1.Ectoparasites: live on the surface of their hosts.
2.Endoparasites: live inside the body of their hosts (small intestine, large intestine, etc.).
According to the number of hosts :
1. Monoxenous: needs only one host for the completion of life cycle as Ascaris and Trichuris
2. Heteroxenous: the life cycle is completed in two or more hosts as Heterophyes
According to the association with their hosts :
1. Obligatory: can't survive outside their hosts, i.e. completely dependant on their hosts.
2. Facultative: capable of free living outside their host (change life style between free-living and parasitic) as Strongyloides stercoralis.
3. Temporary: visit the hosts from time to time for its meal & then leaves, as mosquitoes
4. Permanent: always fixed to their hosts.
5. Opportunistic: capable of producing disease in immuno-compromised host as Cryptosporidium.
Types of hosts :
- Final or definitive host (DH): harbors the adult stages or sexually reproducing forms of the parasite.
- Intermediate host (IH): harbors the larval stages or asexually reproducing form.
- Reservoir host (RH): Animal host that harbors the same species and stages as human. It maintains the life cycle of the parasites in nature
- Vector: an arthropod that transmits parasites from one host to another.
Effects of parasitism: Parasite may :
1- Feed on blood as mosquitoes, fleas, lice and ticks.
2- Cause tissue necrosis, ulceration and inflammation
3- Consume host’s food
4- Mechanically obstruct the intestine, bile duct, or lymphatics.
5- Cause pressure atrophy of surrounding tissues.
6- Produce toxin and induce allergy.
7- Disturb body functions causing indigestions, malabsorption and diarrhoea as in intestinal parasites. Follow Us
Posts
