Myiasis caused by Wohlfahrtia vigil

ARTICLE

A 2-year-old patient living in a rural area of southern Israel was referred to our dermatology clinic because of several lesions on the scalp which had slowly developed over the previous four weeks. On examination, a few ulcerated pulsating nodules were present (Fig. 1). Scrapings from the lesions are shown in Figure 2.

Myiasis caused by Wohlfahrtia vigil

Parasitologic examination of the debris from the ulcerated lesions revealed several maggots showing the characteristic posterior spiracles of the fly Wohlfahrtia vigil (Fig. 2). The lesions were treated with ether and cleaned with povidone-iodine. The lesions resolved completely within three weeks.

Cutaneous myiasis is caused by the deposition of eggs and/or living larvae of Diptera on the skin, where they hatch and burrow, causing furuncle-like lesions associated with an inflammatory reaction [1]. Myiasis can also affect other organs, including the nasopharynx, eyes, intestinal and urogenital systems. The main clinical and pathological aspects of myiasis are summarized in Table I. Myiasis can be classified into three groups, obligatory, facultative and accidental. In the obligatory group, the larvae always pass through the body of an animal. Examples of this group include flies of several families: Calliphoridae, Sarcophagidae, Oestridae, Gasterophilidae and Cuterebridae. In the facultative group, the larvae develop on decaying flesh or vegetable matter, but may infect wounds. This group includes species that are normally saprophages and occasionally adapt themselves to a parasitic existence, for example, Fannia canicularis, Musca domestica, Muscina stabulans. Many species of larvae including: Calliphora, Chrysomya, Sarcophaga haemorrhoidalis, Musca domestica, Magaselia scalaris, Phaenicia sericata and Lucilia illustris that normally breed in meat, may become involved in traumatic and cutaneous myasis. In the accidental group, both the eggs and the larvae are ingested in food producing intestinal myiasis. Etiological agents of this group which include Musca domestica, Fannia canicularis, F. scalaris, other species of Calliphoridae piophilidae and Sarcophagidae [3].

In Israel, several species have been found to be associated with myiasis, including Dermatobia hominis [4], Hypoderma bovis [5], Lucilia [6], Oestrus ovis [7], Sarcophaga sp. [8] and Wohlfahrtia [9].

Treatment of myiasis includes surgical removal of the maggots, douching the wound and application of ether or chloroform [1]. Recently, the ancient procedure of deliberately causing myiasis for treating chronic wounds, particularly in diabetic patients, has been revived [10].

REFERENCES

1. Arnold HL Jr, Odom RB, James WD. In Andrew's diseases of the skin. Clinical Dermatology. 8th edition, Philadelphia, WB Saunders Co, 1990, Chapter 20: 516-8.

2. Burns DA. Diseases caused by arthropods and other noxious animals. In: Champion RH, Buncon JC, Ebling FJG, eds. Rook's Textbook of Dermatology, Oxford, Blackwell Scientific Publication, 1992: 1272-5.

3. Harvood RF, James MT. In Entomology in: Human and Animal Health. Seventh Edition, New York, MacMillan Publishing Ltd. 1979, Chapter 13, 296-318.

4. Rotenberg R, Spitzer A, Pinkus H, Presentey B, Lengy J. Human sub-cutaneous myiasis due to Dermatobia hominis. Harefuah 1976; 91: 336-7.

5. Sachs W, Feldman-Muhsam B. A case of intraocular myiasis due to Hypoderma bovis. Israel J Med Sci 1966; 2: 778-80.

6. Poran J, Gold D, Lengy J. Human intranasal myiasis. Harefuah 1986; 110: 561-2.

7. Cohen H, Rozenman Y, Ronen S. Conjunctival ocular myosis (Ostrus ovis) about 3 cases. J Fr Ophthalmol 1981; 4: 583-5.

8. Bernfeld K. Selected otolaryngological cases. Report 1930-1931. Folia Otolaryng Orient 1933; 1: 249-61.

9. Buxton PA. Applied entomology of Palestine, a report to the Palestine Government. Bull Entomol Res 1924; 14 (3): 289-340.

10. Mumcuoglu KY, Lipo M, Ioffe-Ospensky I, Millen J, Galon R. Maggot therapy for gangrene and osteomyelitis. Harefuah 1997; 132: 323-5.