House , , therapy & Forensic entomology

The common housefly, Musca domestica, lives in close association with people all over the world. The feed on human foodstuffs and wastes where they can pick up and transport various disease agents. In addition to the housefly, a number of other fly species have adapted to life in human settlements, where they present similar problems. In warmer climates, the filth fly, M. sorbens is of particular interest in this regard. It is closely related to the housefly and considered important in the spread of eye infections. Blowflies () and other flies have been associated with the transmission of enteric infections.

Life cycle

There are four stages in the life of a fly: egg, larva or maggot, pupa and adult. Depending on the temperature, it takes from 6 to 42 days for the egg to develop into the adult fly. The length of life is usually 2–3 weeks but in cooler conditions it may be as long as three months. The female housefly usually mates only once and stores the sperm for later use. Eggs are usually laid in masses on organic material such as manure and garbage. Hatching occurs within a few hours. The young larvae burrow into the breeding material; they must obtain oxygen from the atmosphere and can, therefore, survive only where sufficient fresh air is available. When the breeding medium is very wet they can live on its surface only, whereas in drier materials they may penetrate to a depth of several centimeters. The larvae of most species pass through three instars. The time required for development varies from a minimum of three days to several weeks, depending on the species as well as the temperature and type and quantity of food available. After the feeding stage is completed the larvae migrate to a drier place and burrow into the soil or hide under objects offering protection. They form a puparium, within which the transformation from larva to adult takes place. This usually takes 2–10 days, at the end of which the fly pushes open the top of the case and works its way out and up to the surface. Soon after emergence the fly spreads its wings and the body dries and hardens. The adult fly is grey, 6–9 mm long and has four dark stripes running lengthwise on the back. A few days elapse before the adult is capable of reproduction. Under natural conditions an adult female rarely lays eggs more than five times, and seldom lays more than 120– 130 eggs on each occasion.

Food

Both male and female flies feed on all kinds of human food, garbage and excreta, including sweat, and on animal dung. Under natural conditions flies seek a wide variety of food substances. Because of the structure of their mouthparts, food must be either in the liquid state or readily soluble in the salivary gland secretions or in the crop. Water is an essential part of a fly’s diet and flies do not ordinarily live more than 48 hours without access to it. Other common sources of food are milk, sugar, syrup, blood, meat broth and many other materials found in human settlements. The flies evidently need to feed at least two or three times a day.

Breeding sites

Female flies deposit their eggs on decayed, fermenting or rotting organic material of either animal or vegetable origin. Unlike blowflies and fleshflies, houseflies rarely breed in meat or carrion.

1 Prof. Abdelwahab A. Ibrahim

House flies, Myiasis, Maggot therapy & Forensic entomology

Ecology of adult flies

Adult flies are mainly active during the day, when they feed and mate. At night they normally rest, although they adapt to some extent to artificial light.

During the daytime, when not actively feeding, flies may be found resting on floors, walls, ceilings and other interior surfaces as well as outdoors on the ground, fences, walls, steps, simple pit latrines, garbage cans, clothes lines, grasses and weeds. At night, flies are normally inactive. Their favorite resting places at this time are ceilings and other structures. When temperatures remain high during the night, houseflies frequently rest out of doors on fences, clothes lines, electric wires, cords, weeds, grasses, bushes and trees. These resting places are generally near favored daytime feeding and breeding areas and sheltered from the wind.

Fly numbers in a given locality vary with the availability of breeding places, sunshine hours, temperature and humidity.

Control

Flies can be controlled, at least to some extent, by physical, chemical, or biological means. Physical controls include screening with small mesh or the use of vertical strips of plastic or strings of beads in doorways to prevent entry of flies into buildings. Fans to create air movement or air barriers in doorways can deter flies from entering, and food premises often use ultraviolet light traps that electrocute insects. Sticky papers hanging from the ceiling can also be effective. Another approach is the elimination as far as possible of potential breeding sites. Keeping garbage in lidded containers and collecting it regularly and frequently prevents any eggs laid from developing into adults.

Insecticides can be used. Larvicides kill the developing larvae, but large quantities may need to be used to reach areas below the surface. Aerosols can be used in buildings to "kill" flies, but outside applications are only temporarily effective. Residual sprays on walls or resting sites have a longer-lasting effect. Many strains of housefly have become immune to the most commonly used .

Several means of have been investigated. These include the use of the black soldier fly, whose larvae compete with those of the housefly for resources. The introduction of dung beetles to stir up the surface of a manure heap and render it unsuitable for breeding is another approach. Some Fugal and bacterial pathogens as Bacillus thuringiensis can be also used.

