Studies on the prevalence and laboratory transmission of fascioliasis in animals in the Kashmir Valley

Human and Animal Fascioliasis: Origins and Worldwide Evolving Scenario

Fascioliasis is a plant- and waterborne zoonotic parasitic disease caused by two trematode species: (i) Fasciola hepatica in Europe, Asia, Africa, the Americas, and Oceania and (ii) F. gigantica, which is restricted to Africa and Asia. Fasciolid liver flukes infect mainly herbivores as ruminants, equids, and camelids but also omnivore mammals as humans and swine and are transmitted by freshwater Lymnaeidae snail vectors. Two phases may be distinguished in fasciolid evolution. The long predomestication period includes the F. gigantica origin in east-southern Africa around the mid-Miocene, the F. hepatica origin in the Near-Middle East of Asia around the latest Miocene to Early Pliocene, and their subsequent local spread. The short postdomestication period includes the worldwide spread by human-guided movements of animals in the last 12,000 years and the more recent transoceanic anthropogenic introductions of F. hepatica into the Americas and Oceania and of F. gigantica into several large islands of the Pacific with ships transporting livestock in the last 500 years. The routes and chronology of the spreading waves followed by both fasciolids into the five continents are redefined on the basis of recently generated knowledge of human-guided movements of domesticated hosts. No local, zonal, or regional situation showing disagreement with historical records was found, although in a few world zones the available knowledge is still insufficient. The anthropogenically accelerated evolution of fasciolids allows us to call them "peridomestic endoparasites." The multidisciplinary implications for crucial aspects of the disease should therefore lead the present baseline update to be taken into account in future research studies.

Effect of primary and secondary Fasciola gigantica infection on specific IgG responses, hepatic enzyme levels and weight gain in buffaloes

Buffaloes, as highly susceptible definitive hosts of Fasciola gigantica, suffer from a high infection rate of fasciolosis, which causes enormous economic losses. Repeat infection is responsible for this high rate; thus, elucidating the protective immunity mechanism in repeat infection is decisive in fasciolosis prevention. Herein, a secondary experimental infection model was established to preliminarily reveal the protective immunity that occurs in repeat infection. In brief, animals were assigned to three groups: group A (uninfected control), group B (primary infection) and group C (secondary infection). Buffaloes were autopsied 20 weeks post-infection for measurements of the recovered flukes and hepatic examination. In addition, the detection of specific antibody (IgG) responses to F. gigantica excretory-secretory product (FgESP) throughout the whole period and weight gain throughout the first 4 months as a percentage (%) of the starting weight were also determined. The serum hepatic enzyme gamma glutathione transferase (GGT) levels were monitored to assess hepatic damage throughout the study period. Infection establishment was compared between group B and group C. Similar specific IgG patterns were observed between group B and group C, and hepatic damage was more severe in group C than group B. Significant differences in weight gain as a percentage of the start weight were observed between group A and group B at the 3rd and 4th months postprimary infection, while significant differences were not observed between group A and group C or group B and group C. Our results suggest that challenge infection cannot induce resistance against F. gigantica in buffaloes, which is consistent with the protective immunity against Fasciola hepatica reinfection observed in sheep and goats.

Buffalo Infection by Fasciola gigantica Transmitted by Radix acuminata in Uttar Pradesh, India: A Molecular Tool to Improve Snail Vector Epidemiology Assessments and Control Surveillance

PURPOSE

Fascioliasis is caused by Fasciola species transmitted by freshwater Lymnaeidae snails and infecting herbivorous mammals and humans worldwide. In southern Asia, fascioliasis is a problem in livestock from the Near East to Bangladesh, where recent human infection reports are worrying. In this region, Fasciola gigantica is transmitted by species of the Radix auricularia superspecies group. In the densely populated northern Indian state of Uttar Pradesh, livestock appears infected throughout. The economic importance of buffaloes highlights the need to control their very high infection rates.

METHODS

In the Gorakhpur area, a molecular method based on the two specific primer sets of genomic DNA was applied to fasciolids from buffaloes slaughtered in local abattoirs and cercariae from R. acuminata snails from freshwater collections.

RESULTS

PCR products and sequences demonstrated that the cercariae belonged to F. gigantica and that R. acuminata acts as vector for its transmission to buffaloes. The 72.0% rate found in one transmission focus appears to be the highest worldwide record of fasciolid infection in a lymnaeid population. Lymnaeid prevalences and burdens found close to human communities indicate a very high infection risk.

CONCLUSION

This method is simple, fast and cheap because there is no need for sequencing, it differentiates between fasciolid species and between fasciolids and other trematodes infecting R. acuminata, facilitates epidemiological surveys, and is useful for surveillance to evaluate the efficiency of control measures. Within climate change predictions, future increases of rain events and floods suggest the need for control and surveillance efforts in this endemic area.

Fasciolosis in India: An overview

Fasciolosis in ruminants is a relentless constraint in the livestock industry across the world. Immuno-prophylactic vaccines against fasciolosis may not come up in near future, rendering the control of this scourge with chemotherapy and snail population control. With the alarming threats of anti-fasciolid drug resistance reported from certain parts of the world; the control of fasciolosis should be directed towards the development of rapid and reliable diagnostic tools to execute the specific and discrete treatment. Understanding the epidemiology of Fasciola, its genomics and proteomics, host-parasite interplay, and advances in drug design research is vital for improving animal health that would ultimately succour to meet the ever-increasing demand for food. Due to possible differences in immune response depending on the species of the host and parasite, immuno-prophylactic studies in India should aim at achieving protective efficacy in buffalo against F. gigantica as workers from other countries concentrate primarily on vaccination of cattle and sheep against F. hepatica. This manuscript focused on the research that has been carried out in India for understanding the epidemiology, genetic diversity, immuno-diagnosis, and possible control measure in terms of immuno-prophylaxis and drug designing against tropical fasciolosis caused by Fasciola gigantica.

