Understanding the host response of farmed fish to blood flukes (Trematoda: Aporocotylidae) for developing new treatment strategies.

Aporocotylids (Trematoda: Digenea), also known as fish blood flukes infect the circulatory system of fish leading to serious health problems and mortality. Aporocotylids are a particular concern for farmed fish as infection intensity can increase within the farming environment and lead to mortalities. In the context of managing these infections, one of the most crucial aspects to consider is the host response of the infected fish against these blood flukes. Understanding the response is essential to improving current treatment strategies that are largely based on the use of anthelmintic praziquantel to manage infections in aquaculture. This review focuses on the current knowledge of farmed fish host responses against the different life stages of aporocotylids. New treatment strategies that are able to provide protection against reinfections should be a long-term goal and is not possible without understanding the fish response to infection and the interactions between host and parasite.

Resistance to single dose albendazole and reinfection with intestinal helminths among children ages 2 to 11 years from the Peruvian Amazon region: a study protocol.

BACKGROUND: Deworming programs aimed at reducing morbidity and mortality from geohelminth infections are common in many countries where these infections are endemic, but data demonstrating increasing levels of resistance to albendazole and mebendazole are causes for concern. Studies to evaluate the clinical efficacy of deworming programs are critical to maintain high infection control goals. METHODS: We propose to assess the clinical efficacy of Peruvian national guidelines for deworming programs in a prospective observational study conducted in the Amazon River basin area near Iquitos, Peru. Major outcomes to be evaluated include (1) albendazole resistance of intestinal helminths (trichuriasis, ascariasis, hookworm), and (2) frequency of reinfection with intestinal helminths 4 months after treatment with albendazole. Children ages 2-11 years from the Belén District of Iquitos will be identified based on a community census. Following parental informed consent, demographic data, weight, and height will be recorded and a stool specimen for parasitological exam by direct observation and Kato-Katz concentration method, and helminthic egg counts will be collected prior to administration of albendazole, following Peruvian national guidelines. Follow-up stool specimens examined in the same manner will be collected at 20 days, 90 days, and 100 days following initial administration of albendazole, and based on parasites found repeat treatment will be administered in accordance with national guidelines. Real-time multiplex qPCR will be performed on helminth positive samples collected prior to initial deworming and on helminth-positive specimens detected on day 15-20. A total sample size of 380 participants was calculated based on total population in the target group and prevalence estimates of helminth infections and clinical resistance based on recent data. DISCUSSION: Data from observational clinical efficacy studies are important to guide geohelminth infection control programs. Trial registration https://www.researchregistry.com/ . Identification number: researchregistry7736; Registered retrospectively March 13, 2022; https://www.researchregistry.com/browse-the-registry#home/registrationdetails/622e024cf06132001e3327bf/.

Treatment of primate platynosomosis: A word of caution about the use of praziquantel in marmosets.

BACKGROUND: The successive reports of Platynosomum illiciens in Neotropical captive primates have increased interest in platynosomosis; however, its treatment is little known. METHODS: Callithrix penicillata (n = 10) naturally and chronically infected with P. illiciens were treated with praziquantel (25 mg/kg BW, three s.c. doses at 24 hours intervals), and coproparasitological tests performed over 67 days. The proportions of primates with a reduction in fecal egg counts (FEC) or negative results progressively increased after treatment, and at the last fecal tests, marmosets were negative. RESULTS AND CONCLUSIONS: Although all primates tolerated the initial days of study well, 40% (4/10) of them died between the 8th and 16th days after the onset of treatment. Clinical signs and necropsies indicated the occurrence of hepatic involvement, biliary obstruction, and cholangitis. Marmosets with a higher previous FEC were more likely to die after treatment. Use of praziquantel should be considered carefully on a case-by-case basis.

High compliance and effective treatment of fish endoparasitic infections with oral drug delivery nanobioparticles: Safety of intestinal tissue and blood parameters.

