Implications of the Use of the Myiasis for Nurse and Patient Essay

Implications of the Use of the Myiasis for Nurse and Patient Essay

For a patient, wounds are painful and can result in long periods of immobility, while from the perspective of the nursing professionals caring of wounds is demanding with the need to maintain the wound site in a condition amenable to the healing process.

Treatment of wounds using maggots or fly larvae is not a newly developed procedure, as it has been used since ancient times, but was discouraged in by modern medicine as it was believed to be a filthy process. Several factors have seen the resurgence of myiasis by the end of the twentieth century, including the concern with increasing microbial resistance to powerful antibiotics and the realization that maggots remove necrotic tissue effectively, safely and in a simple manner (Sherman, Hall & Thomas, 2000). Furthermore, myiasis has also been found to be effective in cases where the conventional procedures of debridement have not been successful (Bonn, 2000). Implications of the Use of the Myiasis for Nurse and Patient Essay.

The larvae preferred in bio-surgery are the larvae of the green bottle fly Lucilia sericata (Benbow, 2007). The exact manner in which maggots debride wounds is yet to be found. However, the mechanisms involved in debridement by maggots is believed to involve ingestion and destruction of bacteria, the exertion of a bacteriostatic effect through the increase in pH level of the wound, secretion of proteolytic enzymes that are critical to eschar degradation and increase in tissue oxygenation levels (Enoch, 2003).
Air and moisture are essential for the survival of maggots and for wound debridement and the wound site needs to be well lubricated and well supplied with oxygen in the use of myiasis. Myiasis is not used for wounds within the body cavity (Benbow, 2007).

Initial studies on the antimicrobial activity have shown myiasis to be effective in the case of wound infections from Staphylococcus aureus and Streptococcus A and B, and partial activity against Pseudomonas and methicillin-resistant Staph. aureus (MRSA), because of their antimicrobial activity against these pathogens. (Benbow, 2007).


Myiasis, a noun derived from Greek (mya, or fly), was first proposed by Hope to define diseases of humans caused by dipterous larvae, as opposed to those caused by insect larvae in general (161). Myiasis has since been defined as the infestation of live vertebrates (humans and/or animals) with dipterous larvae (371). Recognized in ancient times, flies causing myiasis are still some of the world’s most devastating insects, responsible for severe losses in animal husbandry, with significant economic losses, including reduced milk production, weight and fertility issues, and reduced hide quality (371). In mammals (including humans), dipterous larvae can feed on the host’s living or dead tissue, liquid body substance, or ingested food and can cause a broad range of infestations, depending on the body location and the relationship of the larvae with the host (250). Implications of the Use of the Myiasis for Nurse and Patient Essay. The distribution of human myiasis is worldwide, with more species and greater abundance in poor socioeconomic regions of tropical and subtropical countries. In countries where it is not endemic, myiasis is an important condition, where it can represent the fourth most common travel-associated skin disease (59).

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There are two main systems for categorizing myiasis: anatomical and ecological classifications. The anatomical system of classification, first proposed by Bishopp, is considered useful for practical diagnosis and to classify the infestation in relation to the location on the host (172, 269, 371). Since a single species can be assigned to more than one anatomical location, and the same location can be infested by different species, a classification system based on the degree of parasitism shown by the fly is also used.

Anatomical Classification

The anatomical classification system is based on the one proposed by Bishopp (172), later modified by James (172) and by Zumpt (371). Each of those authors used different terms with the same meaning, as shown in Table 1.

Table 1

Anatomical classification of myiasis

Classification by Zumpt Classification by Bishopp Classification by James
Sanguinivorous Bloodsucking Bloodsucking
Dermal/subdermal Tissue-destroying Furuncular
Subdermal migratory Creeping
Nasopharyngeal Infestation of the head passages Nose, mouth, sinuses
Intestinal Intestinal/urogenital Enteric
Urogenital Intestinal/urogenital Bladder, urinary passages

To avoid confusion, we will use the following classification, which is based in Bishopp’s, James’, and Zumpt’s proposed classifications:

  • Sanguinivorous or bloodsucking

  • Cutaneous myiasis, furuncular and migratory

  • Wound myiasis

  • Cavitary myiasis, where the infestation receives the name of the affected organ, e.g., cerebral myiasis, aural myiasis, nasal myiasis, and ophthalmomyiasis. Implications of the Use of the Myiasis for Nurse and Patient Essay.

