Human fascioliasis infection: gender differences within school-age children from endemic areas of the Nile Delta, Egypt

Clinical characteristics of human fascioliasis in Egypt

There is a lack of epidemiological data on fascioliasis in Egypt regarding disease characteristics and treatment outcomes across different governorates. We aimed to identify the demographic, epidemiologic, clinical, laboratory, and radiological characteristics and treatment outcomes of patients diagnosed with fascioliasis in Egypt. Data on human fascioliasis were collected retrospectively from patients' medical records in the period between January 2018 and January 2020. The study included 261 patients. More than 40% of enrolled patients were in the age group of 21-40 years old. Geographically, 247 (94.6%) were from Assiut Governorate with 69.3% were from rural areas. The most frequent symptoms were right upper quadrant pain (96.9%), and fever (80.1%). Eosinophilia was found in 250 cases (95.8%). Hepatic focal lesions were detected in 131 (50.2%); out of them 64/131 (48.9%) had a single lesion. All patients received a single dose of 10 mg/kg of triclabendazole, 79.7% responded well to a single dose, while in 20.3% a second ± a third dose of treatment was requested. After therapy, there was a reduction in leucocytes, Fasciola antibodies titer, eosinophilic count, bilirubin, and liver enzymes with an increase in hemoglobin level. According to our findings, a high index of suspicion should be raised in cases with fever, right upper abdominal pain, and peripheral eosinophilia, and further imaging workup is mandated to detect hepatic focal lesions. Prompt treatment by triclabendazole can serve as a standard-of-care regimen even for suspected cases.

The global prevalence of human fascioliasis: a systematic review and meta-analysis

Background

Fascioliasis is a parasitic zoonosis that can infect humans and be a source of significant morbidity. The World Health Organization lists human fascioliasis as a neglected tropical disease, but the worldwide prevalence of fascioliasis data is unknown.

Objective

We aimed to estimate the global prevalence of human fascioliasis.

Data sources and methods

We performed a systematic review and prevalence meta-analysis. We used the following inclusion criteria: articles published in the English, Portuguese, or Spanish languages from December 1985 to October 2022 and studies assessing the prevalence of Fasciola in the general population with an appropriate diagnostic methodology, including longitudinal studies, prospective and retrospective cohorts, case series, and randomized clinical trials (RCTs). We excluded animal studies. Two reviewers independently reviewed the selected studies for methodological quality, performing critical standard measures from JBI SUMARI. A random-effects model was conducted of the summary extracted data on the prevalence proportions. We reported the estimates according to the GATHER statement.

Results

In all, 5617 studies were screened for eligibility. Fifty-five studies from 15 countries were selected, including 154,697 patients and 3987 cases. The meta-analysis revealed a pooled prevalence of 4.5% [95% confidence interval (CI): 3.1-6.1; I² = 99.4%; T² = 0.07]. The prevalence in South America, Africa, and Asia was 9.0%, 4.8%, and 2.0%, respectively. The highest prevalence was found in Bolivia (21%), Peru (11%), and Egypt (6%). Subgroup analysis showed higher prevalence estimates in children, in studies from South America, and when Fas2-enzyme-linked immunosorbent assay (ELISA) was used as a diagnostic method. A larger study sample size (p = 0.027) and an increase in female percentage (p = 0.043) correlated with a decrease in prevalence. Multiple meta-regression showed a higher prevalence for hyperendemic than hypoendemic (p = 0.002) or mesoendemic (p = 0.013) regions.

Conclusion

The estimated prevalence and projected disease burden of human fascioliasis are high. Study findings support that fascioliasis continues to be a globally neglected tropical disease. Strengthening epidemiological surveillance and implementing measures to control and treat fascioliasis is imperative in the most affected areas.