Parasite infections in fish require constant surveillance and strategies for efficient treatments which guarantee the fish health, their sale value and the non-propagation of pathogens in new environments. Fish treatments based on nanotechnology become of increasing interest since nanoparticles have been shown as efficient materials for optimizing administration of bioactives. In this study a chitosan derivative, alginate and praziquantel conjugated nanobioparticle of effective action for oral treatment of digenetic trematodes in highly infected Corydoras schwartzi was evaluated in terms of histological and hematological safety. The inherent absence of alterations in intestinal tissue and the reversible blood cells counting during a period up to 35 days showed the safety of the drug delivery nanobioparticles, which thus represent a promising strategy for effective applications in pathogens treatments by oral administration.

Anthelmintic efficacy of natural saponins against Gyrodactylus kobayashii in goldfish (Carassius auratus) and their 3D-QSAR analysis.

Gyrodactylus spp. are common monogenean ectoparasites that may lead to significant fish mortality. To find effective anthelmintic agents with lower toxicity, a series of natural saponins were obtained and evaluated for their anthelmintic activity against Gyrodactylus kobayashii and acute toxicity to goldfish (Carassius auratus). Among all tested compounds, six compounds (1, 2, 3, 8, 10, and 13) shown higher anthelmintic activity and safety than widely used formaldehyde-based parasiticides, especially compound 1 having 100% anthelmintic efficacy against G. kobayashii at 0.3 mg/L and a therapeutic index of 16.6. Also, the three-dimensional quantitative structure-activity relationship (3D-QSAR) studies of these saponins have been performed to explore the structural features reasonable for the anthelmintic activity against G. kobayashii. These models demonstrated that the hydroxyl group at C-17 position and the sugar moieties at C-3 position, especially the hydroxyl groups of the sugar moieties, were critical to the anthelmintic activity. The QSAR studies could provide useful information for further rational design and optimization of novel saponins for the control of gyrodactylosis.

Nanoemulsions with oleoresin of Copaifera reticulata (Leguminosae) improve anthelmintic efficacy in the control of monogenean parasites when compared to oleoresin without nanoformulation.

This study compared the in vitro anthelmintic activity of Copaifera reticulata oleoresin (200, 400, 600, 800 and 1,000 mg/L) and of nanoemulsions prepared with this oleoresin (50, 100, 150, 200 and 250 mg/L) against monogeneans on the gills of Colossoma macropomum. The major compounds present in the oleoresin of C. reticulata were γ-macrocarpene (14.2%), α-bergamotene (13.6%), ß-selinene (13.4%) and ß-caryophyllene (11.7%). All concentrations of the nanoemulsion and the oleoresin without nanoformulation showed anthelmintic efficacy against monogeneans, and higher concentrations led to more rapid parasite mortality. Structural damages to the tegument of the parasites exposed to C. reticulata oleoresin were observed with scanning electron microscopy. At two hours of exposure, fish showed 100% tolerance to all nanoemulsion concentrations used in the in vitro assays, whereas 100% mortality was shown in the fish exposed to the oleoresin without nanoformulation after one hour. The results of this study suggest that nanoemulsions with oleoresin of C. reticulata have advantages in the control and treatment of monogenean infections in C. macropomum when compared to the oleoresin without nanoformulation. In addition, since nanoemulsions with the C. reticulata oleoresin are safe to control monogeneans, the efficacy of these nanoformulations may be assayed in therapeutic baths to treat C. macropomum infected by monogeneans.

Echinostoma aegyptica (Trematoda: Echinostomatidae) Infection in Five Riparian People in Savannakhet Province, Lao PDR.

Human infection with Echinostoma aegyptica Khalil and Abaza, 1924 (Trematoda: Echinostomatidae) is extremely rare. In this study, we confirmed E. aegyptica infection in 5 riparian residents living along the Mekong River in Savannakhet Province, Lao PDR. The patients revealed eggs of Opisthorchis viverrini/minute intestinal flukes, echinostomes, and other parasites in fecal examinations using the Kato-Katz technique. Following treatment with praziquantel 30-40 mg/kg and pyrantel pamoate 10-15 mg/kg in a single dose and purging with magnesium salts, adult specimens of various helminth species were collected. Among the trematodes, echinostome flukes of 4.5-7.6 mm in length (n = 134; av. 22.3 specimens per case) were of taxonomic interest and subjected in this study. The flukes were morphologically characterized by having total 43-45 collar spines arranged in 2 alternating rows (corner spines usually 5 on each side) and compatible with previous descriptions of E. aegyptica. The patients were mixed-infected with other helminths, so specific clinical manifestations due to this echinostome fluke were difficult to determine. The present paper describes for the first time human E. aegyptica infections in Lao PDR. This is the second report of human infection (2nd-6th cases) with E. aegyptica in the world following the first one from China.

