Myiasis is the infestation of living tissue by fly larvae, commonly known as maggots. It happens when certain species of flies lay their eggs on or near a person’s skin, wounds, or body openings, and the hatching larvae burrow in and feed on tissue or body fluids. While the condition is most common in tropical and subtropical regions, it can occur virtually anywhere, and cases in temperate climates appear to be on the rise. The condition ranges from a minor skin nuisance to a serious, tissue-destroying emergency depending on the fly species involved and where the larvae take hold.
What Myiasis Actually Is
The term covers any situation in which fly larvae develop inside or on a living vertebrate host, whether human or animal. The larvae of different fly species behave differently once they contact a host: some feed on dead or decaying tissue within a wound, some consume healthy living flesh, and others feed on the host’s body fluids or even ingested food within the gut.1Clinical Microbiology Reviews. Myiasis Because the larvae’s habits vary so widely, doctors and entomologists classify myiasis by two overlapping schemes: by the body site affected (cutaneous, wound, oral, nasal, urogenital, ocular, and others) and by how dependent the fly is on a living host to complete its life cycle.
Flies that cause myiasis fall into three broad categories based on that dependency. Obligate parasites can only develop inside living tissue; they must infest a host. Facultative parasites normally breed in decaying organic matter but will opportunistically colonize a wound or neglected skin fold if given access. And accidental agents are flies whose larvae are swallowed or otherwise enter the body by chance, typically through contaminated food. The obligate species tend to cause the most damage because their larvae are adapted to burrow into and consume healthy flesh.
How People Get Infested
The routes of transmission depend on the fly species, and some are more inventive than others. Many wound-infesting flies simply land directly on an open wound, a moist skin fold, or a mucous membrane and deposit eggs. The warmth and odor of damaged or infected tissue attract gravid females from a distance, which is why people with untreated wounds, poor hygiene, or conditions like diabetes that produce chronic sores are at higher risk.2European Surgery. Wound myiasis in Western Europe: prevalence and risk factors in a changing climate scenario
The human botfly of Central and South America, Dermatobia hominis, takes a more elaborate approach. Rather than visiting a host directly, the female botfly captures a blood-feeding insect like a mosquito or a stable fly, glues her eggs to its body, and releases it. When that carrier insect lands on a warm-blooded host to feed, the body heat triggers the botfly eggs to hatch, and the tiny larvae drop onto the skin and burrow in. The glue that attaches the eggs to the carrier is remarkably durable, remaining strong for decades under laboratory conditions.3International Journal of Insect Morphology and Embryology. Morphology of the eggs of the human bot fly, Dermatobia hominis (L. Jr.) (Diptera : Cuterebridae) and their adherence to the transport carrier This hitchhiking strategy is one reason the botfly is hard to control with simple insecticide spraying around human habitation.
The tumbu fly (Cordylobia anthropophaga) of sub-Saharan Africa has yet another method. Females lay eggs in soil contaminated with urine or on damp laundry hung out to dry. When a person wears the clothing or walks barefoot on the soil, the larvae penetrate the skin. A case report described a medical student who developed a boil-like lesion on his foot three weeks after returning from a trip to Tanzania; a tumbu fly larva was found inside.4PubMed Central. Furuncular myiasis of the foot caused by the tumbu fly, Cordylobia anthropophaga: report in a medical student returning from a medical mission trip to Tanzania In endemic areas, ironing clothes after line-drying is a well-known preventive measure because the heat kills any eggs on the fabric.
Which Flies Cause the Most Damage
Among the most destructive agents are the screwworm flies. The New World screwworm, Cochliomyia hominivorax (its species name literally means “man-eater”), is an obligate parasite whose larvae feed exclusively on living tissue. It primarily targets livestock but will readily infest humans, especially through wounds or even intact mucous membranes. Its Old World counterpart, Chrysomya bezziana, operates the same way in Africa, the Middle East, and South and Southeast Asia.5PubMed Central. A “boring” worm? New World screwworm neuromyiasis in a patient with Darier disease Screwworm larvae can destroy large volumes of tissue quickly; an untreated infestation in a wound can be fatal.
