Fasciolopsiasis

Fasciolopsiasis results from an infection by the trematode Fasciolopsis buski, the largest intestinal fluke of humans (up to 7.5 cm in length).

Signs and symptoms

Most infections are light and asymptomatic. In heavy infections, symptoms can include abdominal pain, chronic diarrhea, anemia, ascites, toxemia, allergic responses, sensitization caused by the absorption of the worms' allergenic metabolites (may eventually cause death of patient), and intestinal obstruction.

Diagnosis

Microscopic identification of eggs, or more rarely of the adult flukes, in the stool or vomitus is the basis of specific diagnosis. The eggs are indistinguishable from those of Fasciola hepatica.

Cause

The parasite infects an amphibic snail (Segmentina nitidella, Segmentina hemisphaerula, Hippeutis schmackerie, Gyraulus, Lymnaea, Pila, Planorbis (Indoplanorbis)) after being released by infected feces; from this intermediate host, metacercaria infest on aquatic plants like water spinach, which are eaten raw by pigs and humans. Also, the water is possibly infective when drunk unheated ("Encysted cercariae exist not only on aquatic plants, but also on the surface of the water.")

Prevention

Prevention can be easily achieved by immersion of vegetables in boiling water for a few seconds to kill the infective metacercariae, avoiding the use of feces ("nightsoil") as a fertilizer, and maintenance of proper sanitation and good hygiene. Additionally, snail control should be attempted.

Treatment

Praziquantel is the drug of choice for treatment. Treatment is effective in early or light infections. Heavy infections are more difficult to treat. Studies of the effectiveness of various drugs for treatment of children with F. buski have shown tetrachloroethylene as capable of reducing faecal egg counts by up to 99%. Other anthelmintics that can be used include thiabendazole, mebendazole, levamisole and pyrantel pamoate. oxyclozanide, hexachlorophene and nitroxynil are also highly effective.

Epidemiology

F. buski is endemic in Asia including China, Taiwan, South-East Asia, Indonesia, Malaysia and India. It has a prevalence of up to 60% in India and mainland China and has an estimated 10 million human infections. Infections occur most often in school-age children or in impoverished areas with a lack of proper sanitation systems.

A study revealed that F. buski was endemic in central Thailand, affecting approximately 2,936 people due to infected aquatic plants called water caltrops and the snail hosts which were associated with them. The infection, or the eggs which hatch in the aquatic environment, were correlated with the water pollution in different districts of Thailand such as Ayuthaya Province. The high incidence of infection was prevalent in females and children ages 10â€"14 years of age.

References

External links

• Graczyk TK, Gilman RH, Fried B (2001). "Fasciolopsiasis: is it a controllable food-borne disease?". Parasitol. Res. 87 (1): 80â€"3. doi:10.1007/s004360000299. PMID 11199855. 

• Mas-Coma S, Bargues MD, Valero MA (2005). "Fascioliasis and other plant-borne trematode zoonoses". Int. J. Parasitol. 35 (11â€"12): 1255â€"78. doi:10.1016/j.ijpara.2005.07.010. PMID 16150452.