Dermatobia hominis

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Dermatobia hominis
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<p align="CENTER"><span style="font-size: large;"><i><b>Dermatobia</b></i></span><span style="font-size: large;"><i><b>hominis</b></i></span><span style="font-size: large;"><b> (Linnaeus, 1781)</b></span></p> <p align="CENTER"><span style="font-size: large;"><b>(Figure 5-70)</b></span></p> <p align="JUSTIFY"></p> <p align="JUSTIFY"><span style="font-size: medium;"><b>ETYMOLOGY:</b></span><span style="font-size: medium;"><i>Dermato</i></span><span style="font-size: medium;"> = skin + </span><span style="font-size: medium;"><i>obia</i></span><span style="font-size: medium;"> = way of living and hominis for the choice of human hosts. Common names include the human botfly, tropical warble fly, beef worm, bekuru, bikuru, berne, borro, colmoyte, forcel, gusano macaco, gusano de monte, gusano de mosquito, gusano de zancudo, gusano peludo, kturn, kitudn, ikitugn, mberuaró, mirunta, moyocuil, muskietenworm, nuche, nunche, suglacuru, suylacuru, torsel, tórsalo, tupe, ura, and ver macacque </span></p> <p align="JUSTIFY"></p> <p align="JUSTIFY"><span style="font-size: medium;"><b>SYNONYMS:</b></span><span style="font-size: medium;"><i>Oestrus</i></span><span style="font-size: medium;"><i>hominis</i></span><span style="font-size: medium;">, </span><span style="font-size: medium;"><i>Oestrus</i></span><span style="font-size: medium;"><i>humanus</i></span><span style="font-size: medium;">, </span><span style="font-size: medium;"><i>Oestrus</i></span><span style="font-size: medium;"><i>guildingii</i></span><span style="font-size: medium;">, Cute</span><span style="font-size: medium;"><i>r</i></span><span style="font-size: medium;">ebra </span><span style="font-size: medium;"><i>cyaniventris</i></span><span style="font-size: medium;">, </span><span style="font-size: medium;"><i>Cuterebra</i></span><span style="font-size: medium;"><i>noxialis</i></span><span style="font-size: medium;">, </span><span style="font-size: medium;"><i>Dermatobia</i></span><span style="font-size: medium;"><i>noxialis</i></span><span style="font-size: medium;">, and </span><span style="font-size: medium;"><i>Dermatobia</i></span><span style="font-size: medium;"><i>cyaniventris</i></span><span style="font-size: medium;"> (Guimaraes and Papavero, 1966)</span></p> <p align="JUSTIFY"></p> <p align="JUSTIFY"><span style="font-size: medium;"><b>HISTORY:</b></span><span style="font-size: medium;"> Records of early exploration in Panama reveal that </span><span style="font-size: medium;"><i>Dermatobia</i></span><span style="font-size: medium;"><i>hominis</i></span><span style="font-size: medium;"> has been known as a human parasite in Panama for almost a century and a half. If earlier records were available, they would probably show that this fly has been known by indigenous Americans for centuries (Dunn, 1934). The natives of Central and South America have long known animals to be infected with larvae of </span><span style="font-size: medium;"><i>Dermatobia</i></span><span style="font-size: medium;"> species. The ancient Mayans referred to this parasite as "saglacuru" and believed that it owed its existence to the bite of some kind of mosquito (Hoeppli, 1959). It is strange how close to the truth these ancient peoples were. The ancient Mayans extracted the larva of </span><span style="font-size: medium;"><i>Dermatobia</i></span><span style="font-size: medium;"> by covering its breathing pore with heavy oil (Ockenhouse </span><span style="font-size: medium;"><span style="text-decoration: underline;">et</span></span><span style="font-size: medium;"><span style="text-decoration: underline;">al</span></span><span style="font-size: medium;">., 1990). In the earliest report of feline infestation by </span><span style="font-size: medium;"><i>Dermatobia</i></span><span style="font-size: medium;"><i>hominis</i></span><span style="font-size: medium;">, Dunn (1934) reported that "three half-grown larvae were found in a vagrant cat." </span></p> <p align="JUSTIFY"></p> <p align="JUSTIFY"><span style="font-size: medium;"><b>GEOGRAPHIC DISTRIBUTION: </b></span><span style="font-size: medium;">This botfly occurs in Mexico, Central America and South America (File </span><span style="font-size: medium;"><i><span style="text-decoration: underline;">et al.