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Furuncular cuterebrid myiasis
Furuncular By Nicholas
Shorter,
Cuterebrid
Karla Werninghaus, Lebanon,
New
David Mooney,
procedures, J Pediatr Saunders
A
above
CASE REPORTS
Case 1 In August of 1995 an otherwise healthy 3-year-old girl, a resident of New Hampshire, developed a small raised erythematous lesion on her upper anterior chest, containing what was described by her mother as a blackhead in the center, It was slightly pruritic. The lesion subsequently resolved, but several others developed in the same area, all but one of which also spontaneously disappeared. The lesion that persisted continued to enlarge until it was about 1 cm in size, resembling a small boil. She had no systemic symptoms. A central hole developed in it, within which a whitish object was occasionally visible. When this was extruded a few days later, it was found to be a 5-mm X 1.5.mm maggot compatible with an early second instar botfly larva (Fig l).’ Surgical consultation was obtained at this point, but no further intervention was necessary. The lesion subsequently rapidly resolved, and she has had no further difficulties. The time course for the whole process was about 2 weeks. Subsequent questioning to determine a possible source for the infestation revealed that a short time before she had been playing with some old cardboard boxes from a barn, one of which contained an uninhabited mouse nest, and also that her family had recently been caring for a neighbor’s rabbit. There was no history of foreign travel.
Case 2 At the end of August 1996, an otherwise healthy &year-old boy, a resident of eastern Vermont who was vacationing in rural New Hampshire, noted several small papules beneath his right eye. These subsequently disappeared, but another appeared over the orbital rim just Journa/ofPediatricSurgery,Vol32,
No 10 (October),
1997: pp 1511-1513
and Alan Graham
Hampshire
Myiasis is the infestation of skin by the larvae of flies. In North America cases are caused by the botfly (Cuterebra) and occur most commonly in children. The usual presentation is a subcutaneous abscess, and for this reason these patients may be referred to surgeons. Knowledge of this entity can avoid delays in diagnosis, unnecessary incision and drainage
LTHOUGH AMERICANS commonly think of human arthropod infestation as a disease type confined to the Third World, on occasion such cases are seen in North America. One such entity is cuterebrid myiasis, in which maggots of the botfly (Cuter&u) develop in the skin of a human host, forming a lesion that presents as an abscess. Most cases occur in children, and, surprisingly, the disease is most common in northern areas, especially the northeastern United States and southeastern Canada.] These patients may come to the attention of pediatric surgeons, and knowledge of this entity can avoid delays in diagnosis, unnecessary incision and drainage procedures, and unnecessary courses of antibiotics.
Myiasis
INDEX
and unnecessary Surg 32:1511-1513. Company.
WORDS:
Skin
abscess,
courses of antibiotics. Copyright o 1997
myiasis,
by
W.B.
botfly.
and lateral to the eye. Initially pruritic, this lesion increased in size. Despite obvious swelling and erythema, pain and tenderness were minimal. The initial diagnosis was an insect bite with an allergic response, and he was started on diphenhydramine. There was no improvement. Over the next week the lesion continued to increase in size, and an opening appeared in its center from which there was a small amount of serosanguinous drainage. Systemic symptoms were absent, and the lesion remained essentially nontender and pain free. At this point surgical consultation was obtained. The lesion, which had the appearance of a subcutaneous abscess, now measured about 2 cm in diameter (Fig 2). Within the central opening, a black and white object was occasionally visible. The diagnosis of cuterebrid myiasis was made. The opening was initially covered with petroleum jelly, but a portion of the larva could be seen protruding after about 10 minutes, it did not move out any further. Gentle pressure was then applied on each side of the opening, and the larva was expressed in its entirety. Measuring 1.4 cm by 0.6 cm, it was a third instar cuterebiid maggot (Fig 3).’ Slow resolution of the inflammatory lesion followed. The exact source of the infestation is unknown. There was no history of foreign travel.
