Management of Oral Myiasis Caused by Chrysomya bezziana - A Case Series.

Myiasis is a rare disease caused by infestation of tissue by larvae of flies. Oral myiasis is still rare and unique owing to the fact that the oral cavity rarely provides a necessary habitat for a larval life cycle. We discuss the definition, etiology, predisposing factors, classification, and management of myiasis. We hereby report a rare case of oral myiasis in a 75-year-old female with a history of maxillofacial trauma. She complained of pain in the lower lip and commissure region on the left side through which numerous live maggots (larvae) were seen crawling out. Postremoval of approximate seventy maggots resulted in lower lip defect along its commissure which was repaired by Bernard's modification of Gillies flap. Another case was an 18-year-old girl, a known case of congenital cerebral palsy with pain and swelling in the upper vestibule region. Prevention of myiasis involves addressing open wounds, maintaining good oral and personal hygiene, control of fly population, basic cleanliness of surrounding areas, and provision for basic sanitation and health education. Copyright:

INTRODUCTION

Myiasis is derived from a Latin word “muia” which means fly and “iasis” which means disease[1] and a term derived from the Greek word “myia,” meaning invasion of fly larvae into vital tissue of humans or other mammals. They can infest vertebrate animals including humans and feed on living or dead tissue as well as on body fluids.[2] The term was coined by F. W. Hope in 1840.[3]

The dipterous larvae that feed on the host living or dead tissues, liquid body substances, or ingested food causes myiasis. Oral myiasis is a rare pathology and is associated with poor oral hygiene, alcoholism, senility, and suppurating lesions and is well documented in maxillofacial trauma.

In humans, the most common sites of myiasis are the nose, eye, ear, vagina, skin, nasopharynx, and rarely, the oral cavity. The oral cavity does not provide the habitat conducive for life cycle of these larvae. Hence, incidence of oral myiasis is comparatively lesser than that of cutaneous myiasis.[4]

The predominant portions of the lower third of the face which serve an important esthetic unit of the face are lips.[5] They serve as the focal point for communication and expression and maintain the competence of the oral cavity preventing the drooling of saliva and further predisposing to other infections such as candidiasis. The biggest challenge faced by the surgeon is reconstruction of large defects of the lower lip with good functional and esthetic outcomes.

CASE REPORTS

Case report 1

An 18-year-old girl, a known case of congenital cerebral palsy, reported to the department of oral and maxillofacial surgery with complaints of pain and swelling in the upper front region of the jaw for 1 week. Intra-oral examination revealed a diffuse erythematous cavitation that was tender on palpation with worm-like organisms moving out of the defect in the upper labial vestibule. Larvae recovered from the wound were preserved in formaldehyde (40%) and sent to an entomologist for identification.

Case report 2

A 75-year-old female patient reported to the emergency room of Lata Mangeshkar Hospital, Nagpur, with chief complaints of pain and swelling in the lower lip and discomfort in the left cheek region for 5 days. The patient gave an alleged history of fall at home 5 days back. Since then, she had an open wound involving the lower lip and left commissural region. The patient reported to a government hospital 2 days back where approximately thirty maggots were removed. The patient was carrying relevant documents stating the same.

On extraoral examination, a diffuse swelling of approximately 4 cm × 3 cm in size involving the lower lip was noted. The examination also revealed incompetence involving the left corner of the mouth with overlying skin tense and shiny with multiple fenestrations [Figure 1]. The swelling was soft and edematous in consistency and tender to palpation with no suppuration. Intraoral examination revealed complete upper and lower edentulous arches.

Figure 1

Multiple abrasions over the face with swollen lower lip and numerous cavitations

Several cavitations with deep burrows were noted. Multiple larvae were noted crawling within the lower lip and left cheek region. Ultrasonography (USG) of the lower lip and left cheek region was advised. On USG, multiple linear tubular echogenic moving structures were noted in a subcutaneous plane in the left cheek and lower lip. In view of history of the removal of maggots, the above features are likely suggestive of multiple maggots in the present scan [Figure 2].

Figure 2

Suggestive of multiple linear tubular echogenic structures (circled)

Cotton gauze impregnated with oil of turpentine was placed in the deeply burrowed cavitation in the lower lip and left cheek region for approximately 10–12 min. Around 15 Maggots were removed manually with the help of curved artery forceps and were collected in a sample bottle as shown in Figure 3. The same procedure was carried out for the next 3–4 consecutive days with exploration, curettage and irrigation with warm saline, hydrogen peroxide, povidone-iodine and metronidazole till no further larvae could be found. A total of 73 maggots were removed in a span of 3–4 days. The patient was administered injection ceftriaxone, injection pantoprazole, and injection metronidazole for 5 days. No attempt of administering the antiparasitic drug ivermectin was made.

