parasites
Worm Invaders
Parasite
Living organism receiving nourishment & shelter from another organism, where it lives
Host
An organism harbouring parasite
Associations of living organisms with other organisms
Symbiosis Commensalism parasitism
1.Symbiosis
Both are so dependent on each other that one cannot live without other
Contd...
None of the partners suffer any type of harm
2. Commensalism
Parasite only gets the benefit
Contd...
Does not cause harm to host
Contd...
Commensal is capable of living independently
3. parasitism
Parasite gets the benefit, causes injury to the host
Contd...
Host may develop some resistance also
Contd...
Both undergo a number of adaptations
Contd...
Parasite loses power of living independently
Classes of parasites
Ectoparasite Endoparasite Temporary
Permanent
Facultative Obligatory
Occasional Wandering
1.Ectoparasite
Lives outside on surface of body of host
2.Endoparasite
Lives inside the body of host
Contd...
Blood, tissues, body cavities, digestive tract & other organs
3. Temporary
Visits for a short period
4. permanent
Leads parasitic Life throughout its life
5. facultative
Lives parasitic life when gets favourable conditions
6. obligatory
Can’t live without parasitic life
7. occasional
Attacks an unusual host
8. wandering
Reaches a place where it cannot live
Classes of hosts
Definitive Intermediate Paratenic
1. Definitive host
Either harbors adult stage/ carries out sexual reproduction
Contd...
Man definitive host in majority of human parasitic infections
2. Intermediate host
Harbors larval stages
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In some cases more than one intermediate host is needed
Contd...
Referred to as first & second intermediate hosts
3. Paratenic host
Carrier/ temporary host
Contd...
Parasite remains viable but without development
Scheme followed in parasitological studies
1. History of discovery of parasite 2. Geographical distribution
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3. Habitat
4. Morphology and life cycle
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5. Modes of infection 6. Effect of parasite
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7.Immunological responses
8. Diagnosis
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9. Treatment
10. Prophylaxis
1. history
Date & year parasite first identified
2. Geographical distribution
Environmental factors, social customs & habits of individuals greatly affect distribution
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Each parasite has a specific distribution
3. habitat
Parasite selects a particular place of abode according to its mode of existence
Contd...
May get directly established reach suitable place attains sexual maturity
Contd...
attains maturity/ requires another host for further development
4. Morphology & life cycle
General structure, various stages of life cycle
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Life cycle may be passed in one/more host Host may be changed
5. Modes of infection
Transmission of parasite from one host to otherinfective stages
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Means of transmission & avenuesconsideration
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Infection endemic areas continued reservoir & intermediate hosts
6. Pathogenic effects
Vary with nature of parasite 1.Protozoan 2. Helminthic
1. Protozoan infections
Lesions: proliferation, multiplication & metastasis
2. Helminthic infections
Adult parasites no multiplication, effects depend upon habitat
Contd...
Allergic reactions secretion of certain substances, skin tests √
7. Laboratory diagnosis
Depending on nature of parasite, materials may be collected
Blood Stool Urine
Sputum Biopsy material Indirect evidences
8. treatment
Many infections can be treated by chemotherapy
Contd...
Drugs may be taken orally
9. prophylaxis
Preventive measures for controlling spread of parasite
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Eradication of infection in reservoir hosts
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Destruction of intermediate hosts
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Personal hygiene
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