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Myiasis Clinical Presentation

  • Author: Adam B Blechman, MD; Chief Editor: Joe Alcock, MD, MS  more...
 
Updated: May 13, 2016
 

History

Often, a history of traveling to a tropical country or existence of a previous wound is noted. In one study, the average time from exposure to diagnosis was 1.5 months.[9]

Patients complain of boil-like lesions usually on exposed areas of the body, like the scalp, face, forearms, and legs.

Lesions can be painful, pruritic, and tender, and patients often have the sense of something moving under the skin. Sometimes, patients also complain of fever or swollen glands.

In the cases of ophthalmomyiasis, patients complain of severe eye irritation, redness, foreign body sensation, pain, lacrimation, and swelling of the eyelids.[10]

In the cases of nasal myiasis, patients present with epistaxis, foul smell, passage of worms, facial pain, nasal obstruction, nasal discharge, headache, dysphagia, and sensation of foreign body in the nose.[11, 12]

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Physical

Furuncular myiasis

This type of myiasis , caused by both the human botfly and the tumbu fly, causes nonhealing boil-like lesions (see images below). Whereas myiasis from the tumbu fly occurs on the trunk, thigh, and buttocks, botfly lesions are on the exposed areas of the body, including the scalp, face, forearms, and legs. A pruritic erythematous papule develops within 24 hours of penetration, enlarging to 1-3 cm in diameter and almost 1 cm in height. These lesions can be painful and tender. Each has a central punctum (see images below) from which serosanguineous fluid may be discharged. Lesions may become purulent and crusted; the movement of the larva may be noticed by the patient.[1] The tip of the larva may protrude from the central opening (punctum), or bubbles produced by its respiration may be seen.[4] The inflammatory reaction around the lesions may be accompanied by lymphangitis and regional lymphadenopathy.[3]

Boil-like lesion on toe of a patient with botfly m Boil-like lesion on toe of a patient with botfly myiasis; the central punctum is apparent. Image courtesy of Kenneth E Greer.
Boil-like lesions on a patient with botfly myiasis Boil-like lesions on a patient with botfly myiasis; the central punctum is apparent. Image courtesy of Kenneth E Greer.

Wound myiasis

In wound myiasis , the larvae are deposited in a suppurating wound or on decomposing flesh. The diagnosis is obvious when larvae are visible on the surface within or around the wound and more difficult when they have burrowed beneath the surface.[1]

Creeping cutaneous myiasis

Creeping (or migratory) cutaneous myiasis may be caused when there is exposure to infested cattle or in those who work with horses. This form of myiasis resembles cutaneous larva migrans, with an apparent tortuous, thread-like red line that ends in a terminal vesicle marking the passage of the larva through the skin. The larva lies ahead of the vesicle in apparently normal skin.[3]

Ophthalmomyiasis externa

Ophthalmomyiasis externa, caused by Oestrus ovis, is characterized by conjunctivitis, lid edema, and superficial punctate keratopathy in response to movement of larvae across the external surface of the globe. Larvae may appear within the cornea, lens, anterior chamber, or vitreous body but rarely undergo development once the globe has been entered.[7]

Posttraumatic myiasis

Patients who are victims of facial trauma or extensive scalp injury can develop extensive intracranial maggot infestation causing meningitis and encephalitis if not properly managed within a reasonable period of time.[13]

Nasal myiasis

In nasal myiasis, examination of the nose (rhinoscopy) reveals an edematous, ulcerated mucous membrane filled with necrotic material and crawling maggots. Patients may have septal perforation or palatal perforation or both. Erosion of the bridge of the nose and adjacent area of the face can also be seen as well as orbital cellulitis and diffuse cellulitis of the face. In a smaller number of patients, examination reveals extensive ulceration of the tonsils and the posterior pharyngeal wall due to maggots.[12]

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Causes

As mentioned above, the cause for myiasis is the infestation of humans with the larvae of the Diptera order of fly species. More than a hundred species of Diptera have been reported to cause human myiasis. Some of the most common are as follows:

  • Dermatobia hominis (human botfly) causes furuncular myiasis.
  • Cordylobia anthropophaga (tumbu fly) also causes furuncular myiasis.
  • Cochliomyia hominivorax (America) and Chrysomyia bezziana (Africa, Australia, Asia) both cause wound myiasis.
  • Hypoderma bovis (infested cattle) and Gasterophilus intestinalis (infested horses) both cause creeping (migratory) myiasis.
  • Oestrus ovis (sheep botfly) causes ophthalmomyiasis.
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Contributor Information and Disclosures
Author

Adam B Blechman, MD Resident Physician, Department of Dermatology, University of Virginia Health System

Adam B Blechman, MD is a member of the following medical societies: American Academy of Dermatology, American Society for Dermatologic Surgery, Medical Society of Virginia

Disclosure: Nothing to disclose.

Coauthor(s)

Barbara B Wilson, MD Edward P Cawley Associate Professor, Department of Dermatology, University of Virginia School of Medicine

Barbara B Wilson, MD is a member of the following medical societies: Alpha Omega Alpha, Medical Society of Virginia, Sigma Xi, American Academy of Dermatology

Disclosure: Nothing to disclose.

Specialty Editor Board

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Received salary from Medscape for employment. for: Medscape.

