Trematode-Cestode 8.pptx

02/23/25 1 Trematodes (Flukes) 02/23/25 2  According to the site they inhabit , there are four groups of trematodes (flukes): 1. Blood flukes Schistosoma species: Main species: S. Mansoni S. haematobium, S. japonicum Large liver flukes: 2. Liver flukes (Fasciola hepatica and F. gigantica) (in the liver and Small liver flukes: Clonorchis sinensis, biliary duct) Opisthorchis viverrini Large intestinal fluke: 3. Intestinal flukes (Fasciolopsis buski) Small intestinal flukes: (Metagonimus and Heterophyes) Paragonimus westermani 4. Lung fluke 02/23/25 3 Blood Flukes (Schistosomes)  The adult live in the veins that drain the intestine or the urinary bladder (species dependent)  Adults are Cylindrical shaped  Sexes are separate Schistosomiasis is caused by blood trematodes(flukes) Freshwater snails serve as intermediate host Humans the most significant definitive host Cercaria is the infective stage Transmission--- transcutaneous 02/23/25 4 Cont… The three main species infecting humans are: - Schistosoma mansoni - Schistosoma haematobium - Schistosoma japonicum 02/23/25 5 Cont…. Habitat:  Adults (male and female ) – S. mansoni – veins of Large Intestine – S. haematobium – veins of bladder ,prostate, seminal vesicle – S. japonicum – veins of small intestine  Egg:  In the faeces (intestinal schistosomiasis )  In the urine (urinary schistosomiasis )  Cercariae:- In fresh water (infective to human) 02/23/25 6 Schistosoma mansoni Common name: Manson’s blood fluke - Causes Intestinal schistosomiasis (Intestinal bilharziasis) Distribution: many African countries, S. America, Middle East In Ethiopia: reported from all administrative regions Morphology:  Adults:  Egg: has triangular lateral spine at one pole 02/23/25 7 Schistosoma Haematobium Common name: Vesical blood fluke - Causes urinary schistosomiasis Distribution: Africa, middle East, S. Europe In Ethiopia – Awash, Wabeshebele, Asossa Egg: has terminal spine at one pole 02/23/25 8 cercaria cercaria and adult Eggs, 02/23/25 9 Life cycle of Schistosoma species Eggs are eliminated with feces or urine The eggs hatch and release miracidia , which swim and penetrate specific snail intermediate hosts Inside the snail develop to sporocysts (two generations), then to cercariae Cercariae release from the snail , Infective cercariae swim in water (river, pond lake..) penetrate the skin of the human host , Shed their forked tail, becoming schistosomulae (miracidium 02/23/25 /miracidia , cercaria / cercariae , schistosomulum/ schistosomulae) 10 Cont…  Schistosomulae migrate to heart, lung, then to liver to develop into adult  Adults migrate to mesenteric veins or veins around urinary bladder, depending on species to produce eggs by female worms  The eggs are moved progressively toward the lumen of the:  intestine(S. mansoni ) = then passed in faeces  bladder and ureters (S. haematobium) =passed in urine 02/23/25 11 Life cycle of Schistosoma species 02/23/25 12 Developmental stages of blood Fluke (Schistosoma species) Egg miracidium sporocyst cercaria Schistosomulae Adults 02/23/25 13 Immunopathology Host immune response against adult worm is minimal Eggs induce intense inflammatory reaction, leading to granuloma formation Granuloma consists of egg at center surrounded by eosinophils , macrophages and lymphocytes Larvae inside the egg produce enzymes that aid in tissue destruction and allow the eggs to pass through the mucosa and in to lumen of bowel (S. mansoni) and bladder (S. haematobium). 02/23/25 14 Schistosoma granuloma in the Liver A section of an egg is visible in the center of the granuloma 02/23/25 15 Clinical Features Syndromes include: 1. Cercarial dermatitis :- Penetration of skin by cercariae causes transient dermatitis (swimmers' itch) 2. Acute schistosomiasis (Katayama's fever) may occur weeks after the initial infection, especially by S. mansoni and S. japonicum. Associated with heavy primary infection and the initiation of egg production Manifestations include fever, abdominal pain, diarrhea, hepatosplenomegaly, lymphadenopathy and eosinophilia. 