Food-borne Trematode Infections Research Articles

The proteome of extracellular vesicles of the lung fluke Paragonimus kellicotti produced in vitro and in the lung cyst

Paragonimiasis is a zoonotic, food-borne trematode infection that affects 21 million people globally. Trematodes interact with their hosts via extracellular vesicles (EV) that carry protein and RNA cargo. We analyzed EV in excretory-secretory products (ESP) released by Paragonimus kellicotti adult worms cultured in vitro (EV ESP) and EV isolated from lung cyst fluid (EV CFP) recovered from infected gerbils. The majority of EV were approximately 30–50 nm in diameter. We identified 548 P. kellicotti-derived proteins in EV ESP by mass spectrometry and 8 proteins in EV CFP of which 7 were also present in EV ESP. No parasite-derived proteins were reliably detected in EV isolated from plasma samples. A cysteine protease (MK050848, CP-6) was the most abundant protein found in EV CFP in all technical and biological replicates. Immunolocalization of CP-6 showed strong labeling in the tegument of P. kellicotti and in the adjacent cyst and lung tissue that contained worm eggs. It is likely that CP-6 present in EV is involved in parasite-host interactions. These results provide new insights into interactions between Paragonimus and their mammalian hosts, and they provide potential clues for development of novel diagnostic tools and treatments.

A Note on Filopaludina martensi martensi (Frauenfeld, 1865) Artificial Breeding Conditions

Highlight ResearchLong-term maintenance of Filopaludina martensi martensi in artificial conditions (local tap-water and food).Observation of breeding behaviour of F. m. martensi.Observation of birth and development of the juveniles. AbstractFilopaludina martensi martensi Frauenfeld 1865 is an aquatic Viviparidae gastropod found in Thailand, and throughout Southeast Asia. It is popular in the local cousin, a vector of food-borne trematode infections, and used as a bio-indicator of heavy metal contamination, bio-control agent against Bithynia siamensis Lea 1856, and a way to reduce the total organic matter content from faeces and feed residue during Clarias sp. catfish and Nile tilapia aquaculture. The study aims to establish a protocol for breeding F. m. martensi snails in artificial conditions. The snails were maintained in laboratory conditions. The animals gave birth (3 - 4 juveniles) every month. Inflatable, for several hours after the birth, transparent lightly bluish (5 - 6 mm in diameter) spheres are released in which the fully mature juvenile moves, and leaves several hours later after the sphere breaks. All juveniles studied here die after 2 - 3 months failing to grow into a reproductive adults. F. m. martensi is an attractive animal that regardless of the current difficulties to maintain and grow its juveniles may be popularised in the ornamental fish trade, and a possible laboratory model animal.

Neglected Tropical Diseases. The Place of Ivermectin in the Elimination Programs

The World Health Organization identifies as neglected nineteen tropical diseases with bacterial, viral and parasitic etiology, of which two are ophthalmological. These diseases affect over one billion people worldwide, especially communities in developing countries, with limited access to healthcare, clean water, and sewerage. These include: trachoma, onchocerciasis (river blindness), leprosy, leishmaniasis, schistosomiasis, foodborne trematode infections, dracunculiasis, Chagas disease, Human African trypanosomiasis, lymphatic filariasis (elephantiasis), cysticercosis, echinococcosis, soil-transmitted helminthiases, Dengue, rabies, yaws, scabies, Buruli ulcer, mycetoma, chromoblastomycosis and other deep mycoses. The global effort in fighting neglected tropical diseases is one of the biggest initiatives in the field of public health. On the 28th of January 2021 the World Health Organization initiated a new ten-year plan for the eradication of neglected tropical diseases. It aims to lower the mortality, new disability cases and suffering of more than one billion people.

Insights into the effects of inducible and neuronal nitric oxide synthase isoenzymes in experimental intestinal heterophyiasis