Digenean Holostephanus (Trematoda: Digenea: Cyathocotylidae) metacercariae in common carp (Cyprinus carpio Linnaeus, 1758) muscle: zoonotic potential and sensitivity to physico-chemical treatments.

Metacercariae of various species within the genus Holostephanus Szidat, 1936 (Trematoda: Digenea: Cyathocotylidae) occur in muscles of both farmed and wild fish, including common carp (Cyprinus carpio Linnaeus, 1758). The life cycle includes a snail as first intermediate host, fish as second intermediate host and birds or mammals as final hosts. We studied the zoonotic potential and the viability of Holostephanus metacercariae from common carp following exposure to various physical and chemical treatments. Muscle tissue samples of common carp specimens from a fish farm in the north-eastern part of Hungary were examined and metacercariae recovered. The zoonotic potential was evaluated experimentally by using small mammals as models (albino mice, n = 2; and Syrian hamsters, n = 4) infected per os with Holostephanus cysts. Parallelly, Metagonimus metacercariae were used as positive controls. We could not confirm the zoonotic potential of Holostephanus metacercariae as they did not survive in the mammalian intestine whereas Metagonimus metacercariae developed to the adult stage. We assessed the viability of metacercariae isolated from common carp specimens during exposure to different physical treatments (temperatures of -18°C, +20°C, +40°C and +60°C) and chemical agents (5% and 10% acetic acid and 10% sodium chloride (NaCl)). Metacercariae lost viability by freezing at -18°C (2 h), heating at 60°C (20 min), incubation in 5% and 10% acetic acid (5 min) and 10% NaCl (2 h). These methods served as models to investigate the effectiveness of food preparation techniques (such as cold and hot smoking, freezing, salting and pickling) on the survival of metacercariae.

Evaluation of anthelmintic drugs against egg development of rumen flukes recovered from cattle raised in the humid tropics of Mexico.

Paramphistomosis is a parasitic disease endemic in ruminants nearly worldwide. In the present study, an in vitro screening of the main anthelmintics used in Mexico was carried out to determine the mean lethal dose for rumen fluke eggs from cattle in a humid, warm region. Rumen flukes were obtained from cattle slaughtered in the states of Tabasco and Chiapas in Mexico. Eggs were collected using a 37-µm sieve and quantified. Then, an in vitro incubation study was performed: 100 eggs were placed into the wells of polystyrene microtiter plates. Anthelmintic products were tested on the eggs at concentrations ranging from 0.0015 to 3.0 mg/ml for rafoxanide, 0.0025 to 10.20 mg/ml for nitroxinil and 0.0015 to 3 mg/ml for closantel to determine the median lethal dose (LD50) and maximum lethal dose (LD99). A control group (water) was included in each plate. Three different species of rumen flukes (Calicophoron brothriophoron, Calicophoron clavula and Paramphistomum cervi) belonging to five isolates were identified. Nitroxinil had the highest efficacy against rumen fluke eggs, with an LD50 of 0.11 to 65 µg/ml, whereas rafoxanide showed the lowest efficacy with an LD50 ranging from 500 to 1713 µg/ml. Closantel showed high variability in the LD50 among the different analysed isolates (17 to 122 µg/ml). The evaluated flukicidal drugs presented differential efficacy against the development of rumen fluke eggs. The efficacy of the drugs will vary depending on the geographical area of origin of the animals.

Artyfechinostomum sufrartyfex Trematode Infections in Children, Bihar, India.

Eating raw or insufficiently cooked mollusks is a known risk factor for human echinostomiasis. We confirmed identification of Artyfechinostomum sufrartyfex trematodes as the causative agent of disease among 170 children in northern Bihar, India. We also identified the snail Pila globosa as a potential source of infections in the study area.

Multiple food-borne trematodiases with profound systemic involvement: a case report and literature review.

