Fascioliasis in developed countries: a review of classic and aberrant forms of the disease

Immunodiagnosis of fasciolosis using recombinant procathepsin L cystein proteinase

Cathepsin L1, a cysteine protease secreted by the gastrodermis of juvenile and adult Fasciola hepatica, was expressed in Escherichia coli as a fusion protein containing the proregion, supplied with six histidyl residues at the N-terminal end (rproCL1). In this study we tested its potential as antigen for the serologic diagnosis of F. hepatica infections by enzyme-linked immunosorbent assay (ELISA). The analyzed human sera included 16 positive samples, 99 negative controls and 111 from individuals affected by other parasitic and non parasitic diseases. The sensitivity and specificity of the rproCL1-ELISA were 100%. We also assessed the ability to detect antibodies in sera from 10 experimentally infected sheep, obtaining preliminary results that shown a response since the third week post infection in all the studied animals. Therefore, the recombinant rproCL1-based ELISA could be a standardized test for the accurate diagnosis of fasciolosis.

Imported Fasciola hepatica infection in the United States and treatment with triclabendazole

Infection with Fasciola hepatica, a liver trematode, is not frequently reported in the United States. We describe 2 patients, both originally from Cape Verde, who illustrate the spectrum of clinical presentations of F. hepatica as well as the means of treating infection with this parasite. Patient 1 had extensive disease and underwent multiple diagnostic procedures before the correct diagnosis was reached. Patient 2, who had few symptoms, had fascioliasis diagnosed by a noninvasive evaluation. Both patients were treated with triclabendazole without experiencing significant side effects. Fascioliasis that has been imported to the United States may elude prompt or accurate diagnosis. Obtaining a detailed travel history and recognizing the clinical presentation early in the course of infection may permit timely and noninvasive identification of infection. Triclabendazole is now the recommended drug for treating for fascioliasis because of its efficacy, safety, and ease of use.

Vaccination of sheep against Fasciola hepatica with homologous fatty acid binding proteins

The current study was designed to test the immunoprophylactic properties of native (nFh12) and recombinant (rFh15) antigens from Fasciola hepatica in sheep subsequently infected with the fluke. Thirty lambs were divided into six groups according to various patterns of immunisation and times of infection and necropsy. The antigens were emulsified in Freund's adjuvant. Levels of specific anti-nFh12 and anti-rFh15 antibodies rose rapidly by 2 weeks after the first immunisation and were always significantly higher in immunised-infected sheep than in control-infected sheep. On completion of the trial there was no difference in fluke burden between groups vaccinated with either of the antigens and non-immunised controls. However, worm size and faecal egg counts were significantly diminished in the sheep vaccinated with either of the antigens, suggesting an anti-fecundity effect. This is the first report of experimental vaccination of sheep against F. hepatica with purified native and recombinant antigens related to fatty acid binding proteins.

Immunodiagnosis of human fascioliasis by an enzyme-linked immunosorbent assay (ELISA) and a micro-ELISA

Enzyme-linked immunosorbent assay (ELISA) and micro-ELISA were evaluated for their ability to detect anti-Fasciola hepatica antibodies in humans by using excretory-secretory antigen. The sensitivity of each method was 100%, but the specificity was 100% for ELISA and 97% for micro-ELISA. The micro-ELISA could be used as a screening assay and ELISA could be used as a confirmatory method for the serodiagnosis of human fascioliasis.

Conservative management of biliary obstruction due to Fasciola hepatica

We report a case of temporary biliary obstruction due to fascioliasis. This case report shows that in Central Europe, fascioliasis is one of the differential diagnoses of abdominal pain, especially if it is associated with eosinophilia. Successful medical treatment is possible even with obstruction of the bile duct.

Evolution of schistosomiasis-induced pathology after therapy and interruption of exposure to schistosomes: a review of ultrasonographic studies

