Lecture 3: Phylum Platyhelminthes and Nematodes (Zoology)

Damanhour University Faculty of Science Zoology Department Lecture 3 Phylum Platyhelminthes Phylum: Nematodes Prepared by: Ass.Proff.Dr/ Samir El-Abbassy 5-1  General characters 1-Triploplastic & acoelomic. 2-B...

Damanhour University Faculty of Science Zoology Department Lecture 3 Phylum Platyhelminthes Phylum: Nematodes Prepared by: Ass.Proff.Dr/ Samir El-Abbassy 5-1  General characters 1-Triploplastic & acoelomic. 2-Bilaterally symmetrical & dorsoventrally flattened. 3- Most are parasitic. 4- Excretion: by flame cells. 5-Respiratory & circulatory systems :absent. 6-Nervous system: two pairs of cerebral ganglia & 2-3 pairs of longitudinal nerve cords. 9-Hermaphrodite 5-2 except Schisosomatidae.  I- Fasciola Hepatic or Liver Flukes 5-4  Fasciola gigantica (Large liver fluke)  Distribution: Africa, Europe and far East.  Habitat: : liver of herbivorous animals (primarily sheep , cattle , goats ) and occasionally man (zoonoses parasite).  Definitive host :Sheep , goats and occasionally man.  Intermediate host : Snail, Lymnaea cailliaudi.  Reservoir hosts : cattles and 5 - 5 camels.  1) Adult's Morphology :  Large leaf – like , hermaphrodite worm , measuring 3.7×1.5 cm.  Body formed of small anterior conical part Suckers : small oral and large ventral sucker 5-6 5-7  Life cycle  Adult worms live in bile duct  Stages in the life cycle: Egg (in water) → miracidium → Sporocyst → rediae → cercariae → encysted metacercariae Infective stage : Encysted matacercariae in water and on water (Aquatic) vegetations. Diagnostic stage : immature eggs in faeces. 5-8  1-Egg Shape : oval Shell : Thin , operculated. Size : 140 x 70 u. Colour : Light yellowish brown. (immature – then maturation takes place in fresh water within two weeks) 5-9  Eggs : hatches in freshwater within 2 weeks into miracidium. 2- Miracidium :  Pyriform contractile ciliated larva.  Anterior chitinous papilla  One pair of penetration glands.  Primitive gut and two eye spots  Flame cells and Germ cells 5 - 10 The miracidium invades the intermediate host (Lymnea cailliaudi) where it develops into sporocyst, rediae and finally cercaria. ‫يموت بعد يومين إلم يجده‬ 3- Sporocyst  Simple elongated sac.  Body cavity with germ cells that proliferate giving rediae, which escape through rupture of mother sporocyst. 5 - 11  4- Redia  Cylindrical larva.  Primitive gut: mouth, muscular pharynx and blind caecum.  Birth pore anteriorly.  Flame cells.  Two lateral processes posteriorly.  Germ cells from which daughter rediae or cercariae arise and leave through the birth pore. 5 - 12  5- Cercaria  Formed of body (0.3 mm) and simple tail (0.7 mm), (Leptocercous cercaria) ‫ذات الريل البسيط الطويل‬.  Body with oral and ventral suckers , primitive gut, flame cells, and cystogenous glands that secrete the cyst.  Cercaria moves in water , attaches to acquatic vegetations, loses its tail and encysts → encysted metacercaria (infective stage) 5 - 13 6- Metacercaria  surrounded by a cyst wall and contain O.S and V.S , intestine and residues of Cystogenous glands. 5 - 14  Apical papilla L. cailluodi Cilia (F.gigantica) Operculum Apical gland Penetration gland Redia Fertilized Vitelline cell Eye spot develop into ovum hatch under Flame cell Eggshell favourable conditions Excretory duct Germ ball Germ ball Excretory pore L.truncatula 1-Egg (F. hepatica) 1- Bile duct 2-Miracidium 3- Sporocyst 2- Circulatio redia come Grow into adult 3- Peritoneum out by rupture Oral sucker Mouth Cystogenous glandd Pharynx Intestine Gut In intestine, young Ventral sucker Birth pore worm is released and reach liver through Flame cell Excretory bladder Cercaria come out of I.H and Cercaria come out encyst on Cercaria through birth pore Infection grasses By eating vegetables Tail Germ ball (grasses) or drinking water Lateral process contaminated 6-Metacercaria with (Infective stage) 5-Cercaria 4-Redia metacercaria Life cycle of Fasciola sp.  Transmission Aquatic water vegetation – Watercress  DIAGNOSIS  Stool examination for eggs.  Examination of duodenal aspirate for eggs.  CBC for anaemia and eosinophilia.  Immuno-diagnosis is useful in chronic fascioliasis and in ectopic infection where eggs are not found in the stool. 5 - 18  Blood Digeneans (Schistosoma)  Blood Digeneans 1-S. mansoni 2- S. haematobium 3-S. japonicum Habitat : *S.mansoni : Portal veins draining large intestine. *S. haematobium : Vesicle plexus of urinary bladder. 1) Schistosoma haematobium: causes urinary schistosmiasis. 1) Schistosoma mansoni: causes intestinal schistosomiasis. 