SQ20203.2010.part2

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Phylum : 

Phylum Protozoa Mollusk Platyhelminthes 1

Epistylis : 

Epistylis 2 Phylum ciliophora

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These parasites are called sessile peritrichs, and are found in freshwater fish. They can be seen to be a large body rooted to the epidermis by a stalk (hence `sessile'). Interestingly, the parasite only uses the fish for attachment; it does not feed on the host, so it is not a true parasite. However through the attachment, wounding is created and secondary bacterial and fungal infection often follows. 3

Vorticella : 

Vorticella 4

Oodinium - : 

Oodinium - Phylum : dinoflagellate Very similar to Ichthyophthirius 5

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Phylum Platyhelminthes Trematodes, the flukes are divided into ecto-parasitic (external) monogenes and the largely endo-parasitic (internal) digenes on the basis of their life histories. 6

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MONOGENEAN TREMATODES Monogenean trematodes, also called flatworms or flukes, commonly invade the gills, skin, and fins of fish. Monogeneans have a direct life cycle (no intermediate host) and are host- and site-specific. In fact, some adults will remain permanently attached to a single site on the host. 7

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Freshwater fish infested with skin-inhabiting flukes become lethargic, swim near the surface, seek the sides of the pool or pond, and their appetite dwindles. They may be seen rubbing the bottom or sides of the holding facility (flashing). The skin where the flukes are attached shows areas of scale loss and may ooze a pinkish fluid. 8

Gills may be swollen and pale, respiration rate may be increased, and fish will be less tolerant of low oxygen conditions. "Piping", gulping air at the water surface, may be observed in severe respiratory distress. Large numbers (>10 organisms per low power field) of monogeneans on either the skin or gills may result in significant damage and mortality. Secondary infection by bacteria and fungus is common on tissue with monogenean damage. : 

Gills may be swollen and pale, respiration rate may be increased, and fish will be less tolerant of low oxygen conditions. "Piping", gulping air at the water surface, may be observed in severe respiratory distress. Large numbers (>10 organisms per low power field) of monogeneans on either the skin or gills may result in significant damage and mortality. Secondary infection by bacteria and fungus is common on tissue with monogenean damage. 9

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Gyrodactylus and Dactylogyrus are the two most common genera of monogeneans that infect freshwater fish. They differ in their reproductive strategies and their method of attachment to the host fish. 10

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Gyrodactylus have no eyespots two pairs of anchor hooks generally found on the skin and fins of fish. They are live bearers (viviparous) in which the adult parasite can be seen with a fully developed embryo inside the adult's reproductive tract. This reproductive strategy allows populations of Gyrodactylus to multiply quickly, particularly in closed systems where water exchange is minimal. 11

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Gyrodactylus 12

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Dactylogyrus prefers to attach to gills. They have two to four eyespots, one pair of large anchor hooks, and are egg layers. The eggs hatch into free-swimming larvae and are carried to a new host by water currents and their own ciliated movement. The eggs can be resilient to chemical treatment, and multiple applications of a treatment are usually recommended to control this group of organisms. 13

Dactylogyrus : 

Dactylogyrus 14

Treatment of monogeneans is usually not satisfactory unless the primary cause of increased fluke infestations is found and alleviated. The treatment of choice for freshwater fish is formalin, administered as a short-term or prolonged bath. Fish that are sick do not tolerate formalin well, so they need to be carefully monitored during treatment. Potassium permanganate can also be effective in controlling monogeneans. : 

Treatment of monogeneans is usually not satisfactory unless the primary cause of increased fluke infestations is found and alleviated. The treatment of choice for freshwater fish is formalin, administered as a short-term or prolonged bath. Fish that are sick do not tolerate formalin well, so they need to be carefully monitored during treatment. Potassium permanganate can also be effective in controlling monogeneans. 15

Zoonosis : : 

Zoonosis : is any infectious disease that may be transmitted from other animals, both wild and domestic, to humans or from humans to animals. 16

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An estimated 17 million persons worldwide are infested: 7 million with C. sinensis, 9 million with O. viverrini, and 1.6 million with O. felineus. O. viverrini is prevalent in Thailand, Lao People's Democratic Republic, and Cambodia; C. sinensis is widespread in Korea, China, Taiwan, and Vietnam; and O. felineus is found in the Russian Federation and eastern Europe. 18