Other significant species include Lucilia sericata and Lucilia cuprina, commonly called green bottle blowflies, which are primarily facultative parasites of wounds and damp fleece in sheep but occasionally infest human wounds. The Wohlfahrtia species cause wound myiasis in parts of Europe and Asia. And the botflies and tumbu flies mentioned above cause furuncular myiasis, in which each larva produces a single, boil-like nodule in the skin with a tiny breathing hole at its center.
Who Is Most at Risk
Myiasis is not random. Certain conditions make infestation far more likely. The common risk factors include advanced age, poor hygiene, malnourishment, social isolation, diabetes, cancer, and peripheral artery disease.6European Surgery. Wound myiasis in Western Europe: prevalence and risk factors in a changing climate scenario The thread connecting these is reduced ability to detect or respond to fly activity on the body. An elderly person living alone with a chronic leg ulcer may not feel larvae entering a wound or may lack the mobility to keep flies away. A patient with advanced head and neck cancer may have exposed, necrotic tissue that attracts egg-laying flies, leading to infestations that cause severe pain, foul odor, rapid tissue destruction, and profound psychological distress.7PubMed. Management of myiasis in advanced head and neck cancers: a comprehensive review
Travelers to tropical regions form another distinct risk group. Most cases diagnosed in Western Europe and North America are “imported,” brought home from trips to Central and South America, sub-Saharan Africa, or Southeast Asia. The latency period between exposure and symptoms can be days to weeks, so the patient is often already home before noticing anything.
Diagnosing Myiasis
In furuncular myiasis, the classic sign is a boil-like swelling with a central pore through which the larva breathes. Patients often report a sensation of movement beneath the skin. Wound myiasis is usually obvious once someone looks: the larvae are visible in or around the wound. But in cases where larvae have burrowed deeper into skin folds or tissue, additional tools help. Ultrasound has been used to detect maggots hiding below skin crevices, as in a documented case involving a patient with severe lymphedema.8PubMed Central. Sonographic Detection of Cutaneous Myiasis
Dermoscopy, the same magnification tool dermatologists use to examine moles, has proven useful for confirming furuncular cases. Under magnification, clinicians can see the posterior end of the larva, including its respiratory spiracles (the structures through which it breathes), which have a distinctive branching shape. Larval movement and tiny air bubbles at the pore are also visible.9PubMed. A dermoscopic study of cutaneous myiasis: other findings The surrounding skin often shows dilated blood vessels and a pale halo around the central opening.10PubMed Central. Dermoscopy as an auxiliary tool for the diagnosis of furuncular myiasis Identifying the species of the removed larva matters because it can reveal the geographic origin of infestation and guide surveillance efforts.
Treatment and Removal
Treatment is conceptually simple: get the larvae out. The specifics depend on the type of myiasis. For furuncular cases, the standard first step is to cover the breathing pore with an occlusive substance, such as petroleum jelly, bacon fat, or even nail polish, which cuts off the larva’s air supply and often forces it to migrate toward the surface, making extraction easier. Once the larva is partially protruding, it can be pulled out with forceps. Squeezing too hard risks rupturing the larva, which can trigger a significant inflammatory reaction.
For wound myiasis, the approach involves applying a suffocating agent and then manually removing visible larvae, sometimes over multiple sessions. In one reported case of orbital myiasis in an empty eye socket, turpentine oil was applied as the suffocating agent, and a total of twelve larvae were removed over the course of a week.11BMJ Case Reports. Orbital myiasis in eviscerated socket and review of literature After removal, the wound is irrigated and treated with topical or systemic antibiotics if secondary bacterial infection is present. Ivermectin, an antiparasitic drug, is sometimes used as an adjunct, especially for deep or widespread infestations that are difficult to clear mechanically.