Human fascioliasis in Africa: A systematic review

Fascioliasis is a globally distributed, parasitic zoonosis, caused by Fasciola hepatica and F. gigantica. A comprehensive overview of the epidemiology of human fascioliasis in Africa is missing up to now. Therefore, our objective was to conduct a systematic review aiming to summarize recent knowledge on the distribution, prevalence, and risk factors of human fascioliasis in Africa. A key word search was performed in PubMed, Web of Science and Africa Wide, to gather relevant literature, published between the 1st of January 2000 and 31st of December 2020. A total of 472 records were initially retrieved, with 40 full text articles retained for the qualitative synthesis. Human fascioliasis was reported in 12 African countries, namely Algeria, Angola, Cape Verde, Egypt, Ethiopia, Ghana, Morocco, Nigeria, Senegal, South-Africa, Tanzania and Tunisia. The majority of the studies was conducted in Egypt. A total of 28 records were population surveys. Coproscopy was the most commonly used tool for fascioliasis diagnosis in these surveys. Gender (being female), consumption of raw vegetables/seeds, age, owning livestock, and use of unsafe drinking water sources, were identified as risk factors in 7 studies. Furthermore, 43 case reports were retrieved, described in 12 studies. Eosinophilia was present in 39 of these cases, while 11 had positive coproscopy results. Eight cases described having eaten raw wild vegetables. Overall, the low number and quality of records retrieved indicates that human fascioliasis remains a truly neglected disease in Africa, and more epidemiological studies are urgently needed to both establish the actual distribution as well as risk factors on the continent.

Pathogenicity and virulence of the liver flukes Fasciola hepatica and Fasciola Gigantica that cause the zoonosis Fasciolosis

Fasciolosis caused by the liver flukes Fasciola hepatica and Fasciola gigantica is one of the most important neglected parasitic diseases of humans and animals. The ability of the parasites to infect and multiply in their intermediate snail hosts, and their adaptation to a wide variety of mammalian definitive hosts contribute to their high transmissibility and distribution. Within the mammalian host, the trauma caused by the immature flukes burrowing through the liver parenchyma is associated with most of the pathogenesis. Similarly, the feeding activity and the physical presence of large flukes in the bile ducts can lead to anemia, inflammation, obstruction and cholangitis. The high frequency of non-synonymous polymorphisms found in Fasciola spp. genes allows for adaptation and invasion of a broad range of hosts. This is also facilitated by parasite’s excretory-secretory (ES) molecules that mediate physiological changes that allows their establishment within the host. ES contains cathepsin peptidases that aid parasite invasion by degrading collagen and fibronectin. In the bile ducts, cathepsin-L is critical to hemoglobin digestion during feeding activities. Other molecules (peroxiredoxin, cathepsin-L and Kunitz-type inhibitor) stimulate a strong immune response polarized toward a Treg/Th2 phenotype that favors fluke’s survival. Helminth defense molecule, fatty acid binding proteins, Fasciola-specific glycans and miRNAs modulate host pro-inflammatory responses, while antioxidant scavenger enzymes work in an orchestrated way to deter host oxidant-mediated damage. Combining these strategies Fasciola spp. survive for decades within their mammalian host, where they reproduce and spread to become one of the most widespread zoonotic worm parasites in the world.

Very High Fascioliasis Intensities in Schoolchildren from Nile Delta Governorates, Egypt: The Old World Highest Burdens Found in Lowlands

Quantitative coprological analyses of children were performed in Alexandria and Behera governorates, Egypt, to ascertain whether individual intensities in the Nile Delta lowlands reach high levels as those known in hyperendemic highland areas of Latin America. Analyses focused on subjects presenting intensities higher than 400 eggs per gram of faeces (epg), the high burden cut-off according to WHO classification. A total of 96 children were found to shed between 408 and 2304 epg, with arithmetic and geometric means of 699.5 and 629.07 epg, respectively. Intensities found are the highest hitherto recorded in Egypt, and also in the whole Old World. A total of 38 (39.6%) were males and 58 (60.4%) were females, with high intensities according to gender following a negative binomial distribution. The high burden distribution shows a peak in the 7-10 year-old children group, more precocious in females than males. Results showed high burdens in winter to be remarkably higher than those known in summer. The fascioliasis scenario in Egyptian lowlands shows similarities to highlands of Bolivia and Peru. Diagnostic methods, pathogenicity and morbidity in high burdens should be considered. The need for an appropriate quantitative assessment of heavy infected children to avoid post-treatment colic episodes is highlighted.

