Introduction to the Helminths 蠕虫 Helminths means worms, multicellular organisms. Phylum Class Nemathelminthes Nematoda (round worm) 线虫纲 线形动物门 Platyhelminthes

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<ul><li> Slide 1 </li> <li> Introduction to the Helminths Helminths means worms, multicellular organisms. Phylum Class Nemathelminthes Nematoda (round worm) Platyhelminthes Tremetoda (flatworms) Cestoda </li> <li> Slide 2 </li> <li> The Nematodes There are many, many nematodes 2006 : 2002 C.Elegans </li> <li> Slide 3 </li> <li> Morphology Cylindrical, non-segmented, bilaterally symmetrical and sexes separate Pseudocele ( pseudocoelom) The body wall: cuticle hypodermis longitudinal muscle </li> <li> Slide 4 </li> <li> Holomyarian type ( Whipworm) Polymyarian type ( Ascarids) Meromyarian type (Hookworm) The arrangement of the somatic muscles </li> <li> Slide 5 </li> <li> Digestive system Mouth pharynx esophagus intestine anus </li> <li> Slide 6 </li> <li> Reproductive system male reproductive system Testis seminal vesicle vas deferens ejaculatory duct </li> <li> Slide 7 </li> <li> Most females usually have two ovaries oviducts and uterus.. ovary oviduct uterus. ovary oviduct uterus.. vulva -vagina </li> <li> Slide 8 </li> <li> nervous system Consist of : circumesophageal nerve ring and 2 or 4 longitudinal nerve trunks </li> <li> Slide 9 </li> <li> Excretory system Excretory pore is anterior. No flame cells are present. </li> <li> Slide 10 </li> <li> life cycle M1 M2 M3 M4 Egg L1 L2 L3 L4 Adult larva (male &amp; female) </li> <li> Slide 11 </li> <li> Kinds of life cycle in nematodes Ascaris lumbricoides Trichuris trichiura Enterobius vermicularis Hookworms Indirect life cycle: intermediate host is necessary Trichinella spiralis Filaria Direct life cycle: Intermediate host is not necessary </li> <li> Slide 12 </li> <li> Pathogenesis 1)Larvae ( 1) dermatitis caused by cutaneous invasion and subcutaneous migration of larva; ( 2) injury to organs or tissues by migration of larvae in the body 2) Adults (1) injury to intestinal mucosa caused by the parasites living in gastro- intestinal system (2) injury to lymphatic system, muscles or nervous system caused by the parasites living in tissues What about Egg </li> <li> Slide 13 </li> <li> INTESTINAL HELMINTHS Ascaris lumbricoides (roundworm) Trichuris trichiura (whipworm) Enterobius vermicularis (pinworm) Ancylostoma duodenale and Necator americanus (hookworms) </li> <li> Slide 14 </li> <li> Slide 15 </li> <li> 2004 </li> <li> Slide 16 </li> <li> Ascaris lumbricoides (ascarids) Adults live in intestine of human, cause Ascariasis ( ) Human is the only definitive host of this parasite. &gt; 1 billion world wide the infective rate in China 12.72% </li> <li> Slide 17 </li> <li> Hookworms Five species of hookworms: Ancylostma duodenale Necator americanus Ancylostma ceylanicum Ancylostma caninum Ancylostma brazilience Adult live in the intestine and take blood from the host, cause hookworm disease. </li> <li> Slide 18 </li> <li> Number of humans infected is estimated at 1.2 billion with 50,000 to 60,000 deaths each year. 6.12% </li> <li> Slide 19 </li> <li> Enterobius vermicularis (Pinworm) Almost anybody can become infected with this parasite especially children. The worldwide infection is about 210 million 10.28% </li> <li> Slide 20 </li> <li> Morphology </li> <li> Slide 21 </li> <li> Morphology Adult of Ascaris lumbricoides the largest nematode parasites of humans Creamy white or pinkish in color elongate and cylindrical </li> <li> Slide 22 </li> <li> Female: measuring 35cm long, posterior end is straight Male: measuring 25cm long