Background: Heterophyiasis is one of the food-borne trematode infections, caused by the intestinal flukeHeterophyes heterophyes. The exact role of nitric oxide (NO) in the immune response against the majorityof parasites remains controversial. It proved protective against a wide range of protozoan and helminthicparasites. Nevertheless, its role in intestinal heterophyiasis is yet to be explored.Objectives: The study aims to explore the possible roles of inducible nitric oxide synthase (iNOS) andneuronal nitric oxide synthase (nNOS) in experimental intestinal heterophyiasis.Material and Methods: The experimental study design included infection of male puppies with H.heterophyes encysted metacercariae (EMC), followed by treatment with aminoguanidine (AG) and7-nitroindazole (7-NI) drugs, as selective inhibitors of iNOS and nNOS, respectively. Controls includednon-infected and infected untreated puppies. Intestinal tissue sections from all puppies were stained forhistopathological and immunohistochemical (IHC) assessments.Results: Different intensities of iNOS and nNOS isoenzymes were observed in intestinal sections. The studyshowed the highest concentration of iNOS isoenzyme in the infected-7-NI treated group. The control noninfectedpuppies exhibited the highest levels of nNOS expression, with statistical significance (P<0.05).The study also showed that AG significantly reduced the degree of inflammatory cellular infiltrations.Additionally, the over-production of NO worsened the degree of intestinal apoptotic changes.Conclusion: Results obtained in the study suggested that inhibition of iNOS, to some extent, improvedintestinal architecture, while inhibition of nNOS failed to eliminate experimental intestinal heterophyiasis.

Characterization and localization of antigens for serodiagnosis of human paragonimiasis

Paragonimiasis is a foodborne trematode infection that affects 23 million people, mainly in Asia. Lung fluke infections lead frequently to chronic cough with fever and hemoptysis, and are often confused with lung cancer or tuberculosis. Paragonimiasis can be efficiently treated with praziquantel, but diagnosis is often delayed, and patients are frequently treated for other conditions. To improve diagnosis, we selected five Paragonimus kellicotti proteins based on transcriptional abundance, recognition by patient sera, and conservation among trematodes and expressed them as His-fusion proteins in Escherichia coli. Sequences for these proteins have 76–99% identity with amino acid sequences for orthologs in the genomes of Paragonimus westermani, Paragonimus heterotremus, and Paragonimus miyazakii. Immunohistology studies showed that antibodies raised to four recombinant proteins bound to the tegument of adult P. kellicotti worms, at the parasite host interface. Only a known egg antigen was absent from the tegument but present in developing and mature eggs. We evaluated the diagnostic potential of these antigens by Western blot with sera from patients with paragonimiasis (from MO and the Philippines), fascioliasis, and schistosomiasis, and with sera from healthy North American controls. Two recombinant proteins (a cysteine protease and a myoglobin) showed the highest sensitivity and specificity as diagnostic antigens, and they detected antibodies in sera from paragonimiasis patients with early or mature infections. In contrast, antibodies to egg yolk ferritin appeared to be specific marker for patients with adult fluke infections that produce eggs. Our study has identified and localized antigens that are promising for serodiagnosis of human paragonimiasis.

An Overview on Under Researched and Neglected Emerging Parasitic Zoonosis

Covid-19 made us realize the magnitude of one health and how essential is it to dwell deep into connecting links between animal borne infections that appear of lesser importance to humans. Three quarters of emerging human pathogens are zoonotic and the probability of viral and protozoan disease to emerge as major pathogens is more than other infectious agents. The major contributors to the global burden of parasitic zoonoses are toxoplasmosis, food borne trematode infections, cysticercosis, echinococcosis, leishmaniosis and zoonotic schistosomosis. However, giardiosis, trichenellosis, angiostrongylosis are emerging as upcoming challenges. The foremost possibilities for skewed research on particular parasites is the proportion of populations being affected by the disease mainly driven by the socio economic status/research funding agencies and other being the elusive lifestyle of parasite/ difficult to study/ rarity. As the world is turning into a global village with ease of transportation, travel and trading, the emerging neglected parasites maysoon traverse the socio economic or geographical barriers. It is therefore imperative to include them in international debate, divulge into their epidemiology and transmission to ensure effective monitoring and control.

Targeting Kinases in Fasciola hepatica: Anthelminthic Effects and Tissue Distribution of Selected Kinase Inhibitors.

