Maggots
Scientific Name(s): Phaenicia sericata ; Lucilia caesar , Pharmia regina
Common Name(s): Maggot , fly larva , grub , botfly maggot , “ viable antiseptic ,” “ living antiseptic ,” “ surgical maggot ”
Clinical Overview
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Uses of Maggots
Maggots have been used to promote wound healing and also to treat abscesses, burns, cellulitis, gangrene and ulcers. The most common use of maggots in surgery has been to prevent bone destruction, deformities and other effects of recalcitrant osteomyelitis.
Maggots Dosing
Maggots are applied ad libitum in debridement of wounds.
Contraindications
Contraindications have not yet been identified.
Pregnancy/Lactation
Information regarding safety and efficacy in pregnancy and lactation is lacking.
Maggots Interactions
None well documented.
Maggots Adverse Reactions
Surgical maggots do not appear harmful to living tissues but produce intense pruritus. Maggots can transmit parasitic disease, and larval ocular invasion has occurred.
Toxicology
Surgical maggots are generally not known to cause harm to living tissue.
Maggots are the larvae of various flies. The species Phaenicia sericata (green blow fly) has been used successfully in maggot therapy for many decades. 1 The life cycle of those used in medicine begins with the laying of eggs by the adult female on meat or other substrate suitable for the larvae to feed on. The eggs hatch within one day, and the larvae then proceed to feed and grow. After 5 to 7 days, they become sessile, non-feeding pupae. After about 2 weeks of pupation, the adults emerge and the females begin laying eggs about five days later. 2
Larvae-rearing in the clinical setting can be a simple, low-cost procedure if done correctly. 3 A report on species Lucilia sericata (Meigen) evaluates a sterile mixture of pureed liver and agar as growth medium. This method was not only inexpensive but provided longer storage capacity and no progressive decomposition or odor problems. 4
History
The effects of maggots on wounds have been known since the 1500s when Ambroise Paré described their beneficial actions. It was observed that maggots cleaned untreated wounds, removing necrotic tissue without apparent harm to living tissues. Many military surgeons noticed that soldiers' wounds that became maggot-infested did better than non-infested wounds. The first scientific paper on the surgical use of maggots appeared in 1931, and there was significant interest in the technique during the 1930s and early 1940s. Maggot debridement therapy (MDT) was routinely performed in over 300 hospitals during this time. 1 The first civilian use, based on observations during World War I, was in treating four children with osteomyelitis who did not respond to other available treatments. Subsequent occurrence of tetanus in other cases led to the development of bacteriologically sterile maggots. Early uses for maggot therapy included abscesses, burns, cellulitis, gangrene and ulcers. 2
Around the mid-'40s, use of maggots declined rapidly with the development of antibiotic drugs. Maggot therapy was occasionally employed when all other therapies failed. For example, a 1976 report described use of maggots to treat subacute mastoiditis. 5 In addition, maggots were used to treat women undergoing low-voltage X-ray therapy for cervical carcinoma. The organisms were used to prevent radiation-induced sloughing of the tissues over the sacrum, buttocks and lower abdomen. 6 Actual clinical use of maggots preceded the literature; there was a thriving industry for commercial preparations of maggots at least 10 years before the 1931 report. 2
Maggots Uses and Pharmacology
Wound healerThe mechanisms by which maggots promote wound healing have not been proven conclusively. However, a variety of mechanisms have been suggested. The exudate produced in response to the maggots physically washes bacteria out of the wound. The crawling larvae mechanically stimulate viable tissues to rapidly produce granulation tissue. They also enzymatically liquefy necrotic tissue. Bacteria are destroyed within the alimentary tracts of the larvae, which also use necrotic tissue as food. Maggots may produce antibacterial agents released in their secretions. They also increase the alkalinity of the wound, promoting healthy granulation. Substances proposed as beneficial secretions of maggots include allantoin, ammonium ions and calcium carbonate. 5
The most common use of maggots in surgery has been to prevent bone destruction, deformities and other effects of recalcitrant osteomyelitis in which topical wounds heal poorly. Treatment begins with debridement of the affected area. The wound is then left unsutured for about 2 days, after which, 200 to 1000 maggots are applied to the wound. The maggots are contained by a dressing or cage. They are removed in 3 to 5 days to prevent pupation in the wound, and fresh maggots are applied as needed. Application of maggots is followed by rapid formation of a serosanguineous exudate. Healing occurs within 6 to 7 weeks in children and may take somewhat longer in adults. 2
Animal dataResearch reveals no animal data regarding the use of maggots as a wound healer.