DNA Multi-Marker Genotyping and CIAS Morphometric Phenotyping of Fasciola gigantica-Sized Flukes from Ecuador, with an Analysis of the Radix Absence in the New World and the Evolutionary Lymnaeid Snail Vector Filter

Simple Summary

Fasciolid flukes collected from sheep and cattle in Ecuador showed a high diversity in DNA sequences whose analyses indicated introductions from South America, European and North American countries. These results agree with the numerous livestock importations performed by Ecuador. Abnormally big-sized liver flukes were found in Ecuadorian sheep. The morphometric phenotypic CIAS study showed that its size maximum and mean very pronouncedly and significantly surpassed those of the Fasciola hepatica populations from South America and Spain and proved to be intermediate between standard F. hepatica and F. gigantica populations. Such a feature is only known in intermediate fasciolid forms in Old World areas where the two species and their specific lymnaeid snail vectors overlap. This argues about a past hybridization after F. gigantica importation from Pakistan and/or introduction of intermediate hybrids previously generated in USA. The lack of heterozygotic rDNA ITS positions differentiating the two species, and of introgressed fragments and heteroplasmic positions in mtDNA genes, indicate a post-hybridization period sufficiently long as for rDNA concerted evolution to complete homogenization and mtDNA to return to homoplasmy. The vector specificity filter due to Radix absence should act as a driving force in accelerating such lineage evolution. Public health implications are finally emphasized.

Abstract

Fascioliasis is a disease caused by Fasciola hepatica worldwide transmitted by lymnaeid snails mainly of the Galba/Fossaria group and F. gigantica restricted to parts of Africa and Asia and transmitted by Radix lymnaeids. Concern has recently risen regarding the high pathogenicity and human infection capacity of F. gigantica. Abnormally big-sized fasciolids were found infecting sheep in Ecuador, the only South American country where F. gigantica has been reported. Their phenotypic comparison with F. hepatica infecting sheep from Peru, Bolivia and Spain, and F. gigantica from Egypt and Vietnam demonstrated the Ecuadorian fasciolids to have size-linked parameters of F. gigantica. Genotyping of these big-sized fasciolids by rDNA ITS-2 and ITS-1 and mtDNA cox1 and nad1 and their comparison with other countries proved the big-sized fasciolids to belong to F. hepatica. Neither heterozygotic ITS position differentiated the two species, and no introgressed fragments and heteroplasmic positions in mtDNA were found. The haplotype diversity indicates introductions mainly from other South American countries, Europe and North America. Big-sized fasciolids from Ecuador and USA are considered to be consequences of F.gigantica introductions by past livestock importations. The vector specificity filter due to Radix absence should act as driving force in the evolution in such lineages.

Sex-Biased Prevalence of Intestinal Parasitic Infections and Gender Inequality in Rural Nepal

OBJECTIVES

Intestinal parasitic infections (IPIs) are related to poverty and socioeconomic disparities. In rural Nepal, IPIs are highly endemic and gender inequality is still deeply rooted. This study provides a novel epidemiological assessment of IPIs in Nepal, juxtaposing spatial, age and sex stratification of prevalence.

METHODS

A PRISMA and PICO-based systematic review of peer-reviewed and grey literature provided IPI prevalence data for the Nepalese population. Demographic and environmental variables were considered to investigate differences related to dwelling area and sex. Variations among prevalence rates were calculated with 95% CI and significance level for odds ratio evaluated with chi-square test.

