Review the Basic Concepts of Parasitism with Examples

2. What is the difference between an ectoparasite and an endoparasite?

Ectoparasites are parasites that explore the external surface of the host (such as mites that are parasitic to the skin). Endoparasites are parasites that live within the body of the host (such as the taenia). 

Parasitism Review - Image Diversity: ectoparasite endoparasite

3. Concerning the number of hosts, how are parasites classified?

Parasites that require only one host are called monoxenous parasites. Parasites that need more than one host to complete their life cycle are called heteroxenous parasites.

4. What is the criterion used to classify hosts as intermediate hosts or as definitive hosts?

The criterion used to classify hosts as intermediate hosts or as definitive hosts is the type of reproduction of the parasite, sexual or asexual, within the host. The host within which the sexual reproduction stage of the parasite occurs is the definitive host. The host within which the asexual reproduction stage of the parasite occurs is the intermediate host.

5. What are parasites vectors?

The vectors of a parasite are organisms able to transport the parasite during stages of its life cycle, making the infection of other hosts possible. For example, the mosquito Aedes aegypti is the vector of the dengue virus; triatomine bugs are vectors of Trypanosoma cruzi, the protozoan that causes Chagas’ disease; and mice are vectors of leptospira, the bacteria that cause leptospirosis.

Parasitism Review - Image Diversity: vectors of disease

6. What is an etiological agent of disease?

An etiological agent of disease is the agent that causes the disease. It may be a living organism, a substance or an environmental circumstance.

7. What is the difference between the concepts of epidemic disease and endemic disease?

Endemic diseases are those that often affect people in a given place, whether many or few individuals. Epidemic diseases are those that spread rapidly with a high number of new cases. An endemic disease can turn into an epidemic disease.