2 Prof. Abdelwahab A. Ibrahim

House flies, Myiasis, Maggot therapy & Forensic entomology

Public health importance

Nuisance:

Flies can be an important nuisance by disturbing people. Flies soil houses with their faeces.

Diseases

Houseflies can fly for several miles from their breeding places, carrying a wide variety of organisms on their hairs, mouthparts, vomitus, and faeces. Parasites carried include cysts of protozoa, e.g. Entamoeba histolytica and Giardia lamblia and eggs of helminths, e.g., Ascaris lumbricoides, Trichuris trichiura, Hymenolepis nana, and Enterobius vermicularis. Houseflies do not serve as a secondary host or act as a reservoir of any bacteria of medical or veterinary importance, but they do serve as mechanical vectors to over 100 pathogens, such as those causing typhoid, cholera, salmonellosis, bacillary dysentery, tuberculosis, anthrax, ophthalmia, and pyogenic cocci, making them especially problematic in hospitals and during outbreaks of certain diseases. Disease-causing organisms on the outer surface of the fly may survive for a few hours, but those in the crop or gut can be viable for several days.

In the early 20th century, Canadian public health workers believed that the control of flies was important in controlling the spread of tuberculosis. A "swat that fly" fight was held for children in Montreal in 1912. Flies were targeted in 1916, when a polio epidemic broke out in the eastern United States. The belief that flies control was key to disease control continued, with extensive use of insecticidal spraying, well until the mid-1950s, declining only after the introduction of Salk's vaccine.

In addition to the housefly, a number of other fly species have adapted to life in human settlements, where they present similar problems. In warmer climates, the filth fly, M. sorbens is of particular interest in this regard. It is closely related to the housefly and considered important in the spread of eye infections. Blowflies (Calliphoridae) and other flies have been associated with the transmission of enteric infections.

Myiasis

Myiasis is the parasitic infestation of the body of a live animal by fly larvae () that grow inside the host while feeding on its tissue. Although flies are most commonly attracted to open and urine- or feces-soaked fur, some species (including the most common myiatic flies—the botfly, blowfly [Calliphoridae], and screwfly [ hominivorax]) can create an infestation even on unbroken skin and have been known to use moist soil and non-myiatic flies (such as the common housefly) as vector agents for their parasitic larvae.

Because some animals (particularly 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. Myiasis is also a relatively frequent affliction of humans in rural tropical regions where myiatic flies increase, and often may require medical attention to surgically remove the parasites.

3 Prof. Abdelwahab A. Ibrahim

House flies, Myiasis, Maggot therapy & Forensic entomology

Myiasis varies widely in the forms it takes and its effects on the victims. Such variations are shown in the following table.

Type Definition or Symptoms Cutaneous Painful, slow-developing ulcers or pimple like sores that can last for myiasis a prolonged period Nasal Obstruction of nasal passages and severe irritation. In some cases myiasis facial edema and fever can develop. Auditory Crawling sensations and buzzing noises. Smelly discharge is present. myiasis If located in the middle ear, larvae may get to the brain. Myiasis of the human eye or ophthalmo myiasis can be caused by Ophthalmo larvae of the botfly Hypoderma tarandi. Fairly common, this causes myiasis severe irritation, edema, and pain. It is known to lead to uveitis, glaucoma, and retinal detachment. myiasis occurs when fly larvae infest open wounds. It has been a serious complication of war wounds in tropical areas, and is Wound sometimes seen in neglected wounds in most parts of the world. myiasis Predisposing factors include poor socioeconomic conditions, extremes of age, neglect, mental disability, psychiatric illness, alcoholism, and diabetes. Intestinal Myiasis in gastric, rectal, or intestinal/enteric for the appropriate part myiasis of the digestive system Obligatory Where the parasite cannot complete its life cycle without its parasitic myiasis phase, which may be specific, semi specific, or opportunistic Facultative or Caused by flies that has no preference or need to develop in a host but that will do so on rare occasions. Transmission occurs through Accidental or accidental deposit of eggs on oral or genitourinary openings, or by swallowing eggs or larvae that are on food. pseudomyiasis *Musca domestica (housefly) *Fannia spp. (latrine flies) *Eristalis tenax (rat-tailed maggots) *Muscina spp. Specific Caused by flies that need a host for larval development as: myiasis *Dermatobia hominis (human botfly) *Oestrus ovis (sheep botfly) *Hypoderma spp. (cattle botflies) *Gasterophilus spp. (horse botfly) *Chrysomya bezziana (old world screwworm fly) 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 as: *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)

