Intro to Parasitology Definitions Flashcards
Definitive (final) host
the host in which sexual reproduction (of the parasite) takes place.
Intermediate host
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.
Paratenic host
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).
Transport host
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).
Reservoir host
an infected definitive host which can act as a source of infection for other
animals.
Direct life-cycle
there is no intermediate host in the life-cycle.
Indirect life cycle
an intermediate host is involved in the life-cycle.
Predilection site
most parasites establish at a particular anatomical site or in a particular
tissue.
Prepatent period
the time from infection of the host to the appearance of eggs or larvae in faeces, urine or blood.
Parasitaemia
the presence of parasites in the circulating blood.
Autoinfection
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.
Biotic potential
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.
Generation time
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.
Horizontal transmission
transmission of the parasite through the host population.
Vertical transmission
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).
Bionomics
the influence of environment (particularly temperature and humidity) on the development of free-living life-cycle stages.
Hypobiosis
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.
Mucosal larvae
developing or hypobiotic larvae in the wall of the alimentary tract.
Resistance
the ability of an animal to prevent establishment and/or development of
infection
Resistance 2
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
Resilience
the innate ability of an animal to withstand the effects of infection
Tolerance
An innate insusceptibility of a parasite population to a potentially lethal
chemical (i.e. not dependent on prior exposure)
Refugia
sites where parasites escape exposure to antiparasitic drugs when animal populations are being treated
Formulation
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.