Protein kinases have been discussed as promising druggable targets in various parasitic helminths. New drugs are also needed for control of fascioliasis, a food-borne trematode infection and worldwide spread zoonosis, caused by the liver fluke Fasciola hepatica and related species. In this study, we intended to move protein kinases more into the spotlight of Fasciola drug research and characterized the fasciolicidal activity of two small-molecule inhibitors from human cancer research: the Abelson tyrosine kinase (ABL-TK) inhibitor imatinib and the polo-like 1 (PLK1) inhibitor BI2536. BI2536 reduced viability of 4-week-old immature flukes in vitro, while adult worms showed a blockade of egg production. Together with a significantly higher transcriptional expression of PLK1 in adult compared to immature worms, this argues for a role of PLK1 in fluke reproduction. Both fluke stages expressed ABL1-TK transcripts at similar high levels and were affected by imatinib. To study the uptake kinetic and tissue distribution of imatinib in F. hepatica, we applied matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) for the first time in this parasite. Drug imaging revealed the accumulation of imatinib in different fluke tissues from 20 min to 12 h of exposure. Furthermore, we show that imatinib is metabolized to N-desmethyl imatinib by F. hepatica, a bioactive metabolite also found in humans. Besides the vitellarium, gastrodermal tissue showed strong signal intensities. In situ hybridization demonstrated the gastrodermal presence of abl1 transcripts. Finally, we assessed transcriptional changes of physiologically important genes in imatinib-treated flukes. Moderately increased transcript levels of a gene encoding a multidrug resistance protein were detected, which may reflect an attempt to defend against imatinib. Increased expression levels of the cell cycle dependently expressed histone h2b and of two genes encoding superoxide dismutases (SODs) were also observed. In summary, our pilot study demonstrated cross-stage activity of imatinib but not BI2536 against immature and adult F. hepatica in vitro; a fast incorporation of imatinib within minutes, probably via the oral route; and imatinib-induced expression changes of physiologically relevant genes. We conclude that kinases are worth analyzing in more detail to evaluate the potential as therapeutic targets in F. hepatica.

Production and characterization of monoclonal antibodies against highly immunogenic Opisthorchis viverrini proteins and development of coproantigen detection

Opisthorchis viverrini and other foodborne trematode infections are major health concerns in the Greater Mekong Subregion. Currently, the gold-standard diagnostic method for opisthorchiasis is conventional stool examination for the presence of parasite eggs. This method lacks sensitivity and needs an experienced technician. We therefore produced monoclonal antibodies to highly immunogenic O. viverrini proteins aiming at detecting specific antigens in the feces. In this study, BALB/C mice were immunized using semi-purified somatic antigens and spleen cells were fused with a Sp2/0 myeloma cell line. Four hybridomas (1A2, 1E12, 2C7 and 8D6) were selected and cloned due to their strong reaction against O. viverrini somatic protein, resulting in three IgM clones and one IgG2 clone. Immunohistochemistry showed that 1A2, 1E12, 2C7 and 8D6 stained the parenchyma cells, gut, tegument and muscles, respectively. Western-blot analysis revealed that only antibody 1A2 could detect coproantigen (approx. 73 kDa protein) in feces of hamsters infected with O. viverrini. The 1A2 monoclonal antibody may be of value in the diagnosis of opisthorchiasis by coproantigen detection.

Effectiveness of a community-based integrated strategy to control soil-transmitted helminthiasis and clonorchiasis in the People's Republic of China

Soil-transmitted helminthiases (STHs) are caused by a group of intestinal nematode infections due to poor hygiene and environments, and clonorchiasis is a food-borne trematode (FBT) infection caused by ingestion of raw freshwater fish. Both are endemic in the People's Republic of China. To explore a suitable control strategy, integrated interventions were applied between 2007 and 2009 in ten pilot counties (eight for the STHs and two for clonorchiasis). Drug administration was used for treatment and complementary efforts to improve the situation based on health education, provision of clean water and sanitation were carried out. Significant achievements were gained as reflected by a drastic decrease in prevalence these infections were demonstrated. The overall prevalence of STHs and clonorchiasis decreased from 35.9% to 7.8% and from 41.4% to 7.0%, respectively. The reduction of prevalence and high cost-effectiveness were documented supporting large-scale application of this integrated intervention in China and elsewhere.

A diagnostic fluke

Fascioliasis is a foodborne trematode infection caused by the liver fluke Fasciola hepatica or Fasciola gigantica. In Australia, human cases are seen rarely and infection is often acquired overseas. This study reports the case of an 18-year-old woman from Bangladesh, with a mulitloculated liver abscess suspected secondary to F. hepatica. She presented with fever and right upper quadrant pain, and initial blood examination at our facility revealed an eosinophilia of 1.22×109/L (9%) and a mild elevation of liver function tests. An ultrasound guided drainage was sent only for cytology which revealed no malignancy. Empiric cover was given for bacterial liver abscess and blood cultures were negative. Multiple stool microscopic examinations visualised no ova, cysts or parasites. Serology demonstrated reactivity for Fasciola hepatica IgG enzyme immunoassay (EIA) and Schistosomiasis IgG EIA which was treated with praziquantel. There was non-reactive serology for Entamoeba histolytica, Echinococcus granulosus and Strongyloides. Despite treatment with triclabendazole, her case was later complicated by acute bleeding through the ampulla of vater secondary to a hepatic artery pseudoaneurysm and she received re-treatment with triclabendazole. Although we cannot differentiate between other liver flukes as the cause of her presentation, this case highlights important microbiological diagnostic considerations and treatment challenges.