</span></i></span><span style="font-size: medium;">, 1985).</span></p> <p align="JUSTIFY"></p> <p align="JUSTIFY"><span style="font-size: medium;"><b>LOCATION IN HOST:</b></span><span style="font-size: medium;"> The larval </span><span style="font-size: medium;"><i>Dermatobia</i></span><span style="font-size: medium;">. </span><span style="font-size: medium;"><i>hominis</i></span><span style="font-size: medium;"> penetrates the skin of the definitive host producing a cutaneous furunculoid (boil-like) myiasis (Pallai </span><span style="font-size: medium;"><span style="text-decoration: underline;">et</span></span><span style="font-size: medium;"><span style="text-decoration: underline;">al</span></span><span style="font-size: medium;">., 1992). </span></p> <p align="JUSTIFY"></p> <p align="JUSTIFY"><span style="font-size: medium;"><b>IDENTIFICATION:</b></span><span style="font-size: medium;"> The adult </span><span style="font-size: medium;"><i>Dermatobia</i></span><span style="font-size: medium;"><i>hominis</i></span><span style="font-size: medium;"> is about 1.5 to 1.8 cm in length, approximately the size of a bumblebee. It has a blue-gray thorax, a metallic blue abdomen, and yellow orange legs (Pallai </span><span style="font-size: medium;"><i>et al.</i></span><span style="font-size: medium;">, 1992). The adult has no functional mouthparts and takes no nourishment (Rossi and Zucoloto, 1973). Food stored during the larval stage provides the adults with nourishment (Prasad and Beck, 1969). </span></p> <p align="JUSTIFY"><span style="font-size: medium;"> The mature larva at two to three months of age is 1.8 to 2.4 cm in length (Fig. 5-70). It has a definite club shape and can be identified by rows of posteriorly directed spines on its anterior segments. The larval stage also possesses the caudal spiracles which protrude through the host's skin to the exterior to guarantee an adequate air supply (File </span><span style="font-size: medium;"><span style="text-decoration: underline;">et</span></span><span style="font-size: medium;"><span style="text-decoration: underline;">al</span></span><span style="font-size: medium;">., 1985).</span></p> <p align="JUSTIFY"><span style="font-size: medium;"> The larva of </span><span style="font-size: medium;"><i>Dermatobia</i></span><span style="font-size: medium;"><i>hominis</i></span><span style="font-size: medium;"> is narrow and tubular at its posterior extremity and somewhat flask-shaped anteriorly (Patton and Evans, 1929). The presence of the superficially positioned swelling with a central opening may lead to a tentative diagnosis of myiasis due to </span><span style="font-size: medium;"><i>Dermatobia</i></span><span style="font-size: medium;"><i>hominis</i></span><span style="font-size: medium;">. A definitive diagnosis can be made only after extraction and identification of the typical larva.</span></p> <p align="JUSTIFY"><span style="font-size: medium;"> Diagnosis of infestation with </span><span style="font-size: medium;"><i>Dermatobia</i></span><span style="font-size: medium;"><i>hominis</i></span><span style="font-size: medium;"> may often be made if the patient has a history of residence in or travel to an endemic area (Prasad and Beck, 1969, Rossi and Zucoloto, 1973, Iannini et al., 1975, Kleeman, 1983, Kenny and Baker, 1984, File et al., 1985, Pallai et al., 1992). However, there are other flies from different geographic areas that might produce a similar lesion . These should also be considered in a differential diagnosis. These myiasis-producing flies include: </span><span style="font-size: medium;"><i>Cordylobia</i></span><span style="font-size: medium;"><i>anthropophaga</i></span><span style="font-size: medium;">, the African tumbu fly; </span><span style="font-size: medium;"><i>Wohlfahrtia</i></span><span style="font-size: medium;"><i>vigil</i></span><span style="font-size: medium;">, the grey flesh fly; </span><span style="font-size: medium;"><i>Chrysomyia</i></span><span style="font-size: medium;"><i>bezziana</i></span><span style="font-size: medium;">, the Oriental fly; </span><span style="font-size: medium;"><i>Cochliomyia</i></span><span style="font-size: medium;"><i>hominivorax</i></span><span style="font-size: medium;">, the primary screwworm; and </span><span style="font-size: medium;"><i>Cuterebra</i></span><span style="font-size: medium;"> species, the rabbit botflies. These obligatory myiasis-producing flies should be considered in the differential diagnosis in cats with an appropriate residence or travel history. </span></p> <p align="JUSTIFY"></p> <p align="JUSTIFY"><span style="font-size: medium;"><b>LIFE CYCLE: </b></span><span style="font-size: medium;">This dipteran fly has a most unusual life cycle. The adult fly inhabits the forests of Mexico, Central America and South America. Unlike many of the obligatory myiasis-producing dipterans (with the exception of </span><span style="font-size: medium;"><i>Cuterebra</i></span><span style="font-size: medium;"> species), the female fly does not deposit her eggs directly on the host. Instead, she captures another dipteran fly, usually a bloodsucker, or a tick and using a quick-drying adhesive, cements the eggs to one side of the carrier's body. The eggs are attached to the carrier in such a manner that when contact is made with the prospective definitive host, the anterior end of the egg is directed downward. An operculum forms on this end of the egg, through which the larva emerges. The larva penetrates the skin of the host to the subcutaneous tissues and produces a warble (swelling) at the point of contact. </span><span style="font-size: medium;"><i>Dermatobia</i></span><span style="font-size: medium;"><i>hominis</i></span><span style="font-size: medium;"> does not meander through the subcutis. The tórsalo matures to its most advanced larval stage in the body of the host (Harwood and James, 1979). Development in the host requires 35 to 70 days. The larva then drops to the ground where it enters the soil for pupation. The entire life cycle takes 90 to 120 days (Harwood and James, 1979). </span></p> <p align="JUSTIFY"></p> <p align="JUSTIFY"><span style="font-size: medium;"><b>CLINICAL PRESENTATION AND PATHOGENESIS:</b></span><span style="font-size: medium;"> Although often not reported, cats are host to infestation with this parasite (Silva Junior, et al., 1998). Clinically, the initial lesion is a small, often pruritic, nodule resembling a common insect bite. As the larva matures, the lesion enlarges around it to form an malodorous, purulent, furuncular lesion. It may be 1 to 2 cm in diameter and 0.5 to 1 cm in height. A serosanguinous fluid begins to exude from the lesion during the second week. Purulent discharge may result from excretions from the larva or from secondary bacterial infection. Each nodule contains a central pore that denotes the presence of the larva (Pallai </span><span style="font-size: medium;"><span style="text-decoration: underline;">et</span></span><span style="font-size: medium;"><span style="text-decoration: underline;">al</span></span><span style="font-size: medium;">., 1992). Close examination of the larva </span><span style="font-size: medium;"><i><span style="text-decoration: underline;">in situ</span></i></span><span style="font-size: medium;"> may reveal the up-and-down respiratory movements of the larva (Kenney and Baker, 1984) or actual visualization of the larval spiracles. It is possible to palpate the larva within the nodule (Pallai </span><span style="font-size: medium;"><span