TREMATODES INTRODUCTION Trematodes are unsegmented helminths Flat broad

TREMATODES

INTRODUCTION Trematodes are unsegmented helminths Flat & broad resembling the leaf of a tree or flatfish Fluke derived from ‘Anglo-saxon’ word floc TREMATODES: Large prominent suckers with a hole in the middle (GREEK- trema: hole; eidos: appearance)

ZOOLOGICAL CLASSIFICATION Superfamily Family Genus Species Schistosomatoidea Schistosomatidae Schistosoma S. haematobium S. mansoni S. japonicum S. mekongi S. intercalatum Paramphistomatoid ea Zygocotylidae Gastrodiscoides Watsonius G. hominis W. watsoni Echinostomatoidea Fasciolidae Fasciola Fasciolopsis F. hepatica F. buski Opisthorchioidea Opisthorchiidae Opisthorchis Heterophyidae Clonorchis Heterophyes Metagonimus O. felineus O. viverrini C. sinensis H. heterophyes M. yokogawai Paragonimidae Paragonimus P. westermani Plagiorchioidea

CLASSIFICATION BASED ON HABITAT TREMATODES Blood (Blood fluke) Schistosoma haematobium (vesical & pelvic venous plexus) Schistosoma mansoni (inferior mesentric vein) Schistosoma japonicum (superior mesentric vein) Biliary tract (Liver fluke) Clonorchis sinensis Fasciola hepatica Opisthorchis spp. Gastrointestinal tract (Intestinal fluke) Small intestine Large intestine Fasciolopsis buski Heterophyes heterophyes Metagonimus yokogawai Watsonius watsoni Gastrodiscoides hominis

GENERAL CHARACTERISTICS Flat, unsegmented, leaflike Body cavity absent Size – 1 mm to several cms Distomatous: Oral & ventral suckers (acetabulum) Body covered with integument, also bears spines Alimentary canal present but incomplete: Inverted ‘Y’ Anus absent Excretory system –flame cells, collecting tubules, median bladder opening post. Nervous system present. Reproductive system highly developed. All trematodes are hermaphrodites except the schistosomes. 5 Digenetic: Require 2 hosts

SCHISTOSOMA

Schisto - Split Schisto: split soma: body Bilharzia: “Theodor Bilharz” 8 03 -10 -2020 05: 54: 11

FEATURES DISTINGUISHING SCHISTOSOMES FROM OTHER TREMATODES They are unisexual: DIECIOUS Lack a muscular pharynx Their intestinal caeca reunite after bifurcation to form a single canal They produce non-operculated eggs They have no redia & metacercaria stages The cercariae have forked tails and infect by penetrating the unbroken skin of definitive hosts

Species & Definitive Hosts 8 important species affecting humans S. haematobium, S. mansoni, S. japonicum S. malayensis, S. mekongi, S. intercalatum S. curassoni Definitive hosts: Man, Monkey, Chimpanzee, Baboon, Goats, Antelope, Dogs, Cats, Rodents etc. S. bovis S. mattheei 10 : Cattle : Horse

Intermediate Hosts Fresh Water Snails S. haematobium S. mansoni S. japonicum S. malayensis S. mekongi - Bulinus, Phosopsis - Biomphalaria - Oncomelania - Robertsiella - Neotricula Oncomelania 11 Biomphalaria Bulinus

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Disease types & Distribution Type Urogenital Intestinal 13 Species Geographical distribution S. haematobium Africa, Middle East S. mansoni Africa, Middle East, Caribbean, Brazil, Venezuela S. intercalatum Rainforests of central Africa S. japonicum China, Indonesia, Philippines S. mekongi Cambodia, Lao

L I F E C Y C L E 14 03 -10 -2020 05: 54: 20

Cercaria Miracidium – Little Boy Schistosomulum 15

Predisposing & Risk Factors Defaecation and urination near water sources Presence of snails Bathing Household works Fishing Rice fields 16 03 -10 -2020 05: 54: 23

S. haematobium Mainly in Africa and middle east Vesical, prostatic and uterine venous plexus Endemic haematuria or urinary schistosomiasis 20 – 30 years Life cycle – Snails in India are Ferrissia tenuis (Ratnagiri, Maharashtra) Male 1 – 1. 5 cm x 1 mm Female 2 cm x 0. 25 mm Eggs are laid longitudinally and fills the venules Attach themselves by spines Submucosa → Mucosa → Passed in urine 17

