Administration of triclabendazole is safe and effective in controlling fascioliasis in an endemic community of the bolivian altiplano

Background

The Bolivian northern Altiplano is characterized by a high prevalence of Fasciola hepatica infection. In order to assess the feasibility, safety and efficacy of large-scale administration of triclabendazole as an appropriate public health measure to control morbidity associated with fascioliasis, a pilot intervention was implemented in 2008.

Materials and Methods

Schoolchildren from an endemic community were screened for fascioliasis and treated with a single administration of triclabendazole (10 mg/kg). Interviews to assess the occurrence of adverse events were conducted on treatment day, one week later, and one month after treatment. Further parasitological screenings were performed three months after treatment and again two months later (following a further treatment) in order to evaluate the efficacy of the intervention.

Results

Ninety infected children were administered triclabendazole. Adverse events were infrequent and mild. No serious adverse events were reported. Observed cure rates were 77.8% after one treatment and 97.8% after two treatments, while egg reduction rates ranged between 74% and 90.3% after one treatment, and between 84.2% and 99.9% after two treatments. The proportion of high-intensity infections (≥400 epg) decreased from 7.8% to 1.1% after one treatment and to 0% after two treatments.

Conclusion

Administration of triclabendazole is a feasible, safe and efficacious public health intervention in an endemic community in the Bolivian Altiplano, suggesting that preventive chemotherapy can be applied to control of fascioliasis. Further investigations are needed to define the most appropriate frequency of treatment.     

An Outbreak of Human Fascioliasis gigantica in Southwest China

Fascioliasis is a common parasitic disease in livestock in China. However, human fascioliasis is rarely reported in the country. Here we describe an outbreak of human fascioliasis in Yunnan province. We reviewed the complete clinical records of 29 patients and performed an epidemiological investigation on the general human population and animals in the outbreak locality. Our findings support an outbreak due to Fasciola gigantica with a peak in late November, 2011. The most common symptoms were remittent fever, epigastric tenderness, and hepatalgia. Eosinophilia and tunnel-like lesions in ultrasound imaging in the liver were also commonly seen. Significant improvement of patients’ condition was achieved by administration of triclabendazole®. Fasciola spp. were discovered in local cattle (28.6%) and goats (26.0%). Molecular evidence showed a coexistence of F. gigantica and F. hepatica. However, all eggs seen in humans were confirmed to be F. gigantica. Herb (Houttuynia cordata) was most likely the source of infections. Our findings indicate that human fascioliasis is a neglected disease in China. The distribution of triclabendazole®, the only efficacious drug against human fascioliasis, should be promoted.     

Triclabendazole Sulfoxide Causes Stage-Dependent Embryolethality in Zebrafish and Mouse In Vitro

Background

Fascioliasis and paragonimiasis are widespread foodborne trematode diseases, affecting millions of people in more than 75 countries. The treatment of choice for these parasitic diseases is based on triclabendazole, a benzimidazole derivative which has been suggested as a promising drug to treat pregnant women and children. However, at the moment, this drug is not approved for human use in most countries. Its potential adverse effects on embryonic development have been scarcely studied, and it has not been assigned a pregnancy category by the FDA. Thus, to help in the process of risk-benefit decision making upon triclabendazole treatment during pregnancy, a better characterization of its risks during gestation is needed.

Methodology

The zebrafish embryo test, a preimplantation and a postimplantation rodent whole embryo culture were used to investigate the potential embryotoxicity/teratogenicity of triclabendazole and its first metabolite triclabendazole sulfoxide. Albendazole and albendazole sulfoxide were included as positive controls.

Principal Findings

Triclabendazole was between 10 and 250 times less potent than albendazole in inducing dysmorphogenic effects in zebrafish or postimplantation rodent embryos, respectively. However, during the preimplantation period, both compounds, triclabendazole and triclabendazole sulfoxide, induced a dose-dependent embryolethal effect after only 24 h of exposure in rodent embryos and zebrafish (lowest observed adverse effect concentrations = 10 μM).