Human Fascioliasis: Report of Two Cases from Kashmir Valley

Although few case reports of human fascioliasis have been reported from different parts of India, there is no case reported from the Kashmir valley to date. Herein we report two cases of human fascioliasis. Both patients presented with fever, marked eosinophilia, and liver lesions on imaging. Hepatobiliary imaging showed vague features like mild biliary dilatation and liver lesions representing burrows. A liver biopsy in one of the patients revealed eosinophilic granuloma. Both patients were diagnosed definitively with endoscopic retrograde cholangiopancreatography (ERCP) by demonstrating live adult fasciola worms. Any patient presenting with fever, marked eosinophilia, and liver lesions on imaging should be evaluated for fascioliasis.

Serodiagnosis of Fasciola gigantica Infection in Buffaloes with Native Cathepsin-L Proteases and Recombinant Cathepsin L1-D

AIM

Serodiagnosis of Fasciola gigantica natural infection in buffaloes with recombinant cathepsin L1-D and native cathepsin-L protease antigens.

METHODS

The recombinant cat L1-D antigen was expressed in prokaryotic expression system and native cathepsin-L proteases were purified by alcoholic fractionation from adult F. gigantica flukes. Buffaloes (n  = 325) were screened for anti-Fasciola antibodies with the above antigens in immunoglobulin-G-enzyme linked immunosorbent assay (IgG-ELISA).

RESULTS

The recombinant cat L1-D antigen showed positive reactivity with 101/122 necropsy positive animals but 21/122 necropsy confirmed positive animals were negative in this ELISA (sensitivity 82.8%). However, 30/203 (14.8%) necropsy negative animals for Fasciola were seropositive with specificity of 85.2%. With native cat-L protease, 104/122 necropsy confirmed positive animals were ELISA positive but 18/122 necropsy positive animals were seronegative, thereby depicting the sensitivity of 85.2%. But ELISA with this antigen showed 27/203 (13.3%) necropsy negative animals as positive (specificity 86.7%).

CONCLUSIONS

Comparative evaluation of both the antigens showed that they are suitable for serodiagnosis of F. gigantica infection in buffalo herds.

Molecular Characterization and Immunodiagnostic Potential of Various Antigenic Proteins of Fasciola Gigantica Species Isolated from Sheep of North West Himalayan Region

The control of the digenetic trematode Fasciola gigantica has been the major challenge in both cattle and small ruminants as there is a paucity of an effective and commercial vaccine. Thus, the accurate identification and prepatent diagnosis of F. gigantica is an essential prerequisite for its successful prevention and control. In the present study, the morphologically identified specimens isolated from the liver and bile ducts of sheep (Ovis aries) were validated through molecular data. The sequence analysis of ITS2 of our isolates showed high degree of similarity with F. gigantica and F. hepatica using BLAST function of NCBI. The phylogenetic analysis of our isolates showed a close relationship with previously described F. gigantica and F. hepatica isolates from different countries. The antigenic profile of somatic and E/S antigens of F. gigantica were revealed by SDS-PAGE and immunoblotting using sera from sheep naturally infected with F. gigantica. By SDS-PAGE, 20 distinct bands were revealed from crude somatic fraction. Immunoblotting analysis of these proteins with positive sera exhibited 8 sero-reactive bands ranging from 14 to 97 kDa. Among these 38 and 44 kDa bands were quite specific with high diagnostic specificity and sensitivity. The E/S fraction comprised 7 distinct bands, as revealed by SDS-PAGE analysis. Immunoblotting analysis of these proteins with positive sera exhibited 6 antigenic bands ranging from 23 - 54 kDa. Among these 27 and 33 kDa were found to be quite specific with high diagnostic specificity and sensitivity. The present study concludes that the protein bands of 38 and 44 kDa in somatic fraction and 27 and 33 kDa in E/S fraction can be used for the immunodiagnostic purpose for this economically important parasite, which may also entice further studies regarding their vaccine potential.

Prevalence of GI helminths of cattle in low lying and marshy areas of Kashmir valley

