... Flashcards
Factors that influence the degree of harm done by various parasites are as follows;
- Number of parasites present
- Location of the Parasites
- Nature of their food
- Movements of parasites
- Age of the host
- Virulence of parasites
Effects of Parasitic Life on the Parasites
✓ Loss of certain sense organs
✓ Loss of wings
✓ Loss of alimentary canal
✓ Special development of some organs and adhesion
✓ Special development of organ of reproduction for fecundity
✓ Sexual dimorphism
✓ Complex life-cycle
✓ Multiplication in Intermediate host
✓ Greatly altered metabolism
✓ Stay dormant/inhibited state in unnatural host
PATHOGENICITY and PATHOGENIC EFFECTS; Parasites harm their host in any of the following ways:
- Absorbing part of the digested nutrients, vitamins, minerals
- Sucking blood or lymph
- Feeding on the tissues of the host
- Causing mechanical obstruction or pressure
- Causing growth of nodules and tumors
- Perforating blood vessels
- Causing wounds
- Destruction of tissues
- Irritation and annoyance
- Secretion of toxins and other harmful substances
- Transmitter of the causal agents
- Reducing the resistance of the host
- Causing allergy
- Serving as intermediate host
- Abortion, infertility, lowered productive performance
- Decrease feed conversion
Secretion of toxins and other harmful substances;
✓ anti-digestive enzymes
✓ Digestive enzymes harmful to host tissues
✓ Anticoagulatory and Hemolytic enzymes
✓ Other secretions and excretion and body fluids
Resistance to parasites is also influenced by some factors as follows;
✓ nutrition
✓ age of the host
✓ vitamins
✓ general condition of the host
Manifestations referred to as?
allergy, anaphylaxis, serum, sickness, atrophy, and contact dermatitis
Eye spots in some external parasites
e.g Melophagus ovinus
Loss of certain sense organs
Eye spots in some external parasites
e.g Melophagus ovinus
Loss of certain sense organs
Eye spots in some external parasites
e.g Melophagus ovinus
loss of certain sense organs
loss of wings example
bedbugs and lice
loss of alimentary canal
tapeworms
which is normally in the kidneys can be found in the liver or lungs of cattle
Stephanurus dentatus
are often erratic
incidental parasites
example of incidental parasites
Fasciola hepatica (normally in the liver)
in general species of parasite associates only with one species of host (host specific)
Pediculus capitis in man
if a parasite has more than one host, these host are usually closely associated
Ascaridia galli in chickens, turkey, and pigeons
Few parasites can live in a variety or in a wide range of hosts
Trichinella spiralis in man, pig, cat, rats and birds
where the parasite is able to develop up to sexual maturity and lives normally in it.
natural host of a parasite
If in unsuitable host, the parasite does not reach sexual maturity. Each species of parasite has its predilection site in or on the host. called?
organ specificity
3 examples of organ specificity
✓ Heterakis gallinae in the ceca of chicken
✓ Stephanurus dentatus in the kidneys
✓ Matastrongylus spp. in the lungs of pigs
Kinds of immunity
- Natural immunity
- Acquire immunity
- Age Resistance
True age immunity
presence of natural antibodies (normally produced against bacteria viruses) Many parasites of man do not occur spontaneously in animals. Blacks (Aetas) are more resistant tha whites (Lowlanders) to hookworms and vivax malaria
Natural Immunity
good feeding with balanced ration is one of the best prophylaxis against parasitic infection.
nutrition
the presence slow grade infection precludes succeeding infections.
example: BABESIOSIS
Preimmunition or pre-immunity
