Intestinal myiasis is a rare condition that involves the infestation of the gastrointestinal tract by the larvae, or maggots, of certain fly species. Myiasis generally refers to the infestation of a vertebrate host with two-winged fly larvae, which feed on the host’s living or necrotic tissue, body fluids, or ingested food. The intestinal form is considered an accidental event, where the larvae survive passage through the acidic stomach environment to reside temporarily in the intestines.
Intestinal Myiasis: Understanding the Condition
The intestinal form is specifically classified as accidental myiasis, or pseudomyiasis, because the flies involved typically do not require a living host to complete their life cycle. This type of infestation is distinct from true parasitic myiasis, which is often seen in open wounds or under the skin and is caused by fly species that actively seek out a host for their development. Intestinal myiasis occurs when fly eggs or larvae are inadvertently swallowed and manage to survive the digestive process, subsequently developing within the intestines. The larvae feed on the ingested food within the gut, causing various disturbances as they mature. Common flies associated with accidental intestinal cases include the housefly (Musca domestica), the lesser housefly (Fannia canicularis), flesh flies (Sarcophagidae species), and the false stable fly (Muscina stabulans).
How Intestinal Myiasis is Acquired
The transmission of intestinal myiasis almost always occurs through the ingestion of food or water contaminated with fly eggs or larvae. Female flies, attracted to decaying organic matter, can lay their eggs on exposed food items, such as spoiled meat, fruit, or improperly stored produce. When these contaminated items are consumed, the fly progeny are introduced into the digestive system. Poor sanitation and general hygiene practices are widely recognized as significant risk factors for acquiring this condition. Living in areas with high fly populations, particularly where food is left uncovered or exposed, increases the likelihood of contamination.
Assessing the Risk: Symptoms and Complications
While death is exceptionally rare, the condition can lead to severe, life-threatening complications if left untreated. For most individuals, the larvae are often destroyed by digestive juices or expelled in the feces within a short time. Many patients experience only mild symptoms, or may even be entirely asymptomatic, with the infestation resolving on its own. When symptoms do occur, they are typically related to gastrointestinal distress, including abdominal pain, nausea, vomiting, and diarrhea. The most distinctive sign is the passage of live fly larvae in the stool.
Severe complications are usually linked to a heavy larval load or the larvae attempting to migrate outside the intestinal lumen. A large number of larvae can potentially lead to intestinal obstruction, where the bowel becomes blocked. Furthermore, larvae causing damage to the intestinal walls can result in bowel perforation, which is a medical emergency. Perforation allows the gut contents to leak into the abdominal cavity, leading to peritonitis and subsequent sepsis, a life-threatening infection that can be fatal.
Diagnosis and Effective Treatment
The diagnosis of intestinal myiasis is usually established by a laboratory analysis of the stool. A microscopic examination of the fecal sample allows medical professionals to identify the presence and morphology of the fly larvae or their remnants. Correct identification is important because the symptoms can sometimes be mistaken for other common intestinal parasitic infections.
The primary goal is the prompt removal of the larvae from the gastrointestinal tract. This often involves the administration of a mild cathartic agent or purgatives to physically expel the larvae through increased bowel movements. In cases where the infestation is persistent or not readily cleared, anthelmintic medications, such as albendazole or mebendazole, may be prescribed to kill the larvae. For rare, complicated cases involving intestinal obstruction or perforation, surgical intervention may be required to remove the larvae and repair any damage to the intestinal wall. The prognosis is typically good with early and appropriate management.