Efficacy of 6‐, 12‐, and 24‐h Praziquantel Bath Treatments against Asian Tapeworms Bothriocephalus acheilognathi in Grass Carp

Abstract

Praziquantel is an effective anthelmintic treatment that has been used in dogs Canis lupus familiaris and cats Felis catus. It has also been used successfully against tapeworms and trematodes in fish. This study tested the efficacy of praziquantel bath treatments (6, 12, or 24 h) at various concentrations (0.187, 0.375, 0.75, 1.5, 3.0, 6.0, 9.0, and 12.0 mg of praziquantel/L of water) for controlling natural infestations of Asian tapeworms Bothriocephalus acheilognathi in grass carp Ctenopharyngodon idella (60-100% of the fish were infested). Treatments either were given as a single application or were applied twice (3 d apart) at fish densities of 60 or 120 g/L. The objective of the study was to find a treatment that would completely eliminate Asian tapeworms from all infested fish, as a number of states now require imported fish to be completely free of this parasite. Most of the praziquantel treatments reduced the percentage containing Asian tapeworms. Single, 24-h bath treatments at praziquantel concentrations of 0.75 mg/L or higher applied to fish held at a density of 60 g/L were the only treatments that completely eliminated Asian tapeworms. Raising the fish density from 60 to 120 g/L affected treatment success; the 24-h, 0.75-mg/L praziquantel treatment at the higher fish density did not completely eliminate Asian tapeworms (prevalence ¼ 15%). A 12-h, 1.5-mg/L praziquantel treatment applied twice to fish held at a density of 60 g/L resulted in low Asian tapeworm prevalence (3.3%).

The pathogenic Asian fish tapeworm, Bothriocephalus acheilognathi Yamaguti, 1934 (Cestoda) in the Red discus (Symphysodon discus)

“…As treatment, praziquantel immersions in dose 2 mg per liter were well tolerated and effi cacious. These baths has been widely used in a several fi sh parasite infections caused by adult cestodes (Moser et al, 1986;Mitchell, 2004;Mitchell et al, 2009). Few hours after application of the antihelminthic treatment, massive release of parasites from their hosts was observed.…”

Novel Praziquantel Treatment Regime for Controlling Asian Tapeworm Infections in Pond‐Reared Fish

“…Minimal effective dosages for field use would need to be investigated. Our concentration of praziquantel (2.5 mg/L in water), although applied at a rate recommended by the manufacturer, was higher than that (0.75 mg/L in water) used by Mitchell and Darwish (2009), which proved effective in single 24-h bath treatments of fish held at a densities up to 60 g/L in 22-L containers. Effects of sediment, longer time exposures of bath treatments, fish densities, and other factors important in field situations would have to be examined to estimate a minimal effective dosage.…”

“…Praziquantel kills a wide range of helminth parasites, but fish, amphibians, reptiles, birds, and mammals tolerate it well (Andrews and Riley 1982). Most recent studies of the effectiveness of praziquantel for fish involved adding it directly to the water (Mitchell 2004;Ward 2007;Mitchell and Darwish 2009). These simple bath treatments are effective, expose all fish to the treatment, and avoid handling stress.…”

“…These simple bath treatments are effective, expose all fish to the treatment, and avoid handling stress. With adequate dosage and duration of treatment, 100% of Asian tapeworms can be eliminated from captive fish in a safe manner (Mitchell 2004;Ward 2007;Mitchell and Darwish 2009). In fact, many state agricultural and food departments have mandatory tapeworm eradication procedures that use praziquantel for the intraand interstate movement of live fish (e.g., UDAF 1997).…”

Effects of Praziquantel on Eggs of the Asian Tapeworm Bothriocephalus acheilognathi

“…These concerns have prompted studies into methods of control and treatment for Asian tapeworm, including the use of anthelmintics such as praziquantel (Droncit), developed by Bayer Corporation for treatment of tapeworm infestation in humans and animals (Andrews et al 1983). Fisheries managers and aquaculturists commonly use praziquantel to treat Asian tapeworm infections in fish (Mitchell 2004;Ward 2007;Mitchell and Darwish 2009). Praziquantel offers an advantage over other control methods because it allows the removal of Asian tapeworm without harming the host fish.…”