02/23/25 16 3. Chronic schistosomiasis  May have mild, chronic bloody stools due to passage of egg through intestinal wall  Host reaction to eggs lodged in the intestinal/bladder mucosa leads to the formation of - Granuloma - Ulceration and - Thickening of the wall.. 02/23/25 17 Chronic… Continuing infection may cause granulomatous reactions and fibrosis in the affected organs, which may result in manifestations that include: Colonic polyposis with bloody diarrhea (Schistosoma mansoni mostly); Portal hypertension with hematemesis and splenomegaly (S. mansoni, S. japonicum); Cystitis and ureteritis with hematuria, which can progress to bladder cancer(S. haematobium) 02/23/25 18 Chronic… In less than 10% of cases, granulomas can cause blockage of blood flow in liver causing enlargement of the spleen and fluid retention in abdomen. 02/23/25 19 Laboratory Diagnosis Microscopic identification of eggs in stool or urine is the most practical method for diagnosis. Stool examination should be performed when infection with S. mansoni or S. japonicum is suspected urine examination should be performed if S. haematobium is suspected Treatment Praziquantel: effective against all species 02/23/25 20 Prevention and Control  Avoid contamination of water with the feces/urine of man  Providing safe recreational bathing & swimming sites Latrine construction and sanitary disposal of feces and urine Destroying snail hosts Treatment of infected individuals Health information dissemination 02/23/25 21 Liver, Intestinal, and lung flukes Liver, lung, and intestinal flukes:  General characteristics :  Transmission via food (infected fish, crabs, or water vegetation)  Hermaphrodities  Flat ---leaf-like  Redia and metacercaria (additional stages)  Metacercaria infective stage 02/23/25 22 Liver, Intestinal, and lung flukes The trematodes that infect liver, lung, and intestine are all food-borne. Freshwater fish, crustaceans (crabs), and aquatic vegetation are the sources of human infection. Developmental stages : 02/23/25 23 Cestodes (Tape Worms) 02/23/25 24 Cestodes (Tapeworms) General characteristics: Segmented, tape-like worms Hermaphrodities Size: from few mm to several meters Obtains its nutrient by absorption through body surface 02/23/25 25 Morphology The body is divided in to three main body regions: Head (scolex) – attachment organ Neck – growth region Strobila – a collection of of proglottids 02/23/25 26 Cestode (Tapeworm) Body Structure: 02/23/25 27 Morphology… a, Scolex (head) b. Neck c. Strobila made up of proglottids (segments) 02/23/25 28  Cestodes of medically important include:  Human infection with adult cestodes (intestinal cestodes): o Taenia saginata (Beef tapeworm) o Taenia solium (Pork tapeworm) o Hymenolepis nana (Dwarf tapeworm) o Hymenolepis diminuta (Rat tapeworm) o Dipylidium caninum (Dog tapeworm) o Diphyllobothrium latum (fish tapeworm)  Human infection with larval cestodes (Tissue cestodes): o Echinococcus granulosus (Hydatid tapeworm) o Echinococcus multilocularis 02/23/25 29 1. Taenia saginata Common name: Beef tapeworm Geographical distribution:  Human infection with T. saginata occurs world wide  very common in Ethiopia Habitat – Adult : in the small intesine of human (4 -12 m long, ivory white color) – Larvae: in muscular tissues of cattle – Eggs: in faeces of human or in gravid segments 02/23/25 30 T. Saginata morphology - Scolex with 4suckers, no hooks, no rostellum. - Proglottid(segement) 02/23/25 31 Transmission and Life Cycle Humans are the DH while cattle are the IH The infective form for humans is cysticercus bovis A person is infected with T. saginata after consuming raw or undercooked beef containing cysticerci In the small intestine the process