Phylum Platyhelminthes Class : cestoda- Tapeworms Class: Trematoda-Flukes
Lec.No. Date : 23/3/2017 Name of lecture :Faleeha Habeeb HussienTrematodes (Flukes) Described as leaf-shaped , but they vary considerably in form. Ther are tow suckers (oral and ventral suckers ). Most are hermaphroditic and capable of self-frtilization, except for blood flukes, which are bisexual. All have Complex life-cycle requiring one or more intermediate host. In the vertebrate host,adult flukes live in the digestive tract,ducts associated with the alimentary canal ,in the blood ,lung,gall-bladder,urinary bladder,or in almost any other organ of the animal or human body. Eggs have operculate , a smooth hard shell that is transparent and generally yellow brown ,spine may be present.
Blood flukes -- Schistosoma Liver flukes— Fasciola hepaticaPulmonary flukes— Paragonimus westermaniIntestinal flukes— Heterophyes heterophyes
Schistosoma the causative agents of the disease Schistosomiasis or Bilharziasis The schistosomes differ from other trematodes in that not flattened and leaflike, dioecious, digenetic. their eggs are not operculate infection is acquired by penetration of cercaria through the skin.
Adult worm are elongate tubular worms (10-20 mm long). Males are shorter than females, and they have a longitudinal cleft (gynecophoral canal or schist) in which the longer slender female lies fold. Both sexes have Oral and ventral suckers are present, with the ventral one being lager serving to hold the worms in place, preventing them being carried away by the circulatory current . Intestine (cecum) divides, then fuses near middle of the body. The cuticle of the male is covered with minute papillae. The female only posses these at the anterior and posterior end as the middle section being covered by the male body. they develop in the portal venous system and adult flukes (depending on species) live in the vein of the intestine or bladder. Transmission is by contact with water containing the infective form of parasite (cercariae).
The three main species infecting humans are:Schistosoma mansoni ----Intestinal veinsSchistosoma japonicum---Intestinal veins Schistosoma haematobium –Vesical veins
Schistosoma mansoni caused intestinal schistosomiasis. occurs in Africa, Brazil, Venezuela, Malagasy republic, the Arabian peninsula, the West Indies and Surinam. The intermediate host is an aquatic snail of the genus Biomphalaria. Man is the most common definitive host, The adult worms live in smaller branches of the inferior mesenteric vein in the lower colon.
Morphology: The adult males measure is approximately 1 cm long (0.6–1.1 cm) and is 0.1 cm wide. It is white in coulare .The female has a cylindrical body, longer and thinner than the male (1.2 to 1.6 cm long by 0.016 cm wide). is darker, and it looks gray. the male surrounding the female with his gynaecophoric canal. The male is actually flat but the sides roll up forming the groove.
S. mansoni (male&female)
Schistosoma mansoni egg with the characteristic lateral spine
S.JaponicumCaused intestinal schistosomiasis (schistosomiasis japonica) occurs in China, Indonesia, Thailand and the Philippines. It differs form S. mansoni and S. haematobium in that it is a zoonosis in which a large number of mammals serve as reservoir hosts; cats, dogs and cattle playing major roles in the transmission of the disease. The intermediate host is an aquatic snial of the genus Oncomelania . The worms live coupled together in the superior mesenteric veins and deposit 1500–3500 eggs per day in the vessels of the intestinal wall.
S. japonicum (male&female)
S. japanicum egg with the characteristic minute lateral spineS. haematobium
Caused urinary schistosomiasis, vesical schistosomiasis, or urinary bilharziasis. occurs in tropical and subtropical. Africa, Iran, Iraq, Saudi Arabia, Yemen, Syria, India, Mauritus, Malagasy Republic, Zanzibar The intermediate host is an aquatic snial of the genus Bulinus Adults are found in the venous plexuses around the urinary bladder and the released eggs travels to the wall of the urine bladder causing haematuria and fibrosis of the bladder.Morphology: The male is colorless, and measures about 1 cm in length. Owing to the fact that is lateral margins are curved ventrally, it presents a cylindrical appearance. The female worm is cylindrical, thread-like, often reddish-black in color, and longer than the male, measuring about 2cm in length. The mature worms live in copula mainly in the inferior mesenteric veins and the females deposit their eggs in the walls of the bladder and finally making their way into the urine.