Ecological Classification

Ecological classification (Table 2) takes into account the level of parasitism of the parasite and the host. When designing plague eradication programs for hospitals or nursery homes or in veterinary medicine, it is necessary to consider the ecological classification together with the specie life cycle.

Table 2

Ecological classification of myiasis

Ecological classification Description
Specific/obligatory Parasite dependent on host for part of its life cycle
    Primary Free living and may initiate myiasis
    Secondary Free living and unable to initiate myiasis; may be involved once animal is infested by other species
    Tertiary Free living and unable to initiate myiasis; may be involved when host is near death
Accidental/pseudomyiasis Free-living larva and not able to complete its life cycle; causes pathological reaction when accidentally in contact with the host
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The order Diptera is a large order of insects that are commonly known as true flies. The presence of a single pair of functional wings with a reduced hind wing, termed halteres, distinguishes true flies from other insects (226, 227). Flies are ubiquitous and abundant, with approximately 150,000 species in 10,000 genera and 150 families. This order contains most of the insects vectoring diseases in humans.

The order Diptera is divided into two suborders, the Nematocera and the Brachycera. The Nematocera contain most families of blood-feeding flies that serve as vectors for a variety of viral, protozoan, and helminthic diseases, especially the Culicidae (115). Rarely, agents in this suborder can cause accidental myiasis (Table 3). The Brachycera are composed of infraorders. The infraorder Muscomorpha or “Cyclorrhapha” (term used in nonphylogenetic classifications) contains all species that cause specific myiasis and most of the species responsible for facultative myiasis, especially the species within the Calyptratae.

Table 3

Agents reported to cause human myiasis outside the Calyptratae

Species Taxonomy Clinical picture Reference(s)
Psychoda albipennis Diptera: Psychodidae Urogenital myiasis 2, 149, 159
Telmatoscopus albipunctatus Diptera: Psychodidae Intestinal myiasis 346
Hermetia sp. Diptera: Stratiomydae Intestinal myiasis 55, 133, 201, 308
Hermetia sp. Diptera: Stratiomydae Furuncular myiasis 3
Scenopinus sp. Diptera: Scenopinidae Urogenital myiasis 340
Eristalis tenax Diptera: Syrphidae Urogenital myiasis 5, 85, 96, 191, 241, 362
Intestinal myiasis 242, 330
Megaselia scalaris Diptera: Phoridae Intestinal myiasis 225, 314, 344
Urogenital myiasis 57, 93, 315, 359
Nosocomial myiasis 157
Wound Myiasis 164, 308
Drosophila melanogaster Diptera: Drosophilidae Nasal myiasis 21
Ocular myiasis 69
Piophila casei Diptera: Piophilidae Urogenital myiasis 101, 295

Figure 1 summarizes the taxonomy of the Diptera, and Fig. 2 presents the taxonomic division of the Calyptratae. Both were designed to include the agents related to human myiasis. Table 3 shows the species outside the Calyptratae reported to cause human myiasis. Implications of the Use of the Myiasis for Nurse and Patient Essay. Tables 4 to ​to88 summarize the most important aspects of the species within the Muscoidea, Oestroidea, Calliphoridae, and Sarcophagidae that cause human myiasis.

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Fig 1

Taxonomy of the Diptera. Species within the dashed lines are reported to cause human myiasis and are included in the corresponding group. See Table 3 for references.

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Fig 2

Taxonomic division of the Calyptratae.