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Migration and global tourism are responsible for cases diagnosed in areas where the disease is not endemic. 19

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DIGENEAN TREMATODES Digenean trematodes have a complex life cycle involving a series of hosts . Fish can be the primary or intermediate host depending on the digenean species. They are found externally or internally, in any organ. For the majority of digenean trematodes, pathogenicity to the host is limited. 20

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The life stage most commonly observed in fish is the metacercaria, which encysts in fish tissues. Again, metacercaria that live in fish rarely cause major problems. However, in the ornamental fish industry, digenetic trematodes from the family Heterophyidae, have been responsible for substantial mortalities in pond-raised fish. These digeneans become encysted into gill tissue and respiratory distress is eminent. 21

THE LIFE CYCLE (~3 MONTHS) : 

THE LIFE CYCLE (~3 MONTHS) 1. Embryonated eggs are discharged in the biliary ducts and in the stool.   Eggs are ingested by a suitable snail intermediate host. 2. ASEXUAL REPRODUCTION TAKES PLACE IN THE SNAIL HOST  Each egg releases a miracidia, which goes through several developmental stages:  Sporocysts,  Rediae,  Cercariae . 22

3. DEVELOPMENT INTO METACERCARIAE TAKES PLACE IN FRESHWATER FISH : 

3. DEVELOPMENT INTO METACERCARIAE TAKES PLACE IN FRESHWATER FISH The cercariae are released from the snail and, after a shot period of time swimming free in the water, they come into contact with and penetrate the flesh of freshwater fish.     They discard their tails and encyst as metacercariae in the subcutaneous tissue or in the muscles 23

4. DEVELOPMENT INTO ADULT FLUKES TAKES PLACE IN HUMANS AND RESERVOIRS : 

4. DEVELOPMENT INTO ADULT FLUKES TAKES PLACE IN HUMANS AND RESERVOIRS Infection of humans and reservoir hosts occurs by ingestion of undercooked, salted, pickled, or smoke freshwater fish.  After being acted on by peptic acid within the stomach, the metacercariae encyst in the duodenum .   They then ascend the biliary tract,using their suckers to move against the flow of bile and migrate to the smaller biliary radicles, especially in the left lobe of the liver.  At this point maturation occurs, which takes approximately 1 month.  The adults flukes reside in small and medium sized biliary ducts, and can live up to 30 years.  These adult flukes then shed eggs in the bile. 24

Digenean Trematodes : 

Digenean Trematodes 25

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Liver fluke infection caused by trematodes belonging to the family Opisthorchiidae Opisthorchis viverrini, O. felineus, and Clonorchis sinensis —is a major public health problem in many parts of the Far East, Southeast Asia, and eastern Europe. 26

Clonorchis sinensis = liver fluke : 

Clonorchis sinensis = liver fluke 27

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The easiest way to prevent infection with Clonorchiasis is to avoid eating raw or undercooked fresh water fish.    Additionally, “night soil” (fertilizer contaminated with human feces) is used in many regions to fertilize fish ponds to increase fish production.  This practice stimulates snail growth and increases the number of secondary hosts.  Measures have been taken to control the snail population but were not successful.  In the People’s Republic of China, the slaughter of animals who are reservoirs for the disease (dogs and cats) has probably reduced transmission of the disease in that area. 29

NEMATODES : 

NEMATODES Nematodes, also called roundworms, occur worldwide in all animals. They can infect all organs of the host, causing loss of function of the damaged area. Signs of nematodiasis include anemia, emaciation, unthriftiness and reduced vitality. 30

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G. spinigerum has a multi-host life history. The eggs hatch in fresh water and the larvae are eaten by water fleas of the genus Cyclops. The water fleas are in turn eaten by small fish. Eventually, the larvae end up in the stomachs of carnivores, usually cats and dogs. The larva bores through the stomach wall and migrates around in the host's body for about three months before returning to the stomach and attaching itself in the gastric mucosa. 31

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1) Unembryonated eggs deposited in the intestinal lumen of either the avian or human host are expelled in the feces. (2) The unembryonated eggs become embryonated while in the fresh- or brackish-water. (3) The embryonated eggs are ingested by fresh- or brackish-water fish which serve as the intermediate host for the Capillaria philippinensis. Inside the intestinal lumen of the fish, the larvae hatch, burrow through the intestinal mucosa, and permeate the fish's mesenteric and peripheral tissues. 34

