An Introduction to Parasites

Question 1

Parasite

Answer 1

An organism that lives in a host organism and gets it’s food at the expense of the host.

Question 2

Protozoa

Answer 2

These are microscopic, one-celled organisms which can be free living or parasitic in nature. They are able to multiply in humans. Transmitted via faecal-oral or arthropod vector. E.g malaria, amoebic dysentry, leishmaniosis

Question 3

Helminths

Answer 3

Nematodes (round worms), cestodes (tapeworm), trematodes schistosomiasis (bilharzia/snail fever). Helminth infection is often accompanied with eosinophilia and elevated IgE.

Question 4

Arthropods

Answer 4

E.g. lice, ticks, mites

Question 5

Diagnostic principles in parasitology

Answer 5

Definitive diagnosis through identification of parasites in host tissue or excreta. Microscopy of different stages (often faeces) to identify parasites, ova or cysts. Culture is rarely possible. Blood films are used to identify malaria (thick and thin films). Serology to detect antibodies which is useful when the parasite is located in deep tissue sites.