Table 4

Superfamily Muscoidea

Family, species, and parameter Description (reference[s])
    Muscina sp.
        Distribution Worldwide
        Classification Facultative myiasis
        Hosts Decaying organic matter
        Human myiasis For Muscina stabulans, intestinal and urogenital myiases (18, 19, 37, 87, 249, 311); for Muscina sp., cutaneous myiasis (18, 19, 33, 37, 87, 249, 311)
    Musca domestica (house fly)
        Distribution Worldwide
        Classification Facultative myiasis
        Hosts Decaying organic matter
        Human myiasis Reported to cause intestinal (280, 302, 371), wound (112, 165, 370), and cavitary (209) myiases; related to allergic diseases (114, 336, 337, 357)
    Fannia sp. (lesser house fly)
        Distribution Holarctic and temperate neotropical regions
        Classification Facultative myiasis
        Hosts Decaying organic matter
        Human myiasis For Fannia scalaris, genitourinary myiasis (361); for Fannia canicularis, nasopharyngeal myiasis (17), intestinal myiasis (18, 37, 42, 366), and rectal myiasis (199)

Table 8

Agents responsible for furuncular myiasis

Species Frequency Geographic location No. of lesions No. of maggots per lesion Location(s) of lesions Clinical characteristic(s)
Dermatobia hominis Common Latin America Usually 1 1 Exposed sites Pain more common; history of insect bite
Cordylobia anthropophaga Common Africa Multiple 1 Covered sites Intense inflammatory reaction; more common in children; rainy season
Cordylobia rodhaini Rare Africa Multiple 1 Covered sites; lower limbs Similar to C. anthropophaga
Cuterebra spp. Rare North America Usually 1 1 Face, scalp, neck, shoulder Pruriginous papule, 0.2–2 cm; migratory component; more common in children; summer months
Wohlfahrtia vigil Rare North America Multiple, 12–24 1-5 Head, neck, and skin folds Patch may precede furuncle; more common in infants less than 6 mo old; between June and September
Wohlfahrtia magnifica Rare Old World 1-5 Up to 25 Paroxysmal episodes of sharp pain; eosinophilia may occur
Hypoderma bovis and H. lineatum Rare Northern hemisphere 1 1 Head, neck, and upper chest or back Winter months; before or after migration

Table 5

Family Oestridae

Subfamily, species, and parameter Description (reference[s])
    Dermatobia hominis (human bot fly)
        Distribution Between latitudes 25oN and 32oS (296), extending from Mexico through Central to South America (128, 196)
        Classification Obligatory myiasis
        Hosts Humans, cattle, swine, cats, dogs, horses, sheep, other mammals, and a few birds (143, 172)
        Mechanism of infestation Active delivery of the maggot by an intermediary mosquito (usually Diptera: Psorophora); this method of delivery is called phoresis
        Human myiasis Furuncular myiasis
    Cuterebra sp. (rodent bot flies)
        Distribution North America during summer in August, September, and October (24), with higher prevalence rates in northeastern and southeastern states (90)
        Classification Obligatory myiasis
        Hosts Rodents; humans are occasional hosts
        Mechanism of infestation Eggs are laid on leaves, grass, and stems of underbrush during the spring and early summer; first-stage larva can enter its host through mucous membranes of nose, eyes, mouth, or anus, or it can penetrate the skin directly (72)
        Human myiasis 85% of cases have cutaneous disease, and 15% have visceral infestation (70% eye and 30% upper respiratory tract) (90) Implications of the Use of the Myiasis for Nurse and Patient Essay.
    Alouattamyia baeri
        Distribution Brazilian Amazon region
        Classification Obligatory cutaneous myiasis
        Hosts Primates
        Human myiasis Only 2 reported cases in humans; 1 case was pulmonary, and the other one affected the throat (142)
    Gasterophilus sp. (horse bot flies)
        Distribution Old World species, with three cosmopolitan species, G. haemorrhoidalisG. intestinalis, and G. nasalis, distributed worldwide
        Classification Obligatory myiasis
        Hosts Horses, zebras, elephants and rhinoceroses; may affect humans who deal with horses
        Mechanism of infestation Direct contact with eggs on a horse’s coat or by direct oviposition onto human skin, especially in warmer climates
        Human myiasis Mainly migratory myiasis; rarely external ophthalmomyiasis (230), oral myiasis (343), pulmonary myiasis (7)
    Hypoderma bovis (cattle bot fly)
        Distribution Distributed between latitudes 25° and 60°, in the northern hemisphere, in more than 50 countries of North America, Europe, Africa, and Asia
        Classification Obligatory myiasis
        Hosts Wild and domestic ruminants; human infestation occurs in those who are in close proximity to cattle (258)
        Mechanism of infestation In late spring and early summer, in periods of sunshine on warm days, the female flies attach their eggs onto the hair of the cattle
        Human myiasis Migratory myiasis, with reports of oral myiasis (103) and skin allergies with eosinophilia (244)
    Hypoderma lineatum
        Distribution Distributed between latitudes 25° and 60°, in the northern hemisphere, in more than 50 countries of North America, Europe, Africa, and Asia
        Classification Obligatory myiasis
        Hosts Wild and domestic ruminants; human infestation occurs in those who are in close proximity to cattle (258)
        Human myiasis Migratory myiasis, with a report of meningitis (77)
    Hypoderma tarandi
        Distribution Holarctic distribution (371)
        Classification Obligatory myiasis
        Hosts Reindeer and caribou
        Human myiasis Principal manifestation is ocular disease (181, 195, 333), with reports of cutaneous and oral myiases (105); cases usually occur in August to December in subjects who have visited areas in which reindeer and H. tarandi are found
    O. ovis (sheep nasal bot fly)
        Distribution Worldwide where sheep are tended
        Classification Obligatory cavitary myiasis
        Hosts Sheep and goats; there is no documentation that O. ovis is able to complete its life cycle in the human eye
        Mechanism of infestation The female fly is active during summer and early fall; the gravid adult female ejects the first-instar larvae, which have previously hatched; flies may deposit as many as 500 first-instar larvae; direct contact between the fly and its host is not necessary for infestation
        Human myiasis The most common cause of external ophthalmomyiasis in men (140, 174, 282, 324, 352); Oestrus ovis may cause allergic manifestations, especially when in the throat (223)

