The Language of Parasitology

Question 1

Symbiosis

Answer 1

association (temporary or permanent) between two organisms of different species; each member is called a symbiont

Question 2

List the 5 types of symbiont relationships

Answer 2

Predator-prey
Phoresis
Mutualism
Commensalism
Parasitism

Question 3

Predator-prey

Answer 3

short term relationship in which one symbiont benefits at the expense of another (ex. tiger and water buffalo)

Question 4

Phoresis

Answer 4

relationship in which the smaller member of the relationship is mechanically carried about by the larger member (ex. bacterium Moraxella bovis carried by facefly Musca autumnalis)

Question 5

Mutualism

Answer 5

association between two organisms of different species in which both are benefitted (ex. tick birds on rhinos; ciliate in rumen of cow)

Question 6

Commensalism

Answer 6

association between two organisms of different species in which one partner is neither benefitted nor harmed (ex. sharks and remoras)

Question 7

Parasitism

Answer 7

association between two organisms of different species in which one member (the parasite) lives on or in the other member (the host) and may cause harm; parasitism implies metabolic dependency

Question 8

Parasitiasis

Answer 8

association between two organisms of different species in which one organism is potentially pathogenic, but does not cause outward signs of disease (ex. healthy cattle on pasture harbor GI parasites, but do not exhibit outward signs)

Question 9

Parasitosis

Answer 9

association between two organisms of different species in which one organism injures the other and produces outward signs of disease (ex. emaciated cow exhibits outward signs of parasitism)

Question 10

Parasitology

Answer 10

the study of parasitic relationships

Question 11

Endoparasite

Answer 11

parasite that lives within the body of the host (ex. Dirofilaria immitis- heartworm)

Question 12

Ectoparasite

Answer 12

parasite that lives on the outside of the body of the host (ex. fleas and ticks)

Question 13

Erratic/Aberrant parasite

Answer 13

parasite that has wandered into an organ or tissue in which it does not normally live

Question 14

Incidental parasite

Answer 14

parasite in a host which it does not usually live

Question 15

Facultative parasite

Answer 15

organism that is capable of living either free or as a parasite

Question 16

Obligatory parasite

Answer 16

organism that must live a parasitic existence

Question 17

Periodic parasite

Answer 17

parasite that makes short visits to its host to obtain nourishment or other benefit

Question 18

Pseudoparasite

Answer 18

object that is mistaken for a parasite (ex. pollen grain on a fecal)

Question 19

Life cycle

Answer 19

development of a parasite through its various life stages

Question 20

Definitive host

Answer 20

the host that harbors the adult, sexual or mature stages of the parasite

Question 21

Intermediate host

Answer 21

host that harbors the larval, asexual, or immature stages of the parasite

Question 22

First intermediate host

Answer 22

first host parasitized by the larval stages of the parasite

Question 23

Second intermediate host

Answer 23

second host parasitized by the larval stages of the parasite

Question 24

Transport/Paratenic host

Answer 24

host in which the parasite does not undergo any further development, usually remaining encysted until eaten by the definitive host

Question 25

Reservoir host

Answer 25

vertebrate host in which a parasite (or disease) occurs naturally and which is a source of infection for human beings and their domestic animals

Question 26

Infection

Answer 26

parasitism by an internal parasite

Question 27

Infestation

Answer 27

parasitism by an external parasite

Question 28

Homoxenous/monoxenous parasite

Answer 28

a parasite that has only one type of host- the definitive host

Question 29

Heteroxenous parasite

Answer 29

parasite that has more than one type of host- the definitive host and one or more intermediate hosts

Question 30

Stenoxenous parasite

Answer 30

parasite that has a narrow host range (ex. Eimeria tenella will only infect chickens)

Question 31

Euryxenous parasite

Answer 31

parasite that has a wide host range (ex. Toxoplasma gondii will infect over 300+ species of mammals)

Question 32

Hyperparasitism

Answer 32

parasite infecting parasites (ex. Dirofilaria immitis microfilariae in a mosquito)

Question 33

Zoonosis

Answer 33

any disease that is transmissable from lower animals to human beings

Question 34

Prepatent period

Answer 34

time from infection of a parasite until diagnostic stages can be recovered from the host (i.e. eggs, oocysts, cysts, larvae, trophozoites) generally recovered from feces, urine or blood (in definitive host)

Question 35

Hypobiosis

Answer 35

the ability of nematodes to arrest their development and go dormant for a variable period of time