of strobilization start & adult worm forms. Eggs are produced in the gravid segment of the worm Cattle while grazing, ingest eggs along with their food The ingested eggs hatch to liberate oncospheres in the animals intestine The hooked oncospheres penetrate the mucosa to invade bloodstream or lymphatic's to reach muscles of cattle An oncosphere develop into cysticercus bovis Cysticerci can develop anywhere in the animal’s body; the preferred locations being striated muscles of hind limbs, diaphragm & tongue When beef is consumed raw or undercooked by humans 02/23/25 the life cycle completes. 32 Cont… Larval form of T. saginata is called cysticercus bovis. (in bovine musculature, see below)  It consists of a fluid filled sac, containing a small invaginated scolex. 02/23/25 33 Life Cycle 02/23/25 34 Clinical features and pathology  T. saginata infections are usually asymptomatic  When the infection is symptomatic; vague abdominal discomfort, nausea, weakness and weight loss may be present.  Very rarely migrating segments may cause appendicitis or cholangitis  Entanglement of worms may lead to intestinal obstruction 02/23/25 35 Laboratory Diagnosis  Diagnosis of T. saginata infection is made by detection of Eggs (microscopy)  Demonstration of proglottids in feces Treatment Praziquantel or Niclosamide Prevention and control Avoid eating raw or or insufficiently cooked meat Cooking of beef at 560C for 5 minutes will destroy cysticerci Proper sewage disposal prevents infection of cattle Treating infected persons & providing health education 02/23/25 36 2. Hymenolepis nana Distribution: occurs worlwide Common name: Dwarf tapeworm It is a common cestode infection of humans More common in children Organism Characteristics and Life Cycle Hymenolepis nana exists in two forms, an adult and a larval stage Both the forms live in the human intestine The adult worm lives in the small intestine. It is 2 to 4 cm long. The smallest tapeworm known to infect humans. The scolex has 4 suckers and rostellum with a single row of hooklets 02/23/25 37 Transmission and life cycle Infection is acquired by ingestion of infective eggs The oncosphrere is set free in the intestine It penetrates the intestinal villi and transforms into a cysticercoid larva Larvae migrate back into the intestinal lumen, attach to the mucosa, and mature into adult worm. Eggs pass in feces to infect a new host. Eggs are infective when passed in the feces. Eggs can also hatch in the intestine of the same individual to cause autoinfection (internal autoinfection) 02/23/25 38 Hymenolepis nana (Dwarf Tape worm) 02/23/25 39 Clinical features and pathology Even with a large number of intestinal worms the infection is usually asymptomatic When symptomatic, patients have( especially children) - anorexia, abdominal pain and - diarrhoea 02/23/25 40 Laboratory Diagnosis H. nana infection is diagnosed by finding eggs in feces Eggs of Hymenolepis nana 02/23/25 41 Treatment Praziquantel: the treatment of choice (acts against both adult and larval forms of the parasite) Niclosamide Prevention and control Good personal hygiene and improved sanitation can prevent the disease Health education Treatment of infected persons 02/23/25 42 3. Diphyllobothrium latum (fish tapeworm) Habitat: Adult- in the small intestine of man and fish-eating animals Larval forms: Coracidium (1st stage larva ) --------- in water Procercoid ( 2nd stage larva ) ------ in the body cavity of Cyclops/ copepod (crustacean ) Plerocercoid ( 3rd stage larva ) ----- in the fresh water fish  Human Infection acquired by ingesting the infective stage, plerocercoid in raw or undercooked fresh water fish. 02/23/25 43 D. latum 02/23/25 44 Developmental stages of Diphylobothrium latum 02/23/25 45 Life cycle Immature eggs passed with in the feces of human. Eggs mature and yield oncospheres which develop into a coracidia. Coracidia ingested by a suitable freshwater crustacean (copepod 1st IH), develop into procercoid larvae. Ingestion of the copepod by 2nd IH (small freshwater fish), the procercoid larvae are released from the crustacean and migrate into the fish flesh, develop into a plerocercoid larvae. After ingestion of the infected fish by the human host, the plerocercoid develop into mature adult tapeworms which will reside in the small intestine of human. The adults of D. latum attach to the intestinal mucosa by means of the two bilateral groves (bothria) of their scolex. 