Table 6

Family Calliphoridae

Subfamily or tribe, species, and parameter Description (reference[s])
Cochliomyia hominivorax
    Distribution Once found in the tropics and warm temperate zones of the Southern United States, the Caribbean, and most of Latin America, its distribution is nowadays limited to South and Central America
    Classification Obligatory wound myiasis
    Hosts True obligate parasite of mammals
    Mechanism of infestation Eggs are laid on the wound or nearby (300 eggs in a few minutes)
    Human myiasis Typical infestation in humans is wound myiasis, where it can be very severe, with penetration and destruction of the underlying tissue; when in the nose or ears, the fatality rate may reach 8% (250)
Chrysomya bezziana (Old World screwworm)
    Distribution India, Arabian Peninsula, Indonesia, Philippines, and New Guinea (not Australia)
    Classification Obligatory wound myiasis
    Hosts Sheep and humans
    Mechanism of infestation Eggs are laid on the wound or nearby (150 eggs)
    Human myiasis Wound myiasis
Chrysomya megacephala
    Distribution Worldwide, with more prevalence in Oriental and Australasian regions
    Classification Facultative wound myiasis
    Hosts Decomposing flesh and feces
    Human myiasis Wound myiasis (111) and aural myiasis (203); important in forensic medicine (63)
Chrysomya albiceps and Chrysomya rufifacies
    Distribution Native to Australia; is found worldwide
    Classification Facultative parasite of wound myiasis
Secondary myiasis in sheep
    Hosts Feeding habits vary from excrement, urban garbage, and decomposing meat to fresh food; primary and secondary myiases in humans as well as other animals (371)
    Human myiasis Wound myiasis (112, 329) and nasal myiasis (172); important in forensic medicine
    Auchmeromyia senegalensis (Congo floor maggot)
        Distribution Sub-Saharan Africa and Cape Verde Islands
        Classification Sanguinivorous myiasis
        Hosts Humans
        Mechanism of infestation Eggs are laid in the soil or sand floors of traditional huts; the larvae hatch in 1 to 3 days, stay buried during the day, and emerge at night; maggot feeds on sleeping individuals for 20 min once, every 24 h, up to 16 times to complete its development; all three larval stages are bloodsucking
        Human myiasis No infestation
    Lucilia sp.
        Distribution South Africa and Australia (L. cuprina), Europe and North America (L. sericata)
        Classification Facultative wound myiasis
        Hosts These species prefer to feed on dead tissue, although they are able to invade living tissue when there are few options (355)
        Mechanism of infestation Females lay their eggs on carcasses, in neglected and suppurating wounds, and, in particular, on the wool of sheep soiled with urine, feces, or blood
        Human myiasis Facultative wound myiasis (355)
    Calliphora sp.
        Distribution Females are attracted for oviposition to any decomposing flesh, of which carrion is most suitable; usually involved in myiasis as secondary species
        Classification Facultative myiasis
        Hosts Decomposing flesh
        Mechanism of infestation C. vicina in particular may be a primary invader (318, 371)
        Human myiasis For C. vicina, aural (172), intestinal (45), nasal (316), oral (147), wound (89), and urogenital (371) myiases; for C. hilli, ocular myiasis (200)
    Cordylobia anthropophaga (tumbu fly)
        Distribution Sub-Saharan Africa; was recently described in Portugal (73)
        Classification Obligatory cutaneous myiasis
        Hosts Wild rats are the main hosts, but other wild mammals are infested, including mice, monkeys, squirrels, antelopes, boars, leopards, and mongooses; dogs, cats, rabbits, guinea pigs, goats, and chickens are among the domestic animals infested; humans
        Mechanism of infestation Female flies deposit eggs on shaded soil, preferably contaminated with urine or feces, or drying clothes (especially improperly washed diapers and damp clothing laid on the ground)
        Human myiasis Furuncular myiasis
    Cordylobia rodhaini (Lund’s fly)
        Distribution African tropical humid forest areas
        Classification Obligatory cutaneous myiasis
        Hosts Various thin-skinned forest mammals (particularly rodents); occasionally causes human myiasis
        Mechanism of infestation Females lay about 500 eggs in sand or soil containing feces or urine or on sun-exposed laundry
        Human myiasis Furuncular myiasis
    Phormia regina and Protophormia terranovae
        Distribution Confined to areas north of the Tropic of Cancer
        Classification Facultative wound myiasis
        Hosts Decomposing flesh; Protophormia terraenovae in particular may be a serious parasite of cattle, sheep, and reindeer (172, 318)
        Mechanism of infestation Females lay about 500 eggs in sand or soil containing feces or urine or on sun-exposed laundry
        Human myiasis P. regina has been found in wound myiasis in men (9, 154, 236, 301) and is an important agent in forensic entomology (52)