4 Prof. Abdelwahab A. Ibrahim

House flies, Myiasis, Maggot therapy & Forensic entomology

Aanimal myiasis

Animal myiasis occur worldwide, especially in countries where livestock, particularly sheep, are kept under hot, wet, conditions, including most of Africa and the Americas, ranging from the cold temperate regions in the north, to corresponding latitudes in the south. This condition is caused by the blowfly. Blowfly strike accounts for over A$170 million a year in losses in the Australian sheep industry, the largest such losses in the world. Myiasis is also not restricted to sheep; screwworm flies (Cochliomyia hominivorax in particular) regularly cause upwards of US$100 million in annual damages to domestic cows and goats.

Development of myiasis

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 septicemia. This leads to anorexia and weakness and is generally fatal if untreated.

Prevention

The first control method is preventive and aims to eradicate the adult flies before they can cause any damage. The second control method is the treatment once the infestation is present, and concerns the infected animals (including humans).

The principal control method of adult populations of myiasis inducing flies involves applications in the environment where the target livestock is kept. One alternative prevention method is the sterile technique (SIT) where a significant number of artificially reared sterilized (usually through irradiation) male flies are introduced. The male flies compete with wild breed males for females in order to copulate and thus cause females to lay batches of unfertilized eggs which cannot develop into the larval stage.

One prevention method involves removing the environment most favorable to the flies, such as by removal of the tail. Another example is the crutching of sheep, which involves the removal of wool from around the tail and between the rear legs, which is a favorable environment for the larvae.

To prevent myiasis in humans, there is a need for general improvement of sanitation, personal hygiene, and extermination of the flies by insecticides. Clothes should be washed thoroughly, preferably in hot water, dried away from flies, and ironed thoroughly. The heat of the iron kills the eggs of myiasis-causing flies.

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House flies, Myiasis, Maggot therapy & Forensic entomology

Treatment

This applies once an infestation is established. The first response to cutaneous myiasis is to cover the air hole thickly with petroleum jelly. Lack of oxygen then forces the larva to the surface, where it can more easily be dealt with. In a clinical or veterinary setting there may not be time for such tentative approaches, and the treatment of choice might be more direct, with or without an incision. First the larva must be eliminated through pressure around the lesion and the use of forceps. Secondly the wound must be cleaned and disinfected. Further control is necessary to avoid further reinfestation.

Livestock may be treated prophylactically with slow release dress containing Ivermectin which can provide long-term protection against the development of the larvae.

Sheep also may be dipped, a process which involves drenching the animals in persistent insecticide to poison the larvae before they develop into a problem.

Maggot therapy

Maggot therapy (also known as maggot debridement therapy (MDT), larval therapy, larva therapy, larvae therapy, biodebridement or biosurgery) is a type of biotherapy involving the intentional introduction by a health care practitioner of live, disinfected maggots (fly larvae) raised in special facilities into the non-healing skin and soft tissue wound(s) of a human or other animal for the purposes of selectively cleaning out only the necrotic tissue within a wound (debridement), disinfection, and promotion of .

History of use

Written records have documented that maggots have been used since antiquity as a wound treatment. There are reports of the successful use of maggots for wound healing by Indians and Australians. Many military physicians observed that soldiers whose wounds had become colonized with maggots experienced significantly less morbidity and mortality than soldiers whose wounds had not become colonized.

Later on, maggot therapy for wound care became very common, particularly in the United States. The pharmaceutical company, Lederle, commercially produced in large numbers "Surgical Maggots", larvae of the green bottle fly (Phaenicia sericata), a facultative, necrophagous organism that only consumes necrotic tissue. Between 1930 and 1940, more than 100 medical papers were published on maggot therapy. Medical literature of this time contains many references to the successful use of maggots in chronic or infected wounds including , abscesses, burns, and sub-acute mastoiditis.

More than 300 American hospitals employed maggot therapy during the 1940s. Maggot therapy’s extensive use prior to World War II was reduced with the discovery and growing use of penicillin.

6 Prof. Abdelwahab A. Ibrahim

House flies, Myiasis, Maggot therapy & Forensic entomology

Reintroduction

With the advent of antibiotic-resistant bacteria, in 1989 Dr. Ronald Sherman re- introduced maggot therapy into modern medical care. The therapeutic maggot used by Sherman is a strain of the green bottle fly (Phaenicia sericata) and marketed under the brand name Medical Maggots.