The Livestock Dimension
Myiasis is arguably a bigger problem in veterinary medicine than in human health, at least in economic terms. Sheep blowfly strike, the cutaneous myiasis of sheep caused by blowflies laying eggs in soiled or damp fleece, is one of the most widespread welfare and economic issues in sheep farming globally. In Australia, the principal culprit is Lucilia cuprina, and the condition is endemic across sheep-producing regions, causing both suffering and major financial loss.12PubMed. Australian surveys on incidence and control of blowfly strike in sheep between 2003 and 2019
Economic modeling has shown that prophylactic treatment of flocks is almost always cheaper than doing nothing, because the deaths caused by untreated strike outweigh the cost of prevention. Lambs are at highest risk during peak fly season and benefit the most from treatment. Early-season treatment of ewes before shearing also substantially reduces strike rates.13PubMed. Sheep blowfly strike: the cost of control in relation to risk For livestock, the New World screwworm was historically devastating across North and Central America, costing the cattle industry hundreds of millions of dollars annually before a massive eradication campaign based on the sterile insect technique succeeded in eliminating the species from the continent. That eradication is considered one of the great successes in pest management, though periodic reintroductions still occur and have spurred interest in modernizing the approach with genetic engineering techniques.14PubMed. Advancing the sterile insect technique for the New World screwworm fly: the case for CRISPR-engineered genetic sexing strains
Geographic Spread and Climate Change
Myiasis has long been considered primarily a tropical disease, and most cases diagnosed in temperate regions have been travel-associated. But that picture may be shifting. New fly species are being observed in parts of Europe where they were not previously established, and rising temperatures could allow tropical species to survive and reproduce in areas that were once too cold for them.15PubMed. Myiasis in humans-a global case report evaluation and literature analysis A global case analysis warned that a noticeable increase in European cases should be expected, particularly among patients in clinical and long-term care settings.
The tumbu fly provides a concrete example. Though currently restricted to sub-Saharan Africa, changing temperature and rainfall patterns could allow it to establish breeding populations elsewhere. After a case series of tumbu fly myiasis in Italian children, researchers noted the risk that autochthonous transmission (meaning locally acquired, not travel-related) could eventually occur in regions that were previously non-endemic.16PLOS Neglected Tropical Diseases. Furuncular myiasis by Cordylobia anthropophaga in three Italian children: First case series and implications for non-endemic regions Global transport of livestock and goods adds another layer of risk by inadvertently moving fly species and larvae across borders.17PubMed. Traumatic Myiasis: A Neglected Disease in a Changing World
Maggot Therapy and Wound Healing
Here is where the story of myiasis takes an unexpected turn. The same general process that makes pathological myiasis so destructive, larvae feeding on tissue, is harnessed deliberately in medicine. Medicinal maggot therapy uses disinfected larvae of Lucilia sericata (a blowfly) placed onto chronic wounds that have resisted other treatment. The larvae clean out dead tissue (debridement), kill bacteria (disinfection), and appear to stimulate the healing process itself.18PubMed Central. Mechanisms of maggot-induced wound healing: what do we know, and where do we go from here?
The biological mechanisms behind this are increasingly well understood. The excretions and secretions released by larvae dampen the inflammatory response in ways that promote healing rather than tissue destruction. In laboratory studies, maggot secretions reduced the output of pro-inflammatory signaling molecules from human immune cells while boosting production of anti-inflammatory ones.19PubMed Central. Maggot secretions suppress pro-inflammatory responses of human monocytes through elevation of cyclic AMP Separately, those same secretions slowed the migration of neutrophils (a type of white blood cell central to inflammation) and inhibited their release of tissue-damaging enzymes, without impairing their ability to kill invading microbes.20PubMed. Maggot excretions/secretions inhibit multiple neutrophil pro-inflammatory responses In effect, the larvae dial down the runaway inflammation that keeps chronic wounds from healing, while leaving the immune system’s pathogen-killing function intact.