DISCUSSION
Cutaneous myiasis is the infestation of skin by the larvae of flies. This may be obligatory (a normal step in the fly’s life cycle) or facultative (larvae usually develop on decaying flesh or vegetable matter but may infect wounds).2 Facultative myiasis is the basis for maggot debridement therapy.3 A number of species have been implicated in human disease. In South and Central America the most common is Dermatobia hominis (human botfly), whereas in Africa it is Cordylobiu anthropophagia (tumbu fl~).~,~There are several reported cases of North American travelers returning from trips to these endemic areas and presenting with myiasis caused by these species.4J-9 Cases acquired in North America are almost all caused by the genus Cuterebru (rodent or rabbit botfly).‘.5 No From the Departments qf Surgery aftd Pediatrics, Dartmouth Medical School, Children 4 Hospital at Dartmouth, Lebailon, NH. Address reprint requests to Nicholas A. Shortei; MD, Departme?lt of Surgery, Children’s Hospital at Darhnouth, Lebanon, NH 03756. Copyright o 1997 by I%B. Saunders Company 0022-3468/97/3210-0031$03.00/O 1511
1512
Fig 1. Early second instar cuterebrid maggot truded from a lesion on the chest of a 3-year-old measurements, 5 mm x 1.5 mm.
SHORTER
ET AL
spontaneously exgirl (case I). Actual
specific species has been implicated because identification of larvae beyond genus, is not presently possible. These are large bumblebeelike flies that are obligatory parasites. The natural hosts in North America are rodents, rabbits, and hares, and eggs are laid near the dwelling places of these animals. The eggs hatch, and the larvae attach to and then enter the host. After a period of development each larva drops to the ground, burrows into the soil and pupates, with subsequent emergence of an adult the following spring. Adult flies do not feed, so all growth occurs in the larval stage. Although humans may be a natural host for some,tropical species of fly, human cuterebrid infestation only occurs accidentally when someone inadvertently comes in contact with eggs that are ready to hatch. Cases are rare, with less than 60 reported in the literature. ix5Most present as subcutaneous abscesseson the face, scalp, neck, shoulders or chest, and the larvae probably enter by direct penetration of the skin. In a few patients, infection of the vitreous humor or of the upper respiratory tract has been reported. Unlike other types of fly only a solitary lesion containing a single larva has been documented in all cases of North American cuterebrid myiasis.
Fig 2. Lesion above the right eye of an &year-old boy (case 2). A drop of serosanguinous drainage is present in the opening, with the tip of the larva just visible as a white spot within it.
Fig 3. Third instar cuterebrid maggot above the right eye of an g-year-old boy ments, 1.4 cm x 0.6 cm.
removed from a lesion (case 2). Actual measure-
Almost all cases present in August, September, or October.’ The typical lesion is an erythematous papule ranging in size from 0.2 to 2 cm. It is typically pruritic but may be painful and tender. There may be a history of a sharp sting at the site a few weeks before, and some patients describe a sensation of something moving within the lesion. A central punctum develops through which the organism breathes, and there is frequently serous, serosanguinous, or purulent drainage. Occasionally the larva is visible through the opening. Typically these lesions are initially diagnosed as furunculosis or cellulitis, which does not respond to antibiotics. Incision and drainage of the lesion may have been performed before arriving at the correct diagnosis. Once the diagnosis is made, a number of therapeutic approaches exist, all directed toward removal of the organism. Theoretically, no treatment is necessary, as by its nature the process is self limited. However, because of the frequently unpleasant local symptoms, not to mention the psychological distress caused by the concept of being infested with maggots, few patients or parents would be willing to opt for that approach. On occasion, as in one of our cases, spontaneous extrusion may occur, with the diagnosis being made at that time. Trying to extract the larva with forceps is difficult, both because of its depth within the skin and because of the presence of surface spines which anchor it. Surgical incision and extraction has been recommended4.8 but is probably excessive unless the larva is dead.5x7Most commonly, occlusion of the punctum has been used, and success has been reported with such agents as pork fat, liquid paraffin, petroleum jelly, heavy oil, and beeswax.6.7 This sutiocates the larva, causing it to come out of the burrow in search of air, where it can be grasped. Extruding the larva, by injecting lidocaine into the blind end of the burrow has been described.9 Alternatively, pressure ap-
FURUNCULAR
CUTEREBRID
MYIASIS
1513
plied on either side of the burrow with wooden spatulas can be used to express the parasite.‘O After removal, resolution of the inflammatory lesion should occur. North American cuterebrid myiasis is rare, and the
diagnosis is frequently delayed. Because the typical presentation is in the form of a subcutaneous abscess, these patients may at some point in their course be referred to a surgeon for evaluation.