Question 36

Direct lifecycle

Answer 36

there is no intermediate host, only the definitive host

Question 37

Indirect lifecycle

Answer 37

there is one or more intermediate hosts

Question 38

Scientific name

Answer 38

comprised of two Latin words, and is usually written in italics or underlined; the first word is capitalized and is the Genus name, and indicates the group to which a particular type of animal belongs; the second word is not capitalized and is the specific epithet and indicates the type of animal itself ex. dog- Canis familiaris; cat- Felis catus; housefly- Musca domestica; heartworm- Dirofilaria immitis

Question 39

List ways parasites injure their hosts

Answer 39

1. feed on blood, lymph or exudates (ex. lice,tick) 2. feed on solid tissues, directly or after liquefying them (ex. fluke) 3. compete with host for food host ingested, either by ingesting the intestinal contents or by absorbing them through the body wall (ex. tapeworms) 4. mechanical obstruction of the intestine, bile ducts, blood vessels, lymph channels, bronchi, or other body channels (ex. heartworms) 5. produce pressure atrophy (ex. parasite that resides in kidney) 6. destroy host cells by growing inside them (ex. apicomplexans) 7. produce various toxic substances, such as hemolysins, histolysins, and anticoagulants (ex. ticks) 8. produce allergic reactions (ex. fleas) 9. produce various host reactions such as inflammation, hypertrophy, hyperplasia and nodule formation 10. (directly or indirectly) promote the neoplastic transformation of cells (ex. Spirocerca lupi- osteosarcoma) 11. carry diseases and other parasites including malaria, swine influenza, salmon poisoning, and heartworm (ex. mosquito) 12. reduce host's resistance to other parasites and to other diseases (ex. Criptosporidium)

Question 40

List types of parasites

Answer 40

Protozoa - Amoebas - Ciliates (found in pigs/rumen in ruminants-beneficial) - Flagellates (Giardia) - Apicomplexans (Coccidia) Helminths - Platyhelminths (flatworms) - Nematodes (roundworms) - Acanthocephalans Arthropods - Insects* - Acarines* - Pentastomes (mostly found in snakes/reptiles) - Crustacea (fish lice)

Question 41

Types of zoonotic cycles

Answer 41

Sylvatic: involve parasites of wild animals | urban/domestic: involve parasites of companion animals

Question 42

Evolution of parasitism

Answer 42

2 general methods: parasite evolves with the host (less likely to be pathogenic) parasite recently colonized the host (more likely to be pathogenic)

Question 43

Patterns of parasitism

Answer 43

Overdispersion Increased susceptibility The host environment

Question 44

Overdispersion

Answer 44

not all animals in a herd harbor the same number of parasites

Question 45

Increased susceptibility

Answer 45

based on factors such as age, immune status, mother/pregnancy

Question 46

Host environment

Answer 46

how parasites escape immunity - molecular mimicry: mimic self epitope - antigenic variation: express new surface proteins - secretion of substances that disable the local immune response: helminths secrete proteins such as proteases/protease inhibitors; adult flukes secrete thoredoxin peroxidase which stimulates alternative activation of macrophages

Question 47

List external factors that affect a parasites ability to infect the host.

Answer 47

1. Parasites ability to survive outside of intermediate/direct host 2. Intermediate host being present in the local environment

Question 48

List 2 ways parasites try to increase the likelihood of completing their life cycle/make it to direct host.

Answer 48

1. Produce large number of eggs 2. hermaphroditism 3. asexual reproduction 4. change behavior of intermediate host to make IH more susceptible to ingestion by DH

Question 49

List potential routes of transmission of parasites and give examples

Answer 49

1. Oral route- eggs (Toxascaris leonina) 1a. Oral route- intermediate host (coprophagous flies with Draschia sp. larvae) 1b. Oral route- transmammary route (Ancylostoma caninum-hookworms) 2. In utero- Toxocara canis 3. Vector bourne transmission- Dirofilaria immitis (Heartworm) 4. Skin penetration- Ancylostoma caninum (Hookworms)

Question 50

List ways parasites use to stay in place.

Answer 50

``` Suckers Hooks Spines "Take a huge bite" (oral attachment) Claws (endoparasites) ```

Question 51

Site specificity

Answer 51

Some parasites may be more or less specific about the site within the host they infect - Generalists can use nearly any tissue - some parasites utilize niche partitioning - specialization in different parts of the gut (reduces competition among parasites)