BACKGROUND: Food-borne trematodiases are an important group of neglected global diseases. Affected patients in regions with low prevalence usually experience delayed diagnosis, especially when presenting with atypical clinical symptoms. Here, we presented a rare case of a Chinese patient infected with three food-borne trematodiases. CASE PRESENTATION: A 42-year-old man presented with diarrhea, lower extremity edema, and symptoms of cardiac dysfunction. He had a history of intermittent consumption of raw freshwater fishes for 6-7 years. Upon evaluation, he had eosinophilia, anemia, intrahepatic bile duct dilatation and a growing space-occupying lesion in the left atrium. The patient underwent a cardiac surgery which revealed an endocardial hematoma due to mechanical injuries. Imaging investigations also revealed intracranial and pulmonary lesions. A total of three trematodiases were diagnosed based upon microscopic stool examination, from which eggs of Clonorchis sinensis, Heterophyidae and Echinostomatidae were identified. Deposition of Clonorchis sinensis eggs was also observed from ileocecal squash slides. The patient was successfully treated with three cycles of praziquantel. CONCLUSIONS: Food-borne trematodiases may present with systemic involvement. Patients with dietary history of high risk or atypical ingestions should be evaluated for parasitic infection, even in non-endemic areas.

An in vitro confirmation of the ethonopharmacological use of Senna plants as anthelmintic against rumen fluke Paramphistomum gracile.

BACKGROUND: Paramphistomosis is a pathogenic disease of domesticated ruminants, causing great economic loss in dairy industry and meat production. It is considered as a neglected tropical disease with highest prevalence throughout tropical and subtropical regions, particularly in Africa, Asia, Europe, and Australia. There are few trematocidal drugs available in the market. Most are resistant and have elevated side effects. Therefore, alternative trematocidal drugs need to discover. This study was conducted to evaluate three plants leaf extracts (from Senna alata, S. alexandrina, and S. occidentalis) as effective remedies against gastrointestinal trematode parasite (Paramphistomum gracile) of ruminants. Live adult parasites were collected in 0.1 M phosphate-buffered saline (PBS) from fresh autopsied goat's rumen. Parasites were incubated in leaf extracts of S. alata, S. alexandrina and, S. occidentalis individually and in combination (1:1) ratio at 37 ± 1°C. Treatment media contain extracts at different concentrations (10, 20 and 40 mg/mL) in 10 mL of 0.1 M PBS with 1% dimethylsulphoxide (DMSO). Parasites in control group were incubated in PBS without extract. The efficacy of three Senna extracts was evaluated on the basis of dose-dependent motility and mortality of the trematode. Immediately after paralysis, all treated parasites were collected for histology, SEM and biochemical study. RESULTS: Dose-dependent efficacy was observed in terms of motility and time of mortality in all treated parasites after exposure in various concentrations of the Senna plant extracts. S. occidentalis and S. alexandrina showed better efficacy in combination than comparing with individual treatment groups. Histological study and scanning electron microscopic observations revealed conspicuous deformity of surface architecture in all treated parasites. Scanning electron micrographs also revealed shrinkage, vacuolization, infoldings and blebbings on the body surface of treated worms. Activities of tegumental enzymes were inhibited in all treatment groups compared to control. CONCLUSION: The overall findings from this study revealed that all three Senna leaf extracts individually and in combination showed potential antitrematocidal activity against Paramphistomum gracile by damaging body tegument and neural propagation. Thus, this study confirmed that all three Senna extracts can be considered as a potential drug-like candidate in indigenous system of traditional medicine against trematode infections in livestock.

Zygocotyle lunata as a model for in vivo screening of anthelmintic activity against paramphistomes: Evaluation of efficacy of praziquantel, albendazole and closantel in experimentally infected mice.