REFERENCES 1. Baird JK, Baird CR, Sabrosky CW: North American cuterebrid myiasis. J Am Acad Dermatol21:763-772, 1989 2. Bums DA: Diseases caused by arthropods and other noxious animals, in Champion RH, Burton JL, Ebling FJG (eds): Textbook of Dermatology, Oxford, Blackwell Scientific, 1992, pp 1272-1275 3. Sherman RA, Tran JM, Sullivan R: Maggot therapy for venous stasis ulcers. Arch Dermatol 132:254-256, 1996 4. Kpea N, Zywocinski C: “Flies in the flesh”: A case report and review of cutaneous myiasis. Cutis 55:47-48, 1995 5. Schiff TA: Furuncular cutaneous myiasis caused by Cuterebra larva. J Am Acad Dermatol28:261-263, 1993
6. Arosemena R, Booth SA, Su WPD: Cutaneous myiasis. J Am Acad Derm 28:254-256, 1993 7. Potter TS, Dorman MA, Ghaemi M, et al: Inflammatory papules on the back of a traveling businessman. Arch Dermatol 131:951-956, 1995 8. Pallai L, Hodge J, Fishman SJ, et al: Case report: Myiasis-The botfly boil. Am J Med Sci 303:245-248, 1992 9. Lui H, Buck HW: Cutaneous myiasis: A simple and effective technique for extraction of Dermatobia hominis larvae. Int J Dermatol 31:657-659, 1992 10. OlumideYM: Letter to the editor. Int J Dermatol33:148, 1994
Shorter,
Cuterebrid
Karla Werninghaus, Lebanon,
New
David Mooney,
procedures, J Pediatr Saunders
A
above
CASE REPORTS
Case 1 In August of 1995 an otherwise healthy 3-year-old girl, a resident of New Hampshire, developed a small raised erythematous lesion on her upper anterior chest, containing what was described by her mother as a blackhead in the center, It was slightly pruritic. The lesion subsequently resolved, but several others developed in the same area, all but one of which also spontaneously disappeared. The lesion that persisted continued to enlarge until it was about 1 cm in size, resembling a small boil. She had no systemic symptoms. A central hole developed in it, within which a whitish object was occasionally visible. When this was extruded a few days later, it was found to be a 5-mm X 1.5.mm maggot compatible with an early second instar botfly larva (Fig l).’ Surgical consultation was obtained at this point, but no further intervention was necessary. The lesion subsequently rapidly resolved, and she has had no further difficulties. The time course for the whole process was about 2 weeks. Subsequent questioning to determine a possible source for the infestation revealed that a short time before she had been playing with some old cardboard boxes from a barn, one of which contained an uninhabited mouse nest, and also that her family had recently been caring for a neighbor’s rabbit. There was no history of foreign travel.
Case 2 At the end of August 1996, an otherwise healthy &year-old boy, a resident of eastern Vermont who was vacationing in rural New Hampshire, noted several small papules beneath his right eye. These subsequently disappeared, but another appeared over the orbital rim just Journa/ofPediatricSurgery,Vol32,
No 10 (October),
1997: pp 1511-1513
and Alan Graham
Hampshire
Myiasis is the infestation of skin by the larvae of flies. In North America cases are caused by the botfly (Cuterebra) and occur most commonly in children. The usual presentation is a subcutaneous abscess, and for this reason these patients may be referred to surgeons. Knowledge of this entity can avoid delays in diagnosis, unnecessary incision and drainage
LTHOUGH AMERICANS commonly think of human arthropod infestation as a disease type confined to the Third World, on occasion such cases are seen in North America. One such entity is cuterebrid myiasis, in which maggots of the botfly (Cuter&u) develop in the skin of a human host, forming a lesion that presents as an abscess. Most cases occur in children, and, surprisingly, the disease is most common in northern areas, especially the northeastern United States and southeastern Canada.] These patients may come to the attention of pediatric surgeons, and knowledge of this entity can avoid delays in diagnosis, unnecessary incision and drainage procedures, and unnecessary courses of antibiotics.
