DETECTION OF CONTRACAECUM SP. LARVAE (NEMATODA: ANISAKIDAE) IN TRACHURUS MEDITERRANEUS AND BOOP BOOPS FISH IN TRIPOLI, LIBYA
GEHAN S. SADEK1, SAMIRA S. RAZEIKA2, OSAMA R. EL-WAAER3 AND WALEED S. SOLIMAN4
Department of Parasitology1, Faculty of Medicine, Menoufiya University, Shebin El-Kom, Egypt, Department of Fish and Poultry Diseases2,4 and Department of Parasitology3, Faculty of Veterinary medicine, El-Fateh University, Tripoli, Libya Present address¹: Department of Parasitology, Faculty of Medicine, Menoufiya University, Shebin El Kom, Egypt. e-mail: firstname.lastname@example.org
Nematode infections in marine fish cause a range of problems. The most important of these problems are health hazards connected to human ingestion of live nematodes in fresh or undercooked fish. Of the nematodes parasitizing marine fish, members of family Anisakidae (e.g. Anisakis spp. and Contracaecum spp.) causing human infections are relatively well documented. Human infection is acquired by the ingestion of raw, pickled, salted or smoked saltwater fish containing the third stage larvae. The larvae often penetrate into the wall of the digestive tract, where they become embedded in eosinophilic granulomas. Depending on the location of the larvae, infections can mimic gastric or duodenal ulcer, carcinoma, appendicitis or other conditions requiring surgery. Unfortunately, there is no recommended therapy other than removal of the larvae through surgery. No studies were performed in Libya to determine the presence of larvae of family Anisakidae in marine fish. So, the aim of the present work was to detect whether larvae of family Anisakidae are present in marine fish in Tripoli, Libya or not. During the period from January 2010 to December 2010, 90 Trachurus mediterraneus and 80 Boop boops fish were collected from Tripoli and examined for the presence of larvae of family Anisakidae. The detected larvae were identified according to certain measurements such as total length, presence of three lips in the mouth, presence of cephalic tooth, oesophagus length, ventricular appendix length and the ratio of the length of intestinal caecum to the ventricular appendix and oesophagus. The prevalence and mean intensity of infection in each type of fish were recorded. Also, the organs affected in each type of fish were recorded. All the recovered larvae were identified as Contracaecum spp. Prevalence of infection was 45.5% in Trachurus mediterraneus fish and 17.5% in Boop boops fish. Difference between the prevalence of infection in the two types of fish was found to be highly statistically significant. Mean intensity of infection (mean number of larvae/fish) was found to be 190.8±52.143 for Trachurus mediterraneus fish and 98.22±56.25 for Boop boops fish. Difference between them was highly statistically significant. In Trachurus mediterraneus fish, the most frequent affected part was the mesentery (70.7%), followed by stomach & intestine (68.5%), next liver (36.2%), then muscles (10.3%) and lastly gonads (9.7%). In Boop boops fish, the most frequent affected part was the mesentery (68.96%), followed by liver (51.03%), then gonads (31.03%), next stomach & intestine (17.93%) and lastly muscles (14.48%). It is concluded that Contracaecum larvae are highly prevalent in marine fish in Tripoli, Libya, so further studies should be carried out to determine the extent of susceptible fish hosts, parasite seasonality and the presence of adults in fish eating birds. Health education must be performed about special precautions while consuming salted, pickled and smoked fish. Also, health education must alert people about avoidance of consuming visceral organs of fish. Also, it will be of great value to study the presence of larvae of family Anisakidae in fresh water and marine fish in Egypt to detect whether they play a zoonotic role in Egypt or not.