style="text-decoration: underline;">et</span></span><span style="font-size: medium;"><span style="text-decoration: underline;">al</span></span><span style="font-size: medium;">., 1992). </span></p> <p align="JUSTIFY"></p> <p align="JUSTIFY"></p> <p align="JUSTIFY"><span style="font-size: medium;"><b>TREATMENT: </b></span><span style="font-size: medium;">The goal of treatment is to remove the larva. In man, several methods have been reported for extraction of larval </span><span style="font-size: medium;"><i>Dermatobia</i></span><span style="font-size: medium;">. </span><span style="font-size: medium;"><i>hominis</i></span><span style="font-size: medium;"> from the skin. These techniques should also apply to the feline definitive host. The simplest method (although somewhat time consuming) is the application of a viscous, occlusive substance (</span><span style="font-size: medium;"><span style="text-decoration: underline;">e</span></span><span style="font-size: medium;">.</span><span style="font-size: medium;"><span style="text-decoration: underline;">g</span></span><span style="font-size: medium;">., petroleum jelly) over the hole through which the larva breathes. This cuts off the larva's air supply and stimulates premature extrusion. Manual extraction of the dead larva may be necessary using this technique. Hot compresses may be used to make the lesion more pliable and reduce discomfort. </span></p> <p align="JUSTIFY"><span style="font-size: medium;"> Topical application of 5% chloroform in olive oil to produce a sublethal hypoxia of </span><span style="font-size: medium;"><i>Dermatobia</i></span><span style="font-size: medium;"><i>hominis</i></span><span style="font-size: medium;">, followed by manual extraction has been used successfully in man. </span></p> <p align="JUSTIFY"><span style="font-size: medium;"> Surgical intervention involves the injection of lidocaine hydrochloride into the furuncular lesion. This anesthetizes both the cat and the larva, allowing the larva to be manually extracted through a linear incision using thumb forceps. The wound should be irrigated, debrided and packed open to provide adequate drainage. A disadvantage of surgical removal is that remains of the larval bodies may be accidentally left in the lesion. Careful inspection of the extracted larva and irrigation of the wound should reduce complications (Pallai </span><span style="font-size: medium;"><span style="text-decoration: underline;">et</span></span><span style="font-size: medium;"><span style="text-decoration: underline;">al</span></span><span style="font-size: medium;">., 1992). </span></p> <p align="JUSTIFY"></p> <p align="JUSTIFY"><span style="font-size: medium;"><b>EPIZOOTIOLOGY:</b></span><span style="font-size: medium;"> Since this parasite is spread by both zoophilous and anthropophilous mosquitoes (and other bloodfeeding arthropods), it may be found in a wide variety of definitive hosts. Host selection is performed by "porter" species - mosquitoes and flies. </span><span style="font-size: medium;"><i>Dermatobia</i></span><span style="font-size: medium;"><i>hominis</i></span><span style="font-size: medium;"> females oviposit on these arthropods and depend on them to carry their eggs to mammalian species. </span></p> <p align="JUSTIFY"></p> <p align="JUSTIFY"><span style="font-size: medium;"><b>HAZARDS TO OTHER ANIMALS:</b></span><span style="font-size: medium;"> Because </span><span style="font-size: medium;"><i>Dermatobia</i></span><span style="font-size: medium;"><i>hominis</i></span><span style="font-size: medium;"> is the human botfly and because it may be transmitted to a wide variety of domesticated and wild animals, it is considered to be a zooanthroponosis. In addition to cats, suitable hosts include cattle, swine, dogs, horses, mules, sheep, goats, monkeys and certain wild mammals. Birds (toucans and ant birds) are known to harbor it (Harwood and James, 1979). </span><span style="font-size: medium;"><i>Dermatobia</i></span><span style="font-size: medium;"><i>hominis</i></span><span style="font-size: medium;"> is a serious pest of livestock in many parts of Latin America (Thomas, 1988).