Myiasis
INDEX
and unnecessary Surg 32:1511-1513. Company.
WORDS:
Skin
abscess,
courses of antibiotics. Copyright o 1997
myiasis,
by
W.B.
botfly.
and lateral to the eye. Initially pruritic, this lesion increased in size. Despite obvious swelling and erythema, pain and tenderness were minimal. The initial diagnosis was an insect bite with an allergic response, and he was started on diphenhydramine. There was no improvement. Over the next week the lesion continued to increase in size, and an opening appeared in its center from which there was a small amount of serosanguinous drainage. Systemic symptoms were absent, and the lesion remained essentially nontender and pain free. At this point surgical consultation was obtained. The lesion, which had the appearance of a subcutaneous abscess, now measured about 2 cm in diameter (Fig 2). Within the central opening, a black and white object was occasionally visible. The diagnosis of cuterebrid myiasis was made. The opening was initially covered with petroleum jelly, but a portion of the larva could be seen protruding after about 10 minutes, it did not move out any further. Gentle pressure was then applied on each side of the opening, and the larva was expressed in its entirety. Measuring 1.4 cm by 0.6 cm, it was a third instar cuterebiid maggot (Fig 3).’ Slow resolution of the inflammatory lesion followed. The exact source of the infestation is unknown. There was no history of foreign travel.
DISCUSSION
Cutaneous myiasis is the infestation of skin by the larvae of flies. This may be obligatory (a normal step in the fly’s life cycle) or facultative (larvae usually develop on decaying flesh or vegetable matter but may infect wounds).2 Facultative myiasis is the basis for maggot debridement therapy.3 A number of species have been implicated in human disease. In South and Central America the most common is Dermatobia hominis (human botfly), whereas in Africa it is Cordylobiu anthropophagia (tumbu fl~).~,~There are several reported cases of North American travelers returning from trips to these endemic areas and presenting with myiasis caused by these species.4J-9 Cases acquired in North America are almost all caused by the genus Cuterebru (rodent or rabbit botfly).‘.5 No From the Departments qf Surgery aftd Pediatrics, Dartmouth Medical School, Children 4 Hospital at Dartmouth, Lebailon, NH. Address reprint requests to Nicholas A. Shortei; MD, Departme?lt of Surgery, Children’s Hospital at Darhnouth, Lebanon, NH 03756. Copyright o 1997 by I%B. Saunders Company 0022-3468/97/3210-0031$03.00/O 1511
1512
Fig 1. Early second instar cuterebrid maggot truded from a lesion on the chest of a 3-year-old measurements, 5 mm x 1.5 mm.
SHORTER
ET AL
spontaneously exgirl (case I). Actual
specific species has been implicated because identification of larvae beyond genus, is not presently possible. These are large bumblebeelike flies that are obligatory parasites. The natural hosts in North America are rodents, rabbits, and hares, and eggs are laid near the dwelling places of these animals. The eggs hatch, and the larvae attach to and then enter the host. After a period of development each larva drops to the ground, burrows into the soil and pupates, with subsequent emergence of an adult the following spring. Adult flies do not feed, so all growth occurs in the larval stage. Although humans may be a natural host for some,tropical species of fly, human cuterebrid infestation only occurs accidentally when someone inadvertently comes in contact with eggs that are ready to hatch. Cases are rare, with less than 60 reported in the literature. ix5Most present as subcutaneous abscesseson the face, scalp, neck, shoulders or chest, and the larvae probably enter by direct penetration of the skin. In a few patients, infection of the vitreous humor or of the upper respiratory tract has been reported. Unlike other types of fly only a solitary lesion containing a single larva has been documented in all cases of North American cuterebrid myiasis.