The study was conducted to find out the prevalence of gastrointestinal (GI) helminths in cattle of low lying and marshy areas of Kashmir valley over a period of one year. The qualitative faecal examination of 885 samples revealed an overall prevalence of GI helminths to the tune of 37.06% comprising 7.80% trematodes, 4.29% cestodes and 31.98% nematodes. Prevalence of paramphistomes (7.34%) was more than that of Fasciola spp (0.45%). Among cestodes, the only genus reported was Moniezia spp (4.29%). In nematodes, maximum prevalence was observed for strongyle worms (31.19%) followed by Strongyloides spp. (1.24%) and Trichuris spp (0.57%). Seasonal variation of GI helminths revealed significantly highest prevalence in autumn (50%) followed by spring (41.62%), summer (33.99%) and winter (25.50%). Overall prevalence of GI helminths was significantly higher in young cattle (64.62%) than adults (32.32%). Significantly higher prevalence of GI helminths was observed in males (50.53%) as compared to females (35.44%). Mean intensity of GI nematodes ranged from 0 to 350 with an average of 177.41±28.25 eggs per gram (EPG). Significantly highest mean intensity of GI nematodes was found in summer (173.61±46.70) followed by spring (148.88±56.70), autumn (113±11.34) and winter (95.83±33.24). Mean EPG in young cattle (192.71±27.20) was significantly higher than that of adults (162.11±29.30). Sex had non-significant influence on intensity of GI nematodes. On the basis of above study, it can be concluded that the prophylactic dosing of cattle against trematodes should be done during late autumn and late winter or early spring. Similarly prophylactic de-worming of animals in mid-autumn, mid-spring and mid-summer shall be useful in preventing production losses. However, it will be better to use broad spectrum drug which is effective against trematodes, cestodes as well as nematodes to avoid frequent dosing.

Prevalence of liver flukes infections and hydatidosis in slaughtered sheep and goats in Nishapour, Khorasan Razavi, Iran

Background:

Food-borne trematode infections and hydatidosis are endemic diseases caused by helminths in Iran that are responsible for great economic loss and getting public health at risk.

Aim:

Aim of this study was to determine the prevalence of fasciolosis, dicrocoeliasis, and hydatidosis infections in slaughtered sheep and goats in Nishapour, Khorasan Razavi province of Iran.

Materials and Methods:

A survey was implemented on 130,107 sheep and goats slaughtered at an abattoir in Nishapour (Neyshbur) city, north central Khorasan Razavi Province, Iran, to determine the prevalence of fascioliasis, dicrocoeliosis and presence of hydatidosis.

Results:

During a 1-year period of study, among 130,107 of sheep and goats slaughtered at Nishapour abattoir, 1064 and 7124 livers were condemned totally and partially, respectively. A total of 255 (0.19%), 181 (0.12 %), and 7751 (5.95%) of livers were condemned due to cysts of Echinococcus granulosus, flukes of Fasciola spp., and Dicrocoelium dendriticum, respectively. Totally, 1932 (1.48%) lungs were condemned due to hydatidosis. The significant seasonal pattern was seen for fasciolosis, dicrocoeliosis, and hydatidosis, statistically (p<0.01).

Conclusion:

According to this study, it seems that Neyshabour is considered as an endemic region for Fasciola spp. and D. dendriticum infections and D. dendriticum is the most widespread liver fluke found in sheep and goats.

A reducing trend of fasciolosis in slaughtered animals based on abattoir data in South of Iran

AIM

Fascioliasis is a zoonosis infection caused by the liver trematodes (Fasciola spp.) which have been considered to be an important disease in livestock. After several large outbreaks, fascioliasis remains one of the serious health concerns of Iran. This study was conducted to evaluate the prevalence and possible trends of fascioliasis in slaughtered animals in South of Iran based on abattoir data during a period of 5 years.

MATERIALS AND METHODS

The daily records for cattle, sheep, and goats slaughtered in the abattoir were extracted from the archived documents of the recent 5 years (2011-2015) and used as the source of data. The collected data were statistically analyzed for finding any probable correlation between the various factors associated with fasciolosis.

RESULTS

Our results showed that 3.44% of all slaughtered animals during 2011-2015 were infected with Fasciola spp. The mean prevalence of fasciolosis for cattle, sheep, and goat was 11.15%, 5.22%, and 2.15%, respectively. In addition, the highest infection rate was in winter (4.02%), and the lowest were entered in summer (2.86%).

CONCLUSION

Our findings showed a reducing trend during the 5 years. Improving the animal husbandry and increasing the awareness through fasciolosis may be a logical explanation for this trend. Since there have been suggested numerous factors associated with the epidemiology of fasciolosis, further studies seem essential for better clarifying the various aspects of fasciolosis in areas.

Prevalence of caprine GI helminths in temperate areas of Jammu & Kashmir

Prevalence study on GastroIntestinal (GI) helminths of goats was carried out at Govt. Farms of twin districts of Bandipora and Ganderbal and locally reared goats of district Baramulla of the Kashmir Valley over a period of one year from December 2011 to November 2012. A total of 1016 faecal samples were examined which revealed overall prevalence of GI helminths to be 74.70%, with platyhelminths and nemathelminths in 14.76 and 70.07% animals, respectively. The helminths recorded in the present study were Fasciola spp. (2.75%), Dicrocoelium spp. (3.44%), paramphistomes (3.05%), Moniezia spp. (9.44%), strongyle worms including Nematodirus spp. (68.30%), Strongyloides spp. (5.90%) and Trichuris spp. (4.29%). On coprocultural examination Haemonchus spp. (71.05%) was found to be the most predominant strongyle worm followed by Trichostrongylus spp. (12.86%), Chabertia spp. (8.47%) and Ostertagia spp. (7.62%). Seasonal prevalence of GI helminths was observed highest in summer (78.03%) followed by spring (75.39%), winter (74.90%) and autumn (70.47%), the difference being statistically non-significant (P > 0.05). The prevalence of platyhelminths was found to be non-significantly higher in winter (20.00%) followed by spring (15.07%), summer (12.54%) and autumn (11.41%). Nemathelminths were recorded highest in summer (75.68%) followed by spring (71.82%), autumn (68.50%) and winter (64.31%). EPG ranged from 0 to 1500 and an average EPG count was found to be 312.7 ± 17.76. EPG was found to be highest in summer (453.80 ± 45.25) followed by spring (313.2 ± 28.76), autumn (256.1 ± 17.48) and winter (190.2 ± 32.0).Overall prevalence of GI helminths was found more in adult goats (77.85%) compared to young ones (67.42%), the difference being statistically significant (P < 0.05). Similarly, it was found to be higher in females (75.89%) as compared to males (66.12%) and the variation being statistically non-significant (P > 0.05).