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(4) The parasite enters the intestinal lumen of humans, fish-eating birds, and other animal hosts upon ingestion of raw or undercooked C. philippinensis infected fish. (5) The adult worms of Capillaria philippinensis burrow into the intestinal mucosa (most typically of the jejunum). 35

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(6)While in the intestinal lumen of the human or avian host, the female worms deposit unembryonated eggs, which are subsequently expelled in the host's feces. (Albeit a rare occurence, the eggs of Capillaria philippinensis may become embryonated within the intestine of the human host. The subsequent release of infective larvae leads autoinfection and hyperinfection. 36

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CESTODES : 

CESTODES Cestodes, also called tapeworms, are found in a wide variety of animals, including fish . The life cycle of cestodes is extremely varied with fish used as the primary or intermediate host. Cestodes infect the alimentary tract, muscle or other internal organs. 38

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One of the most serious adult cestodes that affect fish is the Asian tapeworm, Bothriocephalus acheilognathi . It has been introduced to the United States with grass carp and has caused serious problems with bait minnow producers. 39

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Larval cestodes called plerocercoids are some of the most damaging parasites to freshwater fish. Plerocercoids decrease carcass value if present in muscle, and impair reproduction when they infect gonadal tissue. Problems also occur when the cestode damages vital organs such as the brain, eye or heart. 40

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Praziquantel at 2 -- 10 mg/L for 1 to 3 hours in a bath is effective in treating adult cestode infections in ornamental fish. At this time, there is no treatment that can be used for food fish. Also, there is no successful treatment for plerocercoids. Ponds can be disinfected to eradicate the intermediate host, the copepod. 41

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Diphyllobothrium latum exhibits little host specificity as indicated by this graphic with humans and bears as two potential definitive hosts.  These pseudophyllidean tapeworms are located in the small intestine and pass egg capsules which exit via a uterine pore.  If the feces are deposited in freshwater, embryonation of 8 days to several weeks results in the emergence of a ciliated known as a coracidium.  Copepods of a variety of genera including Cyclops and Diaptomus may ingest the coracidium where it develops into a procercoid in the hemocoel of the crustacean. 42

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When the infected copepod is eaten by a wide variety of freshwater fish, the procercoid develops into a plerocercoid in the muscles of the fish.  Smaller fish may serve as paratenic hosts when eaten by larger fish.  If humans, bears or any other suitable definitive host eats the fish raw or poorly cooked, the plerocercoid develops into the adult worm. 43

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In addition, copepods may accidentally be ingested by humans or other definitive hosts while drinking copepod-contaminated water.  In those cases, the plerocercoid may develop in the definitive or final host as a sparaganum.  The condition in which plerocercoids or spargana develop in the definitive host is known as sparaganosis.  Since the spargana are difficult to identify to species, a number of non-human infecting tapeworms may lead to sparganosis through accidental ingeston of infected copepods.  Diphyllobothrium mansonoides, a tapeworm of cats, is most likely the culprit in sparganosis in North 44

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Pengawalan Penyakit Ikan : 

Pengawalan Penyakit Ikan Untuk mengelakkan kematian dan kerugian yang besar; “Pengawalan penyhakit ikan lebih baik daripada rawatan”. Faktor tekanan adalah salah satu faktor yang boleh menyebabkan penyakit. 7 Langkah-langkah Pengawalan: 46

1. Ciri-ciri kolam : 

1. Ciri-ciri kolam Pemilihan tapak = lokasi dipilih untuk pembinaan kolah terletak di tempat tinggi seperti lereng bukit supaya kolam mudah dikeringkan. Jika kolam tidak dapat dikeringkan dengan sempurna, patogen tidak dapat dihapuskan dan mendatangkan penyakit bila ikan baru dimasukkan ke dalam kolam. Kedalaman air kolam adalah 1- 5 m untuk mengelakkan perubahan suhu yang cepat. Air kolam cetek yang cetek mudah panas waktu siang dan sejuk apabila hujan. 47

2. Sumber dan Mutu Air : 

2. Sumber dan Mutu Air Mutu air mesti yang baik; pH 6-9; tidak mengandungi bahan cemar organik;bahan kimia buangan dan tidak terlalu keruh. Sumber air yang cukup dan sentiasa mengalir walaupun musim kemarau. Jika ikan bergantung kepada microalgae, air mengalir mesti dihadkan bagi mengelakkan makanan tersebut hanyut keluar. Kolam mempunyai “outlet dan inlet” yang berasingan supaya penyakit ikan tidak merebak daripad sebuah kolam ke kolam lain. 48

