Fasciolopsiasis is a parasitic infection caused by Fasciolopsis buski and is considered to be most prevalent in countries of Southeast Asia. The clinical presentation depends on the severity of infection, ranging from asymptomatic to life-threatening intestinal inflammation and bleeding. The diagnosis rests on the ability to detect F. buski eggs in stool through microbiological studies, but a high index of suspicion is necessary.
Fasciolopsiasis, denoting an intestinal infection by the trematode parasite Fasciolopsis buski, is regarded as a rare clinical entity in medical practice, but many reports have emphasized its frequent misdiagnosis and rather high prevalence rates  . Studies show that between 25-50% of children harbor this parasite in countries such as China and Thailand . F. buski lives in two hosts - humans and pigs, and it enters the human body after ingestion of contaminated food  . Raw freshwater and aquatic plants (water chestnut, bamboo, lotus, water caltrops, hyacinth, etc.) are the principal sources of F. buski, but direct contact with infected pigs is also a potential mode of transmission  . Signs and symptoms seem to correlate directly with the severity of infection  . Milder cases are usually asymptomatic, whereas a range of gastrointestinal complaints - abdominal pain, nausea, vomiting, and diarrhea, may be seen in patients who ingest a large number of eggs    . In addition, fever, edema (principally of the face and lower extremities), often as a result of an allergic reaction, and headaches are common symptoms  . When the patients are suffering from a severe infestation, the gastrointestinal tract can be severely damaged due to erosions, ulceration and severe inflammation that could result in bleeding and become life-threatening  . Furthermore, altered consciousness and multiorgan failure, although rare, have been reported . For this reason, an early diagnosis is pivotal.
To identify F. buski as the causative agent of the patient's symptoms, a detailed clinical investigation must be conducted. A thorough patient history, especially about recent travel to Southeast Asia (or if they are residents of the area) and contact with pigs or ingestion of local aquatic plants, is of importance for gaining sufficient evidence to make a presumptive diagnosis. Physical examination may reveal typical symptoms, after which microbiological studies, the cornerstone of infectious disease diagnostics, are necessary. At this moment, fasciolopsiasis is diagnosed by identifying F. buski eggs or adult worms in the intestinal lumen by obtaining a stool sample, but some reports claim that the worms can be sometimes found in vomit during the presence of symptoms  . Alternatively, drug-induced expulsion using praziquantel has been described as a useful method for detection of worms . A useful indicator of a parasitic infection, in addition to microbiological studies, is the presence of eosinophilia (both relative and absolute number) in the complete blood count (CBC) , suggesting that this test might be of great benefit in the initial workup. Imaging studies, such as computed tomography (CT), ultrasonography, and even upper endoscopy have been reported as a useful method in solidifying the diagnosis of fasciolopsiasis .