Myiasis is a parasitic condition resulting from the infestation of a host’s body by the larvae of various fly species (Diptera order). While many types of myiasis involve the skin or open wounds, intestinal myiasis is a less common internal affliction. This condition occurs when fly larvae successfully invade the gastrointestinal tract.
Defining Intestinal Myiasis and Causes
Intestinal myiasis is categorized as an accidental parasitic infection of the gastrointestinal tract by fly larvae. This infestation happens when eggs or larvae are inadvertently consumed, distinct from flies laying eggs directly on tissue. The primary route of transmission is through the ingestion of food or water contaminated by flies.
A variety of fly species are implicated, as they are drawn to lay eggs on decaying organic matter, including improperly stored food. Common culprits include the common housefly (Musca domestica), the flesh fly (Sarcophaga species), and the false stable fly (Muscina stabulans). To establish an active infestation, the larvae must be hardy enough to survive the acidic environment of the stomach and intestinal digestive processes.
Individuals who are debilitated, bedridden, or have poor hygiene may also ingest eggs laid around the mouth area. Once swallowed, the eggs or larvae attempt to develop within the digestive system, leading to the clinical condition. The survival and development of the larvae within the gut confirm a true case of myiasis, distinguishing it from pseudomyiasis, where dead larvae are simply passed in the stool.
Lethality and Severe Health Risks
The direct answer is that intestinal myiasis rarely causes death, but the condition is not without risk. In most cases, the parasitic larvae are passed out in the feces, resulting in only mild or self-limiting symptoms. The prognosis is generally favorable, especially with prompt medical intervention to clear the infestation.
Lethality is a possibility when the infestation leads to severe secondary complications. If the larvae cause significant irritation, they can trigger inflammatory responses or intestinal obstruction. Secondary bacterial infection is a serious complication that can occur and may lead to sepsis, a life-threatening response to infection.
In high-risk or immunocompromised patients, or in cases of massive infestation, the larvae may attempt to penetrate the intestinal wall. This rare event can cause intestinal perforation, allowing gut contents and bacteria to spill into the abdominal cavity, a condition called peritonitis. Both sepsis and peritonitis represent severe health crises that can lead to organ failure and death if not treated.
Diagnosis and Medical Treatment
Confirming a diagnosis relies on the observation and specific identification of fly larvae in the patient’s stool sample. A patient may report seeing “worms” in their feces, prompting a physician to order a microscopic analysis. The laboratory must identify the species of the larva to differentiate myiasis from other parasitic infections or to confirm it is not pseudomyiasis.
Once intestinal myiasis is confirmed, the immediate goal of treatment is to expel or eliminate the parasites. Treatment often begins with administering a purgative or a mild cathartic agent to flush the larvae from the intestinal tract. Specific anti-parasitic medications, such as benzimidazoles like albendazole or mebendazole, may also be prescribed to kill the remaining larvae within the gut.
In severe or complicated presentations, medical treatment may need to be escalated. If the infestation results in a serious intestinal obstruction or if there is evidence of perforation, surgical intervention becomes necessary. Surgery is used to manually remove the larvae and repair any damage to the intestinal wall. Antibiotics are also administered if a secondary bacterial infection or sepsis is suspected.
Preventing Intestinal Myiasis
Avoiding intestinal myiasis centers on rigorous food and personal hygiene practices that limit the opportunity for flies to contaminate consumables. All fruits and vegetables should be thoroughly washed before consumption. Any food items kept outside of refrigeration must be adequately covered to prevent flies from landing on them.
Maintaining good environmental hygiene is also paramount. This includes prompt and proper disposal of refuse in tightly sealed containers. These measures reduce the breeding grounds for flies, lowering the overall fly population where food is prepared. Drinking only clean, filtered, or boiled water further mitigates the risk of ingesting eggs or larvae.