EFFECTS OF PARASITES ON HOSTS
In general, the parasites cause weakening of the body of their hosts by causing the deprivation of nutrients, fluids and metabolites as they compete with their hosts for the same. They may also cause pathological effects in their hosts such as
e.g. Hypertrophy is exhibited by RBC’s that are infected by plasmodium.
2. HYPERPLASIA-`Some parasites cause an abnormal increase in the number of cells . This kind of parasitic effect is called hyperplasia.
e.g., Fasciola hepatica causes the thickening of bile ducts in the sheep by stimulating cell division.
3. NEOPLASIA-Some parasites cause an abnormal growth in the host cells in a tissue to form new structures. This kind of parasitic effect is called Neoplasia.
4. GIGANTISM-Some parasites cause an abnormal increase in the size of the host. This kind of parasitic effect is called Gigantism.
e.g., The larval stages of Fasciola hepatica cause gigantism in snail, an intermediate host.
5. PARASITIC CASTRATION-Some parasites cause the degeneration of gonads of the host, making it sterile. This effect is called Parasitic castration.
e.g., Sacculina (root headed barnacle, a crustacean), which lives as an ectoparasite on crab(Carcinus maenas) causes the degeneration of gonads of the ovaries in it.
6. PATHOGENIC EFFECTS-Most of the parasites cause various types of diseases like
A. Malaria by Plasmodium sps,
B. Amoebiasis by Entamoeba histolytica,
C. Elephantiasis by Wuchereria bancrofti,
D. African sleeping sickness by Trypanosoma gambiense,
E. Delhi boils/Taskent ulsers/ Oriental sores by Leishmania tropica,
F. Kala azar/ Dum dum fever/ Visceral leishmanniasis by Leishmania donovani,