RESULTS

The IPI prevalence rate for the Nepalese general population was 37.6%. Moreover, IPI prevalence (52.3%) was significantly higher in rural areas than in urban areas (32.4%), and school-age girls (55.2%) were more infected than boys (48.6%).

CONCLUSIONS

The IPI infection rate appeared to be enhanced among young women living in rural Nepal, where they experienced low school attendance and heavy enrolment in agricultural work, as result of gender discrimination. Plausibly, these dynamics affect both girls' environmental exposure and fruition of periodic school-based preventive chemotherapy, thus increasing the chances of IPI 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.

Towards the comprehension of fasciolosis (re-)emergence: an integrative overview

The increasing distribution and prevalence of fasciolosis in both human and livestock are concerning. Here, we examine the various types of factors influencing fasciolosis transmission and burden and the interrelations that may exist between them. We present the arsenal of molecules, 'adjusting' capabilities and parasitic strategies of Fasciola to infect. Such features define the high adaptability of Fasciola species for parasitism that facilitate their transmission. We discuss current environmental perturbations (increase of livestock and land use, climate change, introduction of alien species and biodiversity loss) in relation to fasciolosis dynamics. As Fasciola infection is directly and ultimately linked to livestock management, living conditions and cultural habits, which are also changing under the pressure of globalization and climate change, the social component of transmission is also discussed. Lastly, we examine the implication of increasing scientific and political awareness in highlighting the current circulation of fasciolosis and boosting epidemiological surveys and novel diagnostic techniques. From a joint perspective, it becomes clear that factors weight differently at each place and moment, depending on the biological, environmental, social and political interrelating contexts. Therefore, the analyses of a disease as complex as fasciolosis should be as integrative as possible to dissect the realities featuring each epidemiological scenario. Such a comprehensive appraisal is presented in this review and constitutes its main asset to serve as a fresh integrative understanding of fasciolosis.

Human Fascioliasis: Current Epidemiological Status and Strategies for Diagnosis, Treatment, and Control

Purpose of the Review

This review aims to critically assess current knowledge about the epidemiology, diagnosis, and management of Fasciola infection in humans.

Recent Findings

Fascioliasis is an emerging neglected zoonotic infection affecting the health and wellbeing of human populations. The burden of infection is unclear, and studies have shown the geographic expansion of fascioliasis in human and livestock likely related to climate change. The infection can be asymptomatic or present in acute or chronic forms. Regardless of the presentation, fascioliasis can be associated with long-term complications such as anemia and malnutrition. Early in the infection, antibody testing is the only tool available for diagnosis confirmation. In the chronic forms serology and stool microscopy are helpful. Other tests such as antigen detection and PCR-based methods including isothermal tests have shown promising results. Triclabendazole is the only drug available to treat Fasciola infection. However, reports of resistant infections in livestock and human threaten the clinical care and control of the infection in endemic areas.

Summary

Fascioliasis is an emerging infection around the world with an uncertain burden. Lack of standardization of diagnostic testing and treatment alternatives hinder treatment and control of the infection.

Genetically 'pure' Fasciola gigantica discovered in Algeria: DNA multimarker characterization, trans-Saharan introduction from a Sahel origin and spreading risk into north-western Maghreb countries