Conclusions/Significance

In humans, after ingestion of the recommended doses of triclabendazole to treat fascioliasis and paragonimiasis (10 mg/kg), the main compound found in plasma is triclabendazole sulfoxide (maximum concentration 38.6 μM), while triclabendazole concentrations are approximately 30 times lower (1.16 μM). From our results it can be concluded that triclabendazole, at concentrations of the same order of magnitude as the clinically relevant ones, does not entail teratogenic potential in vitro during the organogenesis period, but its first metabolite triclabendazole sulfoxide has a high embryotoxic capacity in vitro during the preimplantation stage.     

The Diagnosis of Human Fascioliasis by Enzyme-Linked Immunosorbent Assay (ELISA) Using Recombinant Cathepsin L Protease

Background

Fascioliasis is a worldwide parasitic disease of domestic animals caused by helminths of the genus Fasciola. In many parts of the world, particularly in poor rural areas where animal disease is endemic, the parasite also infects humans. Adult parasites reside in the bile ducts of the host and therefore diagnosis of human fascioliasis is usually achieved by coprological examinations that search for parasite eggs that are carried into the intestine with the bile juices. However, these methods are insensitive due to the fact that eggs are released sporadically and may be missed in low-level infections, and fasciola eggs may be misclassified as other parasites, leading to problems with specificity. Furthermore, acute clinical symptoms as a result of parasites migrating to the bile ducts appear before the parasite matures and begins egg laying. A human immune response to Fasciola antigens occurs early in infection. Therefore, an immunological method such as ELISA may be a more reliable, easy and cheap means to diagnose human fascioliasis than coprological analysis.

Methodology/Principal findings

Using a panel of serum from Fasciola hepatica-infected patients and from uninfected controls we have optimized an enzyme-linked immunosorbent assay (ELISA) which employs a recombinant form of the major F. hepatica cathepsin L1 as the antigen for the diagnosis of human fascioliasis. We examined the ability of the ELISA test to discern fascioliasis from various other helminth and non-helminth parasitic diseases.

Conclusions/Significance

A sensitive and specific fascioliasis ELISA test has been developed. This test is rapid and easy to use and can discriminate fasciola-infected individuals from patients harbouring other parasites with at least 99.9% sensitivity and 99.9% specificity. This test will be a useful standardized method not only for testing individual samples but also in mass screening programs to assess the extent of human fascioliasis in regions where this zoonosis is suspected.     

Triclabendazole: new skills to unravel an old(ish) enigma

Triclabendazole was introduced in the early 1980s for the treatment of Fasciola hepatica infections in livestock. Due to its high activity against immature flukes, it has become established as the principal anti-fluke drug on the market. More recently, triclabendazole has been used to treat human cases of fascioliasis and is now the drug of choice for this infection, too. Resistance to triclabendazole was first reported in 1995 in a field population in Australia and, since that time, resistant populations have been identified in several countries in Europe. Parallel to the spread of resistance has been a sharp increase in the prevalence of fascioliasis, which has been attributed largely to climate changes. Consequently, farmers are faced with an alarming scenario, as none of the other fasciolicides on the market possess such high activity against the damaging immature stages of fluke. The main aim of this review is to assess current understanding of the mechanism of action of triclabendazole against the fluke and the mechanism by which the fluke has become resistant to it. The use of triclabendazole against animal and human infections is summarized and suggestions are given on ways to deal with resistance. Gaps in the knowledge of various aspects of its use are highlighted and this may serve to open up future research areas.     

Efficacy and safety of artemether in the treatment of chronic fascioliasis in Egypt: exploratory phase-2 trials

Background

Fascioliasis is an emerging zoonotic disease of considerable veterinary and public health importance. Triclabendazole is the only available drug for treatment. Laboratory studies have documented promising fasciocidal properties of the artemisinins (e.g., artemether).

Methodology

We carried out two exploratory phase-2 trials to assess the efficacy and safety of oral artemether administered at (i) 6×80 mg over 3 consecutive days, and (ii) 3×200 mg within 24 h in 36 Fasciola-infected individuals in Egypt. Efficacy was determined by cure rate (CR) and egg reduction rate (ERR) based on multiple Kato-Katz thick smears before and after drug administration. Patients who remained Fasciola-positive following artemether dosing were treated with single 10 mg/kg oral triclabendazole. In case of treatment failure, triclabendazole was re-administered at 20 mg/kg in two divided doses.

