MEDICAL

HELMINTHOLOGY

Bushehr University of Medical Sciences

Department: Microbiology and Parasitology

Module: Medical Parasitology (Introduction)

Instructor: Dr. Mohammad Rayani, Ph.D

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(پسشکی)ٌا کرم بىذی طبقً

زیر ی شاخً سً بً متعلق کً دارد اشاري ماوىذی کرم جاوُران بً «َرم» کرم َاژي

:ٌستىذ

1- وماتُدا یا (گرد کرمٍای) وخی کرمٍای

2- است ردي دَ شامل کً (تخت کرمٍای) پٍه کرمٍای:

1- (وُاری کرمٍای) سستُدا

2- (شکل برگی کرمٍای) ترماتُدا

2Dr. M. Rayani (Bushehr University of Medical Sciences)

HELMINTH - a multicellular organism (metazoa)

helminths do not multiply within hosts

cause different diseases in humans; (human suffering)

cause of high morbidity and mortality of people worldwide

few helminthic infections cause life threatening diseases

Medical Helminthology

is concerned with the study of helminthes or parasitic worms

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Multicellular

Well developed organ systems

Worldwide Tropical, subtropical Survival of eggs, larval stages

Less developed Sanitation, intermediate host survival

Severity of disease depends on:

parasite burden and immunologic response to parasites

Pathological complications is depend to:

reaction of organs and parasitic population

Characteristics

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1. Platyhelminths (Flat worms)

- Cestoda (Tape worms)

- Trematoda (Flukes)

- Turbelaria (Free living, Rarely parasite)

2. Nematohelminthes

- Nematoda (Roundworms)

3. Nematomorpha

(Rarely human parasite, mail and female separate, threadlike,Unsegmented, symmetrical)

4. Acantocephala

(Unsegmented, Rarely parasite, mail and female separate)

5. Annelida (Segmented, symmetrical, Leech, earthworm)

Classification

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Classification of helminths

Nematodes (roundworms)

Platyhelminthes (flatworms):

Trematodes )“flukes”(

Cestodes )“tapeworms”(

METAZOA (HELIMINTHS)

1- Platyhelminthes

1-1 Trematoda

(a) Genus Fasciola E.g. F. hepatica

(b) Genus Schistosoma E.g. S. hematobium

1-2 Cestoda

(a) Genus Taenia E.g. T. saginata

(b) Genus Echinococcus E.g. E. granulosus

(c) Genus Hymenolepsis E.g. H. nana

(d) Genus Diphylobotrium E.g. D. latum

2- Nemathelminthes

Nematodes

(a) Intestinal Nematodes E.g. Ascaris lumbricoides

(b) Somatic Nematodes E.g. Wuchereria bancrofti

CLASSIFICATION OF MEDICALLY IMPORTANT PARASITES

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Helminthic diseases

Intestinal

Strongyloidiasis

Invasive

Trichinosis

Filariasis

Schistosomiasis

Cysticercosis

Echinococoosis

(autoinfection cycle)

(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)

roundworms

flukes

tapeworms

Exposure of humans to the parasites may occur in one of the following

ways:

1. Contaminated soil (Geo-helminthes)

2. Blood sucking insects or arthropods (as in filarial worms)

3. food (Taenia saginata in raw meat)

4. Water-snail (cercariae of blood flukes)

5. Person to person (as in Enterobius vermicularis, Hymenolopis nana)

They enter the body through different routes including:

mouth, skin and the respiratory tract

Modes of transmission

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Soil transmitted helminths (Ascaris, Hookworms)

Arthropod transmitted helminths (Filaria, Dracunculus)

Food –animal transmitted helminths (Taenia)

Snail transmitted helminths (Fasciola, Schistosoma)

Direct or contagious transmitted helminths (Enterobius,

Hymenolopis)

Classification based on modes of transmission

10Dr. M. Rayani (Bushehr University of Medical Sciences)

Pathogenesis

Direct Damage

Blockage

Pressure

Anemia

Malnutrition

Tissue Necrosis

Tissue destruction

Indirect Damage

Host response

Inflammation

Hypersensitivity

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Clinical manifestation

Asymptomatic

Symptomatic

Acute

Chronic

Complication

Pathology produced due to

Adult, Larvae, Eggs

Diagnosis

Parasitological Qualitative and

Quantitative

Sample Stool, blood, tissue biopsy,

duodenal aspiration, sputum, urine

Diagnostic stage Adult

Proglottid or segment

Eggs

Larvae (cysticercus, rabditiform, filariform and microfilariae)

Naked eye, microscopy

Parasitological

Smear

Direct

Blood

Concentration techniques

Stool culture

Histopathological findings

Non parasitological

Clinical

Serum

ELISA

Molecular12

Control and Prevention

Primary prevention – (before infection occur)

Health education

Environmental improvement, e.g. Sanitary control of drinkingwater and food; Proper waste disposal

Specific protection

Secondary prevention – (when infection occur)

Early diagnosis: history, clinical, lab

Prompt treatment: symptomatic, antihelminthic

13Dr. M. Rayani (Bushehr University of Medical Sciences)