</span></p> <p align="JUSTIFY"></p> <p align="JUSTIFY"><span style="font-size: medium;"><b>HAZARDS TO HUMANS:</b></span><span style="font-size: medium;"><i>Dermatobia</i></span><span style="font-size: medium;"><i>hominis</i></span><span style="font-size: medium;"> is also known as the human botfly. Its larval forms have been extracted from various parts of the human body, primarily the head, arms, back, abdomen, buttocks, genitalia, thighs and axilla (Prasad and Beck, 1969, Rossi and Zucoloto, 1973, Iannini </span><span style="font-size: medium;"><i>et al</i></span><span style="font-size: medium;">., 1975, Kleeman, 1983, Kenny and Baker, 1984, File </span><span style="font-size: medium;"><span style="text-decoration: underline;">et</span></span><span style="font-size: medium;"><span style="text-decoration: underline;">al</span></span><span style="font-size: medium;">., 1985, Pallai </span><span style="font-size: medium;"><span style="text-decoration: underline;">et</span></span><span style="font-size: medium;"><span style="text-decoration: underline;">al</span></span><span style="font-size: medium;">., 1992).</span></p> <p align="JUSTIFY"></p> <p align="JUSTIFY"><span style="font-size: medium;"><b>CONTROL/PREVENTION:</b></span><span style="font-size: medium;"> Perhaps the best method of controlling this parasite depends on controlling </span><span style="font-size: medium;"><i>Dermatobia</i></span><span style="font-size: medium;"><i>hominis</i></span><span style="font-size: medium;"> in cattle, its major definitive host in Latin America. Ivermectin in both topical application and in slow-release bolus forms has been demonstrated to be effective in controlling this parasite in cattle (McMullin </span><span style="font-size: medium;"><i>et al</i></span><span style="font-size: medium;">., 1989, Uribe </span><span style="font-size: medium;"><i>et al.</i></span><span style="font-size: medium;">, 1989). Mosquitoes and other blood feeding flies that can serve as phoretic hosts of this fly should be restricted from indoor environments </span></p> <p align="JUSTIFY"></p> <p align="JUSTIFY"><span style="font-size: medium;"><b>LITERATURE CITATIONS</b></span></p> <p align="JUSTIFY"><span style="font-size: medium;">Chitwood M, Lichtenfels JR. 1972. Identification of parasitic metazoa in tissue sections. Exp Parasitol 32:404-519.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Dunn LH. 1934. Prevalence and importance of the tropical warble fly, </span><span style="font-size: medium;"><i>Dermatobia</i></span><span style="font-size: medium;"><i>hominis</i></span><span style="font-size: medium;"> Linn., in Panama. J Parasitol 20:219-226.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Elgart ML. 1990. Flies and myiasis. Dermatol Clin 8:237-244. </span></p> <p align="JUSTIFY"><span style="font-size: medium;">File TM, Thomson RB, Tan JS. 1985. </span><span style="font-size: medium;"><i>Dermatobia</i></span><span style="font-size: medium;"><i>hominis</i></span><span style="font-size: medium;"> dermal myiasis. Arch Dermatol 121:1195-1196.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Guimaraes JH, Papavero N. 1966. A tentative annotated bibliography of </span><span style="font-size: medium;"><i>Dermatobia</i></span><span style="font-size: medium;"><i>hominis</i></span><span style="font-size: medium;"> (Linnaeus Jr., 1781) (Diptera, Cuterebridae). Arq Zool 14:223-294.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Harwood RF, James MT. 1979. </span><span style="font-size: medium;"><span style="text-decoration: underline;">In</span></span><span style="font-size: medium;">: Entomology In Human and Animal Health. 