Principal Findings

CRs achieved with 6×80 mg and 3×200 mg artemether were 35% and 6%, respectively. The corresponding ERRs were 63% and nil, respectively. Artemether was well tolerated. A high efficacy was observed with triclabendazole administered at 10 mg/kg (16 patients; CR: 67%, ERR: 94%) and 20 mg/kg (4 patients; CR: 75%, ERR: 96%).

Conclusions/Significance

Artemether, administered at malaria treatment regimens, shows no or only little effect against fascioliasis, and hence does not represent an alternative to triclabendazole. The role of artemether and other artemisinin derivatives as partner drug in combination chemotherapy remains to be elucidated.     

Fascioliasis and Intestinal Parasitoses Affecting Schoolchildren in Atlixco,Puebla State,Mexico: Epidemiology and Treatment with Nitazoxanide

Background

The Atlixco municipality, Puebla State, at a mean altitude of 1840 m, was selected for a study of Fasciola hepatica infection in schoolchildren in Mexico. This area presents permanent water collections continuously receiving thaw water from Popocatepetl volcano (5426 m altitude) through the community supply channels, conforming an epidemiological scenario similar to those known in hyperendemic areas of Andean countries.

Methodology and Findings

A total of 865 6–14 year-old schoolchildren were analyzed with FasciDIG coproantigen test and Lumbreras rapid sedimentation technique, and quantitatively assessed with Kato-Katz. Fascioliasis prevalences ranged 2.94–13.33% according to localities (mean 5.78%). Intensities were however low (24–384 epg). The association between fascioliasis and the habit of eating raw vegetables was identified, including watercress and radish with pronouncedly higher relative risk than lettuce, corncob, spinach, alfalfa juice, and broccoli. Many F. hepatica-infected children were coinfected by other parasites. Entamoeba histolytica/dispar, Giardia intestinalis, Blastocystis hominis, Hymenolepis nana and Ascaris lumbricoides infection resulted in risk factors for F. hepatica infection. Nitazoxanide efficacy against fascioliasis was 94.0% and 100% after first and second treatment courses, respectively. The few children, for whom a second treatment course was needed, were concomitantly infected by moderate ascariasis burdens. Its efficacy was also very high in the treatment of E. histolytica/E. dispar, G. intestinalis, B. hominis, H. nana, A. lumbricoides, Trichuris trichiura, and Enterobius vermicularis. A second treatment course was needed for all children affected by ancylostomatids.

Conclusions

Fascioliasis prevalences indicate this area to be mesoendemic, with isolated hyperendemic foci. This is the first time that a human fascioliasis endemic area is described in North America. Nitazoxanide appears as an appropriate alternative to triclabendazole, the present drug of choice for chronic fascioliasis. Its wide spectrum efficacy against intestinal protozooses and helminthiasis, usually coinfecting liver fluke infected subjects in human endemic areas, represents an important added value.     

Serodiagnosis of experimental fascioliasis by immunoprecipitation tests

Hillyer G. V. and Santiago de Weil N. 1981. Serodiagnosis of experimental fascioliasis by immunoprecipitation tests. International Journal for Parasitology11: 71–78. Counterelectrophoresis (CEP) was useful in detecting 100% of infections with fascioliasis in mice, rats, and rabbits by 4–5 weeks post infection, and in most rats as early as 2 weeks post infection. A rapid decrease of precipitins was observed when the animals were cured with a fasciolicidal drug at 4 or more weeks post infection. When rats were treated at 2 weeks, however, antibody reactivity remained high for at least 3 weeks post treatment suggesting that worm antigens are released in the liver parenchyma stimulating additional antibody production. Partial purification of F. hepatica adult worm extracts using Sephacryl S-200 was necessary for testing the serum of rats by CEP. In addition, the Sephacryl S-200 elution profile of F. hepatica antigens reactive with antisera to S. mansoni adult worms or eggs was shown. These studies demonstrate that CEP is useful for the early detection of antibodies in experimental fascioliasis and for the clear prediction of chemotherapeutic success when treatment is carried out at 4 or more weeks after infection.     

