Fasciola gigantica is a parasitic flatworm of the class Trematoda, which causes tropical fascioliasis. It is regarded as one of the most important single platyhelminth infections of ruminants in Asia and Africa. The infection is commonly called fasciolosis.
The prevalence of F. gigantica often overlaps with that of Fasciola hepatica, and the two species are so closely related in terms of genetics, behaviour, and morphological and anatomical structures that distinguishing them is notoriously difficult. Therefore, sophisticated molecular techniques are required to correctly identify and diagnose the infection.
Distribution
Fasciola gigantica causes outbreaks in tropical areas of South Asia, Southeast Asia, and Africa. The geographical distribution of F. gigantica overlaps with F. hepatica in many African and Asian countries and sometimes in the same country, although in such cases, the ecological requirement of the flukes and their snail hosts are distinct. Infection is most prevalent in regions with intensive sheep and cattle production. In Egypt, F. gigantica has existed in domestic animals since the times of the pharaohs.
Lifecycle
The lifecycle of F. gigantica is: Eggs (transported with feces) → egg hatch → miracidium → miracidium infect snail intermediate host → (parthenogenesis in 24 hours) sporocyst → redia → daughter redia → cercaria → (gets outside the snail) → metacercaria → infection of the host → adult stage produces eggs.
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Intermediate hosts
As with other trematodes, Fasciola spp. develop in a molluscan intermediate host. Species of the freshwater snails from the family Lymnaeidae are well known for their role as intermediate hosts in the lifecycle of F. gigantica; however, throughout the years, an increasing number of other molluscan intermediate hosts of F. gigantica have been reported. The Australian Lymnaea tomentosa (host of F. hepatica) was shown to be receptive to miracidia of F. gigantica from East Africa, Malaysia, and Indonesia. and the very rapid loop-mediated isothermal amplification (LAMP).
Treatment
Triclabendazole is the drug of choice in fasciolosis, as it is highly effective against both mature and immature flukes. Artemether has been demonstrated in vitro to be equally effective. Though slightly less potent, artesunate is also useful in human fasciolosis.
References
This article incorporates CC-BY-3.0 text from references.