Figure 3

Manual removal of maggots with the help of hemostat and collecting in sample bottle

On the 7th postoperative day, there was no evidence of maggots on repeat USG. A magnetic resonance imaging of the oral cavity (plain + contrast) was suggestive of minimally enhancing mucosal thickening along the gingivobuccal and gingivolabial sulcus on the left side likely of inflammatory etiology postoperative changes. However, the clinical examination confirmed a serious loss of the lip tissue with necrosed margins. Competence involving left commissure was lost and constant drooling of saliva was visible [Figure 4a].

Figure 4

Reconstruction of the defect with Bernard's modification of Gillies flap: (a) Necrosed margins surrounding the defect, (b and c) after removal of necrosed margins and fibrosis, the upper lip was rotated in a medial direction, (d) lip commissure anatomy was restored

The defect was reconstructed with Bernard's modification of Gillies flap. The flap consists of an incision along the perioral area around nasolabial fold [Figure 4b and c]. The flap viability was maintained by preserving the vascular bundle. After accomplishing sufficient mobilization, the flaps were medially oriented to allow closure in three planes, namely oral mucosa, orbicularis muscle and skin maintaining the integrity of oral sphincter. However, there is some microstomia with minimal impact on function [Figure 4d].

Diagnosis of myiasis causing larvae was done based on the form of spiracles, cephalon-pharyngeal skeleton, shape and size of developed larvae as shown in Figure 5. The posterior spiracles, a distinct button, and the number of lobes on the anterior spiracles are six, which would give a definitive identification of Chrysomya bezziana. The robust spine bands are other indicative criteria of C. bezziana.

Figure 5

Photomicrograph suggestive of the parasite: (a) Anterior cephalopharyngeal skeletal end, (b) anterior spiracle, (c) posterior spiracle of Chrysomya bezziana

Based on the mentioned diagnostic keys and comparing the whole shape of the larvae, posterior spiracles and cephalopharyngeal skeleton, the larvae were diagnosed as C. bezziana (Diptera: Calliphoridae).

DISCUSSION

Myiasis defined by Zumpt as “the infestation of live human and vertebrate animals with dipterous larvae which at least for a certain period feed on the host's dead or living tissue, liquid body substance, or ingested food.”[6] According to the documented cases in literature, myiasis occurs more in rural than urban areas. The predisposing factors could be Diabetes mellitus, leprosy, psychiatric illness with impaired manual dexterity, poor oral hygiene, open wounds due to maxillofacial trauma or patients who are senile, mouth breathers or hemiplegic.[7] In the abovementioned case, the patient belonged to a low socioeconomic status residing in a rural area and a history of trauma to the face due to fall which was not addressed are thought to be as the predisposing and contributing factors to myiasis.

Myiasis can be classified as following as primary when larvae feed on living tissue and secondary when larvae feed on dead tissues.

Myiasis is also classified as shown in Illustration 1.[8]

Illustration 1

Classification of myiasis

The treatment modality for myiasis comprises local and systemic measures. Local measures consist of topical application of oil of turpentine, mineral oil, ether, chloroform, ethyl chloride, mercuric chloride, creosote, saline, phenol, calomel, olive oil, iodoform, or other such comparable solvents as advocated in the literature.[9] These local measures irritate the maggots causing larval asphyxia and force them out of the deeply burrowed cavitations. Topical application of placentrex aids in granulation.[10] Systemic treatment includes broad-spectrum antibiotics. In the present patient, debridement with oil of turpentine along with copious irrigation with normal saline, povidone-iodine, hydrogen peroxide, and metronidazole followed by mechanical removal of maggots and injectable antibiotic coverage was used for the treatment.

CONCLUSION

Oral myiasis is an uncommon entity. The clinician should be aware of this disease and should take appropriate measures for its prevention. Prevention of myiasis involves addressing open wounds, maintaining good oral and personal hygiene, control of fly population, basic cleanliness of surrounding areas and provision for basic sanitation and health education. An intimate care needs to be taken in patients who lack manual dexterity in maintaining oral hygiene.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patients have given their consent for images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal identity but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.