posterior end is curved. Morphology Adults of Ascaris lumbricoides </li> <li> Slide 23 </li> <li> Three lips around the mouth in type and possess small teeth Morphology Adults of Ascaris lumbricoides </li> <li> Slide 24 </li> <li> 50 mm long with a slender anterior and a thicker posterior end The male is smaller and has a coiled posterior end Morphology Adults of Trichuris trichiura </li> <li> Slide 25 </li> <li> Morphology Adults of Enterobius vermicularis Adults: pin-like, white, small worm Female showing esophageal bulb &amp; cephalic alae Male with curved posterior end, Female has a long pointed end. </li> <li> Slide 26 </li> <li> Morphology Adults of hookworms Adult: Slender, pinkish or creamy-gray in color, about 10mm in length. </li> <li> Slide 27 </li> <li> Females: 9-13 mm long with egg-filled uterus Males: 7-11 mm long, Posterior end forms a Copulatory bursa ( ) Morphology Adults of hookworms </li> <li> Slide 28 </li> <li> Morphology of Ancylostoma duodenale Buccal capsule contains 2 pairs of large ventral (anterior) teeth Copulatory bursa is at posterior end and contains 2 thin spicules that separate distally. </li> <li> Slide 29 </li> <li> Morphology of Necator americanus Buccal capsule contains a pair of ventral and dorsal cutting plates. Copulatory bursa contains spicules that are fused distally. </li> <li> Slide 30 </li> <li> shape c , 1cm s , 1cm buccal capsule flat and oval-shape oval-shape two pairs one pair cutting plates Copulatory bursa round oblate spicule two, separated two, fused at their ends A.duodenale N. americanus Difference between A.duodenale and N. americanus </li> <li> Slide 31 </li> <li> Morphology larva of hookworms rhabditiform Larva filariform larva : infective stage </li> <li> Slide 32 </li> <li> Eggs are unembryonated when passed in the feces. Embryonation occurs in the soil. Unembryonated egg in feces broadly oval yellowish to brown in color Thick shell ovum protein coat fertilized Morphology Eggs of Ascaris lumbricoides unfertilized and fertilized egg </li> <li> Slide 33 </li> <li> Decorticated egg (lost outer albuminous coating) Embryonated egg in soil Morphology Eggs of Ascaris lumbricoides </li> <li> Slide 34 </li> <li> Morphology Eggs of Trichuris trichiura size: 50-54 m by 22-23 m, smaller than Ascarids Shape a typical barrel Color yellow-brown unstained two polar plugs Shell quite thick Contains unembryonated egg </li> <li> Slide 35 </li> <li> Morphology Eggs of Enterobius vermicularis size: smaller than Ascarids Shape oval, flattened on one side Color colorless Shell quite thick Contains an undeveloped larva inside </li> <li> Slide 36 </li> <li> Shape: oval-round Shell: thin with smooth and colorless (transparent) eggshell Size: 57-76 m by 35- 47 m Contains: clear space between the egg-shell and the ovum. Usually 2 to 16 cells in feces Morphology Eggs of hookworms </li> <li> Slide 37 </li> <li> Slide 38 </li> <li> Life cycle </li> <li> Slide 39 </li> <li> Life cycle of Ascaris lumbricoides </li> <li> Slide 40 </li> <li> Adult egg infective egg larva Ingested by man migration Life cycle Migration of larva in the host: Vessels of intestine liver heart lungs trachea pharynx intestine (swallowed) </li> <li> Slide 41 </li> <li> Life cycle of hookworm </li> <li> Slide 42 </li> <li> Life Cycle Adult egg rhabditiform filariform larva larva Swallowed pharynx trachea lung circulation Penetrate skin </li> <li> Slide 43 </li> <li> Life cycle of Enterobius vermicularis </li> <li> Slide 44 </li> <li> Life cycle ingested Adultegginfective egg (in lumen of cecum) </li> <li> Slide 45 </li> <li> Pathogenesis </li> <li> Slide 46 </li> <li> Pathogenesis