Case Report Oral Myiasis: Case report Jimson S, Prakash CA1, Balachandran C2, Raman M3 Departments of Oral and Maxillofacial Surgery, Tagore Dental College and Hospital, Research Scholar, Bharath University, 1Tagore Dental College and Hospital, 2Veterinary Pathology, 3Veterinary Parasitology, Madras Veterinary College, Chennai Received : 23‑10‑13 Review completed : 03‑11‑13 Accepted : 03‑11‑13
ABSTRACT Oral myiasis is a rare disease caused by larvae of dipteran flies. Houseflies are strongly suspected of transmitting at least 65 diseases to humans, including typhoid fever, dysentery and cholera. Flies regurgitate and excrete wherever they come to rest and thereby mechanically are the root cause for disease organisms. A case of oral myiasis caused by Chrysomya bezziana in the maxillary anterior region in a 40‑year‑old patient is presented. Manual removal of maggots, and surgical debridement of wound was done followed by broad‑spectrum anti‑parasitic medications. A note on the identification of the larva and histopathology of the tissue is also highlighted here. Key words: Chrysomya bezziana, larvae, myiasis
Oral myiasis is a rare condition that results in invasion of tissue by the larvae of fly. Myiasis is an infestation of a live vertebrate by dipterous larvae, which at least for a time, feed on living, or dead host tissue, liquid body substances, or undigested food. The term Myiasis (Greek: myia = fly, iasis = disease) was coined by Hope in 1840 and Laurence first described it in 1909. Myiasis can originate in the skin and mucosa by maggots from the families Cuterbridae, Hypodermatidae and a few Calliphoridae and Sacrophagidae species. Human myiasis is reported mainly in Asian countries and very rarely from western countries. Human myiasis due to chrysomys bezziana was first reported in Hong Kong in 2003. Myiasis occurs in rural areas, infecting bovid mammals, and in humans prevail in unhealthy individuals in third world countries. The life cycle of dipteran fly, from egg to adult, may take as short as 1 week, but normally requires 3 weeks for completion. The fertile female fly lay eggs and after 12-24 hours (in summer) the first formed larvae hatch. They enter the living tissues and feed for 5-7 days. The larvae exuviate twice during this period and in the third instar (last stage), ceases to eat. They leave the host to pupate inside the ground and the adult fly emerges after 1-2 weeks. Address for correspondence: Dr. Jimson S E‑mail: –jims[email protected]
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Depending on the condition of the involved tissue. • Accidental myiasis – when larvae get ingested along with food • Semi‑specific myiasis – when the larvae are laid on necrotic tissue of the wound • Obligatory myiasis –in which the larvae affect undamaged skin. Based on Anatomic site • Cutaneous myiasis • Myiasis of external orifices • Myiasis of internal organs. Clinically • Primary: Caused by biophagous larvae (feed on living tissues) also called as obligatory myiasis • Secondary: Caused by the necrobiophagous larvae (feed on dead tissues) also called as facultative myiasis.
CASE REPORT A 40‑year‑old male of low socioeconomic status [Figure 1] presented to the department of oral and maxillofacial surgery with a chief complaint of pain, swelling and presence of worms in the gums in the upper front teeth region for 1 week. Clinical oral examination revealed burrowing in the palatal aspect in relation to 21 and 22 with worm like roving. The surrounding mucosa was inflamed and tender to palpation, but bleeding and discharge were not evident [Figure 2]. Grade 1 mobility of anterior teeth with poor periodontal status was noted. The patient had incompetent lips, poor oral hygiene, malaise and was febrile. A provisional diagnosis of oral myiasis was made based on the presence of maggots. Radiographic examination [Figures 3 and 4] revealed bone loss and a Indian Journal of Dental Research, 24(6), 2013
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Chrysomya bezziana in Oral Myiasis
periapical radiolucency in 21. Routine blood investigations did not yield any abnormal values and was negative for HIV and hepatitis. The patient was admitted in our Medical college hospital and given a single dose of ivermectin 12 mg orally. He was also prescribed with amoxicillin 500 mg three times daily for 5 days. A total of six larvae were extricated with the help of tweezers after application of turpentine oil. Maxillary left central incisor was extracted and the area was debrided and irrigated with saline. Larvae recovered appeared whitish black with transverse rows of segments [Figure 5]. Follow‑up was done and the wound healed uneventfully [Figure 6].