02/23/25 46 Clinical features and pathology  Clinical symptoms may be mild, depending on the number of worms  Major symptoms:  Abdominal pain  Diarrhoea, constipation  Weight loss, intestinal obstruction  Eosinophilia  As many as 40% of D. latum carriers may have low serum levels of vitamin B12, presumably because of the competition between the host and the worm for dietary vitamin B12. 02/23/25 47 Laboratory diagnosis Diagnosis of D. latum infection is made by the recovery of eggs in human feces. ( microscopy) Treatment praziquantel Prevention and control Avoid eating raw, poorly cooked,or pickled fish Proper disposal of faeces Treatment of individuals and health education // 02/23/25 48 Human infection with larval cestodes 4. Echinococcus granulosus  Common name: Hydatid worm or minute tape worm of dog.  In Ethiopia  pastoral people in the South and South-East of Ethiopia  The smallest of all tapeworms (adult)  Largest larval stage of all tapeworms (Hydatid cyst) 02/23/25 49 Habitat Adult: small intestine of carnivores such as dog, fox Hydatid cyst/larvae: in the different body parts (liver, lung, kidney, brain, etc) of human and herbivorous animals (sheep) 02/23/25 50 Cont… The larval form of E. granulosus is the hydatid cyst Hydatid cysts develop in tissues of the intermediate host e.g. sheep, cattle, human.. The growth rate of hydatid cyst is 1 to 5 cm per year hydatid cysts are filled with fluid (hydatid fluid) and have a doubled layered covering. 02/23/25 51 02/23/25 Life cycle of E.granulosus 52 Clinical features and Pathology The symptoms depend upon the location and size of the hydatid cyst. Causes obstruction and pressure on vital organs The cyst grows slowly but continuously The majority of hydatid cyst occur in the liver Liver cysts cause obstructive jaundice 02/23/25 53 Clinical … Cysts in the lungs may produce cough, dyspnea and chest pain. Cyst rupture can lead to pulmonary abscesses Large abdominal cysts ----- increasing discomfort Kidney cysts cause renal dysfunction Brain cysts produce intracranial pressure and epilepsy In bones, the growing hydatid cyst leads to bone erosion and pathological fractures. // 02/23/25 54 Cont… Group of Turkana people waiting for an operation to remove hydatid cysts. 02/23/25 55 Laboratory diagnosis Serological diagnosis – ELISA for Antibody detection Examination of cystic fluid (for brood capsules and protoscolices) following surgical removal of a cyst or fine needle aspiration In symptomatic hydatid cyst: X-ray, CT scan, ultrasound studies are useful 02/23/25 56 Treatment Surgery is the main line of treatment in hydatid cyst disease Albendazole Puncture -Aspiration-Injection- Reaspiration (PAIR ) PAIR is minimally invasive and includes the following steps: 1. Under ultrasonographic guidance, percutaneous Puncture of the cyst 2. Aspiration of 10 -15 ml of the cyst fluid 3. Injection of a parasitocidalsolution (95% ethanol ) in a volume one-third the amount of fluid aspirated; and 4. Reaspiration of the fluid after 5 minutes // 02/23/25 57 Prevention and Control  Proper personal hygiene  Thorough washing of hands after handling dogs  Periodic deworming of pet dogs  Preventing dogs access to butchering site or offals of infected animals is useful in controlling E. granulosus 02/23/25 58

Trematode-Cestode 8.pptx

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