Paramphistomes are important parasites in veterinary medicine. There are few anthelmintic drugs available against them. The development of new drugs is urgently needed and this process can be accelerated through the development of rodent models for in vivo testing. Among the few paramphistomes that develop in rodents is the caecal fluke Zygocotyle lunata, a species with which several biological studies have been performed over several decades. Nevertheless, its use as a model for evaluation of anthelmintic drugs had not yet been evaluated. In the present study, we evaluated the efficacy of praziquantel (PZQ 300 mg/kg 5x), albendazole (ABZ 200 mg/kg 5x) and closantel (CLO 50 mg/kg single dose, 50 mg/kg 3x and 25 mg/kg 3x) for treatment of mice experimentally infected with Z. lunata. The animals were infected with 20 metacercariae of the parasite and were treated 30 days post-infection. Untreated groups were maintained as controls. Seven days after the treatments, the animals were euthanized for recovery and counting of parasites. We found that PZQ and ABZ, at the dosages and therapeutic schedule employed here, did not cause significant alterations in worm burden [worm counts 16.0 ±â€¯2.8 (13-19), 17.6 ±â€¯2.1 (14-19) and 16.2 ±â€¯1.9 (13-18) (p = 0.51) in PZQ, ALB and control, respectively]. CLO 50 mg/kg in a single dose caused significant reduction in the number of parasites [treated: 1.8 ±â€¯0.9 (1-3); control: 15.6 ±â€¯2.5 (12-19)], although it did not result in complete elimination of the parasites in any animal. Despite the fact that three doses of CLO 50 mg/kg or CLO 25 mg/kg caused complete elimination of the parasites in most surviving animals, there was significant host mortality. In general, results here obtained are concordant with those of studies performed on ruminant paramphistomes. Given that Z. lunata can be maintained in laboratory rodents, it is a suitable model for screening anthelmintic drugs against paramphistomes.

Form and Function in the Digenea.

This review aims at covering the general aspects of the form and function of the major body systems in digenetic trematodes, with emphasis on the advances that have been made on this topic since the publication of the first edition of this book; this is since 2012. In particular, the advancement in the knowledge of form and function of tegumentary, sensory, neuromuscular, alimentary, respiratory, excretory, and reproductive systems is covered. Furthermore, a brief mention of the current trends in the targeting of trematode body systems for developing novel opportunities of treatment and control is provided.

Intestinal Trematode Infections.

Intestinal trematodes are among the most common types of parasitic worms. About 76 species belonging to 14 families have been recorded infecting humans. Infection commonly occurs when humans eat raw or undercooked foods that contain the infective metacercariae. These parasites are diverse with regard to their morphology, geographical distribution, and life cycle, which make it difficult to study the parasitic diseases that they cause. Many of these intestinal trematodes have been considered as endemic parasites in the past. However, the geographical limits and the population at risk are currently expanding and changing in relation to factors such as growing international markets, improved transportation systems, new eating habits in developed countries and demographic changes. These factors make it necessary to better understand intestinal trematode infections. This chapter describes the main features of human intestinal trematodes in relation to their biology, epidemiology, host-parasite relationships, pathogenicity, clinical aspects, diagnosis, treatment, and control.

Albendazole, levamisole and ivermectin are effective against monogeneans of Colossoma macropomum (Pisces: Serrasalmidae).

This study evaluated the efficacy of albendazole, ivermectin, levamisole, mebendazole and praziquantel on monogeneans of Colossoma macropomum, based on in vitro and in vivo assays. In vitro assays indicated that albendazole (500, 100, 1,500 and 2,000 mg/L), ivermectin (200, 250, 300 and 350 mg/L) and levamisole (50, 75, 100 and 125 mg/L) were 100% effective against Anacanthorus spatulatus, Notozothecium janauachensis, Mymarothecium boegeri and Linguadactyloides brinkmanni, while mebendazole (125, 150, 175 and 200 mg/L) and praziquantel (5, 10, 15 and 20 mg/L) were ineffective. Fish mortality in 24 hr therapeutic baths with 500 mg/L of albendazole was 6.6%, but the behaviour of the animals remained unchanged, while 200 mg/L of ivermectin caused lethargy, signs of hypoxia and 100% mortality within 2 hr, and 125 mg/L of levamisole caused no mortality. The efficacy of 500 mg/L of albendazole was 48.6% in the 24 hr baths, while that of 125 mg/L levamisole was 88.2%. Although ivermectin showed in vitro efficacy, the lowest concentration used in baths was highly toxic to fish. Therefore, we recommend the use of 125 mg/L of levamisole to control and treat monogenean infestations on C. macropomum in fish farming.

Efficacy of silver nanoparticles against the adults and eggs of monogenean parasites of fish.