S. Haematobium (male&female)
S.haematobium.egg with the characteristic terminal spineBulinus snail Biomphalaria snail
Oncomelania snailSchistosome Cercaria
Schistosome Miracidium
Diagnosis 1-by detection of the characteristic ova in the stool (S.mansoni , S.japanicum) , in the urine (S.haematobium). 2-Biopsy material. 3-Serological test such as ELISA, is used to test for antibodies specific to Schistosomes and is specially useful when schistosomes eggs cannot be found. complement fixation test.
S.Japanicum egg
S.Haematobium egg
S.Mansoni egg
Swimmer’s itchAlso called cercarial dermatitis, appears as a skin rash caused by an allergic reaction to certain microscopic parasites that infect some birds and mammals. These parasites are released from infected snails into fresh and salt water (such as lakes, ponds, and oceans). While the parasite's preferred host is the specific bird or mammal, if the parasite comes into contact with a swimmer, it burrows into the skin causing an allergic reaction and rash. Swimmer's itch is found throughout the world and is more frequent during summer months.
Haematuria The mature flukes of S. haematobium migrate to the veins surrounding the bladder. After mating, the eggs are laid in the venules of the bladder and many penetrate through the mucosa, enter the lumen of the bladder and are excreted in the urine accompanied by blood. Thus haematuria and proteinuria are characteristic, though not invariable features of urinary schistosomiasis.
Avoid swimming or bathing in contaminated or potentially contaminated water Avoid bodies of water of unknown safety Reduction of sources of infection Prevent water contamination
Fasciola hepatica also known as the common sheep liver fluke It infects the livers of various mammals, including humans. causing fasciolosis. It causes great economic losses in cattle and sheep.
Geographical distribution: it is common in sheep raising countries (Europe), detected in Egypt.
Mode of infection:Eating raw vegetables or vegetablespreviously washed in infected water.Drinking infected water, polluted by encysted Metacercariae.
Morphology Adult worm it is a large leaf-shaped fluke, pointed posteriorly,and wide anteriorly , measuring 3cm in length by 1.5 cm in breadth. brown to pale grey in color. 3) ) The tegument is covered with large and scale- like spines.
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3)Suckers: oral sucker and large ventral sucker. 4)Digestive system: intestinal caeca with lateral compound branches and medial T or Y-shaped ones. 5)Genital system: -Testes: two highly branched. -Ovary: branched in front of testes. -Uterus: short and convoluted. -Vitelline glands: highly branched along the lateral fields.
Eggs of Paragonimus sp. taken from a lung biopsy stained with hematoxylin and eosin
Egg: Size: 140 x70 μ. Shape: oval. Shell: thin. Colour: light yellowish brown (bile stained). Special character: operculated.Saline preparation of Fasciola hepatica egg in the stool The arrow indicates the operculum of the egg.
operculum
operculum
F.hepatica passes its life cycle in two different hosts.• Definitive hosts-Sheep,goat, cattle or man. Adultworm in the biliary passages of the liver.Reservoir host- is primarily the sheep.• Intermediate hosts-Snails of the genus Lymnaea.Larval development proceeds in this snail.
Life cycle
Adults in the biliary passages Immature eggs are evacuated with feaces Meracidium invades snails (lymnea spieces) leading (sporocyst, 1st & 2nd generation radia then cercaria) Cercaria encyst as meta cercaria on (aquatic plants & vegitations) ingested by mammalsLife cycle
Adults in the biliary passages Immature eggs are evacuated with feaces Meracidium invades snails (lymnea spieces) leading (sporocyst, 1st & 2nd generation radia then cercaria) Cercaria encyst as meta cercaria on (aquatic plants & vegitations) ingested by mammalsCercaria
Miracidium
redia
• Diagnosis1. Detection of eggs by:a. Stool examination.b. Examination of duodenal aspirate. 2. Complete blood count for anaemia &Eosinophilia.3. Serological tests: are of value during migratoryor chronic stage and ectopic infection.ELISA
Pathogenicity: • Adult worm can live in sheep for 5 years andcause liver cirrhosis and ascitis.• In man: young adults burrow through the livertissue feeding on its cells inflammation,necrosis (liver rot) and marked eosinophilia.Disease: fascioliasis.1-Abdominal pain due to penetration ofintestinal wall.2-Peritonitis: occurs by penetration of intestinalwall and the presence of metacercariae in theperitoneal cavity.
3- Liver rot: occurs by mechanical and toxic destruction of liver tissue by passage of immature worms necrosis, fibrosis, hepatitis, and hepatomegaly. 4- Obstructive jaundice: adults in the bile duct irritation, thickening of the duct and stone formation obstructive jaundice and cholangitis. 5- Allergy and eosinophilia. 6-Ectopic fascioliasis: when metacercariae enter the circulation and are distributed in abnormal sites e.g. peritoneum, lungs, brain, eyes and cause fibrosis.