Antimicrobial Compounds From Fly Larvae
Beyond their direct use in wound care, maggots are becoming a source of novel antimicrobial compounds at a time when antibiotic resistance is a growing global threat. Researchers have identified dozens of antimicrobial peptides produced by blowfly larvae, small proteins that kill bacteria and fungi through mechanisms different from conventional antibiotics. A study of Lucilia sericata identified 47 genes encoding potential antimicrobial peptides, including novel members of several peptide families. Synthetic versions of many of these showed activity against a broad range of troublesome pathogens, including Pseudomonas aeruginosa and Enterococcus faecalis. Some are already being produced in bulk for testing in therapeutic wound dressings.21PubMed Central. Antimicrobial peptides expressed in medicinal maggots of the blow fly Lucilia sericata show combinatorial activity against bacteria
Work on other blowfly species has confirmed the trend. A peptide called cecropin A2 from Lucilia illustris showed the strongest antimicrobial activity of any peptide tested against a panel of bacteria and fungi, without damaging human red blood cells, a key safety requirement for any potential drug.22PubMed. Characterization of anti-microbial peptides and proteins from maggots of Calliphoridae and Sarcophagidae fly species (Diptera) A broader review of maggot-derived antimicrobial compounds emphasized that the collective evidence points toward real potential for developing new anti-infectives from these sources, particularly as resistance to existing antibiotics continues to rise.23PubMed. Antimicrobial Potential of Maggot Excretions/Secretions From Blowflies (Diptera: Calliphoridae)
Myiasis in Forensic Investigation
Fly larvae on or in a body carry information, and forensic investigators use them routinely. In death investigations, the species and developmental stage of fly larvae found on a body help estimate the minimum time since death. The logic is straightforward: different fly species arrive at a body in a predictable sequence, and their larvae grow at known rates depending on temperature, so the size and species of larvae found at a scene set a biological clock.24PubMed. Review on forensic importance of myiasis: Focus on medicolegal issues on post-mortem interval estimation and neglect evaluation
In living people, myiasis serves as an important forensic marker of a different kind. Finding maggots in a living person’s wounds, particularly in settings like nursing homes or home care for elderly or disabled individuals, is treated as a red flag for neglect. The reasoning is that a properly cared-for person would have their wounds cleaned, dressed, and protected from flies. Myiasis in a dependent person signals a failure of care that may have legal consequences.
How Parasitism Evolved in Blowflies
The ability to infest living vertebrates did not evolve just once in flies. Phylogenetic studies of blowflies have shown that obligate parasitism arose independently multiple times across the family Calliphoridae and also in the bot fly family Oestridae, and within at least three separate subfamilies of blowflies.25International Journal for Parasitology. The evolution of myiasis in blowflies (Calliphoridae) The ancestral blowfly was most likely a saprophage or facultative parasite, feeding on corpses or the dead tissue in wounds. From that starting point, some lineages independently crossed the threshold to obligate parasitism, meaning their larvae can only survive in living hosts.
More recent modeling of blowfly evolution supports the idea that facultative parasitism serves as an evolutionary stepping stone. Species that occasionally feed on living tissue as well as dead matter seem to represent the transitional stage between free-living scavengers and committed parasites.26PubMed Central. Origins and Diversification of Myiasis Across Blowflies This matters beyond pure academic interest. Understanding which fly lineages are on the verge of becoming obligate parasites could help predict which species pose emerging risks to livestock and human health, especially as climate shifts push fly populations into new territories.
Traditional Plant Remedies
Long before modern veterinary drugs, pastoral communities in tropical and subtropical regions developed their own approaches to treating myiasis. In southern Africa, four plants, Aloe zebrina, Clausena anisata, Erythrina lysistemon, and Spirostachys africana, have been used traditionally to combat or treat fly larvae infestations. Laboratory testing of extracts from these plants showed that they influenced the development of blowfly larvae, affecting rates of pupation, pupal mass, and adult emergence in Lucilia cuprina and Chrysomya marginalis.27PubMed. Extracts of four plant species used traditionally to treat myiasis influence pupation rate, pupal mass and adult blowfly emergence of Lucilia cuprina and Chrysomya marginalis (Diptera: Calliphoridae) This kind of ethnopharmacological research validates indigenous knowledge and may identify compounds useful in managing myiasis in settings where modern insecticides are unavailable or where resistance to them is developing.