Parasitology Flashcards
1
Q
Why is parasitism considered a successful survival strategy?
A
Over 50% of animals are parasites and they’ve evolved in nearly every phylum.
2
Q
If an organism is not a parasite, what is it?
A
A host.
3
Q
What percentage of animals are parasites?
A
Over 50%.
4
Q
What does DALY stand for?
A
Disability-Adjusted Life Year.
5
Q
What does a DALY measure?
A
The burden of disease using years lost to death and years lived with disability.
6
Q
What are the two components of DALY?
A
YLL (Years of Life Lost) and YLD (Years Lost to Disability).
7
Q
Which kingdoms are traditionally studied in parasitology?
A
Animalia and Protista.
8
Q
What are the four main groups of parasites?
A
Protozoa, parasitic worms, arthropods, and chordates.
9
Q
What does parasitology overlap with?
A
Bacteriology, virology, and mycology.
10
Q
What is symbiosis?
A
A relationship where two organisms live together with varying degrees of dependence.
11
Q
What is phoresis?
A
A symbiotic relationship where one organism travels with another without interaction or harm.
12
Q
Give an example of phoresis.
A
Fierasfer spp. on sea cucumbers.
13
Q
What is mutualism?
A
Both organisms benefit without harming each other.
14
Q
Give an example of mutualism.
A
Cleaner wrasse removing parasites from moray eels.
15
Q
What is commensalism?
A
One organism benefits, the other is unaffected.
16
Q
Give an example of commensalism.
A
Hermit crab with sea anemones.
17
Q
What is parasitism?
A
One organism benefits at the expense of the host.
18
Q
How can oxpeckers be both mutualistic and parasitic?
A
They eat ticks (mutualism) but also feed on wounds (parasitism).
19
Q
How are parasites distributed in host populations?
A
They are over-dispersed or clustered.
20
Q
Can parasites kill their host?
A
Yes, pathogenicity varies.
21
Q
Why is a parasite’s reproductive rate higher than the host’s?
A
To increase transmission chances.
22
Q
What is an obligate parasite?
A
A parasite that requires a host to complete its life cycle.
23
Q
What is a facultative parasite?
A
An organism that can live independently but may become parasitic under certain conditions.
24
Q
What’s the difference between permanent and temporary parasites?
A
Permanent stay in the host, temporary leave after feeding.
25
What are ectoparasites?
Parasites that live on the surface of the host.
26
What are endoparasites?
Parasites that live inside the host.
27
What is a definitive host?
The host where the parasite reaches sexual maturity.
28
What is an intermediate host?
A host where the parasite undergoes development but does not reach sexual maturity.
29
What is a paratenic host?
A host that carries the parasite without development.
30
What is a reservoir host?
A host that harbors a parasite and can transmit it to humans.
31
What is the urban cycle?
Transmission involving domestic animals and humans.
32
What is the sylvatic cycle?
Transmission involving wild animals.
33
What is a mechanical vector?
A vector that carries the parasite without any development.
34
What is a biological vector?
A vector in which the parasite develops or multiplies.
35
How do microparasites and macroparasites differ in reproduction?
Microparasites reproduce at a high rate; macroparasites reproduce slowly.
36
How do infections differ between micro and macroparasites?
Microparasites cause epidemics; macroparasites cause chronic infections.
37
How does immunity differ between micro and macroparasites?
Microparasites trigger strong immunity; macroparasites trigger weak immunity.
38
How is transmission different in micro vs macroparasites?
Microparasites spread directly or via vectors; macroparasites use life cycle stages.
39
What is a direct life cycle?
A life cycle that uses one host.
40
Give an example of a parasite with a direct life cycle.
Monogenean fish parasites.
41
What is an indirect life cycle?
A life cycle involving more than one host.
42
Give an example of a parasite with an indirect life cycle.
Schistosoma mansoni.
43
What is haemozoin?
A toxic waste product from malaria parasites that causes fever.
44
What triggers malaria parasite reproduction?
Synchronous bursting of red blood cells.
45
Name four types of microparasites.
Prions, viruses, bacteria, protozoa.
46
Name three types of macroparasites.
Platyhelminths, nematodes, arthropods.
47
Which monogenean infects flatfish?
Entobdella soleae.
48
Name two trematodes.
Schistosoma, Fasciola.
49
Name two cestodes.
Taenia, Echinococcus.
50
Name two nematodes.
Ascaris, Trichinella.
51
What arthropods act as parasites?
Lice, fleas, mites, and ticks.
52
What is Trichinella spiralis?
A nematode that causes Trichinosis.
53
What are the two transmission cycles of Trichinella spiralis?
Urban (pigs/rats) and sylvatic (wild carnivores).
54
Where do Trichinella larvae encyst?
In the muscle tissue.
55
What type of parasite is Trichinella spiralis?
Endoparasite, obligate, permanent, macroparasite.
56
What type of host is a human in Trichinella infection?
Definitive and reservoir host.
57
What type of life cycle does Trichinella spiralis have?
Direct life cycle.
58
What is the key difference between epidemic and endemic diseases?
Epidemic rises and falls quickly (micro); endemic persists over time (macro).
