7 Questions
Which type of parasite cannot exist without a host?
Wuchereria bancrofti
Which parasite is an example of an accidental/incidental parasite?
Echinococcus granulosus
Which parasite lives between the cells in the tissues of the host?
Entamoeba histolytica
Which parasite is completely dependent on the host during a segment or all of its life cycle?
Plasmodium species
Which parasite can either live as a parasitic form or free-living form?
Entamoeba histolytica
Which parasite lives within the cavities of the host’s body?
Trichuris trichiura
Which parasite usually infects canines but can infect humans if accidentally ingested?
Echinococcus granulosus
Study Notes
Medical Helminthology
- Studies biological features and geographic distribution of parasitic worms (helminthes)
- Examples of helminthes: Ascaris lumbricoides, hookworms, Strongyloides stercoralis, and Trichuris trichiura
- Involves the study of the course of helminthic invasions, diagnosis, prophylaxis, and control of helminthic diseases
Medical Protozoology
- Deals with parasites of unicellular origin
- Protozoans are motile and can be found in watery stool
- Protozoans can invade tissues and cells, but are not worms
- They have flagella, cilia, and propellers
- Four groups of protozoans based on mode of movement:
- Sarcodina: uses pseudopods (e.g. Amoebas like Entamoeba histolytica)
- Mastigophora: uses flagella (e.g. Giardia lamblia)
- Ciliophora: uses cilia (e.g. Balantidium coli)
- Sporozoa: non-motile at adult stage (e.g. Plasmodium and Cryptosporidium which causes malaria)
Importance of Diagnostic Parasitology Testing
- Reasons for testing: travel, population movements, control issues, climate change, epidemiologic considerations, compromised patients, potential sex bias regarding infection susceptibility, and aging
Biological Relationships
- Symbiotic relationships: organisms develop unique relationships due to their habitual and long associations with one another
- Symbiosis: living together of unlike organisms
- Symbionts: organisms living together, often with one living in or on the body of the other
- Types of symbionts:
- Ectosymbionts: attached to the outside of the host
- Phoresis: two symbiotes traveling together, with no physiological or biochemical dependence
- Endosymbionts: inside or within the body of the host
Types of Symbiotic Relationships
- Facultative Commensalism: partners do not necessarily require one another to survive and reproduce
- Obligate Commensalism: at least one of the partners cannot complete its life cycle on its own
- Parasitism: one organism benefits at the expense of the host, which can be a human or an animal
Parasites
- Types of parasites:
- Ectoparasites: inhabit only the body surface of the host without penetrating the tissue (e.g. head lice, ticks, and mites)
- Endoparasites: lives within the body of the host and causes an infection (e.g. Entamoeba histolytica)
Test your knowledge about the different types of symbiotic relationships such as facultative commensalism, obligate commensalism, and parasitism. Understand the characteristics and differences between these relationships in the animal kingdom.
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