Prevalence, infection intensity and risk factors of Opisthorchis viverrini infection in rural area of Central Thailand

Opisthorchis viverrini (OV) infection is a food-borne trematode infection through the consumption of uncooked cyprinoid fish containing infective stage, metacercariae. Adult flukes are living in hepato-biliary system. Infected cases could be unaware of the infection because of asymptomatic clinical presentation and chronic infection is strongly associated with cholangiocarcinoma, which IARC has declared OV to be carcinogenic to human. In Thailand, uncooked cyprinoid fish is popular in the North and Northeastern region as a traditional dish especially Koi pla (Chopped raw fish mixed with spicy herbal ingredients). The study was conducted in Phra-plerng sub district located in Sa Kaeo Province, Central Thailand in 2015 using cross-sectional design. The study areas are combined of Central and Northeastern descendants. Stool specimen was examined with three methods; direct smear, modified Kato-Katz and FECT aimed to measure prevalence and intensity of OV infection. Infection intensity was measured as EPG (eggs per gram) and risk behaviours were assessed by questionnaires. Zero-inflated model was used for zero-excess data from EPG. Study areas comprised of 5 villages with 1267 participants. Overall prevalence of OV infection was 9.4%. The prevalence was significantly higher in Village Moo 9 (P < 0.001) where most of villagers are Northeasterners. Male gender increased risk of acquiring infection (OR = 2.8, 95% CI: 1.1–7.5). Infection intensity showed overdispersion with mean EPG = 3.2 and SD = 28.1. Zero-inflated negative binomial model showed that male gender, increasing age and Koi pla consumption were associated with increasing EPG (P < 0.05). Modelling zero-excess and overdispersion for infection intensity could help shaping more robust analysis. Up-to-date information on risk factors are valuable for targeting intervention to high-risk population.

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.

Travel-Related Parasitic Infections in Travellers to Southeast Asia and Western Pacific Countries.

In the last decades, there has been a significant increase in international human mobility with increase in the prosperity, travel possibilities, and number of refugees. In the first half of 2016, the Asian continent showed the fastest growth in the number of tourists. Such increase is seen due to the interest in Asian history, culture, and cuisine. In the globalizing world, human mobility causes changes in the epidemiology of diseases and the spread of various infections across continents. Parasitic infections that may pose a risk for travellers to the Asia-Pacific are malaria, leishmaniasis, filariasis, foodborne trematode infections, schistosomiasis, soil-transmitted infections, and tourist diarrhea. Consulting a travel medical expert and using health services such as pre-travel vaccination and chemoprophylaxis will reduce the risk of infectious diseases among travelers.

Food-borne zoonotic trematodes: devious old flukes in an urbanized, global village

Food-borne trematodes constitute a family of lung, liver and intestinal flukes that have parasitized mankind and domesticated animals since the distant past. In the modern global village, food-borne trematodes present a daunting challenge of infection with severe morbidity, despite being highly neglected as causes of disease. Urbanization is the population shift from rural to urban centers, as a necessity for industrialization and development. It is currently the hallmark of rapidly developing low and middle income countries and usually characterized by both poor planning and sustainability. In many communities, the population shift observed is mainly due to rural-urban migration. With urban industrialization and globalization however, immigration plays a significant role as well. The most significant effect is seen in rapid population growth, beyond the capacity of available resources. Aside from localized businesses, cuisine and cultural centers are the first and fastest growing establishments in newly emerging urban centers. In the low and middle income countries, water and food safety are most affected in this environment. The opportunity for introduction and transmission of imported water and food-borne trematode infections is particularly high in coastal cities or those emerging around major natural and man-made water bodies. A typical outcome of globalization, urbanization and immigration is a rise in the prevalence and spread of food-borne trematodiases.

Systems biology studies of adult paragonimus lung flukes facilitate the identification of immunodominant parasite antigens.

