Pre-Modular Parasitology Words

Front 1

Cercaria

Back 1

In the trematode life cycle, the cercaria is the Larval trematode (which may not have a tail, depending on the species) Cercaria develops fom the germinal cells of the sporocyst and emerges from the snail (intermediate host) to later become (in most species) the metacercaria

Front 2

Control

Back 2

Reduction of disease incidence, prevalence, morbidity, or mortality to a locally acceptable level as a result of deliberate efforts. Continued intervention measures are required to maintain the reduction

Front 3

Cysticercoid

Back 3

a single, evaginated scolex that is embedded in a small solid cyst that are typically found in small intermediate hosts such as arthropods

Front 4

Definitive Host

Back 4

found in all parasitic life cycles. It's the host in which the sexual stages of the parasite ("adults") mature. if there are no sexual stages in the life cycle, then the definitive host is the host in the life cycle considered most important to humans.

Front 5

Direct Parasite life cycle

Back 5

a life cycle of a parasite in which the pre-parasitic larvae develop in the environment as free-living stages in which the eggs will EITHER hatch and the pre-parasitic larvae are entirely free-living and the infective stage is usually an L3 and infection occurs via ingestion of infective stage of skin penetration OR the eggs DO NOT hatch and pre-parasitic larvae develop inside their eggs and infective stage is usually the egg containing the infective larva and infection of the definitive host occurs via ingestion of the infective stage.

Front 6

Ectoparasite

Back 6

a parasite that lives ON the surfaces of the body of the host (i.e. fleas, ticks)

Front 7

Embryonated egg (larvated egg)

Back 7

a nematode egg with a developed larva inside it. most nematode eggs leave the host in the morula stage and develop in the environment to the emryonated stage (the stage just before hatching). a few nematode eggs are embryonated at the time they leave the host

Front 8

Endoparasite

Back 8

a parasite that lives INSIDE the body of the host (i.e. roundworms)

Front 9

Eradication

Back 9

permanent reduction to zero of the worldwide incidence of infection caused by a specific agent as a result of deliberate efforts. Intervention measures are not longer needed

Front 10

Extinction

Back 10

the specific organism no longer exists in nature or the laboratory

Front 11

Final Host

Back 11

Definitive Host

Front 12

Helminths

Back 12

a general term referring to the nematodes (roundworms), trematodes (flat worms, flukes), cestodes (tape worms) and acanthocephalans (thorny-headed worms)

Front 13

Hydatid Cyst

Back 13

Larva of the Echinococcus spp. which is a large fluid filled cyst containing many invaginated scolecies and daughter cysts that also contain many invaginated scolecies. There are two types of hydatid cysts: E. granulosus has uniloculular (one chambered) cyst and E. multilocularis has a multi-locular (many chambered cyst)

Front 14

Hypobiosis

Back 14

In Parasitology: A temporary halt in nematode development within the host at an early stage in the parasitic phase of the life cycle in nematodes with direct life cycles only. Nematodes arrest as immature forms in the definitive hosts ata time when conditions in the external environment pose a hazard to survival of free living pre-parasitic stages (usually in winter or dry seasons). Once conditions are more favorable, the arrested development resume their development to adults the life cycle continues

Front 15

Incidental Host

Back 15

designates the host in which that particular parasite is NOT found (i.e. a dog flea on a human)

Front 16

Intermediate Host

Back 16

a stage in the life cycle that is essential to parasite development (with some exceptions), and the mode of transmission of the parasite to the definitive host is usually by predation. Intermediate hosts are not required for all parasite life cycles. i.e. rodents are the IH for tapeworms

Front 17

Indirect life cycle

Back 17

a life cycle of a parasite in which the pre-parasitic larvae develop inside an appropriate intermediate host

Front 18

Life Cycle

Back 18

the stages an organism goes through over time containing a possible pre-parasitic and a parasitic phase. Usually represented as a circle beginning with the formation of a individual and ending with the production of the next generation. In Parasitology, the life cycle of the parasite gives the investigator predictive value for understanding pathogenesis and clinical signs, and for understanding the epidemiology and control of the parasite. Life cycles can either be direct or indirect

Front 19

Metacercaria

Back 19

stage of trematode life cycle that the cercaria after invading the second intermediate host or attaching itself to vegetation, develop into. When ingested by the definitive host, the metacercaria will develop to the adult stage

Front 20

Metacestode

Back 20

Mature tapeworm larvae

Front 21

Miracidium

Back 21

the pyriform, ciliated larva of a trematode that developed in and hatched from the egg. The miracidium will penetrate the snail and undergo development to the next stage in the lifecycle

Front 22

Myiasis

Back 22

Infestation of organs and tissues of vertebrates by larval dipterans (true flies)

Front 23

Normal Host

Back 23

designates the usual or preferred host in which that species of parasite is found. i.e. fleas to dogs

Front 24

Occult Infection

Back 24

an infection with adult worms but no corresponding diagnostic stage. i.e. Infections with heartworm (Dirofilaria immitis) some hosts may not have circulating microfilaria (this may be a result of immune-mediated clearance of the microfilaria, a single-sex infection, chemosterilization of the adult worms by drug treatment, or senescent adults). This would be known as an "OCCULT heartworm infection".

