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

Lethal effects of praziquantel and albendazole, on the cercariae of Echinochasmus sp. (Dietz, 1909) in-vitro

Echinochasmidae are considered one of the digenean intestinal parasites of carnivorous mammals and humans. Some larvicidal medications, such as praziquantel and albendazole, were employed to interrupt the life cycle of Echinochasmidae, which may cause harmful and serious effects on the domestic fish, ducks, and humans in our ecosystem. Cercariae of Echinochasmus sp. (gymnocephalus type) were harvested by exposing snails to strong artificial illumination. The emerging cercariae were exposed in vitro to different concentrations of praziquantel and albendazole at the same period of incubation 12 h. Using probit analysis in SPSS version 25, the lethal concentrations 50 and 95% were determined. They were 0.036 and 0.82 ppm, respectively, for praziquantel and 5.3 and 9.2 ppm, respectively, for albendazole. The ultrastructural changes using scanning electron microscope on the tegumental surface of the treated cercariae with the two drugs were compared to the untreated cercariae. The untreated cercariae have a pear-shaped body with a long tail. The oral sucker is armed with a spiny collar and decorated with ciliated and unciliated sensory papillae. The cardinal ventral sucker has a thick, muscular wall. The cercarial tail is decorated with parallel longitudinal tegumental processes and spherical, unciliated papillae. In comparisons, cercariae treated with both drugs lost all healthy morphological features, but in varying degrees and effects between the two drugs. Our findings suggest that the use of both drugs can be recommended during the design of control strategies to combat this type of intestinal parasite.

First report of Dactylogyrus formosus from India: a case of co-existence with Paradactylogyrus catlaius causing mass mortality in Indian major carp, Catla catla

The family Dactylogyridae, known for its role as a frequent pathogen in Cyprinids, was identified in a case of mass mortality involving Catla catla fingerlings (measuring 6.5 ± 2.0 cm and weighing 40.5 ± 10 g) in West Bengal, India. Microscopic examination revealed the presence of two co-existing parasites, Dactylogyrus formosus and Paradactylogyrus catlaius, attached to different sections of the gill filament. Despite their coexistence, these parasites exhibited marked differences in their haptoral hard parts, genital organs, and preferred habitats. Molecular analysis of the Internal Transcribed Spacer 1 and 4 genes indicated more than 90% similarity between the detected parasite and D. formosus previously reported in China. Histopathological observations illustrated the parasites' specific attachment to the distal end of the primary gill lamellae, gradually causing destruction to a maximum number of secondary lamellae. Internally, infiltration of eosinophilic granular cells was observed in gill and kidney blood vessels, while the liver exhibited hepatocytes filled with hemosiderin. The infected fish were treated for 24 h with a safe dose of common salt (5.6 ppt) and albendazole (62 ppm). The survivability rate was significantly higher (p < 0.05) in both treated groups compared to the control. Interestingly, the group treated with common salt showed superior results compared to the albendazole-treated fish. This study presents the sympatric speciation of D. formosus in a new host (C. catla) and explores its host specificity, histopathology, and treatment methods. This case marks the first report of D. formosus causing substantial mortality in cultured Catla in India, alongside the coexistence with Paradactylogyrus catlaius.

Essential oil of Piper hispidum (Piperaceae) has efficacy against monogeneans, and effects on hematology and gill histology of Colossoma macropomum

This study investigated for the first time the effectiveness of therapeutic baths with essential oil (EO) of Piper hispidum against monogeneans Anacanthorus spathulatus, Notozothecium janauachensis, Mymarothecium boegeri and Linguadactyloides brinkmanni from the gills of Colossoma macropomum, as well as the hematological and histological effects on this fish. In therapeutic baths, 100 mg/L of P. hispidum essential oil and two control groups (water from the culture tank and water from the culture tank with 70% alcohol) were exposed for 1 h/day, with intervals of 48 hours for 3 days, and three replicates each were used. Therapeutic baths with 100 mg/L of P. hispidum essential oil had an efficacy of 78.6% against monogeneans. The toxicity of this essential oil was low, since there were a few physiological and histopathological changes that did not compromise the functioning of the gills of the fish. Therefore, 100 mg/L of P. hispidum essential oil was effective for controlling monogeneans in C. macropomum, when short therapeutic baths were used without compromising the health of the exposed fish.

