Clinical, histopathological and phylogenetic analysis of Myxobolus lentisturalis (Myxozoa: Myxobolidae) infecting the musculature of farmed population of goldfish (Carassius auratus) in Iran: 2021-2022.

There is a claimed increase in the global prevalence and incidence of emerging diseases observed in many organisms. Myxozoa represents an essential group of metazoan parasites that hold both economic and ecological significance. In the current study, 1% of the fish population at two commercial goldfish (Carassius auratus) farms in Tehran and Ghom province, Iran, developed cavitating muscular lesions resembling humps in February 2021 and January 2022. Fish displaying pathological abnormalities were transported to the Ornamental Fish Clinic and subjected to clinical examination. Light microscopy was subsequently used to examine wet smears of skin and gills, as well as whitish exudate. In addition, tissue homogenates were collected for more precise identification and molecular confirmation. The study discovered that individuals from the goldfish farms were infected with the pathogenic myxozoan Myxobolus lentisuturalis, which caused significant damage to the epaxial muscles. The spores collected from the humps had a lack of uniformity and were primarily ellipsoidal in shape. Histopathological analysis also revealed parasites in various stages of development, such as plasmodia and spores, as well as inflammatory cell infiltration (macrophage, giant cell and lymphoplasmacytic infiltration) between skeletal muscle fibers. Phylogenetic analysis of M. lentisuturalis was performed by using MEGA 11 and the maximum likelihood method. M. lentisuturalis is a myxozoan parasite that has been sparsely recorded and lacks widespread recognition. The current study is the first clinical, histopathological, and molecular characterization of M. lentisuturalis isolated from the skeletal musculature of goldfish (C. auratus) in Iran.

The in vitro and in vivo effect of tannic acid on Ichthyophthirius multifiliis in zebrafish (Danio rerio) to treat ichthyophthiriasis.

The in vitro antiparasitic effect of polyphenol tannic acid (TA) on Ichthyophthirius multifiliis theronts and tomonts was evaluated. In vitro antiparasitic assays revealed that TA in a dose- and time-dependent pattern through the damage of parasite plasma membrane could be 100% effective against I. multifiliis theronts at concentrations of 8 and 11 ppm during all the exposure times (45-270 min). The tomonts proliferation was completely inhibited by penetrating TA (at least 15 ppm for 22-hr exposure) into encysted tomont across the cyst wall. However, 10 ppm TA could result in a ninefold decrease in the population of live tomonts compared to the control group (p < 0.05). Although at theront concentrations of over 6,000 per zebrafish (Danio rerio), a 100% prevalence of ichthyophthiriasis during a 5-day exposure was recorded, results of in vivo tests showed that the parasite that pretreated up to 10 ppm TA for 70 min had not any capability to infect the studied zebrafish population. The acute toxicity (96 hr-LC50 ) of TA for zebrafish was 19.51 ppm. Thus, TA can be considered as a natural therapeutant to safely and efficiently improve the health of aquatic systems by controlling ichthyophthiriasis.

Evaluation of the antifungal activity of Zataria multiflora, Geranium herbarium, and Eucalyptus camaldolensis essential oils on Saprolegnia parasitica-infected rainbow trout (Oncorhynchus mykiss) eggs.

The purpose of the present study was to evaluate and assess the capability of Zataria multiflora, Geranium herbarium, and Eucalyptus camaldolensis essential oils in treating Saprolegnia parasitica-infected rainbow (Oncorhynchus mykiss) trout eggs. A total of 150 infected eggs were collected and plated on glucose-pepton agar at 24°C for 2 weeks. The antifungal assay of essential oils against S. parasitica was determined by a macrodilution broth technique. The eggs were treated with essential oils at concentrations of 1, 5, 10, 25, 50, and 100 ppm daily with three repetitions until the eyed eggs stage. Of 150 eggs examined, S. parasitica (54.3%), Saprolegnia spp. (45%), and Fusarium solani (0.7%) were isolated. The minimum inhibitory concentrations of Z. multiflora, E. camaldolensis, and G. herbarium essential oils against S. parasitica were 0.9, 2.3, and 4.8 ppm, respectively. Zataria multiflora and E. camaldolensis at concentrations of 25, 50, and 100 ppm, and G. herbarium at concentration of 100 ppm had significant differences in comparison with negative control (p<0.05). The results revealed that malachite green, followed by Z. multiflora, E. camaldolensis, and G. herbarium treated eggs had remained the most number of final eyed eggs after treatment. The highest final larvae rates belonged to malachite green, E. camaldolensis, Z. multiflora, and G. herbarium, respectively. The most hatching rates were recorded with malachite green (22%), and then Z. multiflora (11%), E. camaldolensis (7%), G. herbarium (3%), and negative control (1%). Zataria multiflora and E. camaldolensis were more effective than G. herbarium for the treatment of S. parasitica-infected rainbow trout eggs in aquaculture environment.