TASHKENT MEDICAL ACADEMY Infectious and children infectious diseases department

1. Theme:Early and Comparative diagnosis of Helminthiasis TASHKENT MEDICAL ACADEMY Infectious and children infectious diseases department Lecturer:

2. INTRODUCTION • Helminth is a general term meaning worm. • The helminths are invertebrates characterized by elongated, flat or round bodies. • In medically oriented schemes the flatworms or platyhelminths (platy from the Greek root meaning "flat") include flukes and tapeworms. • Roundwormsare nematodes (nemato from the Greek root meaning "thread"). These groups are subdivided for convenience according to the host organ in which they reside, e.g., lung flukes, extraintestinal tapeworms, and intestinal roundworms.

3. INTRODUCTION • helminths have similar anatomic features that reflect common physiologic requirements and functions. • The outer covering of helminths is the cuticle or tegument. • Prominent external structures of flukes and tape worms are acetabula (suckers) or bothria (false suckers). • Male nematodes of several species possess accessory sex organs that are external modifications of the cuticle. • Internally, the alimentary, excretory, and reproductive systems can be identified by an experienced observer. • Tapeworms are unique in lacking an alimentary canal. This lack means that nutrients must be absorbed through the tegument. • All flukes and tapeworm species that infect humans are hermaphroditic.

4. INTRODUCTION • Helminths, or worms, are bilaterally symmetrical—that is, they have left and right halves that are mirror images. • A helminth also has a head and tail end, and its tissues are differentiated into three distinct tissue layers: • ectoderm, • mesoderm, and • endoderm. • The definitive classification is based on the external and internal morphology of egg, larval, and adult stages. • Helminths that parasitize humans include flatworms and roundworms

5. Parasite modes of entry • Ingestion • Arthropod bites • Penetration of intact skin or mucous membranes

6. Spread and tropisms • Some parasites must migrate to certain locations within the host in order to complete their life cycle • Non-human parasites, in humans, often fail to migrate properly and become “dead-end infections”

7. Mechanisms for evading the host response • antigenic variation - trypanosomes • intracellular infection - plasmodia • encystation* - amoebae, cestodes • camouflage - schistosomes

8. Tissue damage and host response • direct destruction of tissue • hypersensitivity reactions • eosinophilia • occurs with helminths, not protozoa • results from tissue migration

9. Classification of helminths Nematodes (roundworms) Platyhelminthes (flatworms): -Trematodes (“flukes”) - Cestodes (“tapeworms”)

10. roundworms flukes tapeworms Helminthic diseases (autoinfection cycle) • Intestinal • Others • Strongyloides • Invasive • Trichinosis • Filaria • Schistosomiasis • Cysticercosis • Echinococcus (muscle pain, uncooked carnivores) (worms in lymphatics or under skin) (liver or urinary tract granulomas and fibrosis) (cysts in brain, seizures) (massive cysts in liver or lung)

11. Roundworms (Nematodes) • In contrast to platyhelminths, nematodes are cylindrical rather than flattened; hence the common name roundworm. • The body wall is composed of an outer cuticle that has a noncellular, chemically complex structure, a thin hypodermis, and musculature. The cuticle in some species has longitudinal ridges calledalae. The bursa, a flaplike extension of the cuticle on the posterior end of some species of male nematodes, is used to grasp the female during copulation.

12. Structure of nematodes. • (A) Female. (B) Male. Transverse sections through the midregion of the female worm (C) and through the esophageal region (D).

13. Roundworms (Nematodes) • The alimentary canal of roundworms is complete, with both mouth and anus. The mouth is surrounded by lips bearing sensory papillae (bristles). The esophagus, an important feature of nematodes, is a muscular structure that pumps food into the intestine; it differs in shape in different species.