Fascioliasis is a freshwater snail-borne zoonotic helminth disease caused by two species of trematodes: Fasciola hepatica of almost worldwide distribution and the more pathogenic F. gigantica restricted to parts of Asia and most of Africa. Of high pathological impact in ruminants, it underlies large livestock husbandry losses. Fascioliasis is moreover of high public health importance and accordingly included within the main neglected tropical diseases by WHO. Additionally, this is an emerging disease due to influences of climate and global changes. In Africa, F. gigantica is distributed throughout almost the whole continent except in the north-western Maghreb countries of Morocco, Algeria and Tunisia where only F. hepatica is present. The present study concerns the DNA multimarker characterization of the first finding of F. gigantica in sheep in Algeria by the complete sequences of rDNA ITS-1 and ITS-2 and mtDNA cox1 and nad1 genes. Sequence comparisons and network analyses show sequence identities and similarities suggesting a south-north trans-Saharan geographical origin, with introduction from Ghana, through the Sahel countries of Burkina Faso and Mali into Algeria. This way perfectly fits with nomadic pastoralism according to interconnecting intranational and transborder herd transhumance routes traditionally followed in this western part of Africa from very long ago. The risk for further spread throughout the three north-western Maghreb countries is multidisciplinarily analysed, mainly considering the present extensive motorization of the intranational transhumance system in Algeria, the lymnaeid snail vector species present throughout the north-western Maghreb, the increasing demand for animal products in the growing cities of northern Algeria and the continued human infection reports. Control measures should assure making anti-fasciolid drugs available and affordable for herders from the beginning and along their transhumant routes and include diffusion and rules within the regional regulatory framework about the need for herd treatments.

Ectopic Human Fasciola hepatica Infection by an Adult Worm in the Mesocolon

We report here an ectopic case of Fasciola hepatica infection confirmed by recovery of an adult worm in the mesocolon. A 56-year-old female was admitted to our hospital with discomfort and pain in the left lower quadrant of the abdomen. Abdominal CT showed 3 abscesses in the left upper quadrant, mesentery, and pelvic cavity. On surgical exploration, abscess pockets were found in the mesocolon of the sigmoid colon and transverse colon. A leaf-like worm found in the abscess pocket of the mesocolon of the left colon was diagnosed as an adult fluke of F. hepatica. Histologically, numerous eggs of F. hepatica were noted with acute and chronic granulomatous inflammations in the subserosa and pericolic adipose tissues. Conclusively, a rare case of ectopic fascioliasis has been confirmed in this study by the adult worm recovery of F. hepatica in the mesocolon.

Diagnosis of human fascioliasis in Arusha region, northern Tanzania by microscopy and clinical manifestations in patients

Background

Human fascioliasis (HF) is a zoonotic disease that has been identified in many countries worldwide. This report concerns the identification and clinical management of cases of human fascioliasis in the suburbs of Arusha city, northern Tanzania in 2013. Fascioliasis is included among the WHO’s Neglected Tropical Diseases as a plant transmitted trematode infection. Human fascioliasis has not been described before in the East Africa region, including Tanzania.

Methods

Patients presenting at a primary healthcare centre in Arusha Region, northern Tanzania provided fresh stool samples for routine ova and parasite screening (saline and iodine preparations). Subsequent stool samples were preserved in 5 % formalin in saline and subjected to ether sedimentation for examination.

Results

Out of 1460 patients, 305 (21 %) were diagnosed positive for fascioliasis based on the demonstration of brownish, oval eggs with inconspicuous opercula in stool. Two distinct egg sizes were identified; large 170–212.5 by 115–150 μm (mean 194.5 by 130.5 μm) and smaller eggs 120–150 by 87.5 – 112.5 μm (mean 138.8 by 101 μm). Clinically, patients presented with fever (39 - 40 °C) and abdominal pain. Some patients had pruritis around the mouth and their lips were swollen. 3 patients were treated and cured with single dose Triclabendazole. The remaining 302 patients were treated with Nitazoxanide and 122 (40 %) were cleared of infection with a single course. Snails of the genus Lymnaea were found in the surroundings.

Conclusions

This report serves to remind medical professionals in East Africa that HF is a probable differential diagnosis in patients presenting with similar symptoms. It is possible to diagnose fascioliasis by light microscopy although specific antigen tests are required for confirmation. Human fascioliasis however, has not been described or reported in Tanzania before and begs further investigation.