Stunting in pre-school and school-age children in the Peruvian highlands and its association with Fasciola infection and demographic factors

Fascioliasis is a zoonotic trematode infection that is endemic in the highlands of Peru. Chronic fascioliasis can be asymptomatic and remain undiagnosed for years. Chronic malnutrition in children, as manifested by stunting, leads to delayed cognitive development and lost productivity. We hypothesized that fascioliasis is among the factors associated with stunting in children from endemic areas. We conducted a cross-sectional study among children attending pre-school and school in 26 communities in the Anta province in the Cusco region of Peru. We conducted interviews to collect information on demographic, socioeconomic, and medical history. Blood was collected and tested for complete cell count and FAS2 ELISA for Fasciola antibodies. Three stool samples per participant were tested for parasites by Kato-Katz and Lumbreras rapid sedimentation methods. Chronic fascioliasis was determined by the presence of ova in stool. Children’s height, weight, and age were recorded and used to calculate height for age Z scores (HAZ). Three thousand children participated in the study. Nine percent (264) of children had at least one positive test for Fasciola infection, 6% (164) had chronic fascioliasis, and 3% (102) had only positive antibody tests. The median HAZ was -1.41 (IQR: -2.03 to -0.81) and was similar in males and females. Twenty six percent (776) of children had stunting with HAZ < -2. Children with chronic fascioliasis had a lower median HAZ than children without Fasciola (-1.54 vs. -1.4, p = 0.014). History of treatment for malnutrition, history of treatment for anemia, having other helminths in stool, lower socioeconomic score, living at a higher elevation, and fewer years of schooling of both parents were associated with a lower HAZ score. In a multiple regression analysis, older age and a lower socioeconomic score were associated with a lower HAZ score. While fascioliasis and other helminths were associated with lower HAZ, they were not independent of the socioeconomic score.     

A praziquantel-ineffective fascioliasis case successfully treated with triclabendazole

Human fascioliasis cases in Japan have been reported infrequently and the most appropriate therapy for this disease remains to be determined. This case report describes a patient with the infection unsuccessfully treated with multiple high doses of praziquantel for over 1 year and eventually cured by the administration of triclabendazole in two single doses of 10 mg/kg and 12.5 mg/kg 5 months apart.     

Clinical considerations on 2 cases of hepatic fascioliasis. Importance of the imaging examinations]

Two cases of hepatic human fascioliasis, both with antecedents of eating watercress, hepatobiliary symptoms and high eosinophilia are described. In the first one (42 year-old male), at the beginning the abdominal ecotomographical and computed tomography images suggested an hepatic tumor, but afterwards, the finding of Fasciola hepatica ova in feces and the observation of numerous typical images of the fluke in the choledochus by means of an endoscopic cholangiography, plus lesions related to a L?ffler syndrome detected in a chest radiography, lead to the diagnosis of hepatic fascioliasis. The patient was treated with dehydroemetine. In the second case (52 year-old male), presented pain in the upper right abdominal quadrant; in an abdominal ecography three cystic lesions in the right liver lobe were found. Nor in the feces neither in the bile F. hepatica eggs were observed. Serological tests for fascioliasis and hydatidosis resulted positive. The endoscopic cholangiography was normal. With the presumptive diagnosis of fascioliasis the patient was treated with dehydroemetine. But as his disturbances remained during the following six months, and raising the possibility of a suppurated hydatid cyst or hepatic abscesses, he was submitted to surgery, finding F. hepatica eggs in the chocolate-like hematic liquid. In the wall and in a liver mass resected a grunuloma with eggs of the parasite was detected. The patient was treated again and cured with dehydroemetine. The existence of subcapsular hematomata and granulomas in hepatic fascioliasis, which can give raise to a diagnosis confusion due to their aspect in the ecotomography and computed tomography are commented. The cholangiographic aspect of the affection is discussed.     