Chief Editor

Joe Alcock, MD, MS Associate Professor, Department of Emergency Medicine, University of New Mexico Health Sciences Center

Joe Alcock, MD, MS is a member of the following medical societies: American Academy of Emergency Medicine

Disclosure: Nothing to disclose.

Additional Contributors

Robert L Norris, MD Professor, Department of Emergency Medicine, Stanford University Medical Center

Robert L Norris, MD is a member of the following medical societies: American College of Emergency Physicians, Society for Academic Emergency Medicine, International Society of Toxinology, American Medical Association, California Medical Association, Wilderness Medical Society

Disclosure: Nothing to disclose.

Acknowledgements

Eleni Grammatikopoulou, MD Visiting Physician, University of Virginia School of Medicine

Disclosure: Nothing to disclose

References
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  2. Diaz JH. The epidemiology, diagnosis, management, and prevention of ectoparasitic diseases in travelers. J Travel Med. 2006 Mar-Apr. 13(2):100-11. [Medline].

  3. Burns T, Breathnach S, Cox N, Griffiths C. Diseases caused by arthropods and other noxious animals. Rook's Textbook of Dermatology. 7th ed. Malden, MA: Blackwell Publishing; 2004. Vol 2: 33.8 - 11.

  4. Auerbach PS. Arthropod envenomation and parasitism. Wilderness Medicine. 5th ed. Philadelphia, PA: Mosby Elsevier; 2007. 969-974.

  5. Davis RF, Johnston GA, Sladden MJ. Recognition and management of common ectoparasitic diseases in travelers. Am J Clin Dermatol. 2009. 10(1):1-8. [Medline].

  6. James, WD, Berger, TG, Elston, DM. Myiasis. Andrews’ Diseases of the Skin. 11th ed. Elsevier; 2011. 438.

  7. Mandell GL, Bennett JE, Dolin R. Infectious diseases and their etiologic agents. Principles and Practice of Infectious Diseases. 5th ed. Philadelphia, PA: Churchill Livingstone; 2000. Vol 2: 2976-2979.

  8. Cestari TF, Pessato S, Ramos-e-Silva M. Tungiasis and myiasis. Clin Dermatol. 2007 Mar-Apr. 25(2):158-64. [Medline].

  9. Schwartz E, Gur H. Dermatobia hominis myiasis: an emerging disease among travelers to the Amazon basin of Bolivia. J Travel Med. 2002 Mar-Apr. 9(2):97-9. [Medline].

  10. Masoodi M, Hosseini K. External ophthalmomyiasis caused by sheepbotfly (Oestrus Ovis) larva: a report of 8 cases. Arch Iran Med. 2004. 7:136-139.

  11. Aydin E, Uysal S, Akkuzu B, et al. Nasal myiasis by fruit fly larvae: a case report. Eur Arch Otorhinolaryngol. 2006 Dec. 263(12):1142-3. [Medline].

  12. Sharma H, Dayal D, Agrawal SP. Nasal myiasis: review of 10 years experience. J Laryngol Otol. 1989 May. 103(5):489-91. [Medline].

  13. Terterov S, Taghva A, MacDougall M, Giannotta S. Posttraumatic human cerebral myiasis. World Neurosurg. 2010 May. 73(5):557-9. [Medline].

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  16. Quintanilla-Cedillo MR, Leon-Urena H, Contreras-Ruiz J, Arenas R. The value of Doppler ultrasound in diagnosis in 25 cases of furunculoid myiasis. Int J Dermatol. 2005 Jan. 44(1):34-7. [Medline].

  17. Maier H, Hönigsmann H. Furuncular myiasis caused by Dermatobia hominis, the human botfly. J Am Acad Dermatol. 2004 Feb. 50(2 Suppl):S26-30. [Medline].

  18. Brewer TF, Wilson ME, Gonzalez E, Felsenstein D. Bacon therapy and furuncular myiasis. JAMA. 1993 Nov 3. 270(17):2087-8. [Medline].

  19. Ruch DM. Botfly myiasis. Arch Dermatol. 1967 Dec. 96(6):677-80. [Medline].

  20. Lebwohl MG, Heymann WR, Berth-Jones J, Coulson I. Myiasis. Treatment of Skin Diseases. Comprehensive Therapeutic Strategies. 2nd ed. Elesevier-Mosby; 2006. 420-421.

  21. Osorio J, Moncada L, Molano A, et al. Role of ivermectin in the treatment of severe orbital myiasis due to Cochliomyia hominivorax. Clin Infect Dis. 2006 Sep 15. 43(6):e57-9. [Medline].

  22. Costa DC, Pierre-Filho Pde T, Medina FM, Mota RG, Carrera CR. Use of oral ivermectin in a patient with destructive rhino-orbital myiasis. Eye. 2005 Sep. 19(9):1018-20. [Medline].

  23. Clyti E, Nacher M, Merrien L, et al. Myiasis owing to Dermatobia hominis in a HIV-infected subject: Treatment by topical ivermectin. Int J Dermatol. 2007 Jan. 46(1):52-4. [Medline].

 
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Mature larva of the Dermatobia hominis fly; rows of hooks apparent on its tapered body. Image courtesy of Kenneth E Greer.
Boil-like lesion on toe of a patient with botfly myiasis; the central punctum is apparent. Image courtesy of Kenneth E Greer.
Boil-like lesions on a patient with botfly myiasis; the central punctum is apparent. Image courtesy of Kenneth E Greer.
 
 
 
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