Larva was identified to be of the third stage of Chrysomya bezziana. Palmate‑shaped anterior spiracles had 4‑6 lobes [Figure 8]. Peritreme of the posterior spiracles was thick, incomplete and open [Figure 9]. Intersegment spines were seen in between the pro and mesothorax. Based on the morphological characteristics, the larva was confirmed as C. bezziana.
Histopathology of surrounding tissue showed mild hyperplasia and lymphoplasmacytic infiltration in the connective tissue layer [Figure 7].
A member of dipteral fly family that lay eggs on open wounds, necrotic tissue, food, and unbroken tissue causes myiasis. C. bezziana, the old world screwworm fly is the source of obligatory myiasis. The genera commonly reported are sarcophagidae (flesh flies), calliphoridae (blowflies), oestridae, and muscidae form the dipteral order. They are most functional during the summer and rainy seasons.
Figure 1: Extra oral view
Figure 2: Intra oral view
Figure 3: OPG
Figure 4: Occlusal view
Figure 5: Larva
Figure 6: Post treatment
Indian Journal of Dental Research, 24(6), 2013
Jimson, et al.
Chrysomya bezziana in Oral Myiasis
Figure 7: Hyperplastic epithelium
Systemic treatment includes broad‑spectrum antibiotic such as ampicillin and amoxicillin, especially when the wound is secondarily infected. Local measure consists of mechanical removal of maggots with hemostats, with or without the administration of topical asphyxiation drugs, which forces the larvae to come out. Larval rupture should be avoided as it can cause foreign body reaction. Recently, a systemic treatment with ivermectin, a semisynthetic macrolide antibiotic, derived from a group of natural substances is given orally in just one dose of 150‑200 mg/kg. Of late, with the identification of prion rods in both fly larvae and pupae, transmission of prions by ectoparasites has given cause for much apprehension. Myiasis of orofacial region can be prevented by educating the people from rural areas and low socio‑economic groups about personal hygiene, taking care of any wound, control of fly population, and maintenance of sanitation of the surroundings. We must enlighten parents/guardians to make them aware of such conditions, and encourage them to bring their children at the earliest for dental examination to prevent such episodes.
ACKNOWLEDGMENTS Figure 8: Chrysomyia bezziana anterior spiracle
The Authors wish to acknowledge and thank Prof.Dr.Chitraa R. Chandran, Principal, Tagore Dental College for her help and support and Dr.Sudha Jimson, Oral Pathologist, Sree Balaji Dental College and Hospital for her help in reviewing the manuscript.
Figure 9: Chrysomyia bezziana posterior spiracle
During fertilization the adult female flies get hooked due to the wound odor. The eggs hatch within 24 hours and the culminating larvae burrow into host tissues, head downwards into the wound in a characteristic screw like fashion, feeding on living tissue. Larvae will exterminate the host tissue by discharging toxins. The larval development is completed in 5‑7 days following, which they wriggle out and fall to the ground to pupate. The presence of tissue invasion was notable even in the absence of necrotic tissue. Chrysomya infection may cause deliberate damage to tissue and may even cause death in treatment‑neglected individuals. In the present case, poor oral hygiene and low socioeconomic status are the probable causes for oral myiasis. The larvae placed themselves deep into the tissue in the anterior palate. The treatment of myiasis comprises of systemic and local approaches.
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Indian Journal of Dental Research, 24(6), 2013