Prevalence of gastro-intestinal helminths in cattle at north Kashmir

Copro samples (1,126) of locally reared cattle at north Kashmir (Baramulla, Kupwara and Bandipora) were examined over a period of 1 year by qualitative and quantitative techniques. The overall prevalence of gastrointestinal (GI) helminths was 59.86% with trematodes, cestodes and nematodes in 11.63, 4.44 and 53.02% animals, respectively. Paramphistomes (7.10%) were the most prevalent trematodes followed by Fasciola spp. (4.53%) and Dicrocoelium spp. (0.27%). Prevalence of Moniezia spp. the only cestode found in the study was 4.44%. Among nematodes, the prevalence of strongyle worms was the highest (49.91%) followed by Trichuris spp. (3.64%) and Strongyloides spp. (2.04%). Seasonal variation revealed significantly highest prevalence of GI helminths during spring (68.21%) followed by autumn (67.50%), summer (55.59%) and winter (48.21%). Overall young cattle had significantly higher prevalence (68.13%) than adult animals (55.10%) but trematode infection was significantly higher in adults. Overall GI helminths were non-significantly higher in females (60.56%) as compared to males (58.24%) but the prevalence of paramphistomes was significantly higher in females. The prevalence of Dicrocoelium spp. and all the nematodes was nonsignificantly higher in males. EPG was ranging between 0 and 400 with an average EPG of 177.44±6.29. Highest EPG was recorded in spring (231.11±14.15) followed by summer (211.11±11.56), autumn (148.00±11.15) and winter (132.73±8.32). On coprocultural examination, Haemonchus spp. (65%) was found to be the most predominant strongyle worm followed by Bunostomum spp. (20%) and Trichostrongylus spp. (15%).

Effect of induced Fasciola gigantica infection during pre-patency on the performance of buffalo calves fed on different percentage of protein

Thirty growing Murrah buffalo calves (8-12 months of age, 109.85 ± 2.43) were reared in parasite free conditions and randomly divided into three equal groups as per CRD. They were fed on iso-caloric (2.01 ME Mcal/Kg diet) diets containing standard protein (SP) diet at 100 %, 90 % of SP (medium protein, MP) and 80 % of SP (low protein, LP) of the protein requirements (Kearl 1982). After 21 days of feeding, each group was further subdivided into two sub-groups (A & B). Animals in sub-groups 'A' served as non-infected control, while in sub group 'B' were orally infected with Fasciola gigantica metacercarie (mc; 1,000 each). A metabolic trial of 40 days post infection was carried out in control and parasitized animals. Intake of digestible dry matter, organic matter and acid detergent fibre (ADF) was significantly higher (P < 0.05) in SP group compared to LP group. The digestibility of crude protein (CP) and ADF was significantly higher in SP group compared to MP and LP groups. The digestible crude protein (DCP) and total digestible nutrients (TDN) intakes (g/kgW(0.75)) were also significantly (P < 0.001) higher in SP than MP and LP groups. However, DCP intake was significantly (P < 0.001) lower in infected subgroups compared to control subgroups. Intake and balance (g/d) of nitrogen, calcium and phosphorus were significantly (P < 0.01) higher in SP than MP and LP groups. The average daily gain of buffalo calves fed on SP Uninfected (SPU), SP Infected (SPI), MPU, MPI and LPU, LPI groups was 333, 178, 356, 144, 222 and 144 g and was significantly (P < 0.01) lower in animals fed LP ration. The feed conversion ratio (FCR) was also significantly (P < 0.01) higher in infected sub-groups as compared to respective control groups. The results showed that a SP diet substantially improved the overall performance of buffalo calves in control and infected groups and reduced adverse effect of F. gigantica infection.

Molecular characterization of veterinary important trematode and cestode species in the mithun Bos frontalis from north-east India

Helminth infections in the mithun Bos frontalis, including the liver fluke Fasciola gigantica, hepato-gastric amphistomes Explanatum explanatum, Paramphistomum epiclitum and Calicophoron calicophorum, and the cestodes Echinococcus granulosus and E. ortleppi were studied in north-east India over a 2-year period from 2012 to 2014. Cystic echinococcosis caused by E. granulosus and E. ortleppi was found to be highly prevalent in the mithun, with E. ortleppi being reported for the first time. Molecular markers, including the internal transcribed spacer 2 (ITS-2), 28S rDNA and mitochondrial NADH dehydrogenase sub-unit1 (nad1) were used to confirm the identification of the trematode and cestode species.