Ultrasonography (US) is suitable for diagnosing schistosomiasis-related organic pathology and is particularly useful to assess its evolution after therapy and/or interruption of exposure to the Schistosoma parasites. Evolution of pathology after treatment: Regression of hepatic abnormalities in Schistosma mansoni-infected children and adolescents has been observed already from 7 months post-therapy on. This does, however, not occur in all cases: individual differences are great ranging from spontaneous regression of pathology without treatment to persistence of pathology lasting for years after therapy even without re-infection. Intensity and duration of exposure, different parasite strains, patients' age and genetic background all influence the evolution of pathology. In communities at continuous exposure to S. mansoni infection, repeated re-treatment is required to control hepatosplenic morbidity. In Schistosoma japonicum infection, changes around the portal tree may regress, but characteristic diffuse abnormalities described as 'network pattern' abnormalities do not resolve. In Schistosoma haematobium infection bladder abnormalities and urinary tract obstruction frequently resolve after treatment. Clinically relevant pathology may resurge from 1 year after therapy on if exposure continues. Subjects with more advanced pathology before therapy, appear to be at higher risk of pathology re-appearance. Evolution of pathology after interruption of exposure to schistosomiasis: Knowledge on the evolution of pathology induced by S. mansoni is limited to some reports in emigrants and to the experience of ultrasonographists working in areas, where transmission has been partially interrupted. Due to the longevity of the parasite, infection may last for many years. Even after elimination of the parasites severe pathology may persist for long. In S. haematobium infection spontaneous healing after interruption of re-exposure may occur, but cases have been reported where urogenital lesions led to complications many years after exposure. Contrary to hepatosplenic and urinary pathology, knowlegde on the evolution of other organic abnormalities is very limited: studies on the evolution of biliary abnormalities or intestinal pathology have not been published. Genital pathology may be induced by all Schistosoma spp. Post-therapy evolution of genital schistosomiasis is largely ignored. In some European travellers partial regression of prostatic fibrosis has been described. Schistosomal adnexitis leading to infertility and/or ectopic pregnancy has been reported occurring many years after interruption of exposure. Ultrasonography (US) has never been used to study the influence of schistosomiasis on pregnancy. Concluding, current knowlegde on the evolution of pathology after treatment and/or interruption of exposure is still fragmentary. Frequently, fibrosis reverses after therapy, but advanced pathology may persist for long. Therefore, the possibility of severe clinical complications has to be taken into account, even if the infection is inactive since many years. In interventions aimed at controlling schistosomiasis-related morbidity, evolution of pathology must be monitored by US in representative patient cohorts. Further systematic US-studies are needed not only on the evolution of hepatosplenic and urinary pathology but also on that of intestinal, biliary and genital pathology induced by schistosomiasis, as well as on the influence of schistosomiasis on the outcome of pregnancy.

Eosinophilia and helminthic infections

Among microbial agents, helminths are the most common cause of eosinophilia. An approach to the evaluation of a patient with eosinophilia is outlined, with particular emphasis on clues in the history, examination and routine laboratory data that can help with the diagnosis. Multiple helminthic infections have been associated with eosinophilia, and the characteristic modes of spread, clinical manifestations, diagnostic tests and therapeutic considerations of these infections are discussed.

Recurrent eosinophilic panniculitis associated with Fasciola hepatica infection

Eosinophilic panniculitis is characterized by a prominent infiltration of subcutaneous fat with eosinophils. We report a case of Fasciola hepatica infection presenting with eosinophilic panniculitis successfully treated with bithionol. To our knowledge, this is the first report of recurrent eosinophilic panniculitis associated with Fasciola hepatica infection.

Update on Hepatobiliary and Pulmonary Flukes

Hepatobiliary and pulmonary trematodes continue to cause significant morbidity and mortality worldwide. This article provides a selected update on the clinical features, diagnosis, immunology, treatment, and control of infections caused by Clonorchis sinensis, Opisthorchis species, Fasciola hepatica, and Paragonimus species. Although recent molecular studies have elucidated novel mechanisms of immune evasion in Paragonimus westermani and F. hepatica, there are no immediate prospects for a vaccine for any of these trematodes. Although treatment of paragonimiasis, clonorchiasis, and opisthorchiasis was simplified with praziquantel in the 1980s, eradication of fascioliasis remains difficult because of the limited availablity of bithionol. Several experimental drugs have been tested as possible alternatives. Despite successful pilot public health programs designed to decrease transmission of these trematodes, their prevalence remains high and underlines the importance of allocating resources to control them.

Fascioliasis: sonographic abnormalities of the biliary tract and evolution after treatment with triclabendazole

Diagnosis of infection with the liver fluke Fasciola hepatica is usually difficult. Ultrasonography (US) might be a useful diagnostic alternative, and we assessed the value of sequential US in the diagnosis and monitoring of fascioliasis in 76 patients at baseline and for 60 days after treatment with triclabendazole. At baseline, biliary abnormalities were observed in 52 patients. Crescent-shaped parasites were seen in 11 patients; in 2 cases parasites were spontaneously moving and in 4 patients parasites were motionless. Postprandial examination revealed parasites adhering to the gallbladder wall in a further 5 cases. In 3 further cases, gallbladder contents were mobile but did not sediment downwards after patients changed position. Non-specific abnormalities were: impaired gallbladder contractility (n = 23), gallbladder tenderness (n = 19), debris (n = 6), calculi (n = 5), wall thickening (n = 2) and bile duct dilatation (n = 12). During day 1-7, Fasciola-like crescents in the gallbladder or passing through the bile duct were detected in another 15 patients, impaired gallbladder contractility in 16, gallbladder tenderness in 16, and bile duct dilatation in an additional 28 patients. Thirty-two patients with these US abnormalities experienced colic-like abdominal pain accompanied by increased alkaline phosphatase in 25 cases. During day 30-60, abnormalities regressed completely in 45 patients; 2/6 triclabendazole failures were evident by detection of living parasites. Biliary tract abnormalities are frequently observed by US, but the detection-rate of Fasciola hepatica is disappointingly low despite the parasite's relatively large size. US findings must therefore be interpreted together with other clinical measurements. The visualization of parasites being expelled through the dilated common bile duct allowed the causal interpretation of post-therapeutic abdominal pain and increase of liver enzymes. When triclabendazole is given on suspicion, visualization of worm expulsion and bile duct dilatation by US may be used to confirm diagnosis.