BackgroundParagonimiasis is a food-borne trematode infection acquired by eating raw or undercooked crustaceans. It is a major public health problem in the far East, but it also occurs in South Asia, Africa, and in the Americas. Paragonimus worms cause chronic lung disease with cough, fever and hemoptysis that can be confused with tuberculosis or other non-parasitic diseases. Treatment is straightforward, but diagnosis is often delayed due to a lack of reliable parasitological or serodiagnostic tests. Hence, the purpose of this study was to use a systems biology approach to identify key parasite proteins that may be useful for development of improved diagnostic tests.Methodology/Principal FindingsThe transcriptome of adult Paragonimus kellicotti was sequenced with Illumina technology. Raw reads were pre-processed and assembled into 78,674 unique transcripts derived from 54,622 genetic loci, and 77,123 unique protein translations were predicted. A total of 2,555 predicted proteins (from 1,863 genetic loci) were verified by mass spectrometric analysis of total worm homogenate, including 63 proteins lacking homology to previously characterized sequences. Parasite proteins encoded by 321 transcripts (227 genetic loci) were reactive with antibodies from infected patients, as demonstrated by immunoaffinity purification and high-resolution liquid chromatography-mass spectrometry. Serodiagnostic candidates were prioritized based on several criteria, especially low conservation with proteins in other trematodes. Cysteine proteases, MFP6 proteins and myoglobins were abundant among the immunoreactive proteins, and these warrant further study as diagnostic candidates.ConclusionsThe transcriptome, proteome and immunolome of adult P. kellicotti represent a major advance in the study of Paragonimus species. These data provide a powerful foundation for translational research to develop improved diagnostic tests. Similar integrated approaches may be useful for identifying novel targets for drugs and vaccines in the future.

Specific diagnosis of Opisthorchis viverrini using loop-mediated isothermal amplification (LAMP) targeting parasite microsatellites

Opisthorchis viverrini and other food-borne trematode infections are major health problems in Thailand, the Lao People's Democratic Republic, Vietnam and Cambodia. Differential diagnosis of O. viverrini based on the microscopic observation of parasite eggs is difficult in areas where Clonorchis sinensis and minute intestinal flukes coexist. Recently, loop-mediated isothermal amplification (LAMP) has been widely used for detection and identification of trematode for its simple method that is useful in low-resource or field settings. We have reported ITS1-LAMP assay to detect O. viverrini infection from human feces. The sensitivity and specificity of the test was 100% and 61.5%. The sensitivity of the test appeared to be higher than microscopic egg examination; however non-specific amplification from other parasites could not be ruled out. We therefore targeted microsatellites of O. viverrini that is a species specific sequence. By using hydroxyl naphthol blue (HNB)-LAMP, O. viverrini microsatellite 6 (OVMS6) could specifically amplify DNA from O. viverrini genome, but not other parasites such as C. sinensis, Opisthorchis felineus, Centrocestus caninus, Haplorchis taichui, Fasciola gigantica and Haplorchoodes sp. The detection limit of the test is 1ng genomic DNA, which was 1000 times lower than the ITS1-LAMP, but targeting microstellites showed more specific detection of O. viverrini. In addition, the colorimetric LAMP assay was simple and effective; this makes it potentially applicable for point-of-care diagnosis.

Prevalence of Helminthic Infections among Inhabitants of Lao PDR

The prevalence of helminthic infections was surveyed on a total of 6,178 residents (males 2,549 and females 3,629) in 102 villages of 9 provinces in Lao PDR between 2007 and 2011 under the project of Korea-Laos Collaborative Project for Control of Foodborne Trematode Infections in Lao PDR. Fecal specimens were collected and examined by the Kato-Katz thick smear and Stoll's egg counting techniques. The overall liver/intestinal helminth egg positive rate was 71.9% with a single or mixed infections with Opisthorchis viverrini and minute intestinal flukes (Ov/MIF), Ascaris lumbricoides, hookworms, Trichuris trichiura, Trichostrongylus sp., echinostomes, Taenia spp., and others. Ov/MIF revealed the highest prevalence (55.6%) followed by hookworms (27.8%) and T. trichiura (6.5%). The endemic regions with the highest prevalence of Ov/MIF were Savannakhet, Khammouane, Vientiane (Nam Ngum), Champasak (Khong Island), and Saravane Province. High prevalences of A. lumbricoides (33.8%), hookworms (47.8%), and T. trichiura (32.6%) were observed in Phongsaly, Luang Prabang, and Vientiane (Nam Ngum) areas, respectively. The results of this study highlight helminth parasites of current public health significance in different areas of Lao PDR.