A retrospective survey of liver flukes in livestock based on abattoir data in Kermanshah, west of Iran

A retrospective study was carried from 2008 to 2013 to estimate the prevalence of liver flukes in ruminants slaughtered at the abattoir of Kermanshah province, west of Iran. A total of 663,633 animals slaughtered in the 5-year period and totally 1.95 % of livers were condemned due to liver flukes. Fasciolosis were responsible for 0.8, 0.7 and 1.5 % of liver condemnations, whereas 1, 0.8 and 1 % of liver were condemned because of Dicrocoelium dendriticum infection in the sheep, goats and cattle, respectively. A significant difference in the prevalence of liver flukes were observed among studied animals (p < 0.001) and the highest and lowest prevalence were detected in cattle and goats, respectively. Data showed significant seasonal pattern for distomatosis in sheep and goat (p < 0.001). Liver condemnations due to fasciolosis were prevalent in sheep and goats and cattle slaughtered during winter, summer and autumn, respectively, whereas dicrocoeliosis were common in autumn season for sheep and cattle and in winter for goats. This survey provides baseline data for the future monitoring of these potentially important parasitic infections in the region.

Prevalence of liver fluke infections in slaughtered animals in Lorestan, Iran

Fasciola spp. and Dicrocoelium dendriticum as liver flukes, contaminate ruminants and other mammalian extensively and cause major diseases of livestock that create considerable economic losses. This retrospective study has been done to evaluate contamination rate of slaughtered animals with fasciolosis and dicrocoeliosis at Lorestan abattoirs. In this survey, prevalence rate of fasciolosis and dicrocoeliosis in slaughtered animals in a 3-year period (2010-2013) has been analyzed. A total of 356,605 livestock including 265,692 sheep and 90,913 goats were slaughtered in the 3-year period and overall 39,613 (11.1 %) livers were condemned. Fascioliasis and dicrocoeliosis were responsible for 6.3 and 4.8 % of total liver condemnations in this period, respectively. Fasciola spp. and D. dendriticum infection in sheep (7.1 and 5.6 %, respectively) were considerably higher than goats (3.9 and 2.6 %, respectively). The annual prevalence rates showed a significant decline in the fasciolosis and dicrocoeliosis infection in goats (p < 0.001). Data showed significant seasonal pattern for distomatosis in sheep and goats (p < 0.001). Liver condemnations due to fasciolosis were prevalent in sheep and goats slaughtered during spring and autumn, respectively, whereas dicrocoeliosis were common in spring season for both sheep and goats. This survey provides baseline data for the future monitoring of these potentially important parasitic infections in the region.

Prevalence of bovine fasciolosis based on faecal examination and abattoir survey in Karnataka

The prevalence of fasciolosis was evaluated in bovines based on coprological examination and postmortem liver examination of slaughtered cattle and buffaloes. The faecal examination of 130 cattle and 135 buffaloes revealed a prevalence of 9.9 % in cattle and 13.3 % in buffaloes respectively. The examination of livers from cattle and buffaloes (155 each) slaughtered at the KMPMCL abattoir revealed the prevalence of fasciolosis was 20.6 % in cattle and 22.5 % in buffaloes. The results were statistically significant in faecal examination and not significant in liver examination from cattle and buffaloes respectively.

Genetic characterization of Fasciola gigantica from different geographical regions of India by ribosomal DNA markers

Ribosomal DNA sequences of the second internal transcribed spacer (ITS-2) and 28S ribosomal DNA (618 bp) of Fasciola gigantica collected from cattle and buffaloes from four different geographical locations of India, were characterized for genotyping. ITS-2 sequence was analyzed in 28 worms that was typical of F. gigantica and differed at six positions, with one of these being a distinguishing deletion (T) at the 327th position in F. gigantica relative to F. hepatica. However, Fasciola specimens also showed intraspecies sequence polymorphism in the ITS-2, with two different ITS-2 sequences existing in the ribosomal DNA (rDNA) array within a single Fasciola worm. One of the sequences was identical to that of F. gigantica and the other showed extensive sequence polymorphism in the ITS-2. Using BspH1-restriction fragment length polymorphism, six variable ITS-2 sequences in F. gigantica were identified within these parasite specimens and were found distributed in these four geographical regions. 28S rDNA sequence of 24 flukes, collected from the above four geographical regions, showed a single nucleotide polymorphism at 284th nucleotide (G/A). Analyzing the sequence data of 28S rDNA of F. gigantica available from some African and Asian countries for this polymorphic 284th nucleotide position, it is proposed that there are two basic lineages of the F. gigantica for 28S rDNA existing in the fluke populations from five African and several Asian countries.

Serodiagnosis of bovine fasciolosis by Dot-enzyme immuno assay in Chennai, Tamil Nadu

Excretory/secretory (E/S) antigen of adult Fasciola gigantica was used for diagnosis of fasciolosis in cattle and buffaloes sera from slaughter houses and different places in and around Chennai, Tamil Nadu. A total of 6.4 mg of E/S antigen was obtained from the 60 flukes collected from slaughter houses. Coprological examination was done to detect endoparasitic infection in 321 fecal samples. Dot-enzyme immuno assay (Dot-EIA) was standardized with optimum working dilution of E/S antigen, serum, and conjugate by the checker board titration as 1 in 10 (50 ng/ml), 1 in 20, and 1 in 1,000, respectively. A total of 321 sera samples consisting of 168 cattle and 153 buffaloes were tested by Dot-EIA. A total of 25 cattle (14.88 %) and 38 buffaloes (24.83 %) showed positive results in Dot-EIA. Sensitivity of Dot-EIA for cattle and buffaloes sera was 100 %. Specificity of Dot-EIA for cattle and buffaloes was 95.28 and 92.10 %, respectively in comparison to fecal examination by sedimentation method. Dot-EIA can be easily adapted in the field to detect fasciolosis in cattle and buffaloes.