59
60
What is the most common lifestyle on Earth?
Parasitism – approximately 50% of species are parasitic.
61
What are three major benefits parasites get from hosts?
Habitat, mobility, and energy efficiency.
62
What are the four key challenges parasites face?
Spatial gaps, temporal gaps, immune defenses, host evolution.
63
What is the body plan of Platyhelminthes?
Acoelomate (no body cavity), solid body, tegument instead of a cuticle.
64
What is the body plan of Nematodes?
Pseudocoelomate with a cuticle and fluid-filled cavity.
65
What are the key steps in a parasite's life cycle?
Find host, enter host, locate site, survive, reproduce, disperse.
66
How did parasitism likely evolve?
From free-living forms through phoresis and facultative parasitism to obligate parasitism.
67
How many times did parasitism evolve in nematodes?
At least 18 times independently across different host groups.
68
What is a benefit of complex life cycles in parasites?
They offer more reproductive niches and increased transmission opportunities.
69
What are three influences on host-parasite evolution?
Co-evolution, host-switching, biogeography.
70
Name the oldest known parasite traces.
Traces in trilobites dating to 570 million years ago.
71
What organism is considered the oldest symbiont?
Mitochondria – evolved from a parasitic α-proteobacterium.
72
How do Symsagittifera roscoffensis survive?
By incorporating algal chloroplasts for photosynthesis (kleptoplasty).
73
What is the Red Queen Hypothesis?
Hosts and parasites must constantly evolve to maintain their relationship.
74
What evidence supports Red Queen dynamics?
Oscillating allele frequencies in host populations under parasite pressure.
75
What other pressures influence parasite evolution?
Environmental conditions, host evolution, and control measures like drugs.
76
Can parasites have beneficial effects?
Yes – some modulate the immune system or treat diseases like Crohn’s.
77
How are maggots used medicinally?
They clean wounds and secrete antimicrobial compounds; genetically modified ones produce growth factors.
78
What parasite is explored for immune modulation?
Whipworm (Trichuris suis) – used in Crohn’s disease research.
79
What hypothesis links parasites to allergy suppression?
Hygiene hypothesis – suggests helminth exposure reduces allergy risk.
80
What is the function of parasite attachment structures?
To anchor the parasite to the host and resist dislodgement.
81
What structure do Monogeneans use to attach to hosts?
A posterior opisthaptor with hooks, clamps, and suckers.
82
What structures do Digeneans use for attachment?
Oral and ventral suckers.
83
What is a scolex?
The anterior attachment organ in cestodes, often with hooks or suckers.
84
What is the trade-off between complex and simple parasite attachment?
Complex structures provide strong anchorage but reduce mobility.
85
Name four feeding strategies of macroparasites.
Surface browsing, blood feeding, bulk tissue feeding, and absorption across the body wall.
86
What issues do blood-feeding parasites face?
Coagulation, toxicity, vitamin depletion, and immune exposure.
87
How do parasites handle coagulation?
By producing anticoagulants to prevent clotting.
88
What is antigenic variation?
A process by which parasites change surface proteins to evade immune detection.
89
What is antigen disguise?
Parasites coat themselves with host-like molecules to avoid detection.
90
What is concomitant immunity?
Host is protected from reinfection but carries the existing parasite.
91
What is premunition?
Partial resistance allowing low-level parasite persistence.
92
What is the benefit of hermaphroditism in parasites?
Ensures reproduction even when mates are scarce.
93
What is protandry?
A form of sequential hermaphroditism where male organs mature before female organs.
94
What are oviparous parasites?
Parasites that lay eggs which develop outside the body.
95
What are viviparous parasites?
Parasites that give birth to live young without egg laying.
96
What are ovoviviparous parasites?
Parasites whose eggs hatch inside the parent before birth.
97
What is parthenogenesis?
Asexual reproduction from unfertilized eggs.
98
How does Polystoma integerrimum synchronize with its host?
It times reproduction with frog spawning and can mature on tadpole gills.
99
What is contact transmission in parasites?
Direct movement from one host to another, e.g., via skin contact.
100
What is intermediate host ingestion?
Parasites reach their definitive host when the intermediate host is consumed.
101
How does Dicrocoelium dendriticum manipulate ants?
Infected ants cling to grass tips to be eaten by grazing animals.
102
How does Toxoplasma gondii alter rodent behavior?
Infected rodents lose fear of cats, increasing predation.
103
How is Toxoplasma transmitted to humans?
Via undercooked meat, contaminated water, cat feces, or placental transfer.
104
What does Toxoplasma gondii produce that may affect human behavior?
Tyrosine hydroxylase, which increases dopamine levels.
105
What is phototaxis in parasites?
Movement toward or away from light, used by larvae to find hosts.
106
What is rheotaxis?
Movement in response to water currents, aiding host location.
107
What is chemotaxis?
Movement in response to chemical stimuli to locate a host.
108
Why do parasites produce large numbers of offspring?
To increase the chance of transmission to new hosts.
109
List five traits of a successful parasite.
Strong attachment, efficient feeding, immune evasion, high reproduction, and effective transmission.