Fascioliasis: An Ongoing Zoonotic Trematode Infection

Zoonotic trematode infections are an area of the neglected tropical diseases that have become of major interest to global and public health due to their associated morbidity. Human fascioliasis is a trematode zoonosis of interest in public health. It affects approximately 50 million people worldwide and over 180 million are at risk of infection in both developed and underdeveloped countries. The one health paradigm is an area that seeks to address the problem of zoonotic infections through a comprehensive and sustainable approach. This review attempts to address the major challenges in managing human and animal fascioliasis with valuable insights gained from the one health paradigm to global health and multidisciplinary integration.

Diagnosis of human fascioliasis by stool and blood techniques: update for the present global scenario

Before the 1990s, human fascioliasis diagnosis focused on individual patients in hospitals or health centres. Case reports were mainly from developed countries and usually concerned isolated human infection in animal endemic areas. From the mid-1990s onwards, due to the progressive description of human endemic areas and human infection reports in developing countries, but also new knowledge on clinical manifestations and pathology, new situations, hitherto neglected, entered in the global scenario. Human fascioliasis has proved to be pronouncedly more heterogeneous than previously thought, including different transmission patterns and epidemiological situations. Stool and blood techniques, the main tools for diagnosis in humans, have been improved for both patient and survey diagnosis. Present availabilities for human diagnosis are reviewed focusing on advantages and weaknesses, sample management, egg differentiation, qualitative and quantitative diagnosis, antibody and antigen detection, post-treatment monitoring and post-control surveillance. Main conclusions refer to the pronounced difficulties of diagnosing fascioliasis in humans given the different infection phases and parasite migration capacities, clinical heterogeneity, immunological complexity, different epidemiological situations and transmission patterns, the lack of a diagnostic technique covering all needs and situations, and the advisability for a combined use of different techniques, at least including a stool technique and a blood technique.

Epidemiology of human fascioliasis and intestinal parasitosis among schoolchildren in Lake Tana Basin, northwest Ethiopia

BACKGROUND

Parasitic diseases are the second most frequent cause of outpatient morbidity in Ethiopia.

METHODS

A cross-sectional study was conducted in Lake Tana Basin, northwest Ethiopia, from November 2007 to February 2008, to assess the magnitude and associated risk factors for parasitic diseases, including human fascioliasis. We examined 520 stool samples from randomly selected schoolchildren in six schools by microscopy. Rapid sedimentation and Kato-Katz techniques were used to detect and count Fasciola and Schistosoma eggs. The formol-ether concentration method was used for the identification of other helminth eggs, larvae and cysts of protozoan parasites.

RESULTS

The overall prevalence of intestinal parasitic infections was 71.3% (95% CI 67.3-75.1%). Hookworm was the predominant intestinal parasite (23.5%, 95% CI 19.8-27.1%), followed by Ascaris lumbricoides (18.5%, 95% CI 15.2-21.9%) and Schistosoma mansoni (16.7%, 95% CI 13.5-19.9%). One hundred and sixty-three (31.4%) children had multiple parasitic infections. The most relevant finding was a prevalence of Fasciola spp. of 3.3% in an area where only sporadic cases have been reported previously. The risk of Fasciola spp. infection was significantly associated with raw vegetable consumption, use of unsafe drinking water sources, irrigation practices and sheep and/or cattle ownership. Irrigation practices, male gender, raw vegetable consumption and use of unsafe drinking water sources were risk factors for S. mansoni infection.

CONCLUSIONS

A high prevalence of parasitic infections among children in the region was found, including a relatively high prevalence of Fasciola spp. infection. Epidemiological studies on the magnitude of parasitic infections in different regions will enable high-risk communities to be identified and allow for planning of appropriate interventions.

New developments in epidemiology, diagnosis, and treatment of fascioliasis

PURPOSE OF REVIEW

This review focuses on the recent developments in the epidemiology, burden of disease, diagnostic tests, and treatment of fascioliasis.