Over fifty scientific papers have been published that describe the medical use of maggots. Six thousand maggot therapy patients have been included in case histories or other studies.

In a 2007, maggots were used successfully to treat patients whose wounds were infected with MRSA, a bacterium (staphylococcus aureus) with resistance to most antibiotics, including methicillin. Some of these strains include "flesh eating bacteria" causing frequent deaths upon infection of deep tissue. Maggots clean up the already dead tissue thus preventing further infection spread.

In 1995, a handful of doctors in 4 countries were using maggot therapy. Today, any physician in the U.S. can prescribe maggot therapy. There are over 800 health care centers in the United States that have utilized maggot therapy. Over 4,000 therapists are using maggot therapy in 20 countries. Approximately 50,000 treatments were applied to wounds in the year 2006

In January 2004, the U.S. Food and Drug Administration granted permission to produce and market maggots for use in human cases.

In February 2004, the British National Health Service permitted its doctors to prescribe maggot therapy.

Veterinary maggot therapy

The use of maggots to clean dead tissue from animal wounds is part of folk medicine in many parts of the world. It is particularly helpful with chronic osteomyelitis, chronic ulcers, and other -producing infections that are frequently caused by chafing due to work equipment. Maggot therapy for horses in the United States was re-introduced in 2003.

Mechanisms of action

The maggots have three principal actions reported in the medical literature:

 Debride wounds by dissolving only necrotic, infected tissue;  Disinfect the wound by killing bacteria; and  Stimulate wound healing.

Maggot therapy has been shown to accelerate debridement of necrotic wounds and reduce the bacterial load of the wound, leading to earlier healing, reduced wound odor, and less pain. The combination and interactions of these actions make maggots an extremely potent tool in wound care.

7 Prof. Abdelwahab A. Ibrahim

House flies, Myiasis, Maggot therapy & Forensic entomology

Debridement

The debridement of necrotic tissue is a prerequisite for successful wound care. If debridement does not take place, wound repair is significantly impaired. Necrotic tissue in the wound is not only an obstacle for localized treatment, but becomes an ideal breeding ground for bacteria and may lead to , necessitating limb amputation, and potentially fatal septicemia.

Surgeons cannot be very precise in debriding dead tissue while leaving living tissue. The human eye is simply not very discriminating in identifying healthy tissue from necrotic tissue, and surgeons only have a very limited time to operate while their patient is under anesthesia. Consequently, surgeons use their scalpels to remove far more viable tissue than is needed, producing a wound larger than necessary that has more bleeding and a greater chance of becoming infected. Patients also experience more wound-associated pain after removal of healthy tissue. Wound care therapists can find themselves needing to debride a wound day after day, deeper and deeper; this is impractical as surgeons simply do not have the time to perform frequent surgical debridements. The requirement for frequent surgical debridement complicates and lengthens wound healing, lengthening hospital stays and increasing costs.

In maggot therapy, a large number of small maggots selectively consume only necrotic tissue far more precisely than is possible in a normal surgical operation, and can debride a wound in a day or two. These maggots do not damage healthy tissue: they operate with precision at the boundary between healthy and necrotic tissue. They derive nutrients through a process known as "extracorporeal digestion" by secreting a broad spectrum of proteolytic enzymes that liquefy necrotic tissue, and absorb the semi-liquid result within a few days. In an optimum wound environment and within a period of 3-4 days by ingesting necrotic tissue, leaving a clean wound free of necrotic tissue when they are removed.

Disinfection

For wounds already infected, maggot therapy is effective even against antibiotic- resistant bacteria. Maggot secretions were experimentally shown to possess potent antimicrobial activity. As early as 1957, a specific antibiotic factor was found in maggot secretions and published in the journal Nature. Secretions believed to have broad-spectrum antimicrobial activity include allantoin, , phenylacetic acid, phenylacetaldehyde, calcium carbonate, and proteolytic enzymes. Bacteria not killed by these secretions are subsequently ingested and lysed within the maggots.

In vitro studies have shown that maggots inhibit and destroy a wide range of pathogenic bacteria including methicillin-resistant Staphylococcus aureus (MRSA), group A and B streptococci, and Gram-positive aerobic and anaerobic strains. In a published review of five patients who were infected with MRSA, some having failed conventional therapy for up to 18 months, maggot therapy was able to eliminate the bacterium from all wounds in an average of 4 days. Maggot therapy therefore represents a highly cost-effective method for managing MRSA infection without exacerbating the problems of antibiotic resistance.