3. Pengawalan Patogen : 

3. Pengawalan Patogen Jika kemungkinan ikan liar membawa masuk penyakit ke dalam kolam, penapis (batu + pasir) diperlukan. Ini juga dapat mengawal kemasukan siput dan parasit seperti Lernea dan Argulus. Untuk tempat penetasan, lampu UV digalakkan. UV dapat menghapuskan bakteria dan virus. Pengapuran perlu apabila kolam dikeringkan. Ia dapat membunuh patogen dan mengawal keasidan dasar kolam. 865 kg : 1 hektar kolam. 49

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Anak ikan yang baru dibeli mesti dirawat terlebih dahulu dgn. Formalin (200 ppm) selama 10-20 minit sebelum masuk ke dlm kolam. Anak ikan juga boleh dirawat dlm. Tangki/kolam kecil selama 1-2 minggu utk. Memastikan ikan tidak mempunyai penyakit sebelum masuk dalam kolam. Langkah-langkah rawatan ikan tidak pelu jika ikan dibeli dari hatceri yang bebas dari penyakit. Sebelum proses pengawanan induk mesti dirawat menggunakan formalin bagi mengelakkan patogen merebak ke anak ikan. 50

4. Pembajaan kolam : 

4. Pembajaan kolam Anak ikan hanya dimasukkan ke dlm kolam selepas 1 minggu kolam dibajakan . Selepas ikan dimasukkan pembajaan peru untuk plankton. 51

5. Makanan Ikan : 

5. Makanan Ikan Kadar pemberian makanan mesti seperti yang disyorkan utk elakkan pencemaran air dan mutu air merosot. Ikan baja yang busuk tidak sesuai untuk ikan. Pellet ikan perlu disimpan ditempat khas untuk kekalkan zat makanan. 52

6. Pengurusan kolam/tangki/sangkar : 

6. Pengurusan kolam/tangki/sangkar Kadar pelepasan ikan mesti mengikut yang ditetapkan. Jika berlebihan akan menyebabkan tekanan dan tumbesaran perlahan. Siput dan burung perlu dihindarkan dari persekitaran kolam kerana terdapat parasit yang mempunyai kitaran hidup melaluinya. Alatan di hatceri juga perlu dikawal utk. Mengelakkan penyakit merebak. Rendam dalam Iodophor (200 ppm) dan dikeringkan sebelum diguna semula. Jaring perlu sentias dibersihkan dan dikeringkan. 53

7. Pengangkutan Ikan : 

7. Pengangkutan Ikan Untuk destinasi jauh ikan perlu dilaparkan selama 12 jam. MS-222 (ubat bius) 10 ppm = ikan tidak merasakan tekanan dan pelalian ini mengurangkan penggunaan O2. Jika ikan luka, ubat Furanace 0.05-0.1 ppm digunakan dalam masa pengangkutan. 54

Cara-cara membuat diagnosa penyakit ektoparasit ikan : 

Cara-cara membuat diagnosa penyakit ektoparasit ikan Ikan mestilah hidup dan menunjukkan tanda-tanda penyakit. Ikan mati??? 5-10 ekor ikan perlu dikaji (bergantung kpd. Kepadatan ikan) Ikan mesti disimpan dalam air atau dalam keadaan basah. Keadaan kering memecahkan parasit. Jika ikan dikaji adalah besar, saraf spinal perlu dipotong utk. elakkan ikan melompat. Ikan diletakkan dalam talam dengan sedikit air dan dikaji keadaan insang dan tanda-tanda klinikal di badan. 55

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Tanda-tanda seperti lendir berlebihan, bintik putih, kesan-kesan merah dll mesti direkodkan. Argulus atau Lernea dapat dilihat dengan mata kasar. Pisau digunak untuk mengambil lendir dari badan, sirip dan insang dipindahkan ke slaid. Jika lendir kering, letakkan 2-3 titik air. Tutup lendir dengan penutup slaid. Perhatikan di bawah mikroskop (x 40) Rekodkan pemerhatian. Untuk pengenalpastian, rujuk buku-buku berkenaan. Faktor-faktor lain seperti mutu air dan faktor tekanan juga perlu dikaji. 56

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