Intestinal myiasis caused by Clogmia albipunctata in Nepal: a case report

Abstract

Background

Intestinal myiasis is a type of myiasis resulting from the accidental consumption of Clogmia albipunctata larvae. This type of myiasis generally displays symptoms such as nausea, vomiting, abdominal distention and discomfort, loss of appetite, weight loss, and intermittent diarrhea. It is a rare form of myiasis with relatively scarce literature in Nepal.

Case presentation

We report probably the first case of human intestinal myiasis caused by Clogmia albipunctata in Nepal. A 39-year-old nondiabetic female, Brahmin belonging to khas/arya ethnicity presented with complaints of abdominal discomfort, perianal itching, occasional nausea, and vomiting in the outpatient clinic of Sukraraj Tropical and Infectious Disease Hospital, Teku, Kathmandu. With an additional history of the passing of worms in stool, the sample was examined in the microbiology department, which revealed multiple larvae. Macroscopy followed by microscopic examination through wet mount preparation was performed, leading to the morphological identification of larva of Clogmia albipunctata. Diagnosis of a rare human intestinal myiasis was made, and the patient was advised to take ivermectin.

Conclusion

Personal hygiene and sanitation, which prevent fly infestation, can help reduce the incidence of the disease.

Introduction

Myiasis is defined as the infestation of humans and/or animals by dipterous larvae belonging to the class Insecta. Although cosmopolitan, the most common geographical distribution of human myiasis lies in tropical and subtropical regions, with greater occurrence in poor socioeconomic conditions. Dipterous larvae can feed on various tissues and cause a variety of infestations according to the site involved in mammals. There are several different ways that human myiasis can manifest, but the most prevalent kind is cutaneous myiasis. In addition, other areas of infestation encompass the gastrointestinal and urogenital tracts, as well as the nasal, auditory, pulmonary, and ocular cavities [1]. Broadly, myiasis can be classified as obligatory, facultative, and pseudomyiasis. Pseudomyiasis, in particular, occurs owing to the accidental ingestion of food or water contaminated with larvae or when a fly lays its eggs in a person’s anus or genital area [2, 3].

The drain fly, or Clogmia albipunctata, which belongs to the family Pychodidae, is a nonhematophagous insect that has a distribution akin to the other agents of human myiasis. This holometabolous insect has four stages in its lifecycle, including egg, larva (four instars), pupa, and adult, taking 27 ± 5 days to grow from the egg to adult stage [3]. While the role of C. albipuntata in true human myiasis has been in question, its association with accidental myiasis (pseudomyiasis) has been reported for a long time in humans. They are generally found in moist and shallow water microhabitats. Moreover, the flies reside in synanthropic habitats in large numbers and are considered as nuisance pests [3]. This is the first reported case of human intestinal myiasis caused by the larvae of C. albipuntata to date in Nepal.

Case presentation

A 39-year-old nondiabetic female, Brahmin belonging to khas/arya ethnicity from Balaju, Kathmandu visited a general practitioner’s clinic in a teaching hospital with complaints of abdominal discomfort and perianal itching for more than 1 month, which aggravated particularly during nights. The patient had occasional nausea and vomiting. There was no history of fever or recent travel. There was no history of similar symptoms in other family members. The patient further provided the history of passing out of worms, which she noticed on the toilet floor after she cleaned up post defecation. The patient further stated that she uses a different toilet than other family members, having a pan-type toilet seat and being situated outside her house separately. The patient was prescribed albendazole, tinidazole, and itopride and was advised for ultrasonography of the abdomen and pelvis, and stool routine, and a microscopic examination. The result of ultrasonography showed a normal scan, but stool routine and microscopic examination yielded two live worms that were reported with unknown identification. There was no improvement in the symptoms, and the patient was referred to Sukraraj Tropical and Infectious Disease Hospital, Teku, Kathmandu, where she attended. The patient on examination was well looking and had stable vitals. There was no pallor, jaundice, lymphadenopathy, clubbing, cyanosis, edema, or dehydration. Abdominal examination revealed a symmetrical nondistended abdomen with no tenderness and normal bowel sounds with no hepatomegaly or splenomegaly. She was again advised for stool examination and ultrasonography of the abdomen and pelvis, chest X-ray, and related other blood examinations including human immunodeficiency virus (HIV). On further questioning, the patient also informed about the presence of flies in the toilet where she regularly defecates. She was asked to collect the worms and flies from the toilet as well while delivering the stool samples.

Informed consent was taken, and the condition was explained to the patient.

A fecal sample was received in the microbiology laboratory later, which revealed plenty of live larval forms in scanty stool. Stool examination for other common parasitic forms was negative. The larvae were washed several times with normal saline, following which macroscopic and microscopic examination was performed.

Macroscopic examination of larvae

Macroscopically, the larvae were cylindrical with dark-brown color, possessing a rounded curved anterior end and a tapering posterior end. The size ranged from 1 to 1.5 cm in length and 1–2 mm in width. The body of the larvae was hairy and segmented. The color of the ventral aspect appeared lighter than the dorsal part. The dead larvae were preserved and fixed in 5% formalin.

