Absorption, distribution and excretion of the anthelmintic praziquantel (Droncit) in rainbow trout (Salmo gairdneri R.)

Evaluation of Praziquantel effectiveness in treating Nile tilapia clinostomid infections and its relationships to fish health and water quality : By

This study aimed to conduct a multidisciplinary investigation integrating detailed morphology, molecular characterization, water parameters, histopathology alteration, and the trials of treatment of Clinostomum spp. In this study, 300 Nile tilapia (Oreochromis niloticus) were collected from the farmed and wild Nile River at Al Bahr Al Aazam, Giza Governorate to assess Clinostomid infection prevalence. Fish and water samples were collected from private fish farms, and water drains at Dakahlia, and Giza, Egypt. Analysis of the water revealed inadequate water quality, particularly in the fish farms. Snails and piscivorous birds were abundant at fish collection sites. The recovered Clinostomid MCs morphological characteristics and COI gene sequence analysis identified them as Clinostomum complanatum, C. phalacrocoracis, and Euclinostomum heterostomum. Clinostomid MCs disturbed the fish's hematological and biochemical blood parameters. Bath treatment of parasitized fish with praziquantel (2 mg/L for 24 h) revealed a significant reduction in the number of vital MCs vs. infected fish (non-treated). Praziquantel (PZQ) is an effective and safe therapy for controlling Clinostomid infections affecting farmed Nile tilapia. The current findings indicate a link between poor environmental conditions and Clinostomum infections in tilapia. The study highlights the impacts of Clinostomid MCs on fish health and recommends bath treatment with PZQ as an efficient control method for these dangerous parasites to protect human and fish health.

Acute toxicity of praziquantel to fish Danio rerio and planktonic crustacean Daphnia magna

This study evaluated the toxicity of the pyrazino isoquinoline anthelmintic praziquantel (PZQ) to the Danio rerio zebrafish and Daphnia magna water flea. The estimated 24 h and 96 h LC50 of PZQ to the zebrafish was 39.9 mg/l and 30.4 mg/l, respectively. The highest 24 h and 96 h non-lethal concentration (LC0) was 21.7 mg/l and 21.2 mg/l, respectively. The mobility inhibition test of the juvenile Daphnia magna revealed a 48 h EC50 of 42.7 mg/l.

Praziquantel use in aquaculture - Current status and emerging issues

Parasitic diseases are major constraints in fish mariculture. The anthelmintic praziquantel (PZQ) can effectively treat a range of flatworm parasites in a variety of fish species and has potential for broader application than its current use in the global aquaculture industry. In this review we report on PZQ's current use in the aquaculture industry and discuss its efficacy against various flatworm parasites of fish. Routes of PZQ administration are evaluated, along with issues related to palatability, pharmacokinetics and toxicity in fish, while PZQ's effects on non-target species, environmental impacts, and the development of drug-resistance are discussed.

Efficient Treatment of Fish Intestinal Parasites Applying a Membrane-Penetrating Oral Drug Delivery Nanoparticle

Nanodelivery of drugs aims to ensure drug stability in the face of adverse biochemical conditions in the course of administration, concomitant with appropriate pharmacological action provided by delivery at the targeted site. In this study, the application potential of a nanoparticle produced with biopolymers chitosan-N-arginine and alginate as an oral drug delivery material is evaluated. Both macromolecules being weak polyelectrolytes, the nanoparticle presents strong thermodynamic interactions with a biological model membrane consisting of a charged lipid liposome bilayer, leading to membrane disruption and membrane penetration of the nanoparticles in ideal conditions of pH corresponding to the oral route. The powder form of the nanoparticle was obtained by lyophilization and with a high percentage of entrapment of the anthelmintic drug praziquantel. In vivo studies were conducted with oral administration to Corydoras schwartzi fish with high intensity of intestinal parasites infection. The in vivo experiments confirmed the mucoadhesive and revealed membrane-penetrating properties of the nanoparticle by translocating the parasite cyst, which provided target drug release and reduction of over 97% of the fish intestinal parasites. Thus, it was evidenced that the nanoparticle was effective in transporting and releasing the drug to the target, providing an efficient treatment.

