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Year : 2012  |  Volume : 55  |  Issue : 3  |  Page : 384-385
Invasive intestinal myiasis in a young male presenting as fungating rectal mass: An unusual presentation

1 Department of Pathology, CSM Medical University, Lucknow, India
2 Department of Surgery, CSM Medical University, Lucknow, India

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Date of Web Publication29-Sep-2012


Intestinal myiasis is usually an accidental phenomenon which is transient and asymptomatic. It occurs due to intake of contaminated food or water containing fly larvae or eggs. We report a case of invasive intestinal myiasis presenting with complaint of pain, blood-mixed mucous discharge per rectum along with passage of maggots in stool. On proctoscopy an irregular fungating rectal growth with maggots was detected in rectum and anal canal. Excision of growth with diversion colostomy was done. On histopathology numerous variable-sized larvae in different stages of development were detected throughout the inflamed and necrosed bowel wall. No tumor was seen. With maintenance of proper hygiene, vermicide anti inflammatory and purgatives were given. Patient became alright after colostomy closure. The symptomatic presentation as a mass lesion and necessity for surgical intervention prompted us to report this rare case.

Keywords: Intestinal, maggots, myiasis, rectal growth

How to cite this article:
Kumari M, Goel MM, Singh D. Invasive intestinal myiasis in a young male presenting as fungating rectal mass: An unusual presentation. Indian J Pathol Microbiol 2012;55:384-5

How to cite this URL:
Kumari M, Goel MM, Singh D. Invasive intestinal myiasis in a young male presenting as fungating rectal mass: An unusual presentation. Indian J Pathol Microbiol [serial online] 2012 [cited 2023 Sep 24];55:384-5. Available from:

   Introduction Top

German entomologist Fritz Zumpt describes myiasis as "the infestation of live human and vertebrate animals with dipterous larvae, which at least for a period, feed on the host's dead or living tissue, liquid body substances or ingested food. [1] Depending on site of involvement it may be classified as intestinal, cutaneous, ocular, wound and urinary. Intestinal myiasis is usually an accidental phenomenon. It occurs due to ingestion of contaminated food or water containing fly larvae or eggs. Usually the patient is asymptomatic and the larvae are excreted harmlessly in feces. In some cases, however, the passage of larvae may be associated with symptoms. [2]

   Case Report Top

A 23-year-old male presented to surgery out door with complaint of passing maggots in stool since 7 days along with history of off and on blood-mixed mucous discharge per rectum, pain, intermittent fever, anorexia and weight loss of 3-month duration. There was no history of itching, trauma or other chronic illness in anal region was present. He was mildly anemic. Physical examination and his routine blood investigations were within normal limits. On proctoscopy, an irregular fungating mass with maggots creeping over it in the rectum and anal canal were found. The clinical diagnosis was rectal mass likely to be an infected polyp. Excision of mass with diversion colostomy was done and tissue was sent for histopathology.

Grossly a fungating necrotic soft tissue piece was received measuring 4 × 3.5 × 2 cm. It was invaded by numerous maggots (larvae). Cut surfaces were congested and necrotic. Maggots were dull white in color, 7-8 mm in length with both the ends tapering [Figure 1]. Representative sections were taken.
Figure 1: Necrosed bowel segment with numerous larvae (maggots)

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   Microscopy Top

Sections showed necrosed bowel wall tissue infiltrated by mixed inflammatory infiltrate. Variable-sized larvae lying in different stages of development were present throughout the necrosed wall showing mouth hooks, pharyngeal sclerites, spiracular breathing plates and cuticle [Figure 2]. There was no evidence of any tumor. Based on above findings, a diagnosis of invasive intestinal myiasis was rendered.
Figure 2: (a) Necrosed bowel mucosa with mild inflammation (hematoxylin and eosin, ×100), (b) Bowel wall with multiple eggs (arrow) (hematoxylin and eosin, ×200), (c) Muscle bundles of bowel enclosing multiple larvae (hematoxylin and eosin, ×200) and (d) Cuticle containing sclerites and breathing plates (hematoxylin and eosin, ×400)

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   Discussion Top

Severity of myiasis depends on site of infestation. It is commonly classified according to part of the host involved including dermal, sub dermal, cutaneous, arterial nasopharyngeal, ocular, auricular, intestinal, gastric and urogenital. [2],[3]

According to relationship between the host and the parasite, myiasis can also be classified as:

