Lecture 3: Pathogenesis of Parasitic Diseases

Question 1

How can location be used for information on life cycle of parasite

Answer 1

Egg are ingested

hatched larvae in intestines

eggs in feces

Question 2

Milk spots in liver and lung damage indicate what life cycle stage for ascaris suum

Answer 2

Hatched larvae

Question 4

What does the likelihood and severity of a parasitic disease depend on

Answer 4

1. Status of host defenses
2. Number of parasites present
3. Parasite pathogenicity

Question 5

Pathology may result from….

Answer 5

1. Damage and or loss to host cells, tissues and organs
2. Alteration of host cellular growth patterns
3. Interference with host nutrition
4. Toxins released by the parasites
5. Host immune response to infection/infestation

Question 6

What are mixed infections

Answer 6

More than one parasite- Additive pathogenic effects on host and may occur with gastrointestinal parasites

Question 7

What are three ways parasites can cause damage to and or loss of host cells, tissues and organs

Answer 7

1. Destruction/loss due to migrating, developing, feeding or reproducing stages
2. Obstruction of hollow structures by worms
3. Compression or distesion of structures by larval or adult worms

Question 8

How do ancylostoma caninum (hookworm) cause damage to tissue

Answer 8

Results in blood loss during feeding and also produces anticoagulants

Question 9

How does dirofilaria immitis (heart worm) damage host cells, tissues and organs

Answer 9

Blocks pulmonary vessels and can cause pulmonary hypertension and heart failure

Question 10

How does the larval stage (Coenurus) of Taenia multiceps tapeworm damage sheep brain

Answer 10

Forms cysts, puts compression on brain, result in Gid (ataxia and circling)

Question 11

how does Ostertagi ostertagi cause damage to and/or loss of host cells, tissues and organs

Answer 11

Larvae develop in gastric glands and damage abomasal mucosa

Question 12

how can parasites alter host cellular growth patterns

Answer 12

1. Cellular hypertrophy
2. Hyperplasia
3. Metaplasia
4. Neoplasia

Question 13

What is an example of a parasite that causes cellular hypertrophy

Answer 13

Trypanosoma Cruzi in cardiomyoctes

Question 14

What type of parasite is Trypanosoma cruzi

Answer 14

Protozoan

Question 15

What is an example of a parasite that causes hyperplasia

Answer 15

Ostertagia ostertagi acting on abomasal mucous neck cells

Question 16

How does Ostertagia ostertagi cause hyperplasia in abomasum

Answer 16

Causes cells in gastric pits in abomasum to overgrow and can been seen post mortem as bumps on abomasum

Question 17

What is an example of a parasite that causes metaplasia

Answer 17

Trichinella spiralis and skeletal muscle fibers

Question 18

Where does trichinella spiralis act and what does it do to cells

Answer 18

Goes into skeletal muscle fibers and changes cell type so no longer functional muscle cell and becomes hypertrophied

Question 19

What is an example of a parasite that causes neoplasia

Answer 19

Spirocera lupi causes esophageal sarcoma

Question 20

What are three common examples of parasites that interfere with host nutrition

Answer 20

Ascaris suum, dibothriocephalus latus, and giardia

Question 21

How does ascaris suum interfere with host nutrition

Answer 21

Ingestion of chyme

Question 22

How does dibothriocephalus Altus interfere with host nutrition

Answer 22

Absorption of vitamins- B12 (anemia)

Question 23

How does giardia interfere with host nutrition

Answer 23

Causes damage to microvilli and surrounding tissue causing decreased absorption of nutrients

Question 24

What is a common toxin released by plasmodium (malaria)

Answer 24

Hemozoin

Question 25

What is hemozoin

Answer 25

Crystallized dimmers of heme that impair macrophage phagocytic function

Question 26

What is parasite induced immunopathology

Answer 26

Damage that occurs as a result of an inappropriate immune response to infection or infestation

Question 27

What is an example of parasite induced immunopathology

Answer 27

Flea allergy dermatitis- hypersensitivity to allergens in flea saliva

Question 28

Behavioral changes can ____transmission of parasites in taenia multiceps to canids

Answer 28

Facilitate

Question 29

What is the definitive host for Taenia multiceps (tapeworm) and where is it found

Answer 29

Canids- found in gut

Question 30

What is the intermediate host for taenia multiceps (tapeworm)

Answer 30

Sheep; other ruminants

Question 31

What does taenia multiceps (tapeworm) cause in sheep

Answer 31

Larva migrate to sheep brain and cause “gid”—> ataxia, circling

Question 32

How is taenia multiceps transmitted from sheep to canids

Answer 32

Sheep that are infected and become ataxic are easy prey for canids and transmission is facilitated upon ingestion