Exploring the Efficacy and Safety of Levamisole Hydrochloride against Microcotyle sebastis in Korean Rockfish (Sebastes schlegelii): An In Vitro and In Vivo Approach

Parasitic infections pose significant challenges in aquaculture, and the increasing resistance to conventional anthelmintics necessitates the exploration of alternative treatments. Levamisole hydrochloride (HCl) has demonstrated efficacy against monogenean infections in various fish species; however, research focused on Microcotyle sebastis infections in Korean rockfish (Sebastes schlegelii) remains limited. Therefore, this study aimed to evaluate the efficacy of levamisole HCl against M. sebastis infections in Korean rockfish with the goal of optimizing anthelmintic usage in aquaculture. In this study, we first assessed the susceptibility of M. sebastis to levamisole HCl in vitro. Subsequently, in vivo evaluations were conducted to assess the drug's efficacy, safety, and to identify optimal administration methods. In vitro experiments revealed concentration-dependent sensitivity of M. sebastis to levamisole HCl, with a minimum effective concentration (MEC) of 100 mg/L. In vivo experiments employed oral administration, intraperitoneal injection, and immersion treatments based on the MEC. Oral administration proved to be a safe method, yielding efficacy rates of 27.3% and 41.6% for 100 mg/kg and 200 mg/kg doses, respectively, in contrast to the immersion and injection methods, which induced symptoms of abnormal swimming, vomiting, and death. Biochemical analyses conducted to assess the safety of levamisole HCl revealed a transient, statistically significant elevation in the levels of glutamic oxaloacetic transaminase (GOT) and glutamic pyruvic transaminase (GPT) on day three post-administration at 20 °C. Following this, no substantial differences were observed. However, at 13 °C, the enzyme levels remained relatively consistent, emphasizing the role of water temperature conditions in influencing the action of levamisole HCl. Our research findings substantiate the efficacy of levamisole HCl against M. sebastis in Korean rockfish, underscoring its potential for safe oral administration. These results provide valuable insights for developing parasite control strategies involving levamisole HCl in Korean rockfish populations while minimizing adverse impacts on fish health and the environment. However, this study bears limitations due to its controlled setting and narrow focus. Future research should expand on these findings by testing levamisole HCl in diverse environments, exploring different administration protocols, and examining wider temperature ranges.

Efficacy of a therapeutic bath with selected antiparasitic drugs on a Dactylogyrus anchoratus infection in juvenile common carp (Cyprinus carpio)

The study aimed to assess the effects of a therapeutic bath of five different antiparasitic drugs, in different baths and durations: fenbendazole (25 mg l-1, 12 h and 2 × 12 h), formaldehyde (0.17 ml l-1, 15 min), ivermectin (0.031 mg l-1, 1 h), mebendazole (1 mg l-1, 12 h) and levamisole (50 mg l-1, 2 h and 3 × 1 h) on the reduction on the intensity and prevalence of a monogenean infection (Dactylogyrus anchoratus) in juvenile carp. The best effect on reducing the parasite number was achieved with the bath in formaldehyde (0.17 ml l-1, 15 min) and fenbendazole (25 mg l-1, 2 × 12 h with 24 h break), where the infection was reduced by more than 90%. Registered veterinary medicinal products (VMPs) with the active substance of fenbendazole can successfully replace the use of unregistered formaldehyde in the treatment of monogenean infections.

Seeds of Cucurbita maxima and Carica papaya are effective for controlling monogeneans in the gills of Leporinus macrocephalus

This study was carried out to evaluate the anthelminthic efficacy of seeds of Cucurbita maxima and Carica papaya for controlling monogeneans in the gills of Leporinus macrocephalus, besides hepatosomatic and splenosomatic index and condition factor of host. The fish were fed with seeds of C. maxima or C. papaya for seven days, and these treatments did not cause any mortality among them. Jainus leporini, Urocleidoides paradoxus, Urocleidoides eremitus and Tereancistrum parvus were the monogeneans found, and their prevalence in fish fed with seeds of C. papaya was 100%, while in fish fed with C. maxima the prevalence was 42.8%. Fish fed with seeds of C. papaya showed decreased in intensity and abundance of monogeneans, while fish fed with seeds of C. maxima presented decreased in abundance. Feeding of L. macrocephalus with seeds of C. maxima or C. papaya had efficacy of 69.6 and 67.8%, respectively. The hepatosomatic index of fish fed with seeds of C. maxima or C. papaya was not affected by the treatments. However, the splenosomatic index and condition factor of fish fed with C. maxima seeds decreased. Seeds of C. maxima and C. papaya may be used for controlling monogeneans of L. macrocephalus in fish farming.

