Intro to Parasitology Definitions

Question 1

Definitive (final) host

Answer 1

the host in which sexual reproduction (of the parasite) takes place.

Question 2

Intermediate host

Answer 2

a host (other than the final host) in which development (sometimes including asexual reproduction) of the parasite takes place - usually an essential part of the life-cycle.

Question 3

Paratenic host

Answer 3

the parasite enters host tissues but no development or growth takes
place (often, the parasite is waiting for its paratenic host to be eaten by
its next intermediate or final host, e.g. Toxocara cati in a mouse).

Question 4

Transport host

Answer 4

a loose association in which the parasite “hitches a lift”, i.e. is merely
carried. This may be a means of geographical dispersal or of enhancing
opportunity for infecting host (e.g. Syngamus trachaea  earthworm
transport host  eaten by pheasant).

Question 5

Reservoir host

Answer 5

an infected definitive host which can act as a source of infection for other
animals.

Question 6

Direct life-cycle

Answer 6

there is no intermediate host in the life-cycle.

Question 7

Indirect life cycle

Answer 7

an intermediate host is involved in the life-cycle.

Question 8

Predilection site

Answer 8

most parasites establish at a particular anatomical site or in a particular
tissue.

Question 9

Prepatent period

Answer 9

the time from infection of the host to the appearance of eggs or larvae in faeces, urine or blood.

Question 10

Parasitaemia

Answer 10

the presence of parasites in the circulating blood.

Question 11

Autoinfection

Answer 11

establishment of the products of sexual reproduction in the individual animal in which they were formed.

Very few parasites do this - parasite eggs, cysts or larvae usually have to leave
the final host to become disseminated in the environment.

Question 12

Biotic potential

Answer 12

the ability of an organism to increase in numbers; for parasites, this is largely determined by the numbers of off-spring produced by sexual and asexual phases of reproduction, and the generation time.

Question 13

Generation time

Answer 13

time taken for one generation to complete its life-cycle. This can be from
a few days (egg coccidia) to several years (egg the sheep tick) and may be dependent on climate.

Question 14

Horizontal transmission

Answer 14

transmission of the parasite through the host population.

Question 15

Vertical transmission

Answer 15

direct transmission of the parasite from one host generation to the next;
for example, prenatally (egg Toxocara canis), via milk (egg Strongyloides spp) or neonatal transfer (egg Demodex, Filaroides).

Question 16

Bionomics

Answer 16

the influence of environment (particularly temperature and humidity) on the development of free-living life-cycle stages.

Question 17

Hypobiosis

Answer 17

development of parasite within the host ceases at a particular stage in the life-cycle; this usually occurs when conditions outside the host are unfavourable; the metabolic rate slows considerably; the duration of arrested development is probably genetically predetermined.

Question 18

Mucosal larvae

Answer 18

developing or hypobiotic larvae in the wall of the alimentary tract.

Question 19

Resistance

Answer 19

the ability of an animal to prevent establishment and/or development of
infection

Question 20

Resistance 2

Answer 20

this term is also used to describe the inherited ability of a strain of a parasite to tolerate doses of a parasiticide that would prove lethal to the majority of individuals in a normal population of that species

Question 21

Resilience

Answer 21

the innate ability of an animal to withstand the effects of infection

Question 22

Tolerance

Answer 22

An innate insusceptibility of a parasite population to a potentially lethal
chemical (i.e. not dependent on prior exposure)

Question 23

Refugia

Answer 23

sites where parasites escape exposure to antiparasitic drugs when animal populations are being treated

Question 24

Formulation

Answer 24

the process by which the physical or biological characteristics of a
pharmaceutical substance (in our case, a parasiticide) are modified by combining it with other (often inert) substances.