Myiasis of the Toe as a Complication of a Neglected Wound: A Case Report

Introduction. Myiasis is an infestation of the tissues and organs of living vertebrates by fly larva that feed on the host’s necrotic or living tissue; it is a well-recognized complication of neglected wounds. Case. A 17-year-old boy presented to a pediatric outpatient department for delayed wound healing of his left toe. Three months prior, he had undergone left great toenail wedge excision for an ingrown toenail; following the operation, he ignored wound care due to pain while dressing the wound. At presentation, the lateral edge of his left toe was hyperemic and swollen without pain or purulent material. The larvae were observed on the lesion’s necrotic tissues. The orthopedist debrided the necrotic tissues, removed the larvae, and an antibiotic was administered to treat a secondary bacterial infection. The wound was kept clean and dry. Microorganisms did not grow in the debrided necrotic tissue culture, and antibiotic treatment was completed in 14 days. With proper wound care, closure was achieved without reoccurrence or complications. Conclusion. Early diagnosis is important to initiate prompt treatment for myiasis. When open wound healing is delayed despite the appropriate antibiotic treatment, especially in tropical or subtropical regions, myiasis should be suspected.

The infestation of the tissues and organs of living vertebrates by dipteran larvae (maggots) is known as myiasis. It is classified according to the areas involved as¹ cutaneous, subcutaneous (wound), and cavitary (where the infestation receives the name of the affected organs, eg, nasal, aural). Of them, the cutaneous form is the most frequently seen in the clinical form of the disease.² Another classification is made according to the host-parasite relationship: obligatory, facultative, and incidental myiasis. Obligatory myiasis (malignant) develops exclusively in or on living vertebrae, facultative myiasis (benign) develops in decaying organic matter, and incidental myiasis develops when the eggs or larvae of certain flies develop via accidental food ingestion.³ Facultative myiasis and incidental myiasis usually are seen in humans.⁴

Myiasis appears more often in tropical-subtropical countries and in rural regions where people are more likely to have poor hygiene and close contact with domestic animals. Due to poor personal hygiene, patients who are elderly and ill, mentally retarded, homeless, or live with alcoholism or drug addiction are prone to myiasis. Diabetic or other neglected wounds with foul-smelling discharge attract maggots. Infestation develops when flies lay their eggs in decaying tissues of open wounds; subsequently, larvae develop and cause significant damage by their movement and feeding activity. Diagnosis is made when larvae are seen in the tissue or the organ of the host.

Early, accurate diagnosis of myiasis is an important step in treating it; however, because this condition is rarely seen in humans, a delayed diagnosis is common. Delayed diagnosis and continuation of ineffective and unnecessary antibiotic treatments can lead to further risk to tissue destruction, which could result in an amputation of the affected area. The authors report the present case to stress the importance of wound care, as well as to remind readers of the susceptibility of myiasis in humans.

A 17-year-old boy presented to a pediatric outpatient department in August 2015 complaining of prolonged left great toe erythema and edema. Ten days prior to presentation, he had used antibiotics on the wound without improvement. During physical examination, in addition to erythema and edema, the larvae were observed on his left great toe. No pain and purulent drainage was observed (Figure 1). The patient was of a decent socioeconomic status, had no comorbid diseases, and had no contact with animals. His parents said he had undergone lateral nail avulsion matrixectomy for an ingrown left toenail 3 months earlier. After discharge from the hospital, he had refused wound care due to pain when dressing the wound. As a result, he presented to the authors’ clinic with delayed wound healing despite antibiotic usage. After the diagnosis of myiasis, an orthopedist debrided the necrotic tissues and removed the larvae. Later, the patient was admitted to pediatric services, and ampicillin-sulbactam was administered at 1 g 4x/day for coexisting paronychia. By day 3 of exploration and debridement, 16 maggots were removed and sent to the laboratory for larva species identification. The wound was kept clean and dry with saline. To limit tissue granulation, betamethasone and gentamicin ointments were applied. The culture of debrided tissue showed no bacterial growth. Unfortunately, due to loss of larvae in the laboratory, the type of larva could not be identified. After using contrast-enhanced magnetic resonance imagining, there were no clinical and radiological evidences of bone or joint infestation. Following the removal of the maggots and 14 days of nonspecific antibiotic treatment, the patient was discharged with complete wound closure. Figure 2 shows the healed toe 2 months after myiasis treatment concluded. 

Singh and Singh⁵  conducted a global review on myiasis in humans, where they found the majority of the cases involved the fly species from the Calliphoridae and Sarcophagidae families followed by those from the Oestridae, Muscidae, and Psychodidae families. The most commonly infested anatomical regions, according to their report,⁵ were the eyes, mouth, nose, wound, urogenital, enteric, ear, and anus. The case herein presents a case of traumatic myiasis caused by dipteran larvae. Wound myiasis may be the result of facultative or obligatory parasites, which is initiated when flies oviposit in necrotic, hemorrhagic, or pus-filled lesions. It is a sign of a neglected wound in which even the smallest wound or abrasion (such as that caused by a tick bite) is a sufficient site of attraction for the female fly. 

Living in rural areas, having a low standard of living, and being in close proximity to domestic animals are risk factors for wound myiasis.^6-8 The patient in this case study does not possess any of these conditions and does not live with a mental disorder, a comorbid disease (eg, diabetes or peripheral vascular disease), or a neurovascular deficiency. However, neglectful wound care resulted in myiasis. 

In any case of myiasis, treatment consists of removing all larvae, depredating necrotic tissues, intensive washing with antiseptic solution, using sterile dressings, and administering systemic antibiotics for secondary bacterial infections.^4,9 These measures were taken for the patient in this report, and the wound healed without reccurrence. In addition, intraoperative topical administration of hydrogen peroxide and 0.05% chlorhexidine acetate is recommended; chloroform 15% in oil or ether may also be helpful as a larvicidal drug, because it can immobilize the larvae and assist in removal.² When removing larvae, fragments should not be left in the wound, because larvae elements and fly eggs are allergenic. Due to the numerous tiny eggs, resection of all apparently infected tissues is required. 

Conversely, the larvae of the Luciliacuprina or Luciliasericata are used as a wound care treatment. Maggot therapy has been used to treat pressure ulcers, chronic venous ulcers, diabetic ulcers, and other acute and chronic wounds. The larvae secrete proteolytic enzymes that liquefy necrotic tissue, which is subsequently ingested while leaving healthy tissue intact. This therapy also has antimicrobial properties and stimulates wound healing.¹⁰ The larvae can also be applied within a prefabricated “biobag” that facilitates application and dressing change.¹¹ The main disadvantage of maggot therapy is related to negative perceptions about its use by patients and staff. 

People with neglected open wounds and poor hygiene, especially in warmer climates, are at risk for myiasis, and clinicians should be suspicious of nonhealing wound lesions. Early diagnosis and prompt treatment with thorough surgical debridement of necrotic tissues and larvae removal is crucial to stop tissue destruction and save the affected area.

Affiliations: Department of Pediatrics, Division of Pediatric Infectious Diseases, Marmara University School of Medicine; and Department of Microbiology, Marmara University School of Medicine, Istanbul, Turkey

Correspondence:
Ahmet Soysal, Prof, MD
Marmara University Pendik Training and Research Hospital
Department of Pediatrics, Division of Pediatric Infectious Diseases,
Mimar Sinan Street, No: 41, 
Fevzi Cakmak Mah
Ust Kaynarca, Pendik, 
Istanbul, Turkey
drahmetsoysal20@gmail.com 

Disclosure: The authors disclose no financial or other conflicts of interest.