Fig 2. Lesion above the right eye of an &year-old boy (case 2). A drop of serosanguinous drainage is present in the opening, with the tip of the larva just visible as a white spot within it.
Fig 3. Third instar cuterebrid maggot above the right eye of an g-year-old boy ments, 1.4 cm x 0.6 cm.
removed from a lesion (case 2). Actual measure-
Almost all cases present in August, September, or October.’ The typical lesion is an erythematous papule ranging in size from 0.2 to 2 cm. It is typically pruritic but may be painful and tender. There may be a history of a sharp sting at the site a few weeks before, and some patients describe a sensation of something moving within the lesion. A central punctum develops through which the organism breathes, and there is frequently serous, serosanguinous, or purulent drainage. Occasionally the larva is visible through the opening. Typically these lesions are initially diagnosed as furunculosis or cellulitis, which does not respond to antibiotics. Incision and drainage of the lesion may have been performed before arriving at the correct diagnosis. Once the diagnosis is made, a number of therapeutic approaches exist, all directed toward removal of the organism. Theoretically, no treatment is necessary, as by its nature the process is self limited. However, because of the frequently unpleasant local symptoms, not to mention the psychological distress caused by the concept of being infested with maggots, few patients or parents would be willing to opt for that approach. On occasion, as in one of our cases, spontaneous extrusion may occur, with the diagnosis being made at that time. Trying to extract the larva with forceps is difficult, both because of its depth within the skin and because of the presence of surface spines which anchor it. Surgical incision and extraction has been recommended4.8 but is probably excessive unless the larva is dead.5x7Most commonly, occlusion of the punctum has been used, and success has been reported with such agents as pork fat, liquid paraffin, petroleum jelly, heavy oil, and beeswax.6.7 This sutiocates the larva, causing it to come out of the burrow in search of air, where it can be grasped. Extruding the larva, by injecting lidocaine into the blind end of the burrow has been described.9 Alternatively, pressure ap-
FURUNCULAR
CUTEREBRID
MYIASIS
1513
plied on either side of the burrow with wooden spatulas can be used to express the parasite.‘O After removal, resolution of the inflammatory lesion should occur. North American cuterebrid myiasis is rare, and the
diagnosis is frequently delayed. Because the typical presentation is in the form of a subcutaneous abscess, these patients may at some point in their course be referred to a surgeon for evaluation.
REFERENCES 1. Baird JK, Baird CR, Sabrosky CW: North American cuterebrid myiasis. J Am Acad Dermatol21:763-772, 1989 2. Bums DA: Diseases caused by arthropods and other noxious animals, in Champion RH, Burton JL, Ebling FJG (eds): Textbook of Dermatology, Oxford, Blackwell Scientific, 1992, pp 1272-1275 3. Sherman RA, Tran JM, Sullivan R: Maggot therapy for venous stasis ulcers. Arch Dermatol 132:254-256, 1996 4. Kpea N, Zywocinski C: “Flies in the flesh”: A case report and review of cutaneous myiasis. Cutis 55:47-48, 1995 5. Schiff TA: Furuncular cutaneous myiasis caused by Cuterebra larva. J Am Acad Dermatol28:261-263, 1993
6. Arosemena R, Booth SA, Su WPD: Cutaneous myiasis. J Am Acad Derm 28:254-256, 1993 7. Potter TS, Dorman MA, Ghaemi M, et al: Inflammatory papules on the back of a traveling businessman. Arch Dermatol 131:951-956, 1995 8. Pallai L, Hodge J, Fishman SJ, et al: Case report: Myiasis-The botfly boil. Am J Med Sci 303:245-248, 1992 9. Lui H, Buck HW: Cutaneous myiasis: A simple and effective technique for extraction of Dermatobia hominis larvae. Int J Dermatol 31:657-659, 1992 10. OlumideYM: Letter to the editor. Int J Dermatol33:148, 1994