| Fasciolopsiasis | |
|---|---|
 | |
| Eggs ofFasciolopsis buski | |
| Specialty | Infectious diseases  |
Fasciolopsiasis results from aninfection by thetrematodeFasciolopsis buski,[1] the largestintestinalfluke ofhumans, growing up to 7.5 cm (3.0 in) long.
Most infections are light, almostasymptomatic. In heavy infections, symptoms can includeabdominal pain,chronicdiarrhea,anemia,ascites,toxemia,allergic responses, sensitization caused by the absorption of the worms' allergenic metabolites can lead to intestinal obstruction and may eventually cause death of the patient.[2]
The parasite infects an amphibicsnail[3] (Segmentina nitidella,Segmentina hemisphaerula, Hippeutis schmackerie,Gyraulus,Lymnaea, Pila,Planorbis (Indoplanorbis)) after being released by infected mammalian feces;metacercaria released from thisintermediate host encyst onaquatic plants likewater spinach, which are eaten raw by pigs and humans. Water itself can also be infective when drunk unboiled ("Encysted cercariae exist not only onaquatic plants, but also on the surface of the water.")[4]
Microscopic identification of eggs, or more rarely of the adultflukes, in thestool orvomitus is the basis of specific diagnosis. The eggs are indistinguishable from those of the very closely relatedFasciola hepatica liver fluke, but that is largely inconsequential since treatment is essentially identical for both.[citation needed]
Infection can be prevented by immersing vegetables in boiling water for a few seconds to kill the infective metacercariae, avoiding the use of untreated feces ("nightsoil") as a fertilizer, and maintenance of proper sanitation and good hygiene. Additionally,snail control should be attempted.[citation needed]
Praziquantel is thedrug 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 withF. buski have showntetrachloroethylene as capable of reducing faecal egg counts by up to 99%. Otheranthelmintics that can be used includethiabendazole,mebendazole,levamisole andpyrantel pamoate.[5]Oxyclozanide,hexachlorophene and nitroxynil are also highly effective.[6]
F. buski is endemic inAsia includingChina,Taiwan,Southeast Asia,Indonesia,Malaysia, andIndia. It has an up to 60% prevalence in worst-affected communities in southern and easternIndia and mainlandChina and has an estimated 10 million human infections. Infections occur most often in school-aged children or in impoverished areas with a lack of proper sanitation systems.[7]
A study from 1950s found thatF. buski was endemic in central Thailand, affecting about 2,936 people due to infected aquatic plants calledwater 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 10–14 years of age.[8]
