Fasciolosis

Abstract

Fasciolosis is a neglected tropical plant-borne trematode zoonoses caused by Fasciola hepatica and Fasciola gigantica. Fasciolosis is distributed in more than 75 countries, especially in the localities where sheep and cattle are reared. Infection is acquired by ingesting metacercaria encysted on leaves by animals or humans. Infection causes great economic loss in terms of mortality and production losses in sheep and cattle. Infected liver is unsuitable for human consumption. Human fasciolosis is often recorded in the areas where the disease is highly endemic in animals. The geographical distribution of Fasciola species coincides with the availability of suitable species of snails. Demonstration of fluke eggs by microscopy of the faeces, characteristic symptoms and hepatic lesions at necropsy, in addition to grazing history and seasonality of fasciolosis in the locality confirms the diagnosis. Serodiagnostic methods and molecular assays are much more helpful for diagnosis of fasciolosis during early stages of infection. Chemotherapy of infected animals and control of snail population in the area endemic for the diseases prevent transmission of infection to humans. No vaccine is available for prevention of fasciolosis either in humans or animals.

Case Study

A 40-year-old woman from the north-eastern part of India was admitted with the chief complaints of pain in the right hypochondriac region and irregular fever for the last 2 years. Physical examination revealed hepatomegaly, and haematological tests revealed moderate leucocytosis (12,000 cells/cu mm) but with 50% eosinophils. Bilirubin levels and liver enzymes were within normal limits. Ultrasonogram showed hypo-echoic regions in the liver with possibility of necrosis. Ultrasound-directed biopsy of the area showed necrotic granuloma formation with eosinophilia. Bile specimen aspirated by endoscopy revealed many brown, ellipsoidal, unembryonated ova with a small operculum resembling F. hepatica eggs. The patient was treated with a single dose of triclabendazole and on follow-up the patient’s pain and fever had resolved and repeat bile examination showed absence of any ova (adapted from Ramachandran et al. 2012).

• 1. What are the different anti-trematodal drugs recommended for the treatment of fasciolosis?

• 2. What dietary history is important in the above case, which has not been mentioned?

• 3. What alternative non-invasive test could have been done in the above case without taking resort to liver biopsy?

Research Questions

• 1. Which antigenic target of F. hepatica should be utilized for development of sensitive immunodiagnostic test?

• 2. How to proceed for vaccine development using proteomic studies and reverse vaccinology for fasciolosis?