Microscopic examination of larvae

For microscopic examination, the larvae were first fixed in 5% formalin and incubated in 30% potassium hydroxide in a glass bottle. When the larvae became transparent under the microscope, they were washed in distilled water thoroughly. Further, dehydration was carried out in ethyl alcohol of ascending grades, that is, 30%, 50%, 70%, 90%, and 99% for 30 minutes each, followed by xylene for 30 minutes. Finally, the larvae were mounted in DPX and dried at 38 °C in the oven for 2 days and proceeded for microscopy [4].

Microscopic observation (Fig. 1) revealed dark-brown, slender, and hairy larvae. The body of the larva consisted of a head, and 11 thoracic and abdominal segments (3 thoracic and 8 abdominal). The ventral aspect of the larvae was lighter in color as compared with the dorsal aspect, head, and tapering terminal end.

Fig. 1

Microscopic observation

The head was triangular with 2 minute hairy antennae and two ventral mandibles denoting chewing-type mouthparts. The lateral and dorsal aspects of the body segments were covered with 26 saddle-shaped chitinous plates densely covered with long setae on the dorsal and lateral aspects. The terminal end consisted of a siphon, which was cone-shaped, elongated, and broad with tufts of hair. The two respiratory spiracles that originated from the prothorax (anterior spiracles) appeared to end as the posterior spiracles at the tip of the terminal segment. The siphon further showed spinose anal papillae.

On the basis of the macroscopic and microscopic morphological appearance and comparing with literature [5,6,7,8], the patient was diagnosed with intestinal myiasis and the larvae were identified as the larvae of Clogmia albipuntata, in line with the fact that they possess darker bodies and 26 dorsal plates in comparison with the other members of Psychoda that have a lighter color and fewer than 26 dorsal plates [7]. The patient was advised to take ivermectin and take appropriate measures to eliminate drain flies from possible locations of the home where they can survive. Follow-up was done after 2 weeks, and the patient was feeling well but still noticed occasional discharge of larva. However, on performing routine and microscopic examinations, there was no evidence of larvae in the stool. Further, follow-up was continued until 1 month of treatment, when all the symptoms subsided and she no longer noticed the passage of larva in the stool. Stool examination was repeated with no positive findings, indicating the complete disappearance of larvae after the treatment.

We were unable to further confirm identification through scanning electron microscopy and molecular characterization owing to the unavailability of resources, which represents a limitation of this report.

Discussion

Intestinal myiasis where the fly inhabits the gastrointestinal tract is a rare disease. The distribution of human myiasis is worldwide, but it is more frequently found in poorer socioeconomic areas in tropical and subtropical regions [1]. This case report is the first of its kind reported from Nepal. The patient belonged to a lower middle-class family, and we found that she had relatively poor hygiene upon further questioning. She used the toilet alone where multiple drain flies were present, which can further explain her hygiene and the symptoms being present for only her in the family. In addition, she used to store water in uncovered buckets that were used to rinse the anal region after defecation. Such stored water is a good supporting medium for breeding of the flies. The eggs could be introduced during rinsing in the perineal area. After hatching, the eggs release larvae that ascend to feed into the gastrointestinal or urogenital tract [9, 10]. This could be the cause in our patient, as well.

C. albipunctata is a rare cause of myiasis but has been reported as one of the causative agents of accidental myiasis for a long time in Asia, Europe, Africa, and America, especially in places with poor hygienic conditions [3]. The larvae have been reported to cause intestinal, urogenital, and nasopharyngeal myiasis [11]. The first case of intestinal myiasis was reported in Japan [12] followed by other cases in Malaysia, Taiwan, and Egypt [6, 13,14,15].

In addition to infestation, they have been implicated in the potential mechanical transmission of various bacterial pathogens associated with nosocomial infections [3, 16]. Moreover, the presence of dense fine hairs and remains of their dead bodies can act as a potential allergen and cause respiratory illnesses such as allergic rhinitis and asthma [17].

The definitive diagnosis is based on macroscopic and microscopic examination and identification of the larvae. We identified the larvae following the same approach, but our limited diagnostic facilities restricted us from performing scanning electron microscopy for further confirmation as discussed above.

No specific treatment for intestinal myiasis has been recommended, even though purgatives, albendazole, mebendazole, and levamisole have been used with success in some patients. Mesalazine has been used for its antiinflammatory effect. Besides, colonoscopy has been reported to have a role in diagnosis and treatment [1]. Furthermore, ivermectin, a semisynthetic macrocyclic lactone having antihelminthic activity, is used currently for the treatment of myiasis, scabies, pediculosis, and demodicosis [18, 19].

In accordance with recommended practice, we prescribed ivermectin and increased fluid intake to the patient. A single oral dose of 12 mg was followed by the disappearance of symptoms and larval passage.

Conclusion

We report the first case of intestinal myiasis caused by Clogmia albipunctata in Nepal. Although the causative agent has been associated with pseudomyiasis and the presentation of the disease is rare, myiasis in any form may lead to significant morbidity in patients. In addition, the rare appearance of intestinal myiasis can lead to difficulty in diagnosis, especially in resource-limited countries such as Nepal. Moreover, a lack of specific treatment recommendations can lead to prolonged treatment and exposure to multiple antiparasitic agents for the patient. Personal hygiene and sanitation preventing fly infestation can help reduce the incidence of the disease.