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.

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.

Efficacy of injectable praziquantel for elimination of trematode metacercariae in bluegills (Lepomis macrochirus) and quantification of parasite death by propidium iodide staining

Digenean trematodes have complex life cycles and control of these flatworms can be accomplished by eliminating immature parasite stages from intermediate hosts. In aquaculture systems, presence of trematode metacercariae can negatively impact fish health and lead to economic losses. Posthodiplostomum minimum is a parasite of birds that uses bluegill sunfish (Lepomis macrochirus) as the intermediate host and is commonly found in fish used to stock waterways for recreational purposes. In this study, we evaluated killing of P. minimum metacercariae by injectable praziquantel in naturally infected bluegills. Using propidium iodide staining and motility assessment, we found that 5 mg/kg administered intramuscularly was effective for parasite killing. However, metacercarial death was not apparent until day 7 post-treatment. Our results demonstrated that propidium iodide staining is an effective method for detecting death in metacercariae recovered from treated fish. This method was at least as sensitive as objective motility scoring and provided quantitative assessment of parasite death. Future studies involving treatment of metacercariae in fish with praziquantel may need to be carried out over a period of weeks in order to accurately assess parasite killing and would benefit from using the propidium iodide method.

Praziquantel delivery via moist pellets to treat monogenean parasites of yellowtail kingfish Seriola lalandi: efficacy and feed acceptance

Praziquantel (PZQ) is registered for oral use against Benedenia seriolae infecting Seriola spp. in Japan, but its bitter taste causes poor palatability. Incorporating PZQ in a moist pellet may help mask the flavor to improve intake. Altering delivery, however, may influence efficacy. We assessed the minimum effective concentrations of PZQ in moist pellets delivered by intubation for the monogeneans Zeuxapta seriolae and B. seriolae infecting yellowtail kingfish Seriola lalandi in flow-through tanks. The optimised dose was then evaluated in a sea-cage of S. lalandi to assess feed acceptance and efficacy. During intubation trials, efficacy was assessed as a percent reduction compared to control groups; in the field trial, efficacy was assessed by a percent reduction after treatment. PZQ delivered by intubation at 70 mg kg-1 body weight (BW) for 3 d was 99.7 and 81.7% effective against Z. seriolae and B. seriolae, respectively. Increasing the dose to 120 mg kg-1 BW for 3 d had a similar efficacy against Z. seriolae (98.4%) and increased efficacy against B. seriolae to 89.2%, but partial emesis of the medicated feed was sometimes noted. S. lalandi in a sea-cage at 17°C readily consumed PZQ administered daily in moist pellets at 70 mg kg-1 BW for 3 d (inclusion rate: 5.15 g kg-1), which significantly reduced Z. seriolae and B. seriolae abundance with 99.4 and 81.6% efficacy, respectively. Juvenile B. seriolae were common on the eyes of fish post-treatment which indicates a strategically timed repeat treatment is necessary.

Pharmacokinetics and residue depletion of praziquantel in rice field eels Monopterus albus