RECENT FINDINGS

Recent epidemiologic data suggest that either the endemic areas are expanding or disease is being recognized in areas where it was not previously observed. In addition, recent data highlight the effects of fascioliasis on childhood anemia and nutrition. Diagnosis remains problematic, but newer diagnostic tests including antibody, antigen, and DNA detection tests may facilitate earlier diagnosis. Recent studies suggest that point-of-care testing may soon be possible. Treatment with triclabendazole is effective, but resistance is emerging in livestock and may pose a threat for patients.

SUMMARY

Fascioliasis continues to emerge as an important neglected disease, with new studies highlighting the under-recognized burden of disease. Further studies are needed on burden of disease, improved diagnosis, and alternative to triclabendazole treatment.

Experimental murine fascioliasis derives early immune suppression with increased levels of TGF-β and IL-4

In fascioliasis, T-helper 2 (Th2) responses predominate, while little is known regarding early immune phenomenon. We herein analyzed early immunophenotype changes of BALB/c, C57BL/6, and C3H/He mice experimentally infected with 5 Fasciola hepatica metacercariae. A remarkable expansion of CD19(+) B cells was observed as early as week 1 post-infection while CD4(+)/CD8(+) T cells were down-regulated. Accumulation of Mac1(+) cells with time after infection correlated well with splenomegaly of all mice strains tested. The expression of tumor necrosis factor (TNF)-α mRNA in splenocytes significantly decreased while that of IL-4 up-regulated. IL-1β expression was down-modulated in BALB/c and C57BL/6 mice, but not in C3H/He. Serum levels of transforming growth factor (TGF)-β were considerably elevated in all mice during 3 weeks of infection period. These collective results suggest that experimental murine fascioliasis might derive immune suppression with elevated levels of TGF-β and IL-4 during the early stages of infection.

Coinfection of Schistosoma (Trematoda) with bacteria, protozoa and helminths

This review examines coinfection of selected species of Schistosoma with bacteria, protozoa and helminths and focuses on the effects of the coinfection on the hosts. The review is based mainly on tables that contain the salient information on the coinfecting organisms in vertebrate hosts. Further explanation and clarification of the tables are given in the text. A table is also provided that gives synoptic information on the 37 species in the 19 genera considered in this review. Coinfection studies with Schistosoma species and the other organisms were considered in six tables plus the accompanying text. Considerations of the Schistosoma interactions with another species of organism include studies on coinfection with Plasmodium, with protozoa other than Plasmodium; with Salmonella, with bacteria other than Salmonella; and with Fasciola, with helminths other than Fasciola. Numerous factors were found to influence the effects of coinfection on the vertebrate host, including organisms and hosts used in the studies, order and time interval between the first and the second infection, studies on natural versus experimental hosts, dosage of the infectious agents, strains and pedigrees of the parasites, age of hosts at time of exposure to the infectious agents and age of hosts at the time of necropsy. Overall, a prior infection with Schistosoma, particularly a patent infection, often has an effect on the subsequent infection by a protozoan, bacterium or other helminth. In relatively few cases, a prior infection with Schistosoma decreased the severity of the subsequent infection as with Helicobacter pylori, Fasciola hepatica, Echinostoma or Plasmodium, the latter only exhibiting this behaviour when coinfected with Schistosoma haematobium. More often, however, a prior infection with Schistosoma increased the severity of the second infection as with Leishmania, Toxoplasma gondii, Entamoeba histolytica, Staphylococcus aureus or Salmonella. In some of these coinfection studies, the increased severity of the subsequent infection was associated with a specific, prolonged form of the disease in humans, which has implications for patient treatment and recovery. Additional research is needed, particularly on Schistosoma coinfections which currently have a small body of research and are current problems in human populations. Examples of such Schistosoma interactions include the genera of Mycobacteria, Leishmania, Staphylococcus, Necator and Strongyloides. Hopefully, future studies will elucidate valuable new information on the interesting subject of coinfection of Schistosoma with other organisms.

