2 Fascioliasis has world wide effects WHO designated extremely neglected diseaseCases in 51 different countries17 million people affectedWHO has designated fascioliasis as one of the extremely neglected diseases. Cases have been seen in 51 different countries in the past 25 years. The highest known rates of human infection are in the Andean highlands of Bolivia and Peru. It is the second most common trematode infection in the Middle East and North Africa. It mainly affects children in poor rural areas. The estimated number of infected people is at least 2.4 million and might be as high as 17 million.
3 Oral-fecal transmission route Reservoir in livestockWatercressThe fasciola is a liver fluke that is passed through the oral-fecal route. It most commonly occurs where cattle or sheep vectors contaminate water and people become infected by drinking water carrying the worm or eating raw vegetables, specifically watercress, that are exposed to the contaminated water and not cooked prior to eating.
4 1. Unfertilized eggs are released in stool usually from cattle or sheep and fertilized in water. 2. Miracidia hatch and invade the snail intermediate host where they continue to developParasite goes through 3 developmental stages in the snail, the sporocysts then rediae and last the free- swimming cercariae are released from the snailthe metacercariae encyst on water plants5. Humans become sick by eating metacercariae that have attached to plants6. The metacercariea move into the duodenum and migrate to the biliary ducts where they mature and eventually are excreted in the stool
5 Disease manifests in the liver Chronic phaseProducing eggs in bile ductsAsymptomaticSymptomaticAcute phaseFlukes traveling to bile ductsNausea, vomiting, abdominal painInflammation and bleedingLiver tissue destructionThe acute phase of the disease occurs when the flukes are traveling through the small intestinal wall into the liver and the bile duct. It usually begins 4 to 7 days after ingestion of the fasciola and may last from weeks to months. This phase is often asymptomatic, but patients who do experience symptoms may experience gastrointestinal bleeding, inflammation, abdominal pain, nausea, vomiting and diarrhea. Patients may also experience destruction of the liver tissue. The chronic disease occurs when the flukes have made it to the bile ducts and begin producing eggs. symptomatic disease causes Severe, lasting damage while many patients in the chronic phase remain asymptomatic
6 Diagnosis can be difficult Stool ova testELISA or Western BlotLiver ultrasound
7 Few drugs have been used for treatment Bithionol- Less effectiveTriclabendazole- 1983- Effective against early stage parasites- Inhibits parasitic microtubule formation- Resistance in 1995Bithionol causes morphological changes
8 Cathepsin L proteases vaccine testing Fascilitate in tissue penetration, feeding, and immune system evasionCathepsin L1 and L2 are the major fasciola proteasesSecreted from the epithelial cells lining the gut of fasciola. Only tested in sheep and cattle
9 FhSAP2 as a potential vaccine Potential to protect against subsequent fasciola hepatica metacercariae infectionsFluke burdenReduced 83.3% with cDNA-FhSAP2Reduced 60% with FhSAP2 proteinFhSAP2 is a Fasciola antigen. All vaccinated animals had less liver damage
10 Kapplan-Meier analysis to estimate the survival probability over the time after challenge in mice vaccinated with FhSAP2 or cDNA-FhSAP2 compared to positive controls. PC includes mice vaccinated with PBS in FA and vaccinated with the empty pFLAG-CMV−2 plasmid. Log-rank test determined that there are statistical differences (P<.05) between survival probability of DNA-FhSAP2-vaccinated group compared to the PC group
11 Difficulty controlling Fasciola spread Individualized control plansSeparation of livestock and farmingSanitationCooked vegetables
12 ReferencesFarid Z, Kamal M, Woody J (1988). Treatment of acute toxemic fascioliasis. Trans R Soc Trop Med Hyg, 82, 299.Dawes B. Some apparent effects of Bithionol (Actamer) on Fasciola hepatica. Nature –425.Neglected tropical diseases of the Middle East and North Africa: Review of their prevalence, distribution and opportunities for control