Albendazole is effective for controlling monogenean parasites of the gills of Piaractus brachypomus (Serrasalmidae) and Megaleporinus macrocephalus (Anostomidae)

Monogenean infestations can cause high mortality in farmed fish and therefore significant economic losses. The present study investigated the efficacy of albendazole in therapeutic baths against monogeneans of Piaractus brachypomus Cuvier, 1818 and Megaleporinus macrocephalus (Garavello & Britski, 1988). For both fish, a 24 hours therapeutic bath with albendazole concentrations of 150, 300 and 500 mg/L were tested against monogeneans from the gills. The baths had an efficacy from 61.4 ± 32.9 (95%CI=64.5) against monogeneans of P. brachypomus, and from 95.4 ± 5.6 (95%CI=10.9) against monogeneans of M. macrocephalus. In P. brachypomus, the hepatosomatic index (HSI) in fish exposed to 150 mg/L of albendazole was higher than in fish exposed to 300 mg/L. The splenosomatic index (SSI) values in fish exposed to 150 mg/L of albendazole were lower than in fish exposed to 300 mg/L. In M. macrocephalus, the HSI and SSI values decreased in treatments with 150, 300 and 500 mg/L of albendazole to control and treat infestations by monogeneans. For M. macrocephalus, 150 mg/L of albendazole can be used to control and treat infestations by monogeneans, while for P. brachypomus 500 mg/L of albendazole can be used in a 24 hours bath.

Trichlorfon is effective against Dawestrema cycloancistrium and does not alter the physiological parameters of arapaima (Arapaima gigas): A large Neotropical fish from the Amazon

This study investigated the in vitro and in vivo efficacy of trichlorfon against Dawestrema cycloancistrium, as well as its physiological effects on arapaima. Naturally parasitized arapaima gill arches were exposed in vitro to 100, 250, 500 and 750 mg/L of trichlorfon and a control group (only distilled water), in triplicate. Parasites were monitored, and mortality was used to determine the median effective concentration (EC₅₀ ). The 750 mg/L concentration demonstrated 100% in vitro efficacy against D. cycloancistrium after 60 min, while the intermediate (500 mg/L) and the lowest (100 and 250 mg/L) tested concentrations were completely efficient after 90 and 130 min, respectively. The EC_50-1h of trichlorfon for D. cycloancistrium was determined at 171.73 mg/L. Parasitized arapaima juveniles were exposed to a control group and 150 mg/L of trichlorfon in triplicate. Fish were exposed to two therapeutic baths for 60 min with 24-h intervals between treatments. Therapeutic baths with 150 mg/L of trichlorfon were 92.99% effective against D. cycloancistrium and did not bring about haematological alterations (erythrogram, white blood cell count, thrombogram, plasma glucose and total proteins). Therefore, 150 mg/L of trichlorfon can be used in therapeutic baths to control and treat D. cycloancistrium infestations with no physiological impairments for arapaima.

Sterol profile of Neobenedenia melleni, a marine ectoparasite fish

Neobenedenia melleni, a marine fish ectoparasite, is responsible for considerable losses in the mariculture industry. In maintaining the parasite's homeostasis, sterols are structural and functional lipids that perform vital functions. Thus, understanding the mechanisms of biosynthesis and the uptake of sterols can reveal potential pharmacological targets. The objective of this work was thereby to characterize the N. melleni sterols. The most abundant sterol found was cholesterol in either its free (47.48 ± 15.93 %) or esterified form. However, its precursors, squalene (3.53 ± 0.92 %) and desmosterol (0.25 ± 0.03 %), were also found, suggesting the uptake of these intermediates from hosts or an unusual active pathway of sterol biosynthesis, which can be further explored as pharmacological targets.

Depletion study and estimation of the withdrawal period for albendazole in tambaqui (Colossoma macropomum) parasitised by acanthocephalan (Neoechinorhynchus buttnerae) treated with albendazole-containing feed

This study provides the first data related to albendazole (ABZ) and its main metabolites [albendazole sulphoxide (ABZSO), albendazole sulphone (ABZSO₂), and albendazole-2-amino sulphone (ABZ-2-NH₂-SO₂)] residue depletion in tambaqui (Colossoma macropomum) parasitised by acanthocephalan (Neoechinorhynchus buttnerae). The ABZ withdrawal period was also calculated. The fish received a daily dose of 10 mg ABZ kg^-1 body weight (b.w.) via medicated feed for 34 days. Samples of target tissue (muscle plus skin in natural proportions) were collected 24, 48, 72, 120, 168, 240, and 336 h after the end of ABZ administration. The quantitation of ABZ residues and its metabolites in the target tissue was performed using a validated ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) analytical method. After treatment, ABZ in the target tissue was rapidly metabolised over time, and ABZSO was the most persistent metabolite and was shown to be at the highest levels in the target tissue. Considering the maximum residue limit (MRL) established by Codex Alimentarius in the muscle (100 μg kg^-1, species not specified), a withdrawal period of 4 days (112 °C-day) was estimated for the total residue (sum of ABZ and its metabolite residues). Considering data reported in the literature and data obtained in this study, it is suggested that the total residue be considered as marker residue to be adopted for fish in the legislative framework.

