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Linear migrating miase: causes, symptoms, diagnosis, treatment
Last reviewed: 23.04.2024
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[What causes a linear migrating miasis?
The causative agent of the linear migrating miase is Gadrophilidae gadfly larvae : gastrophilus eque (parasitizes in the stomach and intestines of the horse) and less often G. Intestinalis, G. Veterinus, G. Haemorhoidalis, G. Pecorum.
Symptoms of a linear migrating miase
Linear migrating miase in a temperate climate is most often observed in the summer. Female gadfly lay eggs, attaching them to the horse's hair or cattle. The larvae hatching from the testicles during parasitization on the skin of animals, continuing their development, pierce the intradermal trenches and cause itching. During the licking of animals with itchy skin areas, a part of the larvae get to them on the tongue, and from there - into the stomach and intestines. Here the larvae, adhering to their walls, continue to develop. Having reached its full development in the gastrointestinal tract, the larvae then, together with the feces, find themselves in the environment, where they pupate. A person is most often infected by contact with animals, on the wool of which there are larvae of the first stage.
After the larva enters the human skin, it, thanks to its strong biting organs (chitinous hooks), digs the upper layers of the epidermis, penetrates into it and then makes long zigzag-like, sometimes whimsical patterns, like tunnels on the border with the dermis.
At the place where the larva enters the skin, there is an itchy papule-vesicle that transforms into a pustule, surrounded by an acute-inflammatory corolla. The larva advances in the skin mainly at night, and during the night it can make a course length from 4-5 to 25-30 cm and more. Clinically, on the skin in the area of parasitic larvae, an uninterrupted narrow (up to 0.5 mm in width) pale pinkish color slightly edematous line is seen, which strictly corresponds to the larval incision in the skin. Palpable sometimes you can catch that the line is slightly elevated, and outwardly it looks strikingly similar to the bands of sublime dermographism.
Often the movement of the larva in the epidermis can be determined by slightly more juvenile inflammatory phenomena in the region of the head end of the manifested line. In other words, the mobile (active) end of the line is somewhat wider, juicier and more intense.
Despite this, attempts to locate the larva at the most clearly visible end of the strip and its removal are usually unsuccessful, since the larva usually, as a rule, already somewhere further, i.e., in a clinically as yet nonreactive skin lesion zone. In addition, observations of the presence of branching locations of the courses suggested that the larva may return back in the process of its movement and continue its movement in the other direction.
Sometimes in the head part of the stroke, 1-3 cm further from the end of the visible line of movement of the larva, it is possible to determine palpation with a lenticular thickening. Often a living larva can be removed with the help of a needle.
Typically, the lesion is a single, although there are cases of simultaneous introduction and parasitization in the skin of several larvae. The disease is most often observed in children, as well as in women with tender skin. Representatives of the white race in the tropics fall ill more often than the indigenous population. As the disease develops in places earlier moves, the juiciness and brightness of the inflammatory hue gradually decrease, and brownish nuances appear, and sometimes hardly noticeable band-like peeling.
Linear migrating miase usually does not cause trouble to patients. Only occasionally, in addition to mild itching and a certain burning sensation along the larval movement, general symptoms of a linear migrating miase are observed in the form of mild fever, nausea, and in some cases excitement, anxiety and even convulsions in children. The process lasts 1-2 months, less often longer. Despite such a long period, the full development of the larva of the gastric gadflies in human skin still does not undergo. They are usually either extracted or killed under the influence of certain medications.
There are cases of simultaneous destruction of several people in production conditions, especially at stud farms, which can serve as the basis for diagnosing a professional miase with the corresponding socio-economic consequences.
What do need to examine?
Treatment of linear migrating miase
A linear migrating miase is treated by detecting the larvae when examining the skin with a magnifying glass, and especially with side lighting. It is also possible to place the larvae in the presumed position with oil (vaseline, peach, etc.). After this, a thin needle or ophthalmic scalpel can try to extract the larva from the epidermis.
Treatment of linear migrating miase, in addition to mechanical extraction, consists of diathermocoagulation, cryotherapy, freezing with chloroethyl, liquid nitrogen.