NTDs V.2.0: “Blue Marble Health”—Neglected Tropical Disease Control and Elimination in a Shifting Health Policy Landscape

The concept of the neglected tropical diseases (NTDs) was established in the aftermath of the Millennium Development Goals. Here, we summarize the emergence of several new post-2010 global health documents and policies, and how they may alter the way we frame the world's major NTDs since they were first highlighted. These documents include a new Global Burden of Disease 2010 Study that identifies visceral leishmaniasis and food-borne trematode infections as priority diseases beyond the seven NTDs originally targeted by preventive chemotherapy, a London Declaration for access to essential medicines, and a 2013 World Health Assembly resolution on NTDs. Additional information highlights an emerging dengue fever pandemic. New United Nations resolutions on women and the non-communicable diseases (NCDs) have not yet embraced NTDs, which may actually be the most common afflictions of girls and women and represent a stealth cause of NCDs. NTDs also have important direct and collateral effects on HIV/AIDS and malaria, and there is now a robust evidence base and rationale for incorporating NTDs into the Global Fund to Fight AIDS, Tuberculosis, and Malaria. “Blue marble health” is an added concept that recognizes a paradoxical NTD disease burden among the poor living in G20 (Group of Twenty) and other wealthy countries, requiring these nations to take greater ownership for both disease control and research and development. As we advance past the year 2015, it will be essential to incorporate global NTD elimination into newly proposed Sustainable Development Goals.

A survey of metacercarial infections in commonly edible fish and crab hosts prevailing in Manipur, Northeast India

Food-borne trematode infections, which are mainly transmitted through consumption of inadequately cooked or raw fish and crabs, affect a large section of population, particularly in Southeast Asian countries, thus eliciting a remarkable morbidity and causing serious damage to health. In India, centering in several mountainous regions of the Northeast, the natives have the habit of consuming such fish or crabs that still sustain viable infective larval stage (metacercaria) of trematode flukes in their muscle tissue. The present study was undertaken to ascertain the spectrum of metacercarial diversity in commonly edible freshwater fishes and crab species in the northeastern state of Manipur and to adjudge their zoonotic potential, if any. Commonly edible fishes belonging to 15 species from 12 localities and crabs belonging to 2 species from 11 localities across Manipur state were surveyed for the purpose. The study revealed that 3 species of fishes (Channa punctatus, C. straitus and Wallago attu) harboured 4 different types of metacercariae belonging to 4 trematode families-Euclinostomum heterostomum (Clinostomidae); Lophosicyadiplostomum sp. and Posthodiplostomum sp. (Diplostomidae); and Polylekithum sp. (Allocreadiidae) in addition to adult flukes of Isoparorchis hypselobagri (Isoparorchiidae). Among these, metacercariae of Posthodiplostomum showed the highest prevalence (2.33%) though a low abundance, while for other species the prevalence ranged between 0.25 and 1.19%. The crab species (Barythelphusa lugubris masoniana and Potamiscus manipuriensis) were found infected with 4 different types of metacercariae representing the genera Paragonimus (Troglotrematidae) and Microphallus (Microphallidae). The paragonimids showed a higher rate of occurrence (~4-25%) compared to microphallids (~15%). The crustaceans surveyed emerged as prospective intermediate hosts for lungflukes. Identifying the potent vectors for zoonotic parasites helps in control measures towards their transmission to higher mammals.

In vitro PHYTOTHERAPY OF VECTOR SNAILS BY BINARY COMBINATIONS OF LARVICIDAL ACTIVE COMPONENTS IN EFFECTIVE CONTROL OF FASCIOLIASIS

SUMMARYA food-borne trematode infection fascioliasis is one among common public health problems worldwide. It caused a great economic loss for the human race. Control of snail population below a certain threshold level is one of the important methods in the campaign to reduce the incidence of fascioliasis. The life cycle of the parasite can be interrupted by killing the snail or Fasciola larva redia and cercaria inside of the snail Lymnaea acuminata. In vitro toxicity of different binary combinations (1:1 ratio) of plant-derived larvicidal active components such as citral, ferulic acid, umbelliferone, azadirachtin and allicin against Fasciola redia and cercaria were tested. The mortality of larvae was observed at 2h, 4h, 6h and 8h of treatment. In in vitro condition azadirachtin + allicin (1:1 ratio) was highly toxic against redia and cercaria (8h LC50 0.006 and 0.005 mg/L). Toxicity of citral + ferulic acid was lowest against redia and cercaria larvae.