Clinical dataA 1986 report described the use of maggots to treat two patients with severe skin infections. One patient had a large, necrotic, foul-smelling decubitus ulcer of the perianal and presacral areas. The second was an insulin-dependent diabetic with ketoacidosis and a right scrotal ulcer. Excellent wound healing was achieved in both patients although the second patient subsequently died of general debility. 5 Maggot therapy has also been performed effectively for venous stasis ulcers, 7 pressure ulcers in spinal cord injury patients 8 and wound debridement. 9 , 10 , 11 A plantar foot ulcer in one patient existed for several years yet resolved after about 13 weeks of MDT. 10 Some patients with severe tissue destruction may also be receiving antibiotics along with MDT. A report evaluates this combination. Larvae survival was decreased when very high doses of gentamicin and cefazolin were administered. Antibiotics showing no change in survival rate included ampicillin, ceftizoxime, clindamycin, mezlocillin and vancomycin. 12
Other usesAnalysis of maggots found in decomposing bodies can provide information on the time of death, as well as on the presence of specific drugs in the bodies. 13 Maggots can also provide clues about crime location and circumstances. The study of maggots (and other insects) used in this way is termed “forensic entomology.” 1
Dosage
Maggots are applied ad libitum in debridement of wounds.
Pregnancy/Lactation
Information regarding safety and efficacy in pregnancy and lactation is lacking.
Interactions
None well documented.
Adverse Reactions
Surgical maggots in themselves do not appear harmful to living tissues although it should be noted that maggots of screwworms can cause serious tissue damage. The surgical organisms, however, produce intense pruritus. Most patients adapt to this, but some require mild sedation. 5
Toxicology
Non-surgical maggots are commonly used as fishing lures. At least one report has described delayed-onset asthma in an angler who used Calliphora (blue bottle) larvae for bait. The patient was found to have circulating IgG antibody to a larval extract, and symptoms suggestive of immune complex disease subsequently developed. 14 It has been suggested that dyes used to enhance the effectiveness of maggots as fishing lures can induce bladder cancer. 15 A case-control study of more than 1800 subjects found no evidence of an association between the dyes and bladder cancer; however, the number of subjects who used dyed maggots in fishing was small so that an actual association may have escaped detection. 16
Maggots can transmit parasitic diseases resulting in severe destruction of tissues of the ears, nose and throat. This problem is common in India, where it occurs most frequently from September to November. 17 This larval invasion has also been reported in the eye. One case report details the invasion of the ocular orbit of a man by maggots. This infestation was treated successfully by classical wound-cleaning therapy. 18 Another case reports cuterebra larva in the conjunctiva of a boy suffering from decreased vision and subretinal hemorrhages. Successful removal was performed after positive identification of this offending agent by light microscopy. 19 A third case of ophthalmic invasion by larva is reported, this time with successful removal by photocoagulation with an argon green laser resulting in good visual recovery. 20
Bibliography
1. http://www.ucihs.uci.edu2. Chernin E. South Med J 1986;79:1143.
3. Sherman R, et al. Am J Trop Med Hyg 1996;54(1):38-41.
4. Sherman R, et al. Med Vet Entomol 1995;9(4):393-398.
5. Teich S, Myers R. South Med J 1986:79:1153.
6. Diddle AW. South Med J 1987;80:1333.
7. Sherman R, et al. Arch Dermatol 1996;132(3):254-256.
8. Sherman R, et al. J Spinal Cord Med 1995;18(2):71-74.
9. Reames M, et al. Ann Plast Surg 1988;21(4):388-391.
10. Stoddard S, et al. J Am Podiatr Med Assoc 1995;85(4):218-221.
11. Thomas S, et al. J Wound Care 1996;5(2):60-69.
12. Sherman R, et al. J Med Entomol 1995;32(5):646-649.
13. Beyer JC, et al. J Forensic Sci 1980;25:411.
14. Stockley RA. Clin Allergy 1982;12:151.
15. Massey JA, et al. Br Med J 1984;289:1451.
16. Cartwright RA, et al. Carcinogenesis 1983;4:111.
17. Sood VP, et al. J Laryngol Otol 1976:90:393.
18. Mathur SP, Makhija JM. Br J Ophthalmol 1967;51:406.
19. Glasgow B, et al. Am J Ophthalmol 1995:119(4):512-514.
20. Phelan M, et al. Am J Ophthalmol 1995;119(1):106-107.
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