Hypertrophia of bile ducts in liver caused by Fasciola.
Liver rot.Fasciola worms
Treatment: 1-Triclabendazole (Fasinex): drug of choice. It is acting on immature and adult worms. 2-Bithionol (Bitin). 3-Surgical removal of ectopic flukes.
Prevention and control: 1-Mass treatment of infected animal reservoir. 2-Snail destruction. 3-Proper washing or cooking of aquatic vegetation. -4- Sanitary disposal of stool. 5- Boiling or filtration of polluted water. 6- Health education &treatment of infected cases.
Paragonimus westermani causing paragonimiasis. The species sometimes is called the Japanese Lung fluke or Oriental Lung fluke. Human infections are most common in eastern Asia and in South America.
TransmissionEating raw, undercooked or pickled crustaceans such as crab or crayfish• Spitting, a habit in asian countries• Cultures that eat raw crustaceansHabitat:In the cystic cavities in the lungs of man and other devintive host
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Adult of Paragonimus westermani
Eggsmeasure 80 μm to 118 μm by 48 μm to 60 μm.yellow-brown in colorovoid shape and an operculum structure.Life Cycle Unembryonated eggs passed into lung tissue and excreted in sputum; or swallowed and excreted in the feces Eggs embryonate in the water and miracidia emerge from egg and search for specific species of snail (first intermediate host) In the snail, miracidia goes transforms-sporocyst> rediae> cercariae Cercariae leaves snail and invades second intermediate host, a crustacean, typically a crab or crayfish The cercariae encysts into metacercariae (infective stage for human or animal host) Human infected after eating inadequately cooked crustacean Metacercariae excysts in small intestine and penetrates the gut wall Peritoneal cavity> abdominal wall> diaphragm> lungs Develop into adults in the lungs Prepatent period is 2-3 months Infection can last for years to decades
The snial (Melanoides tuberculata )
The Crustacean (Eriocheir sinensis)Crayfish( Austropotamobius pallipes)
Treatment This infection is usually treated with the drug praziquantel. If the infection is severe or involves the brain, corticosteroids may be given.
Prevention• Fully cook shellfish– Heat water to 55oC for 5 minutes• Freeze Fish– -20 C for 7 days– -35 C for 15 hours• Make spitting illegal• Use Moluskicide to control snail population
Heterophyes heterophyes causing heterophyiasis. The adult lives in the intestinal villi of humans . The first intermediate host are snails, Cerithidia sp. and Pironella sp. which are found in Asia and the Middle East respectively. commonly found in the Middle East, Philippines, Taiwan, Korea, China and Japan.
Mode of infection: -By eating raw, improperly cooked or freshly salted fish, containing encysted metacercaria. -Through fingers or cooking utensils contaminated with the metacercaria during preparation of fish.
morphology:Size: 1.5-3mmx 0.5 mm.Shape: pyriform or pear shape,spines cover the cuticle anterior.Suckers: three suckers.– Oral sucker: small.– Ventral sucker: large.– Genital sucker: postero-lateral toventral sucker.-Testes: two, oval, opposite each other.-Ovary: single, globular..
Clinical picture:• Fever, and general malaise.• Pain in the right hypochondrium.• In heavy infection enlarged tender liver.
Egg:Size: 30 Ч15 μ,oval shape ,thick shell, golden yellow. Special character: operculum at one pole and a smallknob at the other.Content: mature (miracidium).
Embryonated eggs in stool Ingested by snail(Sporocyst-radia-cercaria) Cercaria leave the snail encyst as matacercaria on man infection by eating raw or imperfectly cooked fish
Life cycle
Diagnosis 1.by detection of the characteristic mature eggs in stool. 2. Eosinophilia. .
Pathogenicity and clinical picture:Disease: heterophyiasis.1)Intestinal: attachment of parasite to mucosainflammation, superficial ulcers and necrosis.-Mild infection with no symptoms.-Heavy infections cause:• Abdominal colic.• Abdominal discomfort.• Chronic intermittent diarrhea, sometimes withblood.2) Extra-intestinal: eggs general circulationdifferent organs parasitic granulomaand fibrosis.a. heart myocarditis, valvular damage andheart failure.b. brain and spinal cord I.C.T., epilepticfits and neurological disorders.c. lung nodular shadows, mistaken for T.B.