Biology Department, Faculty of Applied Sciences, Umm Al-Qura University, Makkah, KSA
Received Date: 03/06/2016 Accepted Date: 21/03/2017 Published Date: 22/03/2017
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In this study, histopathological effect of different helminthes on the liver of different Serranid fish has been investigated. The fishes examined for liver helminth infections are Epinephelus tauvina, Epinephelus polyphekadion, Epinephelus summana, and Epinephelus chlorostigma. Herein, helminthes were identified as Anisakis simplex larvae; Thynnascaris larvae; Procamallanus chetumalensisn sp., and Camallanus hypophthalmicthys. The parasites were found in blood sinusoids in between the blood cells and among the hepatocytes. Microscopically examination of liver tissue revealed different histopathological and cellular lesions in liver of infected fishes. The pathological alterations included extensive vacuolization and destruction of most hepatocytes and blood vessels, accumulation of lipid droplets, congestion of blood sinusoids and focal haemorrhage. The heavily infected fish species was E. polyphekadion and the intense infestation was recorded for the parasites Anisakis simplex larvae and Thynnascaris larvae.
Histopathology; Liver; Epinephelus spp; Helminthes parasites
Serranid fishes (Epinephelus spp.) are one of the most important commercial fishes living in the Red Sea. They are widely used in Jeddah restaurant and fish markets. Such marine fish could be infected with a variety of helminthes . At least 30,000 species of helminthes that had already been described from fish were estimated by . Helminth parasites Anisakis simplex, Thynnascaris, Procamallanusc hetumalensis and Camallanus hypo phthalmicthys have been previously described in Serranid fishes (Epinephelus. spp) on Jeddah coast by Maghrabi .
The effect of parasite on the fishes is of considerable importance because of its wide spread occurrence and an intermediate link in the food chain . Some parasitic forms cause serious damage to the tissue and also alter the normal physiology, histology and haematology of the host . Liver is one of the most important glands concerned with several vital functions of the body. It is the chief organ for the process of detoxification and plays an important role in the metabolism of carbohydrates, proteins, lipids, storage of glycogen, denaturation of fatty acids and amino acid synthesis . Therefore, the histological study of liver is a direct evidence of robust effect on the fish health and is helpful in knowing the possible effect of parasitism on the functions of different body systems .
Histopathological changes caused by the Paracryptogonimu shirastrictus (Digenea: Cryptogonimidae) and Raphidascar islutiani Raillietet (Nematoda: Heterocheilidae) include severe destruction and necrosis liver tissue were reported by . Destruction of epithelial cells, inflammation and an increase in thickness of sub-mucosa, atrophy and aggregation of inflammatory cells between hepatocytes.
The present study describes the histopathological findings of the natural infection in the liver of some Serranid fishes caused by helminthic parasites on the coast of Jeddah.
200 specimens of the Serranid fish species namely Epinephelus tauvina, Epinephelus polyphekadion, Epinephelus summana, and Epinephelus chlorostigma were collected from Al-Bangalla fish market-Jeddah coast, Red Sea at Saudi Arabia and were transported alive to the laboratory for parasitological examination.
During dissection of fish the number of parasites and their distribution within the infected liver were carefully recorded. Samples of infected liver were immediately fixed in Bouin, washed in distilled water, dehydrated in alcohol, cleared in xylene and embedded in paraffin wax. Sections were cut at 5-6 μm, stained with haematoxylene eosin and mounted with DPX. Finally, through the microscopic examination, photographs had been picked from infested tissues with different helminthes.
Helminthes were identified as Anisakis simplex larvae; Thynnascaris larvae; Procamallanus chetumalensisn sp. and Camallanus hypophthalmicthys. The heavily infected fish spcecies was E. polyphekadion and the intense infestation was recorded for the parasites Anisakis simplex larvae and Thynnascaris larvae.
Liver histology of control fish Epinephelus spp. exhibited the normal structural features. The hepatocytes are arranged in branching and anastomosing cords interrupted by hepatic sinusoids (Figure 1).