Fluke egg characteristics for the diagnosis of human and animal fascioliasis by Fasciola hepatica and F. gigantica

In trematodiases, shape and size of the fluke eggs shed with faeces are crucial diagnostic features because of their typically reduced intraspecific variability. In fascioliasis, the usual diagnosis during the biliary stage of infection is based on the classification of eggs found in stools, duodenal contents or bile. The aim of the present study is to validate the identification of Fasciola species based on the shape and size of eggs shed by humans, characterizing their morphometric traits using a computer image analysis system (CIAS). The influence of both the geographical location and of the host (human and livestock) has been analysed. Coprological studies were carried out in fascioliasis human endemic areas, where only F. hepatica is present (the northern Bolivian Altiplano and the Cajamarca valley in Peru), and where F. hepatica and F. gigantica coexist (the Kutaisi region of Georgia, the Nile Delta in Egypt, and the Quy Nhon province in Vietnam). Classically, it is considered that at the abopercular end of the shell of Fasciola eggs there is often a roughened or irregular area. Nevertheless, results show that the frequency of the presence of this feature in F. hepatica is population-dependent, and therefore is not a pathognomonic criterion in diagnosis. The study reveals that eggs shed by humans show morphological traits different from eggs shed by animals. In humans, F. hepatica eggs are bigger and F. gigantica eggs are smaller than reported to date from livestock, and their measurements overlap when compared. The material analysed in this study shows that the size of eggs shed by humans from Georgia and Egypt corresponds to the F. hepatica morph, while the size of eggs shed by humans from Vietnam corresponds to the F. gigantica morph. Measurements of F. hepatica and F. gigantica eggs originating from humans and animals from sympatric areas overlap, and, therefore, they do not allow differential diagnosis when within this overlapping range. In this sense, the new results should aid clinicians since the application of the classic egg size range in human samples may lead to erroneous conclusions. Fasciolid egg size in human stool samples ought to be corrected in books and monographs related to medical parasitology and/or tropical medicine as well as in guides for clinicians and parasitic disease diagnosis analysts.

Anaemia in advanced chronic fasciolosis

The association between fasciolosis-induced anaemia and related factors has been quantified in a rodent model. Haematological parameters were analysed in Wistar rats at 20 and 60 weeks post-infection (p.i.). Pigment stones and bile specimens were collected. Serum IgG1, IgG2a and IgE were determined in rat serum samples. Cytokine levels have been correlated with haematological parameters. The screening for gastrointestinal bleeding was carried out. Bacteriological bile cultures revealed viable bacteria in 53.8% of specimens at 60 weeks p.i. The results show that the type of anaemia in fasciolosis might be considered a biomarker of the chronicity period of the disease, changing from normocytic to macrocytic in the early chronic period (20 weeks p.i.) and to microcytic in the advanced chronic period (60 weeks p.i.). Likewise, changing from normochromic in the early chronic period to hypochromic in the advanced chronic period. Multivariate analysis suggested an association between anaemia and the following factors: fluke burden, eggs per gram of faeces, body area of parasite, presence of blood in faeces, IgG1 and eosinophil levels, and % of splenic weight. Of all variables analysed, the fluke burden is the one which presents the highest anaemia risk, even exceeding the variable presence of blood in faeces. The development of anaemia appears to be complex and may involve multiple mechanisms. However, to the mechanisms that until now explain Fascioliosis-related anaemia (compensatory increase in erythrocyte production and a continuous drain on iron stores resulting from the parasites' blood-sucking activities) the following causes ought to be added: haemolysis of red blood cells, the general effects of inflammation on erythropoiesis, concomitant parasitic and bacterial infections and pre-morbid nutritional abnormalities. Extrapolation to human fasciolosis is discussed. The results of the rodent model lead to the assumption that a high risk of anaemia in subjects with a heavy parasitic burden in human hyperendemic areas of fasciolosis is to be expected.