Epizootiology, pathogenesis and immunoprophylactic trends to control tropical bubaline fasciolosis: an overview

On the Indian sub-continent, nearly 5,000 years ago, the domestication of the riverine buffalo-the incredible Asian dairy animal was initiated. It plays a versatile role in socio-economic upliftment of its owners from the rural agricultural communities in Asian, African, South American and a few European countries. Comparatively, buffaloes are lesser evolved and susceptible to infectious diseases than cattle. However, poor body thermoregulation and wallowing nature predisposed them to snail borne infections, especially tropical fasciolosis-an incessant major constraint on buffalo production and improvement programmes. This review article is an insight into the global prevalence, varied epizootiological factors, offers possible explanation to pathophysiological clinical signs, deleterious effects of the tropical liver fluke, involving hepato-biliary system, haemopoitic system, endocrine glands and their secretions, oxidative stress, altered metabolism and significant fall in food conversion efficiency with unaffected digestibility of nutrients. Besides, the authors have briefly discussed and reviewed the developments and significance of successful immunodiagnostic approaches for detecting and forecasting the disease during early pre-patency and feasibility of developing a cost effective immunoprotection strategies against tropical fasciolosis.

Molecular characterization of Fasciola spp. from the endemic area of northern Iran based on nuclear ribosomal DNA sequences

Fasciolosis caused by Fasciola spp. (Platyhelminthes: Trematoda: Digenea) is considered as the most important helminth infection of ruminants in tropical countries, causing considerable socioeconomic problems. In the endemic regions of the North of Iran, Fasciola hepatica and Fasciola gigantica have been previously characterized on the basis of morphometric differences, but the use of molecular markers is necessary to distinguish exactly between species and intermediate forms. Samples from buffaloes and goats from different localities of northern Iran were identified morphologically and then genetically characterized by sequences of the first (ITS-1) and second (ITS-2) Internal Transcribed Spacers (ITS) of nuclear ribosomal DNA (rDNA). Comparison of the ITS of the northern Iranian samples with sequences of Fasciola spp. from GenBank showed that the examined specimens had sequences identical to those of the most frequent haplotypes of F. hepatica (n=25, 48.1%) and F. gigantica (n=20, 38.45%), which differed from each other in different variable nucleotide positions of ITS region sequences, and their intermediate forms (n=7, 13.45%), which had nucleotides overlapped between the two Fasciola species in all the positions. The ITS sequences from populations of Fasciola isolates in buffaloes and goats had experienced introgression/hybridization as previously reported in isolates from other ruminants and humans. Based on ITS-1 and ITS-2 sequences, flukes are scattered in pure F. hepatica, F. gigantica and intermediate Fasciola clades, revealing that multiple genotypes of Fasciola are able to infect goats and buffaloes in North of Iran. Furthermore, the phylogenetic trees based upon the ITS-1 and ITS-2 sequences showed a close relationship of the Iranian samples with isolates of F. hepatica and F. gigantica from different localities of Africa and Asia. In the present study, the intergenic transcribed spacers ITS-1 and ITS-2 showed to be reliable approaches for the genetic differentiation of Fasciola spp., providing bases for further studies on F. hepatica, F. gigantica and their intermediate forms in the endemic areas in Asia.

Enzyme Inhibition by Molluscicidal Components of Myristica fragrans Houtt. in the Nervous Tissue of Snail Lymnaea acuminata

This study was designed to investigate the effects of molluscicidal components of Myristica fragrans Houtt. (Myristicaceae) on certain enzymes in the nervous tissue of freshwater snail Lymnaea acuminata Lamarck (Lymnaeidae). In vivo and in vitro treatments of trimyristin and myristicin (active molluscicidal components of Myristica fragrans Houtt.) significantly inhibited the acetylcholinesterase (AChE), acid and alkaline phosphatase (ACP/ALP) activities in the nervous tissue of Lymnaea acuminata. The inhibition kinetics of these enzymes indicates that both the trimyristin and myristicin caused competitive noncompetitive inhibition of AChE. Trimyristin caused uncompetitive and competitive/noncompetitive inhibitions of ACP and ALP, respectively whereas the myristicin caused competitive and uncompetitive inhibition of ACP and ALP, respectively. Thus results from the present study suggest that inhibition of AChE, ACP, and ALP by trimyristin and myristicin in the snail Lymnaea acuminata may be the cause of the molluscicidal activity of Myristica fragrans.