8 Prof. Abdelwahab A. Ibrahim

House flies, Myiasis, Maggot therapy & Forensic entomology

Wound healing

Maggot therapy has wound healing properties. Maggot secretions appear to amplify the wound healing effects of host epidermal . Recent studies have shown that maggot secretions are able to stimulate the growth of human fibroblasts and slow- growing chondrocytes. Micromassage of the wound by maggot movement is further thought to stimulate the formation of and wound exudates by the host.

Limitations of maggot therapy

A moist, exudating wound with sufficient oxygen supply is a prerequisite. Not all wound-types are suitable: wounds which are dry or open wounds of body cavities do not provide a good environment for maggots to feed. In some cases it may be possible to make a dry wound suitable for larval therapy by moistening it with saline soaks, applied for 48 hours.

Maggots have a short shelf life which prevents long term storage before use. Patients and doctors may find maggots distasteful, although studies have shown that this does not cause patients to refuse the offer of maggot therapy. Maggots can be enclosed in opaque polymer bags to hide them from sight. Dressings must be designed to prevent any maggots from escaping, while allowing air to get to the maggots.

Biology of flies and maggots used in maggot therapy

Not all species of flies are safe and effective as medicinal maggots. The flies used most often for the purpose of maggot therapy are "blow flies" (Calliphoridae); and the species used most commonly is Phaenicia sericata, the green blow fly.

FORENSIC ENTOMOLOGY Forensic entomology is the application and study of insect and other arthropod biology to criminal matters. It is primarily associated with death investigations; Forensic entomology practices will become a standard part of the death investigation protocol. The most important group of insects associated with the decomposition of a human corpse is the Calliphoridae (or blow flies). These flies are usually the first insects to appear at animal carrion, often within a few minutes after death. Also, they are the most active and abundant insects found in the early stages of animal decomposition, being responsible for clearing most of the soft tissues of the remains in just a few days. Attraction to the remains Blow flies are the first colonizers and can be attracted over great distances by odors. In South Africa, marked flies of the genus chrysomya sp. were caught in baited traps up to 63.5 km away from the point of the release. 1-Oviposition is elicited primarily by the presence of ammonia, moisture, and tactile stimuli.

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House flies, Myiasis, Maggot therapy & Forensic entomology

2- The odours emanating from a corpse change as the body decomposes becoming more attractive to some species and less attractive to others as time progresses. 3- Some species such as Calliphora vicina preferred decomposed remains to fresh when given a choice. 4- The size of carcasses also seems to affect its attractiveness to blow flies. Callphora vomitoria has prefer large carcasses while Lucilia richards prefers to colonize small rodent carcasses. Factors affecting Succession Geographical region (Biogeoclimatic zone), Season, Sun exposure, Urban Vs. Rural scenarios, Bodies found inside buildings, Burial, Scavenging, Presence or absence of clothing

The application of Forensic entomology 1-Finding Bodies or Body Parts Large aggregations of carrion-feeding adult insects such as blowflies, flesh flies, blue bottle flies and secondary screwworm flies usually indicate the presence of carrion.

2-Estimate Time of Death and Postmortem Interval Information on the developmental stages of insects present at the crime scene can be used to estimate the postmortem interval (PMI) for relatively recent crimes. Environmental data (time, of day, temperature and relative humidity) are essential to properly estimate PMI, since insect development is strongly dependent on temperature and relative humidity). Insect successional sequence can be used to estimate PMI of relatively older crimes. 3-Determine Cause of Death The presence and position of wounds, decomposition may obscure wounds. Insects colonize remains in a specific pattern, usually laying eggs first in the facial orifices, unless there are wounds, in which case they will colonize these first, then proceed down the body. If the maggot activity is centered away from the natural orifices, then it is likely that this is the site of a wound. The presence of drugs can also be determined using insect evidence. There is often not enough flesh left to determine drug presence, but maggots bioaccumulate it so can be analyzed to determine type of drugs present.

4-Identify or Exclude Criminal Suspects Insects can be used to place a suspect at the scene of a crime, and in some cases exonerate criminal suspects.

5-Determine If a Body Has Been Moved After Death The body may have been moved after death, from the scene of the killing to a hiding place. Some of the insects on the body may be native to the first habitat and not the second. This will show that not only was the body moved, but it will also give an indication of the type of area where the murder actually took place.

11 Prof. Abdelwahab A. Ibrahim