Fascioliasis may promote tuberculous infectivity in small ruminants

Fascioliasis and bovine tuberculosis (TB) are global impediments to livestock development. We investigated the co-infectivity of fascioliasis and TB in small ruminants at slaughter. A total of 84 goats and 16 sheep were investigated from different slaughter houses in Mymensingh city, Bangladesh from June 2019 to February 2020. Grossly, acute fascioliasis was characterized by hemorrhagic tracts in the liver and chronic fascioliasis with biliary cirrhosis and pipe-stem liver. Grossly, seven goats and two sheep were associated with the acute and sixty goats and seven sheep were associated with the chronic phase of fascioliasis. Five goats’ livers showed both the acute and chronic phases of fascioliasis. In TB, granulomas with central core of caseous necrosis were seen in the lymph nodes (21), livers (10) and lungs (01) of goats or in the lymph nodes (03) and liver (01) of sheep. Histopathologically, biliary cirrhosis was seen in fascioliasis and granuloma, caseous necrosis and calcification in TB. In co-infection revealed granuloma (TB) with acid-fast bacilli and widespread biliary cirrhosis in the livers of goats (14) and sheep (02). The fragments of the 16S rRNA gene (372 bp, M. tuberculosis complex) and MPB83 gene (600 bp, M. bovis) were detected in the lymph nodes, livers and lungs using polymerase chain reaction. This study showed the existence of co-infectivity of Fasciola and M. bovis in goats and sheep in Bangladesh. Chronic fascioliasis may be associated with establishing tuberculous infection in small ruminants. Therefore, extremely zoonotic bovine TB control programs require active management of fascioliasis.     

The Diterpenoid 7-Keto-Sempervirol,Derived from Lycium chinense,Displays Anthelmintic Activity against both Schistosoma mansoni and Fasciola hepatica

BackgroundTwo platyhelminths of biomedical and commercial significance are Schistosoma mansoni (blood fluke) and Fasciola hepatica (liver fluke). These related trematodes are responsible for the chronic neglected tropical diseases schistosomiasis and fascioliasis, respectively. As no vaccine is currently available for anti-flukicidal immunoprophylaxis, current treatment is mediated by mono-chemical chemotherapy in the form of mass drug administration (MDA) (praziquantel for schistosomiasis) or drenching (triclabendazole for fascioliasis) programmes. This overreliance on single chemotherapeutic classes has dramatically limited the number of novel chemical entities entering anthelmintic drug discovery pipelines, raising significant concerns for the future of sustainable blood and liver fluke control.

Methodology/ Principle Findings

Here we demonstrate that 7-keto-sempervirol, a diterpenoid isolated from Lycium chinense, has dual anthelmintic activity against related S. mansoni and F. hepatica trematodes. Using a microtiter plate-based helminth fluorescent bioassay (HFB), this activity is specific (Therapeutic index = 4.2, when compared to HepG2 cell lines) and moderately potent (LD₅₀ = 19.1 μM) against S. mansoni schistosomula cultured in vitro. This anti-schistosomula effect translates into activity against both adult male and female schistosomes cultured in vitro where 7-keto-sempervirol negatively affects motility/behaviour, surface architecture (inducing tegumental holes, tubercle swelling and spine loss/shortening), oviposition rates and egg morphology. As assessed by the HFB and microscopic phenotypic scoring matrices, 7-keto-sempervirol also effectively kills in vitro cultured F. hepatica newly excysted juveniles (NEJs, LD₅₀ = 17.7 μM). Scanning electron microscopy (SEM) evaluation of adult F. hepatica liver flukes co-cultured in vitro with 7-keto-sempervirol additionally demonstrates phenotypic abnormalities including breaches in tegumental integrity and spine loss.

Conclusions/ Significance

7-keto-sempervirol negatively affects the viability and phenotype of two related pathogenic trematodes responsible for significant human and animal infectious diseases. This plant-derived, natural product is also active against both larval and adult developmental forms. As such, the data collectively indicate that 7-keto-sempervirol is an important starting point for anthelmintic drug development. Medicinal chemistry optimisation of more potent 7-keto-sempervirol analogues could lead to the identification of novel chemical entities useful for future combinatorial or replacement anthelmintic control.     

Advances in Fasciola hepatica research using ‘omics’ technologies

The liver fluke Fasciola hepatica is an economically important pathogen of livestock worldwide, as well as being an important neglected zoonosis. Parasite control is reliant on the use of drugs, particularly triclabendazole, which is effective against multiple parasite stages. However, the spread of parasites resistant to triclabendazole has intensified the pursuit for novel control strategies. Emerging 'omics' technologies are helping advance our understanding of liver fluke biology, specifically the molecules that act at the host-parasite interface and are central to infection, virulence and long-term survival within the definitive host. This review discusses the technological sequencing advances that have facilitated the unbiased analysis of liver fluke biology, resulting in an extensive range of ‘omics’ datasets. In addition, we highlight the ‘omics’ studies of host responses to F. hepatica infection that, when combined with the parasite datasets, provide the opportunity for integrated analyses of host-parasite interactions. These extensive datasets will form the foundation for future in-depth analysis of F. hepatica biology and development, and the search for new drug or vaccine interventions.     