We investigated the pharmacokinetic characteristics of praziquantel (PZQ) in rice field eels Monopterus albus. Pharmacokinetic parameters were determined following a single intravenous administration (5 mg kg(-1) body weight [bw]) and a single oral administration (10 mg kg(-1) bw) at 22.0 ± 0.7°C. We also evaluated residue depletion in tissues following daily administration of PZQ (10 mg kg(-1) bw) that was given orally for 3 consecutive days at 22.0 ± 0.7°C. Following intravenous treatment, the plasma concentration-time curve was best described by a 3-compartment open model, with distribution half-life (t(1/2α)), elimination half-life (t(1/2β)), and area under the concentration-time curve (AUC) of 0.54 h, 17.10 h, and 14505.12 h µg l(-1), respectively. After oral administration, the plasma concentration-time curve was best described by a 1-compartment open model with first-order absorption, with absorption half-life (t(1/2Ka)), elimination half-life (t(1/2Ke)), peak concentration (C(max)), time-to-peak concentration (T(max)), and AUC estimated to be 2.28 h, 6.66 h, 361.29 µg l(-1), 5.36 h, and 6065.46 h µg l(-1), respectively. The oral bioavailability (F) was 20.9%. With respect to residue depletion of PZQ, the t(1/2β) values of muscle, skin, liver, and kidney were 20.2, 28.4, 14.9, and 54.1 h, respectively. Our results indicated rapid absorption, rapid elimination, and low bioavailability of PZQ in rice field eels at the tested dosing conditions.

Single Versus Double Dose Praziquantel Comparison on Efficacy and Schistosoma mansoni Re-Infection in Preschool-Age Children in Uganda: A Randomized Controlled Trial

BACKGROUND

Schistosoma mansoni infection is proven to be a major health problem of preschool-age children in sub-Saharan Africa, yet this age category is not part of the schistosomiasis control program. The objective of this study was to compare the impact of single and double dose praziquantel (PZQ) treatment on cure rates (CRs), egg reduction rates (ERRs) and re-infection rates 8 months later, in children aged 1-5 years living along Lake Victoria, Uganda.

METHODOLOGY/PRINCIPAL FINDINGS

Infected children (n= 1017) were randomized to receive either a single or double dose of PZQ. Initially all children were treated with a single standard oral dose 40 mg/kg body weight of PZQ. Two weeks later a second dose was administered to children in the double dose treatment arm. Side effects were monitored at 30 minutes to 24 hours after each treatment. Efficacy in terms of CRs and ERRs for the two treatments was assessed and compared 1 month after the second treatment. Re-infection with S. mansoni was assessed in the same children 8 months following the second treatment. CRs were non-significantly higher in children treated with two 40 mg/kg PZQ doses (85.5%; 290/339) compared to a single dose (83.2%; 297/357). ERRs were significantly higher in the double dose with 99.3 (95%CI: 99.2-99.5) compared with 98.9 (95%CI: 98.7-99.1) using a single dose, (P = 0.01). Side effects occurred more frequently during the first round of drug administration and were mild and short-lived; these included vomiting, abdominal pain and bloody diarrhea. Overall re-infection rate 8 months post treatment was 44.5%.

CONCLUSIONS

PZQ is efficacious and relatively safe to use in preschool-age children but there is still an unmet need to improve its formulation to suit small children. Two PZQ doses lead to significant reduction in egg excretion compared to a single dose. Re-infection rates with S. mansoni 8 months post treatment is the same among children irrespective of the treatment regimen.

Relative competence of native and exotic fish hosts for two generalist native trematodes

Exotic fish species frequently acquire native parasites despite the absence of closely related native hosts. They thus have the potential to affect native counterparts by altering native host-parasite dynamics. In New Zealand, exotic brown trout Salmo trutta and rainbow trout Oncorhynchus mykiss have acquired two native trematodes (Telogaster opisthorchis and Stegodexamene anguillae) from their native definitive host (the longfin eel Anguilla dieffenbachii). We used a combination of field surveys and experimental infections to determine the relative competence of native and exotic fish hosts for these native parasites. Field observations indicated that the longfin eel was the superior host for both parasites, although differences between native and exotic hosts were less apparent for S. anguillae. Experimental infections indicated that both parasites had poorer establishment and survival in salmonids, although some worms matured and attained similar sizes to those in eels before dying. Overall, the field surveys and experimental infections indicate that these exotic salmonids are poor hosts of both native trematodes and their presence may decrease native parasite flow to native hosts.