Circulating antibodies and antigens correlate with egg counts in human fascioliasis

We explored the relationships between specific IgG antibody levels and circulating E/S antigen to intensity of Fasciola infection in the human host. Twenty patients with patent infection and six healthy individuals were enrolled in the study. Intensity of infection was determined by repeated egg counts in stools, while IgG antibodies against adult Fasciola gigantica somatic FI, FII and against E/S antigens were measured as ELISA O.D. readings. The level of circulating E/S antigens was determined by IELISA. Positivity as well as levels of antibodies and antigen correlated with infection intensity. These findings may disclose in the future a relation between morbidity in the acute phase and worm load.

Experimental hepatobiliary fascioliasis in rabbits: a radiology-pathology correlation

RATIONALE AND OBJECTIVES

The authors sought to correlate the radiologic findings of hepatobiliary fascioliasis with pathologic features.

METHODS

Serial ultrasound, computed tomography (CT), and magnetic resonance findings in seven rabbits with experimentally induced fascioliasis were obtained every other week. Direct cholangiogram was also obtained after the rabbits were killed. Radiology-pathology correlation was done in specimens.

RESULTS

In the parenchymal phase (an acute phase of parenchymal invasion of a larva), CT showed subcapsular clustered areas of low attenuation. Magnetic resonance appearance was similar in shape but better than CT in characterizing the hemorrhagic nature of the lesion. Ultrasound findings were nonspecific in this phase. In the ductal phase (a stationary phase after residing in the bile duct), CT showed dilatation of central ducts with symmetric periportal hypoattenuation (periportal tracking). Magnetic resonance could not depict mild ductal dilatation. Ultrasound was most valuable in demonstrating the moving worm within the dilated duct. Pathologically, the hepatic parenchymal lesions consisted of a cluster of eosinophilic granulomas with hemorrhagic change (migratory tract of the flukes). Ductal changes were observed predominantly in the central bile ducts. Periportal lymphangiectasia was also noted.

CONCLUSIONS

Computed tomography or magnetic resonance can demonstrate the characteristic evolutionary pattern of fascioliasis that reflects the unique life cycle of Fasciola hepatica. The role of ultrasound, although limited in the parenchymal phase, was most useful in the ductal phase in that it demonstrated the moving worms themselves.

Current views on geographic distribution and modes of infection of neurohelminthic diseases

Neurohelminthiases are more prevalent in geographic areas where environmental factors and poor sanitary conditions favor the parasitism between man and animals. In recent years, population shifts and rapid transport have facilitated the spread of certain helminthic diseases from endemic to non-endemic areas. Although many helminthic parasites are known to cause various human diseases afflicting many millions of people in the world, neurohelminthiases are often not diagnosed because they have been unrecognized by clinicians or confirmatory diagnostic tests are not easily available. Paragonimiasis and schistosomiasis (fluke diseases) are endemic in Asia, Africa and Central America; lesions in the central nervous system (CNS) due to ectopic parasitism of the preadult and adult flukes produce various clinical features that often mimic other diseases. In most cestodiasis (tapeworm disease), the adult worm that lodges in the alimentary tract does not involve the CNS; however, the larvae often enter the nervous system by migration or by metastasis via the systemic circulation, where they cause cystic lesions. Cysticercosis is the most common CNS helminthic infection especially in endemic areas where the parasitism between man and pigs is maintained. In other cestodiases, infections to man are often caused by ingestion of food or water contaminated with feces of the definitive hosts (mammals or man). Nematodes (roundworms) generally enter the CNS by ectopic migration of the infective larvae (larva migrans); the routes of infection to man vary with species of the nematodes, and the animal hosts they infest. Angiostrongylus cantonensis is a neurotropic nematode that requires the CNS of mammalian hosts for its growth; the third-stage larvae frequently invade skeletal muscles and the nervous system. Strongyloides, a gastrointestinal nematode, is known to cause CNS involvement in immunosuppressed patients. Recently, some nematodes heretofore unknown to cause human parasitism have been recognized as the causative agents of CNS infections.

Liver and intestinal flukes

A number of trematodes besides schistosomes parasitize humans and domesticated animals. Although they do not have as great a public health impact as schistosomiasis, they are prevalent in Southeast Asia as well as among the greater than 1 million immigrants from this region to North America. The human biliary flukes include C. sinensis, O. viverrini, and O. felineus. These chronic infections are often asymptomatic but over time may cause biliary thickening, cholangitis, and a predisposition to cholangiocarcinoma. Zoonotic trematode infections include the sheep liver fluke F. hepatica and the intestinal flukes Fasciolopsis, Echinostoma, Heterophyes, and Metagonimus.