Eggs & Lesions 18 03 -10 -2020 05: 54: 30

Stage 1: Migratory Phase Rashes and itchy skin [Dermatitis] SWIMMER’S ITCH Respiratory symptoms [Eg. Cough] 19

Stage 2 : Growth 4 th to 5 th week of entry Due to release of toxic metabolites as schistosomulae grow in portal system General anaphylactic reaction: Fever, urticaria, eosinophilia Tender Hepato-splenomegaly KATAYAMA FEVER 20

Stage 3 : Egg laying Due to egg laying Painless terminal haematuria Granuloma or a pseudotubercle Fibrosis Calcification around the eggs 21

Ectopic Lesions & Complications Lungs – Fibrosis, endarteritis Portal hyprtension and Cor pulmonale Space occupying lesions in brain and spinal cord Internal haemorrhage Chronic infection – Vesical cancer (SCC) 22

S. mansoni Manson’s blood fluke Africa and South America Snails – Biomphalaria and Australorbis glabratus Recto-sigmoidal venous plexus Intestinal bilharziasis Eggs - Faeces 23 03 -10 -2020 05: 54: 36

Clinical Features Similar Mainly due to intestinal involvement Abdominal discomfort Dysentery Complications Hepatosplenomegaly Cirrhosis PTH, Varices, Haematemesis Cor-Pulmonale, Myelitis 24 03 -10 -2020 05: 54: 39

S. japonicum Oriental blood fluke Asian schistosomiasis Intestinal and Hepatic Schistosomiasis Snails – Oncomelania species Habitat Superior mesenteric veins – Ileum, Caecum Intrahepatic portal vein Rectal or haemorrhoidal veins Eggs - Faeces 25 03 -10 -2020 05: 54: 41

Pathogenesis Similar to S. mansoni, But more pronounced. Due to larger egg load Proximity to liver Liver – Clay pipe stem cirrhosis Not true cirrhosis, Due to fibrosed granulomas Hepatic fibrosis & Calcification Splenomegaly 26

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LAB DIAGNOSIS 28

Microscopy To demonstrate eggs Species identified by characteristic spines Urine – Centrifuged deposit, Filtration Stool – Kato Katz Smear technique Vesical and Rectal biopsy 1. Crushed between 2 slides & examined 2. Histopathology 29 03 -10 -2020 05: 54: 48

Immunological Tests For demonstration of antibodies in serum Falcon assay screening test (FAST/ELISA) Electro Immuno Transfer Blot (EITB) Both tests are approved by CDC For demonstration of antigens by ELISA CAA [Circulating anodic antigen] CCA [Circulating cathodic antigen] 30

Indirect Evidences Eosinophilia, Hypoalbuminaemia Positive aldehyde test Fairley’s Test Similar to other intradermal tests - DTH Cercarial antigen Positive Other Modalities 31 Radiological X rays, CT, USG IVP, Portal Venography

Prevention & Control Avoid Excretion near lakes, ponds & rice fields. Bathing in contaminated water Anti-snail measures Control of cercariae, miracidium. Filtration or boiling water @ 50 o. C/5 min Allow the water to stand in tanks for 48 hrs Doesn’t survive in chlorinated water [Sea water] Early diagnosis & treatment of cases. 32

Treatment Praziquantel 33 For human use and for fish tanks/ponds Metrifonate Oxamniquine Artemisinin, Artemether ? Albendazole

FASCIOLA

FAMILY FASCIOLIDAE: The adult worm is found in the intestine and biliary tract of man and herbivorous animals These are relatively large flukes characterized by the presence of ventral sucker close to the oral sucker and spinose tegument The eggs are large and undeveloped when freshly laid.

Fasciola hepatica F. hepatica is the main species which causes human fascioliasis throughout the world It was the first trematode to be described by de Brie in the year 1379 It was also the first trematode for which complete life cycle was worked out

HABITAT Adult flukes primarily live in the bile tract of infected domestic and wild herbivorous animals and of humans.

MORPHOLOGY Adult worms: F. hepatica relatively is a large, flat and leaf-shaped brown coloured fluke The fluke measures 2. 5 cm to 3 cm in length and 1. 5 cm in breadth The anterior end shows a distinct conical projection while the posterior end is rounded

Contd…. Egg: The eggs are large, ovoid and bile-stained and have a small, but distinct operculum They measure 130 -150 µm by 63 -90 µm These are unembryonated when freshly passed The eggs are excreted in the bile into the duodenum, from where they are excreted out in the faeces Further development of the eggs take place only in water

INFECTIVE FORM Metacercaria: It is the infective form for man and other definitive hosts. It is found on the surfaces of aquatic vegetations and water cress.

