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Introduction

Myiasis is the infestation of live vertebrate animals with the larvae (maggots) of Diptera (two winged) flies. In humans, infestation may affect the skin, wounds, intestines and body cavities (oral, nasal, aural, ocular, sinusal, vaginal and urethral). When open wounds are involved, myiasis is referred to as traumatic and when boil-like, the lesion is termed furuncular (1). Cordylobia anthropophaga (also referred to as “tumbu fly”, “mango fly”, “skin maggot fly” or “verde cayor”) is endemic in tropical Africa (2). Furuncular myiasis as a result of Cordylobia anthropophaga, though endemic in the East and West African sub region for over 135 years, is an underreported occurrence (3,4). It commonly affects children more than adults which could be due to their relatively thin skin and possibly because adults develop immunity after repeated exposures (5). Immunosuppression (steroid therapy, corticosteroid immunosuppres-sive therapy for psoriasis, malnutrition, HIV/AIDS, diabetes,) prolonged hospitalization, and extreme poverty may all predispose to development of lesions or wounds which may act as pre-existing factors for myiasis (5).

 

The adult female fly lays about 100-300 eggs in sandy soil often contaminated with urine and faeces or on damp clothes contaminated with urine or faeces laid to dry on the ground in the shade. After the eggs hatch, the larvae (first instar) penetrate unbroken skin when the host lies on the ground or comes into contact with contaminated clothing. Cutaneous symptoms which include pain itching usually develop within 2 days. Furuncular lesions with an intense inflammatory reaction in the surrounding tissues develop within a period of 6 days after onset of cutaneous symptoms. Within 8-12 days the second & third instars develop during which time respiratory spiracles may be seen in the central pore. The 3rd instar then leaves the host, drops to the ground, buries itself, and pupates and becomes an adult fly able to reproduce and begin the cycle all over again (6) (Figure 1).

 

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Photo Credit: Geary, M, Bernard, H, Russel, R, and Hardy, A. “Exotic myiasis with Lund’s fly.” Medical Journal of Australia 171 (1999): 654-655. Dogs and small rodents (e.g. rats) are the definitive hosts. Humans are accidental hosts (7). Diagnosis is mainly clinical based on history of recent travel to an endemic area, one or more non healing skin lesions, pruritus and sensation of movement under skin or pain. Other features on examination include serous or sero-sanguineous discharge from a central punctum and observation of small, white thread-like larvae protruding from the lesion(s). The diagnosis is confirmed by the extraction of the larvae (8, 9).

 

Case Presentations

A family of 3 women, resident in Nairobi, Kenya, was initially seen at the Accident and Emergency department of the Aga Khan University Hospital, Nairobi with one week’s history of “multiple itchy, painful boils” on multiple body areas. They were treated as having furunculosis and started on Clindamycin and Ibuprofen.

 

One of the patients returned three days later with worsening pain and swellings on both breasts, diagnosed as breast abscesses. She was referred for incision and drainage. The whole affected family had recently visited a village in Kitui (Eastern Kenya) where Tumbu fly is endemic two weeks prior to presentation. While there, they had hung their washed clothes on a line near the bush and did not iron before wearing them. It is not clear if any of the clothes fell on the bush. Examination of the patient who presented back with worsening bilateral breast swellings showed her to have multiple discharging sinuses on her breasts, left arm and shoulder, right back and superior gluteal area. Each sinus had a whitish crust at the opening, with a pus-discharging central punctum. The patient reported to have known her HIV status to be negative and she was not known to be diabetic or on steroids. A diagnosis of multiple abscesses was made and the patient was admitted into the hospital for Incision Drainage under General Anaesthesia. Intra-operatively, the first incision was made over the “abscess” on the right breast which yielded 2 live larvae. A total of 8 larvae were extracted from all the sites (Figures 2 to 4). The wounds were managed with daily dressing as an outpatient. Her sister and mother were recalled to hospital and had several larvae extracted under local anaesthesia. All three patients gave informed consent for the publication of these cases with the accompanying images.