Isolation of Fasciola hepatica genus-specific antigens

Santiago de Weil N., Hillyer G. V. and Pacheco E. 1984. Isolation of Fasciola hepatica genus-specific antigens. International Journal for Parasitology14: 197–206. The Fasciola hepatica antigens which induce antibody formation in acute fascioliasis were isolated by acid elution after reacting an F. hepatica tegument antigen extract with a CNBr-Sepharose 4B column coupled with IgG obtained from the serum of rabbits infected with fascioliasis for 6–10 weeks. These isolated antigens were further separated by gel filtration using a column packed with Sephacryl S-200. In this manner three major peaks were obtained. The best serologic antigens were found in peak 2 which had a mol. wt range of 14,000–43,000. This peak contains genus-specific F. hepatica antigens which are highly reactive with fascioliasis serum. These antigens do not cross-react with either Schistosoma mansoni or with bovine serum albumin by gel diffusion. Monitoring by ELISA and gel diffusion with heterologous and homologous antisera showed that as purification by antibody affinity chromatography proceeded, cross reactivity with S. mansoni was eliminated. The rabbit antiserum obtained against peak 2, when tested by immunoelectrophoresis with a crude F. hepatica extract shows one main band identical to the main band observed with serum from acutely infected rabbits. Up to two other minor bands can be detected using concentrated homologous antisera. Fractions obtained from preparative iso-electric focusing of the F. hepatica tegument extract were reacted with sera from rabbits with acute fascioliasis. Two main bands were observed in immunodiffusion with antigens eluting in a pH range of 7.4–8.7. When these fractions were monitored with anti peak 2 antisera, two precipitin bands appeared with antigens eluting in a pH range of 7.4–7.9. The F. hepatica genus-specific antigen pool was applied to ELISA to evaluate its ability to detect antibody in a primary F. hepatica infection in rabbits. A rise in absorbance values could be detected by 2 weeks of infection, reached high levels by 6 weeks and remained high through 28 weeks of infection.     

Novel triclabendazole prodrug: A highly water soluble alternative for the treatment of fasciolosis

In this work we present the synthesis, aqueous solubility and stability, hydrolysis by alkaline phosphatase, and in vivo fasciolicidal activity in sheep of a highly water soluble phosphate salt prodrug of triclabendazole (MFR-5). The aqueous solubility of MFR-5 at pH 7 was 88,000-fold that of triclabendazole. MFR-5 showed excellent aqueous stability (>95% after 26 h) at pH 7, making it ideal for developing pharmaceutical compositions in the form of solutions that can easily be hydrolyzed by the enzyme alkaline phosphatase (t = 13.6 s) to liberate the precursor compound. An aqueous solution of MFR-5 administered intramuscularly to sheep at concentrations of 4, 6 and 8 mg/kg presented a fasciolicidal efficiency of 96.5%, 98.4% and 99.2%, respectively. In the in vivo experiments, MFR-5 reduced 100% the excretion of eggs in all of the above concentrations.     

A case of biliary Fascioliasis by Fasciola gigantica in Turkey

A case of Fasciola gigantica-induced biliary obstruction and cholestasis is reported in Turkey. The patient was a 37- year-old woman, and suffered from icterus, ascites, and pain in her right upper abdominal region. A total of 7 living adult flukes were recovered during endoscopic retrograde cholangiopancreatography (ERCP). A single dose of triclabendazole was administered to treat possible remaining worms. She was living in a village of southeast of Anatolia region and had sheeps and cows. She had the history of eating lettuce, mallow, dill, and parsley without washing. This is the first case of fascioliasis which was treated via endoscopic biliary extraction during ERCP in Turkey.     