LIFE CYCLE DEFINITIVE HOST: Sheep is the principal definitive host Goat, cattle and other herbivorous animals and humans are the other definitive hosts

INTERMEDIATE HOSTS First intermediate host: Amphibian snails of the family Lymnaeidae are the first intermediate hosts Second intermediate host: Aquatic vegetations and water cress are the second intermediate hosts. They harbour metacercaria Pre-patent period is 4 to 6 months.

EPIDEMIOLOGY Fascioliasis occurs worldwide in temperate regions, except Oceania Prevalent in specific tropical areas of Southern Asia, Southeast Asia, Americas, Europe & Africa Aquatic vegetations and water cress contaminated with the metacercariae: Main source of infection Sheep is the key reservoir Man is an accidental host

CLINICAL FEATURES Acute fascioliasis Chronic fascioliasis Complications: Ascending cholangitis Severe anaemia Pancreatitis Halzoun in Lebanon or Marrerra in Sudan is a distinct syndrome of fascioliasis

LABORATORY DIAGNOSIS Stool microscopy: It is based on the microscopic demonstration of eggs in the faeces Microscopy of faeces is very useful in the diagnosis of chronic fascioliasis F. hepatica eggs are very similar to those of Fasciolopsis buski, hence cannot be distinguished from each other Stool microscopy is not useful in acute fascioliasis because eggs seldom are excreted in the faeces in acute fascioliasis

Contd…. STOOL ANTIGEN DETECTION: Recently, ELISA has been evaluated to demonstrate Fasciola copro-antigen in stool to diagnose chronic fascioliasis. IMMUNODIAGNOSIS: Specific antibodies against Fasciola are detected in the serum within 2 to 4 weeks after infection, which is 4 to 8 weeks before eggs are detected in the stool. ELISA Western blot

Contd…. SKIN TEST: Intradermal skin test employing fascioline (an extract of adult Fasciola, nitrogen content 0. 3 ng/ml) is also observed MOLECULAR DIAGNOSIS: DNA probes and PCR have been evaluated for studies on the diagnosis and pathogenesis of fascioliasis Use of protein banding patterns after isoelectric focusing has been used to differentiate F. hepatica from F. gigantica

OTHER TESTS Complete blood count may show leucocytosis, peripheral eosinophilia, raised ESR and severe anaemia Liver function tests show raised levels of alkaline phosphatase and bilirubin Imaging techniques like USG, CT scan and MRI can be used

TREATMENT Triclabendazole is a newer fasciolicide which is found to be effective & is DOC Biothionol Praziquantel is recommended only if bithionol or triclabendazole is unavailable

PREVENTION & CONTROL Avoidance of consumption of contaminated raw water cress or other aquatic plants or raw liver The measures to control the infection are: Thorough cleaning and washing of water cress and other water grown vegetables before eating Treatment of infection in sheep and cattle by administering fasciolicides to reduce excretion of eggs in the faeces Health education

Fasciolopsis buski Giant intestinal fluke It causes fasciolopsiasis in humans The fluke was first described by Busk in 1843 in the duodenum of an Indian sailor, who died in London

HABITAT It is found attached to the mucosa of the duodenum and jejunum of pig and man.

MORPHOLOGY • Largest intestinal fluke to parasitise man • Most common human intestinal trematode causing infection in man • ADULT WORM: • It measures 2 cm to 7. 5 cm in length & 8 mm to 20 mm in breadth & 0. 5 mm to 3 mm in thickness.

Contd…. EGG: Each adult worm produces approximately 8000 to 50, 000 eggs per day They are released into the lumen of the intestine These are large (130 -140 µm to 80 -85 µm), bile- stained operculated eggs and are identical to those of F. hepatica

INFECTIVE FORM Metacercariae are infective to man and pig. They are found on the fresh water plants.

LIFE CYCLE • DEFINITIVE HOST: Pig and man • INTERMEDIATE HOSTS: • FIRST INTERMEDIATE HOSTS: Planorbid snails of the genera Polypylis Segmentina, Hippeutis and • SECOND INTERMEDIATE HOSTS: Fresh water plants such as water caltrops, water chestnut, water bamboo, water hyacinth, lotus and other aquatic vegetations, harbour the metacercariae.