The microscopic study of most examined liver specimens of different Epinephelus species infected with helminthes parasites revealed different histopathological and cellular lesions. Sections of Anisakis simplex i Thynnascaris i larvae, were clearly detected in blood sinusoids in between the red blood cells (Figure 2) as well as among the hepatocytes (Figure 3). While, other infected parts of liver were appeared with attached flukes to the serosal coat and damaged the liver tissue itself (Figures 4-6).
Moreover, different alterations were recorded in the liver structure of the infected fishes. Extensive vacuolization and dilatation of most hepatocytes was clearly observed in E. polyphekadion (Figure 7) infected with Thynnascaris larvae. The boundary of many cells was invisible and lipid droplets were accumulated in the hepatic cells.
The liver hepatocytes of E. chlorostigma infected with Anisakis simplex larvae lost their specific shape and appeared necrotic, pale and without nuclei. Other hepatic cells appeared cloudy swollen with pyknotic nuclei (Figure 8). In addition, there was a distinct congestion of the central vein and hepatic sinusoids with focal haemorrhage in E. summana and E. tauvina infected with Anisakis simplex and Thynnascaris larvae (Figures 9 and 10).
Melanomacro phage centre cells proliferation and Kupffer cells activation were characteristic in E. twvina and E. polyphekadion hepatocytes infected with Anisakis simplex and Thynnascaris larvae (Figures 11 and 12). Destruction of the hepato pancreatic cells around the parasite could be clearly observed in E. chlorostigma infected with Anisakis simplex (Figure 13). Leucocytes infiltration was apparent along the parenchymal hepatocytes, around the parasite and in the blood vessels in E. polyphekadion infected with Anisakis simplex and Thynnascaris larvae (Figure 14).
The present study describes the histopathological alterations induced by different helminthic parasites in Serranid fish. Many parasitologists studied histopathology caused by helminth parasites which cause damage to its habitat with the strong armed holdfast organs. The distribution of parasites within the fish liver is variable and they may damage the liver at the point of their attachment . In addition to Hanchla Devi and Pinky Kau studied the effect of helminth parasites in mastacembalus armatus with special reference to hepato-somatic index. As morphologically, infected liver appeared pale yellow and very thin in size. External surface showed few encysted parasites. Histologically, infected liver showed loosening in hepatic parenchyma, irregular lobular arrangement and necrosis. Most of the hepatocytes are indistinguishable with eccentric and enucleated .
The results of this study revealed that there was damage in liver of infected fishes. Vacuolization and dilatation of most hepatocytes were noticed in E. polyphekadion infected with Anisakis simplex larvae and Thynnascaris larvae. While, necrotic hepatocytes with pyknotic nuclei were observed in E. chlorostigma infected with Anisakis simplex larvae. Similar alterations were recorded by Lakshma in liver of fresh water fish Channapunctatus infected with Euclinstomum heterostomum and by Pardeshi in liver of Mastacembelus armatus infected with Allocrea diumkhami. Loosening of hepatic tissue and necrosis of hepatocytes were found in Nandusnandus (Ham.) parasitized by metacercariae of Clinostomum complanatum [9,10]. Atrophy of the liver tissue of C. punctatus due to E. heterostomum infection, which may be a result of inflow of nutrients from the host tissue to the metacercariae, was observed by . They also observed compressed and distorted hepatocytes due to the metacercarial growth in the liver.
Moreover, the results of the present study showed congestion of blood vessels with focal haemorrhage and destruction of hepatic cells in E. summana and E. tauvina infected with Anisakis simplex larvae. Severe necrotic hepatitis and haemorrhages in Thalassomak lunzengri fish infested with helminth parasites were recorded by . He reported that these alterations in the infected tissue could be a direct result of the attachment of the parasites to the wall of the organ which causes damage, degeneration and inflammatory reactions in the infected tissues. Also, El-Mansy mentioned that the nematode parasite Procamallanus laevichonchus lead to haemorrhage at attachment site in the infected fish tissue. According to Bamidele, fish in intensive culture are continuously affected by environmental fluctuations which can cause considerable stress on the homeostatic mechanism of fish, rendering them susceptible to a wide variety of pathogens [1,13].
From the present study, it was concluded that Serranid fish is highly infected with different types of helminthic parasites and the parasitic infection induces severe damage to liver tissue. Also, it is obvious that Anisakis simplex larvae and Thynnascaris larvae might be considered as more negative on fish health