Tropical liver fluke-induced stress in experimentally infected and immunised buffaloes

Disease-related stress associated with Fasciola gigantica infection was investigated in 16 male, yearling Murrah buffaloes. The animals were randomly assigned to one of four groups. Animals in groups 1 and 2 were vaccinated subcutaneously with 4.8 mg of excretory-secretory antigen (group 1) or 1300 μg infection-specific antigen (group 2), in three doses. Subsequently, all the animals in groups 1, 2 and 3 were infected orally with 800 viable F gigantica metacercariae (bubaline origin) on week 6 of the experiment. The animals in group 4 served as healthy controls. The clinical progress of the disease with respect to the adrenocortical response to infection was assessed periodically. The infected animals in group 3 developed characteristic signs of the disease and had the highest in situ fluke population (mean [se] 331.8 [19.5] ). One of the four animals in group 3 died on day 110 postinfection (PI). Animals that had been immunised before infection (groups 1 and 2) acquired adequate levels of immunity, were comparatively healthier and had significantly lower (P<0.05) fluke populations (mean [se] 194.3 [11.8] in group 1 and 164.5 [9.2] in group 2). Throughout the course of the disease, the group 3 animals had significantly higher cortisol levels than those in groups 1 and 2 (P<0.01) from week 4 PI onward. Although animals in the immunised groups (groups 1 and 2) had increased hormone levels, they were not significantly different from those in the control animals in group 4. Cortisol levels were higher during the early prepatency phase (weeks 1 to 6 PI) than during the late prepatency and/or patency phases of the disease. Cortisol levels in the healthy control animals in group 4 remained within the normal range.

Serum enzyme and hematological profile of Fasciola gigantica immunized and experimentally infected riverine buffaloes

Sixteen male, yearling Murrah buffaloes were randomly assigned to four groups of four buffaloes each. Each animal in Gr-I and II were immunized, respectively, with 4.8 mg of excretory secretory antigen and 1,300 microg Infection Specific Antigen, in three divided doses. Subsequently, each animal in Gr-I, II, and III was per os infected with 800 viable Fasciola gigantica metacercariae (bubaline origin) on week-6 after the start of the experiment, while animals in Gr-IV served as healthy controls. The aspartate aminotransferase (AST) and alanine aminotransferase (ALT) concentrations progressively increased during the prepatency and respectively attained the highest levels during week-6 and 8 post-infection (PI). The alkaline phosphatase (AP) exhibited elevated trends from eighth week PI onward and continued to be higher until the end (p < 0.05-0.01). With the cessation of traumatic activities of the diastomes, the AST and ALT levels declined yet were throughout significantly higher than the healthy controls (p < 0.05-0.01). In the immunized animals (Gr-I and II), the fluctuation patterns were similar but the values were significantly lower than the non-immunized (Gr-III) animals (p < 0.05-0.01). The elevated levels of the enzymes had positive correlation with depressed erythrocytic indices, leucocytosis, eosinophilia, necropsy worm recovery, and hepatic lesion score in the respective groups. The increased concentrations of the enzymes revealed two clearly demarcated stages: (a) remarkably elevated AST (40.8%) and ALT (140.0%) levels during the prepatency, signifying traumatic lesions inflicted by the F. gigantica adolescercariae and (b) the significant increase in AP (107.9%), suggestive of bile duct hyperplasia, cholangitis, periportal fibrosis, and biliary obstruction etc. from sixth week PI onward. None of healthy controls developed clinical signs and had normal hematological and serum enzyme profiles. Diagnostic significance of these marker enzymes in the disease forecasting and in time application of control strategies to combat tropical fasciolosis in buffaloes in the endemic areas has been discussed.

Immune responses to polyethylenimine-mannose-delivered plasmid DNA encoding a Fasciola gigantica fatty acid binding protein in mice

Fasciola gigantica fatty acid binding protein (FABP) was evaluated for evoking an immune response in mice, by delivering the gene coding for this protein with mannosylated-polyethylenimine (PEI) to peritoneal cells. Mice were immunized with 50 microg recombinant plasmid DNA (Group I) or DNA-PEI-mannose (a 22 kDa linear cationic polymer with mannose ligand) (Group II) via the intraperitoneal route. Antibody studies showed no significant humoral immune response evoked to this DNA immunization with either PEI-mannose-delivered or naked DNA. However, on protein boosting of these DNA-primed mice there was a significant enhancement of antibody titre. Flow cytometric bead array was used to measure quantities of interleukin (IL)-2, IL-4, IL-5, interferon-gamma (IFN-gamma) and tumour necrosis factor (TNF) cytokines. Overexpression of T-helper 1 (Th1) cytokines such as IFN-gamma and TNF, with a lower but significant expression of the T-helper 2 (Th2) cytokine IL-5 was detected. Gene delivery using polyethylenimine-mannose ligand showed significant expression of IFN-gamma and TNF (P < 0.05), but no significant difference in IL-2, IL-4 and IL-5 (P>0.05) cytokine expression was observed between naked-DNA- and mannosylated PEI-DNA-delivered mice. Naked- or PEI-delivered-DNA immunization produced insignificant levels of IL-2 and IL-4 (P>0.05) cytokines in both groups of mice.

Immune responses to polyethylenimine delivered plasmid DNA encoding aFasciola giganticafatty acid binding protein in mice and rabbits

Fasciola giganticafatty acid binding protein (FABP) was evaluated for evoking an effective immune response in mice and rabbits, when delivered as a DNA vaccine in muscle cells. Polyethylenimine (PEI), 25 kDa, branched cationic polymer was used as a delivery vehicle for this DNA in the muscle cells of mice and rabbits. Naked DNA evoked mixed Th1 and Th2 responses in mice. PEI condensed DNA, at amine nitrogen over DNA phosphate (N/P) ratios of 4, 6 and 8 and with various DNA concentrations, failed to evoke a significantly higher antibody response compared to naked DNA in mice. Similarly, the humoral immune response to naked DNA administration in rabbit thigh muscles was poor and no boosting of this antibody response on administration of DNA complexed to PEI was observed. On metacercarial challenge, rabbits failed to show any significant protective immune response in both the naked DNA and PEI–DNA immunized groups. Administration of PEI alone (12.5 μg) in mouse thigh muscles caused significant muscle cytotoxicity but condensation of DNA with PEI had less of a toxic effect on muscle cells, which was inversely related to the N/P ratio. Delivery of plasmid DNA encodingF. giganticaFABP by high molecular weight polyethylenimine (branched, 25 kDa) did not boost the effective immune response in both the animal species, which could either be attributed to cytotoxicity associated with this cationic polymer or muscle cells being unsuitable target cells for PEI condensed DNA delivery.