7th edition. Macmillan. New York. pp 313-315. </span></p> <p align="JUSTIFY"><span style="font-size: medium;">Hoeppli R. 1959. </span><span style="font-size: medium;"><span style="text-decoration: underline;">In</span></span><span style="font-size: medium;">: Parasites and Parasitic Infections in Early Medicine and Science. University of Malaya Press. Singapore. p 158. </span></p> <p align="JUSTIFY"><span style="font-size: medium;">Iannini PB, Brandt D, LaForce FM. 1975. Furuncular myiasis. J AM Med Assoc 233:1375-1376. </span></p> <p align="JUSTIFY"><span style="font-size: medium;">Kenney RL, Baker FJ. 1984. Botfly (</span><span style="font-size: medium;"><i>Dermatobia</i></span><span style="font-size: medium;"><i>hominis</i></span><span style="font-size: medium;">) myiasis. Int J Dermatol 23:676-677.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Kleeman FJ. </span><span style="font-size: medium;"><i>Dermatobia</i></span><span style="font-size: medium;"><i>hominis</i></span><span style="font-size: medium;"> comes to Boston. N Eng J Med 308:847-848. </span></p> <p align="JUSTIFY"><span style="font-size: medium;">McMullin PF, Cramer LG, Benz G, Jeromel PC, Gross SJ. 1989. Control of </span><span style="font-size: medium;"><i>Dermatobia</i></span><span style="font-size: medium;"><i>hominis</i></span><span style="font-size: medium;"> infestation in cattle using an Ivermectin slow-release bolus. Vet Rec 124:465. </span></p> <p align="JUSTIFY"><span style="font-size: medium;">Ockenhoouse CF, Samlaska CP, Benson PM, Roberts LW, Eliasson A, Malane S, Menich MD. 1990. Cutaneous myiasis caused by the African tumbu fly (</span><span style="font-size: medium;"><i>Cordylobia</i></span><span style="font-size: medium;"><i>anthropophaga</i></span><span style="font-size: medium;">). Arch Dermatol 126:199-202.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Pallai L, Hodge J, Fishman SJ, Millikan LE, Phelps RG. 1992. Case report: Myiasis - the botfly boil. Am J Med Sci 303:245-248.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Patton W, Evans AM. 1929. </span><span style="font-size: medium;"><span style="text-decoration: underline;">In</span></span><span style="font-size: medium;">: Insects, Ticks, Mites, and Venomous Animals, Part I - Medical. H.R. Grubb. Croydon. pp 435.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Prasad , Beck AR. 1969. Myiasis of the scalp from </span><span style="font-size: medium;"><i>Dermatobia</i></span><span style="font-size: medium;"><i>hominis</i></span><span style="font-size: medium;">. J Am Med Assoc 210:133.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Rossi M, Zucoloto S. 1973. Fatal cerebral myiasis caused by the tropical warble fly, </span><span style="font-size: medium;"><i>Dermatobia</i></span><span style="font-size: medium;"><i>hominis</i></span><span style="font-size: medium;">. Am J Trop Med Hyg 22:267-269.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Silva Junior V.P. da, Leandro A.S., Borja G.E.M. 1998. Ocorrencia do berne, Dermatobia hominis (Diptera: Cuterebridae) em varios hospedeiros, no Rio de Janeiro, Brasil. Parasitologia al Dia. 22: 97 101.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Thomas DB, Jr. 1988. The pattern of </span><span style="font-size: medium;"><i>Dermatobia</i></span><span style="font-size: medium;"> (Diptera: Cuterebridae) myiasis in cattle in tropical Mexico. J Med Ent 25:131-135.</span></p> <p align="JUSTIFY"><span style="font-size: medium;">Uribe LF, McMullin PF, Cramer LG, Amaral NK. 1989. Topically applied Ivermectin: Efficacy against torsalo (Diptera: Cuterebridae). J Econ Ent 82:847-849.</span></p> <p align="JUSTIFY"></p> <p align="JUSTIFY"><span style="font-size: medium;"><b>Figure 5-70. </b></span><span style="font-size: medium;"><i>Dermatobia</i></span><span style="font-size: medium;"> ho</span><span style="font-size: medium;"><i>m</i></span><span style="font-size: medium;">inis. Larva recovered from the arm of a human that had been working in South America.</span></p> <p align="JUSTIFY"></p> <p align="JUSTIFY"></p>
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