Front 25

Parasite

Back 25

Organisms that live temporarily or permanently on or withing other living organisms (pant or animal hosts) for the purpose of obtaining food

Front 26

Parasitic Phase of Life Cycle

Back 26

The development and maturation to adult males and females occurring in the definitive host of a parasite cycle

Front 27

Parasitism

Back 27

a two species association in which on species, the parasite, lives on of in a second species, the host, for a significant period of its life and obtains nourishment from it. The parasite may or may not sause disease in the host

Front 28

Parasitology

Back 28

The study of host-parasite relationships. Traditionally this area of study has focused on parasites belonging to the protozoa, helminths and arthropods

Front 29

Paratenic Host (transport host)

Back 29

A type of intermediate host in which immature helminths may survive for indefinite periods but do not undergo development. Further parasitic development depends upon infection of the definitive host, which is usually by predation on the paratenic host. Competion of a life cycle may happen with or without a paratenic host, but the presence of a paratenic host may serve to make infection of the definitive host by the parasite more efficient

Front 30

Periparturient Rise in Fecal Egg Counts (PPR)

Back 30

An increase in the number of parasitic eggs in the feces of an animal around parturition. This can be pronounced in ewes, sows and goats

Front 31

Pre-Parasitic Phase of Life Cycle

Back 31

The development to the infective stage occurring outside the definitive host in the environment of in a second (intermediate) host of the parasite life cycle

Front 32

Predilection Site

Back 32

The site within a host where the parasite is normally found

Front 33

Prepatant Period (PPP)

Back 33

The period of time from infection until mature adult parasites are producing eggs of larvae

Front 34

Proglottid

Back 34

one segment of the body (Strobila) of a tapeworm. Proglottids may be immature, mature (male and/or female sex organs present) or gravid (full of eggs)

Front 35

Resevoir Host

Back 35

Usually refers to wild animals. Infections may be passed on to other species

Front 36

Scolex

Back 36

The anterior end ("head") of the adult cestode, it is the hold-fast organ that anchors the worm in the GI tract

Front 37

Somatic Migration

Back 37

Migration in the host by a parasite through the lungs into the systemic circulation distributed throughout the body and encyst in the tissues

Front 38

Strobila

Back 38

The string of proglottids which make up the "body" of a tapeworm

Front 39

Symbiosis

Back 39

Parasitism belongs within the context of symbiosis, a term for a biological relationship in which two species live in close proximity to each other and interact regularly in such a way a to benefit one or both of the organisms

Front 40

Tracheal Migration

Back 40

Migration in the host by the parasite into alveoli up the respiratory tree and then swallowed and then mature in the intestine

Front 41

Trophozoite

Back 41

The stage of the protozoa in the host which feeds and grows until division commences

Front 42

Vector

Back 42

An intermediate host in the parasitic life cycle, that may or may not be essential for the development of the parasite. a Vector will seek out the definitive host in the life cycle to prey on it, whereas other intermediate hosts will not

Front 43

Visceral Larva Migration

Back 43

Nematode larvae migration in hosts that are suitable for long survival but are unsuitable for development to the adult stage. The larva worms wander for a time in the host's tissues

Front 44

Zoonotic

Back 44

A disease that can be communicated between animals and humans

Front 45

Routes of Infection

Back 45

1. Oral: anything that passes trough the mouth
2. Cutaneous: the parasite burrows or penetrates into the skin via a vector
3. Nasal passage: by sniffing
4. Transplacental (intra-uterine): the parasite (usually in larval form) encysted in the mother's muscle, migrate to the bloodstream, cross the placental barrier and infect the fetus
5. Transmammary: through Milk

Front 46

Ways Parasites cause Disease

Back 46

1. Absorbing Nutrition
2. Sucking blood or Tissue Fluid
3. Mechanical Obstruction (Blocking blood vessels or intestinal tracts)
4. Causing wounds (in which other pathogens may enter)
5. Causing Tissue reaction in the host
6. Tumor Formation
7. Introduction of the host to other harmful pathogens
8. Self Trauma (Due to inflammation, the animal becomes irritated and causes self-trauma or mutilation in efforts of relief)

Front 47

Classification of Parasite Phylae

Back 47

1. Nematodes: includes Roundworms
2. Trematodes: Includes Flatworms
3. Arthropods: includes insects AKA bugs!
4. Protozoa: single celled animals