1-Morphology  Schistosome adult worms nhm.ac.uk pathmicro.med.sc.edu nhm.ac.uk nhm.ac.uk nhm.ac.uk nhm.ac.uk  Comparison between Male and Female Schistosoma Feature Male Female Length Short Long Rough (With tubercles) Tegument Smooth (no tubercles) Gynaecophoric present absent canal Thickness Thick narrow  Shistosoma mansoni and S. hematobium 1- Definitive host: man for the 2 species 2-Intermediate host: Bulinus for S.haematobium and Biomphlaria for S.mansoni. 3- Infective stage: furcocercus cercariae. Life cycle of S.mansoni and S. hematobium Stages in the life cycle : Egg, miracidium, sporocyst and furcocercous cercaria. Ther is no redia or metacercaria. Start of the cycle: Male carries female and migrates against blood flow till they reach the venules of intestine (S.mansoni) and venules of urinary baldder (S.haematobium). Female leaves male and migrates to smaller venules where it deposits eggs. Eggs pass into the intestine (S.mansoni) or urinary bladder (S. haematobium) under the effect of blood pressure, egg spine and lytic secretion of the miracidium inside the egg. Eggs pass out with urine or faces.  Egg Penetration gland shell Apical gland hatch Lateral Enter the Miracidium gland intermedi Lateral Flame cell ate host spine Terminal Cilia Excretory 1- Egg spine duct Bulinus S.mansoni Germ cells (S.hematobium) S.hematobium Excretory pore 2- Miracidium portal vein grow into adult Biomphlaria (S.mansoni) Oral sucker blood circulation Oesophagus Develops Penetration glands into (schistosomule) Ventral sucker Flame cells Excretory bladder Developing cercaria cercaria penetrate skin Spines Excretory ducts Cercaria come out Birth pore through birth pore Infection by Biforked tail 4-cercaria swimming, bathing (Infective stage) 3-sporocyst Excretory pore and drinking water Germ cells contaminated with cercaria(I.S) Life cycle of Schistosoma spp. A- Eggs of Schistosoma a- Egg of S.hematobium : It is oval-shaped and measures 140 × 60 µm. The egg shell is thin and possesses a terminal spine. It contains fully-developed miracidium. nhm.ac.uk nhm.ac.uk b- Egg of S.mansoni - It is oval-shaped and measures 150 x 65 µm. - The egg shell is thin and provided with lateral spin. - It contains fully-developed miracidium. nhm.ac.uk  B- Schistosome miracidium - It measures 200 mm in length path.cam.ac.uk and 40 mm in diameter. - It is provided with 3 types of gland: penetration gland, apical gland and lateral gland. - Boring papilla is tiny and Miracidium Swimming towards Snail retracted. Intermediate Host - Four flame cells and 2 excretory pores are present. - Body contains germ cells and is covered with cilia. - It has no eye spots. path.cam.ac.uk Scanning Electron Micrograph of miracidium newly hatched from egg  The miracidium swims in water by cilia searching for the intermediate host which is Bulinus for S. hematobium and Biomphlaria for S. mansoni. The miracidium invades the intermediate host where it undergoes several developmental stages.  C)Intramolluscan stages 1- Sporocyst: The miracidium penetrates the snail and transforms into sporocyst characterized by a birth pore and filled with cercaria. SPOROCYST pathmicro.med.sc.edu  2- Cercaria in water Cercaria comes out of the sporocyst through birth pore. Body measures 325 mm long and 25 mm breadth. It possesses an oral sucker, ventral sucker and penetration glands. Digestive tract consists of mouth, oesophagus and intestinal caecae. Excretory system includes flame cells, excretory ducts, excretory pores (2) pathmicro.med.sc.edu and excretory bladder. nhm.ac.uk nhm.ac.uk  Cercaria to schistosomula Cercaria swims using its fidssa.co.za biforked tail searching for man (definitive host). It penetrates the skin using penetration glands and loses its tail before entering the circulation where it transforms into schistosomula. After passing through the lungs, schistosomula come to rest in the hepatic portal vein and develop into adult. fidssa.co.za  Pathogenesis and symptomatology: A-Schistosomiasis hematobium (urinary schistosomiasis) There are four stages: 1- Stage of cercarial invasion of human skin causes local dermatitis, itching and irritation. 2- Stage of migration of schistosomula causes: Lung: pneumonitis , haemorrhage and cough. Liver and spleen: hepatosplenomegaly. Metabolic products of adult parasites cause fever, headache, cough and muscle pain. 3- Stage of egg deposition: # Tissue damage and hemorrhage. 