Effects of praziquantel and sanguinarine on expression of immune genes and susceptibility to Aeromonas hydrophila in goldfish (Carassius auratus) infected with Dactylogyrus intermedius

Praziquantel and sanguinarine have been demonstrated positive therapeutic effects on monogenean Dactylogyrus intermedius; however, few studies have considered the post impacts of these antiparasitic chemicals on host after repelling the parasites. The changes of expression of selected immune genes (CCL-1, CXCL-8, IL-1β-1, IL-1β-2, TNFα-1, TNFα-2 and TGF-β) in gill, kidney and spleen and bacterial loads of Aeromonas hydrophila in gill, kidney, spleen and liver following bath administration of these antiparasitic chemicals were evaluated. The results showed that praziquantel and sanguinarine up-regulated to varying degrees of CXCL-8, IL-1β-1, IL-1β-2, TNFα-1 and TNFα-2 in gill, kidney and spleen. They both decreased the CCL-1 expression in gill while increased it in kidney and spleen. However, in all the tested tissues, the expression of TGF-β decreased in praziquantel treated goldfish whereas that increased in sanguinarine treated goldfish. The A. hydrophila challenge test showed that the praziquantel treatment enhanced the susceptibility to A. hydrophila while sanguinarine treatment decreased the susceptibility, as compared with the non-treated group. Overall, the results indicate that bath administration of praziquantel and sanguinarine modulates the immune related genes in goldfish and these may, to some extent, affect their ability to resist bacterial pathogens.

The effect of praziquantel applied per os on selected haematological and biochemical indices in common carp (Cyprinus carpio L.)

The aim of the study was to assess the effects of the anthelminthic, praziquantel, on the haematological and biochemical indices of the blood of common carp (Cyprinus carpio L.). Fish were divided into six groups: two groups received 30 mg kg(-1) body weight (bw) of praziquantel, and two groups were given 50 mg kg(-1) bw of praziquantel mixed into the heat-treated amyloid vehicle. Fish in the remaining two groups were given only the amyloid vehicle and were used as controls. Fish were examined either 24 or 96 h after administration. Praziquantel treatment was characterised by a significantly lower erythrocyte count, haemoglobin level, packed cell volume and total protein at both dose levels after 24 h compared with the controls, but these parameters were similar to the control values at 96 h. The activity of alanine aminotransferase (ALT) was significantly higher after 96 h in the treated groups, which could be attributed to slight hepatocyte damage caused by praziquantel. However, the differences between the treated and the control groups were not great, and we presumed that they were reversible.

Praziquantel treatment of Biomphalaria glabrata infected with Schistosoma mansoni--influence on snail fecundity

Praziquantel, administered over a 72 h period in the food of mature Biomphalaria glabrata harbouring 7-week-old Schistosoma mansoni infections, dramatically reduced the numbers of cercariae shed. Doses of 20-30 micrograms/g body weight (including shell weight) reduced shedding by 85-95% over 5 weeks before recovery was evident. Suppression of cercarial shedding in these infections was accompanied by the temporary recovery of the snail reproductive regression due to S. mansoni infection. Snail fecundity was subsequently re-suppressed 2 weeks prior to recovery of the parasite as evidenced by a resumption of cercarial shedding. Praziquantel destroyed mature and developing cercariae within the daughter sporocysts but had no apparent effect on daughter sporocysts; this may account for the eventual resumption of cercarial production. Reproductive failure of the snail is apparently related to the latter stages of cercarial development specifically. Reproductive recovery did not occur when snails were infected as juveniles or when mature-infected snails harboured 12.5 week i.e. older infections: drug treatment temporarily inhibited cercarial production but no snails produced eggs.

Chemotherapy of fish parasites

There are few agents on the market that control fish parasites. These are substances that are mainly used in other hosts; due to the different metabolism of fish, they often have only moderate effects on fish parasites. Therefore, the research and development of fish-specific antiparasitic compounds is needed to avoid the high losses suffered by commercial fish hatcheries. Drugs similar to toltrazuril would perhaps be promising, due to their broad spectrum of efficacy.