Effect of Fasciola gigantica infection on adrenal and thyroid glands of riverine buffaloes

Effect of Fasciola gigantica infection on adrenal and thyroid glands was investigated using eight male, yearling Murrah buffaloes. The animals were randomly assigned to two groups of four buffaloes each (Group-A, infected; Group-B, non-infected control). Animals of Group-A were orally infected with 1000 F. gigantica viable metacercariae, keeping other four animals of Group-B as uninfected control. In the infected buffaloes, the clinical signs began appearing from 7th week postinfection (p.i.) and eggs were detected in the faeces between day 93 and 99 (95.5+/-1.25) postinfection (p.i.). The serum cortisol level, revealed a significant (P<0.05) rise during initial stage of the infection, followed by a continuous fall from 12th week onward. Peak cortisol level on 10th week (13.30+/-2.57ngml(-1)) was associated with eosinophilia (11.0+/-0.95%). However, non-infected controls maintained almost uniform cortisol levels (3.97+/-0.15-5.88+/-0.09ngml(-1)) throughout the period of the study. The pathological changes of adrenal glands were correlated with physiological dysfunction of the glands. The levels of T(3) and T(4) were significantly (P<0.05-0.01) low from 14th week onward and were synchronous with in situ migration, growth and development of F. gigantica. Significant reduction in the thyroid hormones was further supported by histopathological evidence of lymphocytic thyroiditis confirming hypothyroidism. A decrease in Hb, PCV, total erythrocyte counts and appearance of reticulocytes in the blood of the infected buffaloes suggested regenerative anemia, which could partly be due to hypothyroidism.

Detection of Fasciola gigantica infection in snails by polymerase chain reaction

Polymerase chain reaction (PCR) was used to detect Fasciola gigantica infection in the snail intermediate host. Fasciola specific primers amplified a 124 bp fragment in PCR when the genomic DNA isolated from F. gigantica infected Lymnaea auricularia snails was used as template. In addition to the 124 bp amplicon, a ladder of DNA fragments representing amplification of the 124 bp repetitive sequences was observed. Genomic DNA of the parasite was used as a positive control, which also gave an amplification of the 124 bp fragment. DNA isolated from non-infected snails was used as a negative control and no amplification of this sequence was observed. This technique is highly specific and sensitive and possesses fairly good prospects of its utility as an epidemiological tool for ascertaining the infectivity status in ubiquitous snail populations.

Primary experimental infection of riverine buffaloes with Fasciola gigantica

The clinical course of the primary experimental Fasciola gigantica infection was investigated in riverine buffalo calves of the Murrah breed. Nine male calves aged 12-15 months were randomly assigned to two groups of five (Group I) and four (Group II) animals. Each animal in Group I, was orally infected with 1000 metacercariae (mc) of F. gigantica, whereas Group II animals did not receive any infection dose and served as uninfected controls. No clinical signs of fasciolosis were observed until the sixth week post-infection (PI). Group I animals, however, developed recognised symptoms of acute fasciolosis, comprising apyrexic inappetance, anemia, poor weight gain, diarrhoea and sub-mandibular and facial oedema, respectively, from 5, 6, 8, 16 and 17 weeks PI. The signs were intermittent in nature and of variable duration. The prepatent period was of 92-97 days (mean 95.2 +/- 3.1). One of the five infected animals died on Day 147 PI. At necropsy, 36.8 +/- 11.0% of the infection dose was recovered as adult fluke population. The gross lesions were primarily biliary in nature. Group II, the uninfected controls, throughout the study period of 165 days PI, did not show any symptom and were negative for F. gigantica. The study demonstrated that the onset of adverse effects of F. gigantica on the growth and health of the infected host was mainly noted during late prepatency much before coprological prediction and diagnosis. The significance of preventive therapy against fasciolosis during prepatency has been stressed in endemic areas.

Detection of antibodies of Fasciola hepatica excretory--secretory antigens in experimentally infected goats by enzyme immunosorbent assay

An ELISA with excretory-secretory (ES) antigens has been evaluated as a technique for the early detection of specific antibodies in Fasciola hepatica infections in goats. Goats were experimentally infected with 100 or 200 metacercariae of bovine origin and serum samples were taken periodically over 365 days. The ELISA test was performed with ES antigens (10 micrograms mL-1), a single dilution of sera (1:800) and anti-goat IgG conjugate (1:1000). ES specific antigens were detected in all infected goats between 15 and 30 days postinfection (PI) and maximum antibody levels were reached at 90 days PI. Positive antibody levels (significantly different from those of controls) were still found at 365 days PI. No significant differences were observed between goats infected with 100 or 200 metacercariae. In all infected goats, eggs appeared in faeces between 60 and 90 days PI. ELISA with ES antigens could be a feasible method for the early diagnosis of goat fasciolosis.