Fas2-ELISA in the detection of human infection by Fasciola hepatica

Fasciola hepatica has recently emerged as a major pathogen of humans from reports on areas of endemicity and hyper-endemicity for fascioliasis. This situation is aggravated by the lack of standard assays for the screen diagnosis of F. hepatica infection in humans living in endemic areas. Our laboratory has developed an enzyme-linked immunosorbent assay (Fas2-ELISA) based on the capture of IgG antibody by a purified protein Fas2, which is an adult fluke cysteine proteinase. Fas2-ELISA exhibited 95% sensitivity and 100% specificity in 38 individuals infected with F. hepatica diagnosed by finding eggs in stools and 46 serum samples from healthy volunteers. No cross-reaction was observed with 54 serum samples from patients with ten different parasitic infections including the trematodes Paragonimus westermani and Schistosoma mansoni. The high antigenicity of Fas2 is suggested by the fact that antibodies to Fas2 rise rapidly by 1-2 weeks of infection and rise until patency at 8 weeks of infection in experimentally infected alpacas. Field screening for human fascioliasis using Fas2-ELISA and coprology in three endemic locations of the Peruvian Andes resulted in 95.5% sensitivity, 86.6% specificity in a population of 664 children in an age range of 1 to 16 years old. These results provide evidence of the clinical potential of Fas2-ELISA to diagnose fascioliasis in humans exposed to liver fluke infection in endemic areas for this parasite. Fas2-ELISA is currently developed as a standard assay for both field screening for fascioliasis in people living in endemic areas and detecting occasionally F. hepatica infected patients in clinical laboratories.     

Geospatial analysis of the associations between environmental contamination with livestock feces and children with chronic fascioliasis in the Anta province of Cusco,Peru

Fasciola hepatica is a neglected parasitic infection with significant human health and livestock industry impact. The Andean Altiplano harbors an estimated 50% of the Fasciola’s world infection burden. There is scarce data regarding the spatial associations between different Fasciola hosts. In this project, we aimed to determine the geospatial relationships between Fasciola eggs passed in feces of different livestock species and the risk of infection among each household as a unit. We used data from a cross-sectional study evaluating children and livestock feces for Fasciola infection around households in three districts of Anta province, in the Cusco region of Peru. Each sample was geographically tagged and evaluated for fascioliasis using microscopy methods. A total of 2070 households were included, the median age was 9.1 years (6.7–11.8), 49.5% were female, and 7.2% of the households had at least one infected child. A total of 2420 livestock feces samples were evaluated. The infection rate in livestock samples was 30.9%. The highest infection rate was found in sheep with 40.8%, followed by cattle (33.8%), and swine (26.4%). The median distance between a household with an infected child to a positive animal sample was 44.6 meters (IQR 14.7–112.8) and the distance between a household with no infected children to a positive animal sample was 62.2 meters (IQR 18.3–158.6) (p = 0.025). The multivariable logistic regression adjusted by presence of poor sanitation, unsafe water consumption, altitude, and presence of multiple infected children per household demonstrated an association between household infection and any cattle feces at a 50 meters radius (Uninfected: OR 1.42 (95%CI 1.07–1.89), p = 0.017. Infected: OR 1.89 (95%CI 1.31–2.73), p = 0.001), positive cattle feces at a 100 meters radius (OR 1.35 (95% CI 1.08–1.69), p = 0.008), and negative cattle feces at a 200 meters radius (OR 1.08 (95% CI 1.01–1.15), p = 0.022). We identified potential hot and cold spots for fascioliasis in the Anta province. An association between environmental contamination with feces from different livestock species and infected children in rural households was found in our study. Local health authorities may apply this strategy to estimate the risk of infection in human populations and apply targeted interventions.     

Insights into the Interactions of Fasciola hepatica Cathepsin L3 with a Substrate and Potential Novel Inhibitors through In Silico Approaches

Background Fasciola hepatica is the causative agent of fascioliasis, a disease affecting grazing animals, causing economic losses in global agriculture and currently being an important human zoonosis. Overuse of chemotherapeutics against fascioliasis has increased the populations of drug resistant parasites. F. hepatica cathepsin L3 is a protease that plays important roles during the life cycle of fluke. Due to its particular collagenolytic activity it is considered an attractive target against the infective phase of F. hepatica.Conclusions/SignificanceThe present study is the first computer-aided drug design approach against F. hepatica cathepsins. Here we predict the principal determinants of binding of FhCL3 in complex with a natural substrate by detailed energetic characterization of protease interaction surface. We also propose novel compounds as FhCL3 inhibitors. Overall, these results will foster the future rational design of new inhibitors against FhCL3, as well as other F. hepatica cathepsins.