EPIDEMIOLOGY F. buski infection is commonly found in China, Taiwan, Thailand, Indonesia and Bangladesh The infection has been reported from the states of Assam, Bengal, UP and Bihar • The source of infection to man is aquatic plants infected with the cercariae • Pig is a major reservoir host • Infection occurs orally on ingestion, when various parts (fruits, pods, roots and stem) of infected water chestnut, lotus and other aquatic plants are bitten into or peeled off with teeth

CLINICAL FEATURES • Fasciolopsiasis primarily is an intestinal infection caused by F. buski • The condition usually is asymptomatic • In heavy infections, the symptomatology consists of epigastric pain, nausea, diarrhoea and several anaemia • Complications include asthenia with ascitis and anaemia may occur during late stage of the disease • Prognosis is good with therapy

LABORATORY DIAGNOSIS Presumptive diagnosis of fasciolopsiasis is based on the detection of large operculated eggs in the faeces by microscopy Since F. buski eggs are similar to those of F. hepatica, the specific diagnosis can be made only by identification of the expelled fluke following the administration of an antihelminthic to the affected persons.

TREATMENT Praziquantel is the drug of choice for the treatment of fasciolopsiasis The prognosis is poor especially in children suffering from heavy infection, if they are not treated

PREVENTION & CONTROL Health education to discourage the ingestion of fresh, raw or aquatic plants or peeling off these parts with teeth Cooking water grown vegetables thoroughly before eating Sanitary disposal of faeces Control of snails

Paragonimus westermani P. westermani is an important lung fluke which causes classical endemic haemoptysis or pulmonary paragonimiasis in man The fluke was discovered for the first time by Kerbert in 1878 in Bengal tigers, in Amsterdam zoo.

MORPHOLOGY

HABITAT In man and other definitive hosts, the adult worm lives in parenchyma of the lung close to the bronchioles.

INFECTIVE FORM Metacercaria is infective to man and other definitive hosts. It is the encysted form found in the flesh of various crustaceans (fresh water Cray fish, crabs).

CLINICAL FEATURES Pulmonary paragonimiasis Extra-pulmonary paragonimiasis Complications include lung abscess, effusion, empyema, seizures and coma pleural

LABORATORY DIAGNOSIS PARASITIC DIAGNOSIS: Specimens- Sputum is the specimen of choice followed by faeces. The eggs are detected in these specimens only 2 months to 3 months after infection

OTHER TESTS Immunodiagnosis Intradermal skin tests Charcot-layden crystals is a consistent microscopic finding in the ova positive sputum A blood count may show eosinophilia and anaemia CSF shows pleocytosis and eosinophilia in cases of cerebral paragonimiasis

Clonorchis sinensis (Chinese liver fluke) is the most important liver of humans causing infection of the biliary passage The fluke was described in India by Mc. Connel in 1875 in the bile tract of a Chinese carpenter in Calcutta Medical College Hospital, Calcutta

HABITAT Adult worm lives in the distal biliary passages and pancreatic duct of man and domestic and wild animals.

INFECTIVE STAGE Metacercaria is the infective form. It is found encysted in the flesh of fresh-water fish.

EPIDEMIOLOGY C. sinensis is endemic in Japan, south Korea, China, Taiwan, Hong Kong and Vietnam The source of infection is raw fresh water fish containing the metacercariae Man is the main reservoir Dogs are also important reservoirs. Infection is transmitted orally by eating raw or partially cooked fish or dried, salted and pickled fish Direct transmission between man to man does not occur

CLINICAL FEATURES Incubation period is 6 to 8 weeks Asymptomatic infection Acute infection Chronic infection Most frequent complication of the infection of long standing duration is recurrent pyogenic cholangitis Cholangiocarcinoma is a cancerous condition seen in patients with severe infection of long duration Prognosis is bad with complications such as cholangiocarcinoma

LABORATORY DIAGNOSIS Definitive diagnosis is made by demonstration of the flask- shaped eggs of C. sinensis in the faeces or in the duodenal contents Serological tests: CFT, IHA and ELISA are employed to detect circulating antigen in the sera of patients with C. sinensis infection Skin test

TREATMENT Praziquantel is safe and effective for treatment of clonorchiasis Antibiotics are given to prevent the recurrent attacks of pyogenic cholangitis Mechanical removal of the worm by surgery are useful in cases of biliary tract obstruction.

PREVENTION & CONTROL The infection can be prevented by not consuming raw fish but is difficult at the community level to change the food habit of the people Control measures consist of: Cooking thoroughly the fresh water fishes Sanitary disposal of sewages Controlling snails in fresh water reservoirs