Monogeneans are a diverse group of parasites that are commonly found on fish. Some monogenean species are highly pathogenic to cultured fish. The present study aimed to determine the in vitro anthelmintic effect of silver nanoparticles (AgNPs) against adults and eggs of monogeneans in freshwater using Cichlidogyrus spp. as a model organism. We tested two types of AgNPs with different synthesis methodologies and size diameters: ARGOVIT (35 nm) and UTSA (1-3 nm) nanoparticles. Damage to the parasite tegument was observed by scanning electron microscopy. UTSA AgNPs were more effective than ARGOVIT; in both cases, there was a concentration-dependent effect. A concentration of 36 µg/L UTSA AgNPs for 1 h was 100% effective against eggs and adult parasites, causing swelling, loss of corrugations, and disruption of the parasite's tegument. This is an interesting result considering that monogenean eggs are typically tolerant to antiparasite drugs and chemical agents. To the best of our knowledge, no previous reports have assessed the effect of AgNPs on any metazoan parasites of fish. Therefore, the present work provides a basis for future research on the control of fish parasite diseases.

Use of praziquantel to control platyhelminth parasites of fish.

Fish are common definitive and intermediate hosts for a variety of parasitic flatworms. In unstressed wild populations, parasitic infections often go unnoticed and are perceived to represent a lesser threat to fish health. In contrast, platyhelminth parasitism of captive fish often results in decreased weight gain and increased mortality which often necessitates chemotherapeutic treatment. The presence of platyhelminth parasites in fish tissues is not only unappealing but in some cases also represents a threat to human health. In veterinary medicine, one of the most commonly used agents with anti-flatworm activity is praziquantel; yet, no praziquantel products are labeled for use in fish in the United States. Veterinarians may use praziquantel preparations approved for other vertebrate species under the Animal Medicinal Drug Use Clarification Act (AMDUCA). However, such extra-label use should be informed by scientific evidence including efficacy and tissue residue studies. Herein, we review studies testing the efficacy of praziquantel for treatment of platyhelminthes along with an assessment of routes of administration, pharmacokinetics, and toxicity information.

An Autochthonous Human Case of Fasciolopsiasis in Nepal.

Fasciolopsiasis is rarely known as the parasitic disease in Nepal. Herein, we report a case of fasciolopsiasis in a 22-year-old man who was admitted in the hospital with abdominal pain, distension and loss of appetite for a month. He had previously diagnosed with acute viral hepatitis but, his abdominal pain was not resolving despite improvement in his liver function and general condition. During endoscopy an adult digenean worm was seen in the first part of the duodenum. After isolation, the worm was identified morphologically as Fasciolopsis buski. Microscogic examination of the patient's stool revealed eggs with a morphology consistent with F. buski. Eggs were yellow-brown, ellipsoidal, unembmbryonated, operculated, filled with yolk cells, with thin shell and ranging 118-130 µm in length and 60-69 µm in width. The abdominal pain of the patient was resolved after treatment with praziquantel. By the present study, it was confirmed for the first time that fasciolopsiasis is indigenously transmitted in Nepal. Accordingly, the epidemiological studies in humans and reservoir host animals should be performed intensively in near future.

Effects of a nanoemulsion with Copaifera officinalis oleoresin against monogenean parasites of Colossoma macropomum: A Neotropical Serrasalmidae.

Monogeneans are ectoparasites that may cause losses in production and productivity in the aquaculture of Colossoma macropomum. Chemotherapeutics used in aquaculture usually have major adverse effects on fish; hence, the use of essential oils has been considered advantageous, but these are not soluble in water. Thus, the use of nanostructures to enhance water solubility of compounds and improve bioactivity may be very promising. This study investigated the antiparasitic activity of nanoemulsion prepared with Copaifera officinalis oleoresin (50, 100, 150, 200 and 300 mg/L), against monogenean parasites from the gills of C. macropomum. The particle size distribution and zeta potential suggested that a potentially kinetic stable system was generated. The nanoemulsion from C. officinalis oleoresin achieved high efficacy (100%) at low concentrations (200 and 300 mg/L) after 15 min of exposure. This was the first time that a nanoemulsion was generated from C. officinalis oleoresin using a solvent-free, non-heating and low-energy method. Moreover, this was the first time that an antiparasitic against monogeneans on fish gills, based on nanoemulsion of C. officinalis oleoresin, was tested.