dots appear surrounding the thorax of the microorganism.

The larva has 2 posterior spiracles with which it breathes. After being introduced under the human skin, the spiracles remain at the same level with the dermis.

The duration of the initial stage of development is 7 days, after which the larva molts and moves on to the next phase. After 18 days, she sheds again and then the third stage begins.

After a month, the parasite grows into an adult. At the same time, it continues to parasitize the host’s body for about 12 weeks. Next, the gadfly crawls out from under the skin, leaving the person and falling to the ground.

The larva can take liquid food, since its pharynx is adapted to this. It feeds on the fluids and tissues of the host's body, secreting special dermatolytic enzymes that allow it to dissolve solids.

The larva, which has left the human body, pupates in the soil without feeding on anything. After 14-21 days, an adult insect crawls out of it, which after 2-3 minutes becomes ready to fly.

The gadfly has poor eyesight, but very sensitive palps. Thanks to this, females and males quickly find each other and mate.

Features of reproduction

Insects are characterized by sexual dimorphism, that is, it is quite easy to distinguish between a male and a female by appearance. They have different sizes (in many species, females are several times larger than males), differ in color, and the length of their antennae. In some butterfly species, females do not have wings.

Communication between opposite-sex representatives of a species occurs in various ways:

• Using behavioral characteristics.
• Sound and color signals.
• Chemically - by releasing pheromones.

African tropical myiasis

African tropical myiasis causes a disease called cordylobiosis. This is a type of deep myiasis.

Cordylobiosis

When larvae enter through the skin, an infiltrate is formed. This infiltrate grows and a node is formed that looks like a boil.

This boil contains the larva and the products of its excretion. A characteristic feature of such a boil is a hole for the free breathing of the larva.

With African myiasis, the larvae eat everything: mucous membranes, soft tissues, eye sockets, cartilage, etc. causing irreparable harm to the body.

After a week, the larva leaves the human body.

Symptoms

• severe itching at the location of the parasite;
• swelling;
• strong pain;
• boil formation.

Treatment

1. Parasite extraction
2. Treating the wound with an antiseptic.
3. Applying a sterile dressing.

Do not remove parasites yourself. Rupture of the larva's body will lead to complications!

Myiases in cats and dogs

Myiasis in cats and dogs is not a common occurrence. This is due to the fact that animals carefully lick the affected areas. However, in hard-to-reach places, in weakened animals, this parasitic disease may appear.

The main types of myiases in cats and dogs.

Types of myiases	Symptoms	Treatment
Cutaneous	Anxiety, appearance of wounds.	Remove parasites; treat wounds with antiseptics.
Subcutaneous	Loss of appetite, aggressive behavior, festering wounds, itching. In more severe forms - increased body temperature, depression.	Remove parasites; wash wounds with antibiotics; apply Vishnevsky ointment.
Intestinal	Depression, vomiting, diarrhea, fly larvae in the stool.	Give a laxative and anthelmintic.

The larvae are removed from the animal's body under general anesthesia.

To avoid serious complications, check your dogs' skin regularly. If you notice lumps under the skin, contact your veterinarian immediately.

Do not ignore the appearance of boils and subcutaneous tubercles. If there is any change in the skin, consult a doctor. The earlier treatment is started, the less harm the parasite will cause to the body.

Why do random and facultative myiases occur?

The main cause of these types of disease is common unsanitary conditions. Neglect of personal hygiene and room cleanliness leads to the proliferation of flies, which sooner or later will lay eggs on humans.

Obligate myiases

Caused by flies that initially parasitize warm-blooded organisms. Their other name is gadflies. The reproductive cycle of different individuals may include parasitism of maggots in the stomach, nasal sinuses, or skin.

The gastric botfly attaches eggs to the forelimbs of herbivores. When an animal scratches its leg, it inadvertently ingests eggs, which begin to develop in the gastrointestinal tract. Gastric botfly eggs do not die in the intestines, but humans have little chance of becoming infected with these parasites. The disease is treated with routine deworming of animals. Standard anthelmintic drugs also help a person.

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