  1. obligatory- where the parasite cannot complete its life cycle without its parasitic phase, which may be specific, semispecific or opportunistic. [1],[2]
  2. facultative or accidental- when it is not essential to complete the life cycle of the parasite in the host and perhaps a normally free-living larva accidentally gains entrance to the host. [1],[2]

Usually accidental myiasis is enteric, resulting from intake of contaminated food or water containing fly larvae or eggs. Most larvae are destroyed by digestive juice and the dead larvae are excreted harmlessly in the feces. The effect is also called pseudomyiasis. But some larvae can survive and with help of oral hooks get firmly attached to the intestinal mucosa. [4] They live in the intestinal tract and produce intestinal distress. This is called true myiasis. In our case, patient was from rural background. The larvae were detected in deeper layer of intestinal wall and caused inflammation and necrosis of wall, qualifying the term invasive or true myiasis.

Myasis is common in countries where nutritional and sanitary conditions are very poor. [2],[3],[5] More than 50 fly species have been reported to cause myiasis in human worldwide. Common species are Musca domestica (house fly), Funnia spp. (latrine fly), Eristalis tenax (rat tailed maggots) and Muscina spp. [3] Eristalis tenax is the most common species involved in intestinal myiasis and has a worldwide distribution, while Musca domestica common in India. [4],[6]

Life cycle of fly is about 10-14 days. Adult fly lays its eggs on decaying food material and sometimes in an open wound, and these hatch into larvae which through one or more larval stage develop into pupa and finally converted to adult fly. The larvae feed on live or necrotic tissue causing myiasis to develop. To distinguish among the species it is necessary to examine the lateral processes and other characteristic in the posterior region. [7]

Clinical symptoms are variable ranging from asymptomatic cases to symptoms like abdominal pain, nausea vomiting, anal pruritis and rectal bleeding. Karabiber Hamza et al. [7] reported an unusual case of rectal bleeding in an 8-year-old girl diagnosed as intestinal myiasis. Likewise in our case it presented as rectal growth along with blood and mucus discharge per rectum and surgery was done. Hence it can manifest with severe clinical symptoms and invasive disease as in the present case, depending on the number and species of fly and their location in the intestinal tract.

Myiasis is often misdiagnosed, because it is extremely rare and its symptoms are not specific. Intestinal myiasis and urinary myiasis are especially difficult to diagnose. [6] The presence of larvae in one or more consecutive stool specimen is diagnostic.

There is no specific treatment as larvae are insensitive to drugs. The source of infestation should be identified and eliminated. Vermicide purgative along with anti-inflammatory drugs are used. The correct diagnosis and eradication of vector can avoid the unnecessary treatment. Thorough washing, adequate cooking and proper storage of food or vegetables/fruits/salad before consumption are preventive measures. The presentation of the present case was unusual as clinically there was a mass lesion in the rectum mimicking a neoplastic lesion.

   References Top

1.Zumpt F. Myiasis in man and animals in the old world. A textbook for physicians, veterinarians and zoologists. London: Butterworth; 1967.  Back to cited text no. 1
2.Aguilera A, Cid A, Regueiro BJ, Prieto JM, Noya M. Intestinal myiasis caused by Eristalis tenax. J Clin Microbiol 1999;37:3082.  Back to cited text no. 2
3.Singh S, Samantray JC. Human intestinal myiasis. J Assoc Physicians India 1988;36:741-2.  Back to cited text no. 3
4.Shivekar S, Senthil K, Srinivasan R, Sureshbabu L, Chand P, Shanmugam J, et al. Intestinal myiasis caused by Muscina stabulans. Indian J Med Microbiol 2008;26:83-5.  Back to cited text no. 4
5.Bhatia RS. Accidental intestinal myiasis. J Assoc Physicians India 1989;37:403-5.  Back to cited text no. 5
6.Sehgal R, Bhatti HP, Bhasin DK, Sood AK, Nada R, Malla N, et al. Intestinal myiasis due to Musca domestica: A report of two cases. Jpn J Infect Dis 2002;55:191-3.  Back to cited text no. 6
7.Karabiber K, Oguzkurt DG, Dogan DG, Aktas M, Selimoglu MA. An unusual cause of rectal bleeding: Intestinal myiasis. J Pediatr Gastroenterol Nutr 2010;51:530-1.  Back to cited text no. 7

Correspondence Address:
Malti Kumari
Department of Pathology, CSM (Erstwhile King George's) Medical University, Lucknow-226003
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0377-4929.101753

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This article has been cited by
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