4- Stage of tissue proliferation: # Inflammatory cells around eggs (granuloma) and fibrosis. # Bladder: fibrosis, malignancy, stones, cancer. # Ureters: stricture. # Kidneys: renal failure. # Urethra: stricture. # Genital organs: pseudoelephantiasis of the penis, granuloma in prostate, seminal vesicle, ovaries, uterus, vulva, and vagina. Schistosoma mansoni egg-induced granuloma in a mouse liver york.ac.uk  ‘Intestinal’ asymptomatic schistosomiasis at the Egyptian village level Egyptian boy with hepatosplenomega ly and ascites. (NAMRU-3 clinical ward in Cairo) Cercarial Dermatitis scuba-doc.com Diagnosis of Schistosoma mansoni. 1- Stool examination to detect eggs with lateral spine. 2- Examination of rectal biopsy from mucosa to detect eggs with lateral spine. 3-Using sigmoidoscopy to visualize the pathological lesions and Schistosoma eggs. 4- Serological tests as in S.haematobium. Diagnosis of S.haematobium 1- Examination of urine microscopically to detect eggs with terminal spine. 2- Examination of biopsy from urinary bladder mucosa (using cystoscope) to detect eggs and histopathological lesions. 3- Serological tests: Indirect haemagglutination test (IHA). Indirect fluorescent antibody test (IFA). Enzyme–linked immunosorbant assay (ELISA). Phylum: Nematodes Ascaris  Phylum: Nematodes (Round worms) General characters: 1) Separate sexes (male & female) 2) Body is unsegmented 3) Size: ( from 1 mm to 1 metre in length). 4) Alimentary canal (mouth – oesophagus- intestine-anus) 5)-Excretory system : consists of two longitudinal tubes running in the lateral lines. 9 - No circulatory system. 10- Nervous system: consists of nerve ring around the oesophagus and 6 nerve trunks pass to the head and others to the posterior end.  Intestinal nematodes Ascaris lumbricoides Distribution:Cosmopolitan. Habitat: Small intestine. Definitive host : Only man Infective stage : Egg containing a second stag rhabditiform larva. Separate sexes: Female: 20-40 cm × 5mm, with straight posterior end, two sets of genitalia, and vulva at the junction of anterior and middle thirds of the body ventrally. Male: 15-20 cm × 3 mm, posterior end curved ventrally, one set of genital organs and 2 similar spicules (2 mm each) retractile at the cloaca.  Mouth Mouth Stomodaeum Stomodaeum Anterior ovary Vaginal aperture Vagina Testis 2 uteri Midgut 2 Seminal Midgut Vas deferens receptacles 2 Copulatory spicules Oviduct Vesicula seminalis Cloacal opening Cloaca Proctodaeum Posterior A- Male ovary Proctodaeum Anus B- Female Morphology of Ascaris lumbricoides curezone.com doctorsbiology.blogspot.com stanford.edu  Life cycle Stages in the life cycle Egg in the soil larvated egg with 2nd stage of rhabditiform larva ingested by man adult in the small intestine 1-Types of eggs a) Fertilized egg * broad oval. * 60 × 45 * Structure : mammilated coat + shell layer + fertilized ovum b) Unfertilized egg : * long oval. * 90 × 45 * poorly developed mamillated coat * Thinner shell, * No fertilized ovum c)-Decorticated egg : Partial or complete absence of mammilated coat + shell layer + fertilized ovum d) Larvated egg Mammilated coat+ shell layer + rhabditiform larva Life cycle 1-Eggs come out with the stool. 2- After 2 weeks ,under suitable condition(25ºc, humidity, shade and oxygen) develop in the soil into 1st stage of Rhabditiform larva. 3- After one more week, the larva moult into 2nd stage rhabditiform larva within the egg (infective stage). 4-Method of infection: - Man gets infected by eating food or drinking water contaminated with the eggs containing second stage of rhabditiform larvae. - Also cockroaches and house flies may carry the larvated eggs to human food (mechanical transmission). - (No self infection ? – Geohelmenthis) 5- Egg hatches in the small intestine, liberating the larva. 6- Rhabditiform larvae penetrate the mucosa circulation right side of the heart pulmonary arteries lung moults twice (2nd and 3rd moults). 7-The larva creeps along the bronchioles bronchi trachea larynx pharynx, then swallowed to reach the small intestine where it moults once (4th moult and becomes adult).  Mammilated coat Egg shell Adult Oesophagus Stomach Intestin female in Fertilized Moulting 4 Lay eggs ovum intestine Pharynx 1-Egg in faeces Under suitable Tracea conditions develop Lung (Moultings 2&3) Life cycle of Ascaris Heart lumbricoides 2- Egg with the first stage of rhabditiform larva Moulting 1 Liver Blood In intestine, Infection: by eating circulation egg envelops food or drinking are digested water 3-Egg with the 2nd and larva is contaminated with stage of rhabditiform Penetrates released the infective stage larva (Infective stage) intestinal 4-Larva wall Diagnosis: Laboratory by: 1. Detection of eggs in feaces (smear, concentration). 2. Detection of migrating larvae in sputum or better in gastric lavage ‫محتويات غسيل المعدة‬contents. 3. Detection of adults passing out with or without stool or in vomitus. 4. Eosinophilia (7 – 12%) (Normal 1-4 %) 5 - 62