biology

Myiasis

Myiasis is a biology topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Myiasis rather than just read about it. In short: Myiasis ( my-EYE-ə-səss), also known as flystrike or fly strike, is the parasitic infestation of the body of a live animal by fly larvae (maggots) that grow inside the host while feeding on its tissue. Although flies are most commonly attracted to open wounds and urine- or feces-soaked fur, some species (including the most common myiatic flies—the botfly, blowfly, and screwfly) can create an infestation even on unbr…

Key takeaways

Myiasis belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Myiasis to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Myiasis from memory before moving on to harder problems.

Reference excerpt

Myiasis ( my-EYE-ə-səss), also known as flystrike or fly strike, is the parasitic infestation of the body of a live animal by fly larvae (maggots) that grow inside the host while feeding on its tissue. Although flies are most commonly attracted to open wounds and urine- or feces-soaked fur, some species (including the most common myiatic flies—the botfly, blowfly, and screwfly) can create an infestation even on unbroken skin. Non-myiatic flies (such as the common housefly) can be responsible for accidental myiasis. Because some animals (particularly non-native domestic animals) cannot react as effectively as humans to the causes and effects of myiasis, such infestations present a severe and continuing problem for livestock industries worldwide, causing severe economic losses where they are not mitigated by human action. Although typically a far greater issue for animals, myiasis is also a relatively frequent disease for humans in rural tropical regions where myiatic flies thrive, and often may require medical attention to surgically remove the parasites. Myiasis varies widely in the forms it takes and its effects on those affected. Such variations depend largely on the fly species and where the larvae are located. Some flies lay eggs in open wounds, other larvae may invade unbroken skin or enter the body through the nose or ears, and still others may be swallowed if the eggs are deposited on the lips or food. There can also be accidental myiasis that Eristalis tenax can cause in humans via water containing the larvae or in contaminated uncooked food. The name of the condition derives from ancient Greek μυῖα (myia), meaning "fly".

Signs and symptoms How myiasis affects the human body depends on where the larvae are located. Larvae may infect dead, necrotic (prematurely dying) or living tissue in various sites: the skin, eyes, ears, stomach, and intestinal tract, or in genitourinary sites. They may invade open wounds and lesions or unbroken skin. Some enter the body through the nose or ears. Larvae or eggs can reach the stomach or intestines if they are swallowed with food and cause gastric or intestinal myiasis. In extremely rare cases, maggots may occasionally infest the vulvar area. Several different presentations of myiasis and their symptoms:

Wound Wound myiasis occurs when fly larvae infest open wounds. It has been a serious complication of war wounds in tropical areas and is sometimes seen in neglected wounds in most parts of the world. Predisposing factors include poor socioeconomic conditions, extremes of age, neglect, mental disability, psychiatric illness, alcoholism, diabetes, and vascular occlusive disease.

Eye Myiasis of the human eye or ophthalmomyiasis can be caused by Hypoderma tarandi, a parasitic botfly of caribou. It is known to lead to uveitis, glaucoma, and retinal detachment.

Cause

Life cycle The life cycle in sheep is typical of the disease. The female flies lay their eggs on the sheep in damp, protected areas of the body that are soaked with urine and feces, mainly the sheep's breech (buttocks). It takes approximately eight hours to a day for the eggs to hatch, depending on the conditions. Once hatched, the larvae then lacerate the skin with their mouthparts, causing open sores. Once the skin has been breached, the larvae then tunnel through the sores into the host's subcutaneous tissue, causing deep and irritating lesions highly subject to infection. After about the second day, bacterial infection is likely and, if left untreated, causes bacterial bloodstream infections or sepsis. This leads to anorexia and weakness and is generally fatal if untreated.

Species affecting humans There are three main fly families causing economically important myiasis in livestock and also, occasionally, in humans:

Calliphoridae (blowflies) Some examples include Calliphora vomitoria, Calliphora vicina, and Cordylobia Oestridae (botflies) Sarcophagidae (fleshflies) Sarcophaga barbata are usually found in dead and rotting meat and animal excrement, which are prime environments for them. This is because their larvae are facultative parasites, as they feed on organic tissue and use the hosts' oxygen reserve. Other families occasionally involved are:

Anisopodidae Piophilidae Stratiomyidae Syrphidae

Specific myiasis Caused by flies that need a host for larval development:

Dermatobia hominis (human botfly) Cordylobia anthropophaga (tumbu fly) Cordylobia rodhaini (Lund's fly) Oestrus ovis (sheep botfly) Hypoderma spp. (cattle botflies or ox warbles) Gasterophilus spp. (horse botfly) Cochliomyia hominivorax (new world screwworm fly) Chrysomya bezziana (old world screwworm fly) Auchmeromyia senegalensis (Congo floor maggot) Cuterebra spp. (rodent and rabbit botfly)

Semispecific myiasis

Caused by flies that usually lay their eggs in decaying animal or vegetable matter, but that can develop in a host if open wounds or sores are present:

Lucilia spp. (green-bottle fly) Cochliomyia spp. (screw-worm fly) Phormia spp. (black-bottle fly) Calliphora spp. (blue-bottle fly) Sarcophaga spp. (flesh fly or sarcophagids) Flesh flies, or sarcophagids, members of the family Sarcophagidae, can cause intestinal myiasis in humans if the females deposit larvae on meat or fruit.

Accidental myiasis Accidental myiasis, also called pseudomyiasis, occurs when fly larvae are ingested or deposited on the body, leading to an infestation. It is caused by flies that have no preference or need to develop in a host but may do so on rare occasions. Transmission occurs through accidental deposit of eggs on oral or genitourinary openings, or by swallowing eggs or larvae that are on food. Enteric pseudomyiasis can cause nausea, vomiting and gastrointestinal upset. The cheese fly (Piophila casei) sometimes causes myiasis through intentional consumption of its maggots (which are contained in the traditional Sardinian delicacy casu marzu). Other flies that can accidentally cause myiasis are:

Musca domestica (housefly) Fannia spp. (latrine flies) Eristalis tenax (rat-tailed maggots) Muscina spp. The adult flies are not parasitic, but when they lay their eggs in open wounds and these hatch into their larval stage (also known as maggots or grubs), the larvae feed on live or necrotic tissue, causing myiasis to develop. They may also be ingested or enter through other body apertures.

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Myiasis

Start with the simplest possible case. Write down what Myiasis claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Myiasis before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Myiasis ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Myiasis

In research: Myiasis appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Myiasis in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Myiasis is common in secondary-school and first-year university syllabi. It links to neighbouring topics Arthropod infestations, Parasitic infestations, stings, and bites of the skin, Sheep and goat diseases, so understanding it makes those chapters shorter.
In everyday life: Look for Myiasis outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Myiasis in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Myiasis means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Myiasis out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Myiasis in simple terms?

Why does Myiasis matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Myiasis?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Myiasis.