Table 7

Family Sarcophagidae

Species and parameter Description (reference[s])
Wohlfahrtia magnifica (spotted flesh fly)
    Distribution Mediterranean basin of Europe and North Africa and eastwards into China, including the steppe region of continental Europe and southern and Asiatic Russia (323, 371); it is a thermophilic fly; it likes warmth and light and is active mostly during summer days
    Classification Obligatory wound myiasis
    Hosts Humans and warm-blooded animals and infants are most commonly infested; sheep are a major host, but other livestock, including poultry, as well as wildlife in nature or zoos can be affected (108)
    Mechanism of infestation The female flies, which are larviparous (deposit their living larvae), are attracted to natural body orifices of their hosts (107) or to wounds, where they deposit their first-instar larvae (up to 150), occasionally within their eggshells
    Human myiasis Commonly reported in wound myiasis, although this parasite has also been reported in furuncular myiasis (348, 368), oral myiasis (95), and otomyiasis (100, 180, 264, 350, 369); fatal cases have been reported (172)
Wohlfahrtiavigil and Wohlfahrtia opaca
    Distribution W. vigil is found in the United States from Maine to New York and west to North Dakota, in Central and Southern Europe, in Russia, and in Pakistan (327); W. opaca is found only in western and southwestern North America (319); Most cases occur in June to September
    Classification Obligatory furuncular myiasis
    Hosts Cats, dogs, rabbits, ferrets, mink, foxes, and humans (250)
    Mechanism of infestation In nearly all hosts, including humans, infestation occurs only in the very young, as the larval mouth hooks typically are not strong enough to penetrate adult skin
    Human myiasis Furuncular, with multiple lesions being common, with the avg no. being 12 to 14 (172)
Sarcodexia lambens
    Distribution Widely distributed in the Americas, raging from the southern United States to Paraguay and Argentina
    Classification Obligatory wound myiasis
    Hosts Humans
    Human myiasis This agent infested 12.1% of 66 wound myiasis cases in Brazil (111)
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When treating a patient with myiasis, it is critical to make the correct identification of the larva. It helps not only to understand how the infestation was acquired but also to plan the treatment and to promote preventive measures.

