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Myiasis Workup

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

Laboratory Studies

Diagnosis is typically made by identification of fly larvae or maggots. The exact type of species can be difficult to determine from examination.[5] However, CBC count may show leukocytosis and eosinophilia.

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Imaging Studies

MRI has been used in a number of cases of cerebral myiasis; breast myiasis; and facial, orbital, and furuncular myiasis. Ultrasonography can also be very useful in establishing the diagnosis and in determining the size of the larvae. CT scan has also been suggested.[15]

In one study, Doppler ultrasonography (DUSG) was performed using a high-resolution (10-MHz) soft-tissue transducer. Using the standard mode, hypoechogenic masses underneath the skin were first located, and then DUSG was used, which demonstrated circulation of fluid within the parasite as well as the number of parasites, their size, and their situation within the lesion. This is especially useful when lesions are still small and look like insect bites. Secretion and pain are minimal or absent, and the punctum is almost always absent. In these cases, high-resolution DUSG proved to be 100% effective in diagnosis.[16]

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Procedures

Biopsies are not necessary, but if performed, histopathologic findings include an ulcerated epidermis with an inflammatory infiltrate of neutrophils, lymphocytes, giant cells, mast cells, plasma cells, and eosinophils that occur in stages. The larvae can be seen in cross-section.[1, 16]

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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
  1. Bolognia JL, Jorizzo JL, Rapini R. Cutaneous myiasis. Dermatology. 2nd ed. Mosby Elsevier; 2008. Vol 1: 1300-01.

  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].

  14. Garvin KW, Singh V. Case report: cutaneous myiasis caused by Dermatobia hominis, the human botfly. Travel Med Infect Dis. 2007 May. 5(3):199-201. [Medline].

  15. Ofordeme KG, Papa L, Brennan DF. Botfly myiasis: a case report. CJEM. 2007 Sep. 9(5):380-2. [Medline].

  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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