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Click to view figure 4

 

Discussion

 

Differential diagnosis of furuncular myiasis includes furunculosis, abscess, foreign body reaction and tungaisis. In this case, the lesions were initially diagnosed as multiple abscesses. The treatment goal is larva removal and treatment of any associated infection with antibiotics although secondary bacterial infections are rare in C. anthropophaga infestations (10). The lesions heal rapidly after larva removal (or spontaneous extrusion). Complications include cellulitis, abscess formation, osteomyelitis and tetanus (7). Larva removal techniques include obstructing the cutaneous orifice thus suffocating the larva, which forces it to wriggle out. Substances used include oil, petroleum jelly, butter and liquid paraffin (10). Forceps may also be used or an incision made over the furuncle under local anesthesia. Care must be taken to remove the entire larva as any remnant may provoke an inflammatory response. Digital mechanical pressure on either side of the furuncle can also be applied to extrude the larva (9). Surgery is usually unnecessary while the invasive larvae remain alive but will be used to remove the dead or decayed larvae from an affected site to prevent possible secondary infections (11). In the furunculoid and almost in every migratory myiasis, surgical removal may be needed because the larva does not always emerge, remaining in the subcutaneous tissue and producing inflammation, infection, and granulomas (12). Clear indications for surgical intervention are lacking in the literature but several cases of invasive myiasis, such as ophthalmomyiasis and invasive intestinal myiasis need surgical intervention (13,14). In this case, the surgical removal was based on the initial misdiagnosis of the lesions as multiple abscesses.

 

Conclusion

Awareness  of  the  clinical  features  of  cutaneous avoid unnecessary delay in diagnosis and treatment. Awareness of the endemic zones within the country is also important, and a detailed travel history would heighten the index of suspicion.

 

References

 

1. Gursel M, Aldemir OS, Ozgur Z, et al. A rare case of gingival myiasis caused by Diptera (Calliphoridae). J Clin Periodontol. 2002;29:777-80

2. Veraldi S, Brusasco A, Suss. Cutaneous myiasis caused by larvae of Cordylobia Anthropophaga (Blanchard). Int J Dermat. 1993;32:182-4

3. Pampiglione S, Bettoli V, Cestari G, et al. Furuncular myiasis due to Cordylobia Anthropophaga endemic in the same locality for over 130 years. Ann Trop Med Parasit. 1993;87:219-20

4. Logar J, Šoba B, Parač Z. Cutaneous myiasis caused by Cordylobia Anthropophagi. Wiener Klinische Wochenschrift. 2006;118:180-2

5. Palmieri JR, North D, Santo A. Furuncular myiasis of the foot caused by the Tumbu fly, Cordylobia Anthropophaga: Report in a medical student returning from a medical mission trip to Tanzania. Int Med Case Rep J. 2013;24(6):25-8

6. Mcgraw TA, Turiansky GW. Cutaneous myiasis. J Am Acad Dermatol. 2008;58(6):907-26

7. Mashhood AA. Furuncular myiasis by Tumbu fly. J Coll Physicians Surg Pak. 2003;13:195-7

8. Olumide Y. Cutaneous myiasis: A simple and effective technique for extraction of Dermatobia Hominis larva. Int J Dermatol. 1994;33:148–9

9. Boggild AK, Keystone JS, Kain KC. Furuncular myiasis: A simple and rapid method for extraction of intact Dermatobia Hominis larvae. Clin Infect Dis. 2002;35:336–8

10. Facina G, Nazario ACP, Kemp C, et al. Myiasis by Dermatobia Hominis mimicking periductal mastitis. Rev Bras Mastol. 1999;9:84-5

11. Hu J, Wang C, Chao L, et al. First report of furuncular myiasis caused by the larva of botfly, Dermatobia Hominis, in a Taiwanese traveler. Asian Pac J Trop Biomed. 2013;3(3):229-31

12. Blejter J. Tracheostomy wound myiasis in a child: Case report and review of the literature. Case Rep Pediatr. 2012;2012:317862. doi: 10.1155/2012/317862

13. Kumari M, Goel MM, Singh D. Invasive intestinal myiasis in a young male presenting as fungating rectal mass: An unusual presentation. Indian J Pathol Microbiol. 2012;55(3):384-5

14. Saraiva Vda S, Amaro MH, Belfort R Jr, et al. A case of anterior internal ophthalmomyiasis: Case report. Arq Bras Oftalmol. 2006;69(5):741-3

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