After removal, the maggot should be killed by immersion for 30 s in very hot (enough to produce vapor) but not boiling water, which prevents decay and maintains the natural color. Larvae should then be preserved in a solution of 70% to 95% ethanol. The above-described method best preserves larval length and morphology. Killing of the larvae directly in a preservative will putrefy and shrink them. If a solution of 70% ethanol is not available, 70% isopropyl alcohol can be used instead. Formalin solutions should not be used, because they cause an excessive hardening of the larval tissues, making them difficult to process (229).

Identification can be very challenging and demanding. Specific knowledge of the morphological aspects of the larva is necessary for the identification of the maggot’s species, a task usually done by a trained entomologist. Several aspects of the larva must be analyzed before the final species is determined, which is not possible in some cases. Implications of the Use of the Myiasis for Nurse and Patient Essay. Body shape, aspects of the papillae, the posterior spiracles (position, shape, openings, and structures), pigmentation of the dorsal tracheal trunks, the body surface (spines), the anterior spiracles, the cephalopharyngeal skeleton, and clinical behavior are all taken into account when the offending maggot is analyzed. An excellent Internet resource to help identify the species when a trained expert is not present is the Natural History Museum (London, United Kingdom) website (, using the option, “launch the key to myiasis-causing larvae.”

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Increasing international travel, both for tourism and for business, raises the need for physicians to cover a large spectrum of diseases, especially those caused by infectious agents. Skin diseases, together with systemic febrile illness and acute diarrhea, are the leading causes of health problems in travelers and account for 8% to 12% of all tourists medical problems (160). Myiasis is usually among the five most common dermatologic conditions, representing 7.3% to 11% of cases (212, 290).

Travel clearly raised the importance of myiasis knowledge, especially in countries where the infestation is unusual, rare, and, in some cases, reported as being exotic (120, 124, 150). Even physicians unfamiliar with this condition can easily diagnose cases in which maggots are visible. On the other hand, furuncular, migratory, and cavitary cases and pseudomyiasis pose a diagnostic challenge, especially to those doctors unacquainted with myiasis and its possibilities. For the correct diagnosis, several aspects should be determined: the region where the patient visited, climate conditions, and the species habits of the region visited.

An accurate and timely diagnosis is important not only to alleviate the patient’s symptoms but also to prevent the establishment of myiasis-causing flies in regions where they are not endemic, a phenomenon that is already happening with the movement of farm animals. In many cases, the patient receives unnecessary oral antibiotics, increasing the development of bacterial resistance (150). Implications of the Use of the Myiasis for Nurse and Patient Essay.


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Myiasis is considered, in most cases, an embarrassing and repugnant disease to patients and to health care professionals. Poor hygiene and low socioeconomic status are the most important risk factors for acquiring myiasis (111, 220). Another important factor is an abundance of exposed preexisting suppurative lesions that attract and stimulate the deposit of eggs by the female insect. For specific species, habits of the population, such as sitting or lying on the ground and some religious rites, and climatic conditions influence the occurrence of myiasis (117).

The real importance of human myiasis is unknown, and identification of the species responsible for a case of myiasis is rarely done. Epidemiological data on human myiasis are scant, and registration of the cases is not usually obligatory. Health care professionals judge myiasis to be a disease of minor importance, leading to an inadequate registration of the case: the larva and dressings are normally discarded without further examination. In some countries, domestic and empirical treatments of the patients are made by family members, reducing the number of the cases seen in medical facilities. Access to entomologists with expertise in dipteran classification is usually difficult, especially in developing regions, where myiasis can be a real problem of public health.

Cutaneous Myiasis

Cutaneous myiasis, together with wound myiasis, is the most frequently encountered clinical form (92). Furuncular and migratory forms are included in this group.

Furuncular myiasis.

Furuncular myiasis (warble) occurs after the penetration of the dipteran larva into healthy skin (Fig. 3), where an erythematous, furuncle-like nodule develops, with one or more maggots within it. Dermatobia hominis and Cordylobia anthropophaga are the most common causative agents of furuncular myiasis. Implications of the Use of the Myiasis for Nurse and Patient Essay.