of Ascaris lumbricoides 1) larvae: Ascaris Pneumonitis Asthma Larva in section of lung </li> <li> Slide 47 </li> <li> Pathogenesis 2) Adults (1) Malnutrition (2) Disorder of digestive system: main complaint--- abdominal pain (3) Allergic responses anorexia ( ) nausea ( ) vomiting ( ) diarrhea ( ) </li> <li> Slide 48 </li> <li> Complication penetrate to bile ducts penetrate to the pancreatic and the appendix </li> <li> Slide 49 </li> <li> intestinal obstruction </li> <li> Slide 50 </li> <li> Ectopic parasitism </li> <li> Slide 51 </li> <li> Slide 52 </li> <li> 1. cause irritation( pruritus ) of the anal region Secondary bacterial infection in areas scratched raw may occur. 2.vaginitis and rarely salpingitis in young girls. 3. cause mental anguish Pathogenesis of Enterobius vermicularis </li> <li> Slide 53 </li> <li> Slide 54 </li> <li> Pathogenesis of hookworm 1. Local dermatitis (ground itch) 2.Pulmonary (pneumonia-like) symptoms (symptoms are not as severe as Ascaris migration) </li> <li> Slide 55 </li> <li> 3. Anemia a. The worm sucks blood and the wound oozes blood A. duodenale takes 0.26 ml/day; N. americanus 0.03 ml/day </li> <li> Slide 56 </li> <li> b. The worm usually changes its sucking site c. Disfunction of intestine to absorb iron gradually produce an iron-deficiency anemia </li> <li> Slide 57 </li> <li> 4.gastroenteric symptoms Slight, intermittent abdominal pain 5.Aberration of appetite(geophagy ). loss of normal appetite and desire to eat soil or un-normal materials 6. Hookworm diseases of infant 7. eosinophilia </li> <li> Slide 58 </li> <li> Laboratory Diagnosis </li> <li> Slide 59 </li> <li> 1. By identifying the eggs 1. direct fecal smear 2. brine-floatation method 3. Scotch tape technique (cellophane tape impression) 4. Larval cultivation ( ) </li> <li> Slide 60 </li> <li> 2. By identifying the adults 3. therapeutic test </li> <li> Slide 61 </li> <li> Epidemiology distribution Basic conditions in parasitic epidemiology Patients and infected persons Souce of infection </li> <li> Slide 62 </li> <li> Mode of transmission (Factors of prevalence) For round worm For hookworm Via mouth Warmer and poor sanitation Inadequate disposal of feces Using nightsoil as fertilizer Via skin Bare-foot walking Others: Oral A. doudenale) Placenta Mothers milk Paratenic hosts </li> <li> Slide 63 </li> <li> Susceptible population Hand-to-MouthTransmission retroinfection through anus inhalation of ova For pinworm </li> <li> Slide 64 </li> <li> Epidemiology the reason for wide distribution of Ascaris l 1. simple life cycle 2. high reproductive capacity (240,000 eggs per day) 3. resistance of egg (due to presence of ascarosidal ) 4. social customs and habits </li> <li> Slide 65 </li> <li> Treatment Prevention and control Treatment of patients and carriers, Blockade of the route of transmission Protection of the susceptible population (personal prophylaxis) Chemoprophylaxis, vaccines, other preventive measures </li> <li> Slide 66 </li> <li> Treatment Prevention and control Treatment: Mebendazole Albendazole To prevent re-infection of E.v, treat the whole family. Others for hookworm diseases? </li> <li> Slide 67 </li> <li> Prevention and control: hygienic control of food, feces Good hygiene is the best preventive measure Wash all bed clothes and bedding in hot water to kill infective eggs of E.v. avoidance of contact with infected fecal material Others? </li> <li> Slide 68 </li> <li> Dog and Cat Hookworms HUMANS may serve as accidental hosts of these hookworms when the filariform larvae penetrate human skin Creeping Eruption </li> </ul>


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