High concentration of levamisole in the diet of Colossoma macropomum (Pisces: Serrasalmidae) is effective for controlling monogenean parasites

This study investigated the effects of diets supplemented with levamisole on monogeneans on the gills of Colossoma macropomum. Fish were fed with diets containing levamisole at concentrations of 0, 300, 600, 900 and 1200 mg kg-1 for 24, 96 and 240 h and the infection by Anacanthorus spatulatus, Notozothecium janauachensis and Mymarothecium boegeri were evaluated. None of the levamisole concentrations caused either mortality or behavioral alterations in fishes during 240 h of feeding. After 24 h of feeding with 1200 mg kg-1 of levamisole, the abundance of N. janauachensis decreased in comparison with treatments of 0, 300, 600 and 900 mg kg-1, as did the abundance of M. boegeri after 240 h of feeding with 1200 mg kg-1 of levamisole. The efficacy of 900 mg kg-1 of levamisole was only 55.7% after 96 h of feeding, but it was 84.6% after 240 h of feeding with 1200 mg kg-1. Our results show that 1200 mg kg-1 of levamisole for 10 days has good anthelmintic efficacy against monogeneans of C. macropomum. Since monogeneans elicit some of the worst problems in C. macropomum, this study has provided evidence of an effective control method that may be used in fish farms.

Anthelminthic potential of the Ficus insipida latex on monogeneans of Colossoma macropomum (Serrasalmidae), a medicinal plant from the Amazon

INTRODUCTION

Herbal therapy is a potentially beneficial alternative for fish aquaculture, since it may be cheaper and more effective than chemotherapy. The aim of this study was to investigate the in vitro efficacy of Ficus insipida latex on monogeneans of Colossoma macropomum gills.

MATERIALS AND METHODS

To evaluate the anthelmintic activity, four concentrations of F. insipida latex (250, 500, 750 and 1000 µL/L) and exposure time to cause immobilization on monogeneans were used. In addition, two control groups, being one with water from the breeding tank and the other with breeding water from the tank + 70% ethyl alcohol were used.

RESULTS

At the concentration of 250 µL/L of F. insipida latex, the immobilization of the monogeneans occurred after 4 h of exposure, while at the concentration of 500 µL/L, it occurred after 2 h. At the concentrations of 750 and 1000 µL/L of F. insipida latex, the immobilization of the monogeneans occurred after 1 h and 30 min, respectively. After exposure to 250 µL/L of F. insipida latex, 100% of immobilization of monogeneans was observed within 4 h, to 500 and 750 µL/L, 100% immobilization occurred within 4 h and to 1000 µL/L, 100% mortality occurred after 2 h.

CONCLUSIONS

Thus, we recommended the use of 1000 μL/L of F. insipida latex for therapeutic baths in of C. macropomum against monogeneans, after previous test of toxicity.

Toxicological, hematological and immunological effects of levamisole and ivermectin diet supplementation on Colossoma macropomum (Serrasalmidae)

This study investigated the toxicological, hematological and immunological effects of diets supplemented with levamisole and ivermectin on Colossoma macropomum. Fish were fed for 24, 96 and 240 h with diets containing 300, 600, 900 and 1200 mg of levamisole kg-1 of feed. None of the levamisole concentrations caused either mortality or behavioral alterations among the fish over 10 d of feeding. In comparison, a single feeding of ivermectin at 4500, 9000, 13500 or 18000 mg kg-1 caused 100% mortality among the fish within 10 h. There were no alterations in erythrocyte parameters or albumin in any treatments with levamisole after 24, 96 and 240 h of feeding. At concentrations of 900 and 1200 mg kg-1, levamisole caused decreases in the albumin-to-globulin ratio compared to the control group and the 300 and 600 mg kg-1 diet treatment groups. Levels of glucose and total plasma protein were higher in the fish fed with 600, 900 and 1200 mg kg-1 than in the controls and the 300 mg kg-1 diet treatment group. After 10 d of receiving feed supplemented with levamisole, globulin levels were higher in the 600 mg kg-1 group than in the controls. Respiratory burst activity of leukocytes also increased in the fish supplemented with the 900 and 1200 mg kg-1 diets compared to the controls and other treatments. This is the first study to investigate how diets supplemented with these drugs affect C. macropomum. Our research indicates that all the levamisole concentrations tested can be used in the diet of C. macropomum for antiparasitic treatments against helminth species, and that dietary treatments with levamisole can stimulate components of the innate immune system.