14. Roundworms (Nematodes) • The intestine is a tubular structure composed of a single layer of columnar cells possessing prominent microvilli on their luminal surface. • Females can lay as many as 200,000 eggs per day. • The large number of eggs, well protected by hard shells, ensures that some will survive and reproduce. • Over 80,000 species of roundworms have been described. • They occur free living in soil, fresh water, and salt water and as parasites in every plant and animal species

15. Roundworms (Nematodes) • A single acre of soil can contain billions of roundworms. • Many parasitize insects and plants; only a relatively small number of species infect humans, but they cause significant debilitation,suffering,and death. • Most roundworms that parasitize humans, such as hookworms and pinworms, live mainly in the intestinal tract, • but a few, such as Wuchereria, have larval forms that live in blood or lymph

16. Generalized life cycle of intestinal nematodes. • острица • хлыстовик • аскарида • анкилостома

19. Strongyloides - clinical features • uncomplicated • GI upset • autoinfection • hyperinfection • rash • bronchspasm, infiltrates • diarrhea • profound eosinophilia • recurrent Gram-negative bacteremia

20. Life cycles of two types of filaria Arthropod vector Adult worm pairs Larvae (microfilariae) Lymph- mosquitoes peripheral circulate dwelling lymphatics in bloodstream (e.g, Wuchereria bancroftii ) Skin- biting flies skin nodules migrate through dwelling or migratory dermis

23. O. volvulus microfilaria in skin snip

24. Trichinella spiralis

25. Clinical features of trichinosis • Most common: • muscle pain and tenderness • fever +/- chills • edema (often periorbital) • >10% eosinophilia (often ~50%) • elevated CPK • +/- chronic neurologic/myocardial • self-limited (2% mortality)

26. Treatment of trichinosis • antihelminthic (albendazole) to kill any intestinal adults • steroids to relieve inflammatory reactions • antipyretics

27. Flukes (Trematodes) • Adult flukes are leaf-shaped flatworms. Prominent oral and ventral suckers help maintain position in situ. Flukes are hermaphroditic except for blood flukes, which are bisexual. The life-cycle includes a snail intermediate host. • A dorsoventrally flattened body, bilateral symmetry, and a definite anterior end are features of platyhelminths in general and of trematodes specifically. • Flukes are leaf-shaped, ranging in length from a few millimeters to 7 to 8 cm.

28. Structure of flukes. (A) Hermaphroditic fluke. (B) Bisexual fluke.

29. Geographic distribution of schistosomiasis S. mansoni S. hematobium S. japonicum

30. The life cycle of blood fluke, Schistosoma japonicum. This organism causes chistosomiasis. Unlikesome flukes, S. japonicum does not have a redia stage, nor does it enter an arthropod host.

31. Schistosomiasis - pathogenesis • egg granuloma (type IV reaction)--> fibrosis • morbidity ~ worm (egg) burden • adult worms: invisible to the immune system (survive for years)

32. Drug treatment of schistosomiasis • Praziquantel increases permeability of adult parasite to Ca++. • Tetanospasm --> death

33. Control of Schistosomiasis REDUCE CARRIERSmass rx program ELIMINATE SNAILS molluscicides destroy snail habitats snail-eating fish PREVENT WATER CONTAMINATION latrines, toilets public health education PREVENT HUMAN EXPOSURE water systems

34. Tapeworms (Cestodes) • Adult tapeworms are elongated, segmented, hermaphroditic flatworms that inhabit the intestinal lumen. • Larval forms, which are cystic or solid, inhabit extraintestinal tissues.

35. Structure of tapeworms • Structure of tapeworms

36. Generalized life cycle of tapeworms

38. Cysticerci Hydatid Cyst

39. Isolated cysticerci Hydatid cyst

40. ingestion of eggs in pastures Echinococcosis ingestion of entrails contact with dogs Cystic Hydatid Disease

42. Treatment of cysticercosis and echinococcosis • Antihelminthic therapy (e.g., albendazole, praziquantel) • (Echinococcus only) • Surgical removal • Irrigation-evacuation of cysts

43. The END