Question 33

Behavioral changes are ____ of infection in oestrus Ovis in sheep

Answer 33

Side effects **unlike taenia multiceps which causes ataxia in sheep making them easy targets therefore their behavioral changes make them easy targets for canids and transmission occurs*

Question 34

What is oestrus ovis

Answer 34

Sheep nasal botfly

Question 35

How is oestrus ovis transmitted to sheep

Answer 35

Adult flies deposit bot egg in sinus and larvae then infect nasal and paranasal sinuses

Question 36

Oestrus ovis rarely migrates to brain to cause behavioral changes like taenia multiceps but if it does why does it not facilitate transmission

Answer 36

Although they are easy prey, the botflies die and therefore aren’t transmitted to predator

Question 37

What are virulence factors

Answer 37

Traits that confer pathogenicity

Question 38

How does hemozoin produced by plasmodium spp. (malaria) act as a virulence factor

Answer 38

Hemozoin inhibits phagocytic effect of macrophages therefore allowing plasmodium to survive

Question 39

What does leishmania spp. use as virulence factor and how does that work

Answer 39

Proteases, causes tissue invasion, survival in macrophages, and immune modulation

Question 40

What virulence factor is used by toxoplasma gondii and how does that work

Answer 40

Kinases- disrupt host cell signaling and cause immunomodulation

Question 41

Are Plasmodium spp., Leishmania spp., and Toxoplasma gondii parasitic Protozoa or metazoan parasites

Answer 41

Parasitic Protozoa

Question 42

What virulence factor do nematodes, tapeworms and trematodes take advantage of and how does that work

Answer 42

Proteases- tissue invasion and immune modulation

Question 43

What virulence factordo ticks, mosquitoes and other ectoparasites take advantage of and how does that work

Answer 43

Proteases- diminish pain at bite wound

Question 44

What virulence factor do blood-feeding helminths and ectoparasites use

Answer 44

Anticoagulants

Question 45

What do helminths secrete to act as virulence factors and cause immune modulation

Answer 45

Proteins, glycoproteins, peptides, glycine, glycolipids, eicosanoids that function in immune modulation by the parasite (downregulate immune response)

Question 46

Which age groups are most at risk for parasitic disease

Answer 46

Young and geriatric

Question 47

Are males or females more likely to carry parasite

Answer 47

Males- because of androgens

Question 48

What females are more susceptible to parasitic disease

Answer 48

Pregnant, postpartum and lactating females

Question 49

How does nutrition impact likelihood of getting parasitic disease

Answer 49

Malnourishment causes decreased resistance and resilience, increasing likelihood

Question 50

How does immunological competency impact likelihood of getting parasitic disease (4)

Answer 50

1. Immunodeficiency vs immunocompetent 2. Prior exposure gives partial immunity—> reduced number, migration, development and reproduction 3. Premunition- partial immunity due to chronic, low level infection, protects host against superinfection and more severe 4. Immunization status

Question 51

How does genotype contribute to likelihood of developing disease

Answer 51

Hosts resistance to infection has a genetic component

Question 52

What factors influence pathogenic potential of a parasite (6)

Answer 52

1. Predilection site 2. Migratory pathway 3. Sites of parasite development 4. Feeding habits 5. Immunopathology 6. Transmission of other infectious agents

Question 53

What does osteratagia ostertagi cause in cattle

Answer 53

Chronic abomastitis in young cattle

Question 54

What is the predilection site of ostertagia ostertagi

Answer 54

Abomasum

Question 55

What is the migratory pathway for ostertagia ostertagi

Answer 55

Local (within abomasum)

Question 56

What is the site of development for ostertagia ostertagi

Answer 56

Gastric glands of abomasum

Question 57

What are the feeding habits of ostertagia ostertagi

Answer 57

Adults feed on abomasal contents and epithelial tissue

Question 58

What is the immunopathology of ostertagia ostertagi

Answer 58

Inflammation induced by larvae and adults

Question 59

Is there transmission of other infectious agents for ostertagia ostertagi

Answer 59

No

Question 60

Parasitic development of ostertagia ostertagi In the gastric glands of abomasum does what to parietal (pH) and chief cells (pepsin)

Answer 60

Erodes parietal and chief cells therefore increasing pH (parietal secretes HCl) and decreased pepsin

Question 61

What is the consequence of ostertagia ostertagi larva in gastric glands of abomasum

Answer 61

Impaired protein digestion and bacterial overgrowth (no pepsin and less acidic) This results in diarrhea

Question 62

What do the ostertagia ostertagi Adults damage in gastric glands of abomasum

Answer 62

Epithelium

Question 63

What is the consequence of ostertagia ostertagi Adults

Answer 63

Loss of serum proteins- leaking out and causing diarrhea due to osmotic effect

Question 64

The immunopathology of ostertagia ostertagi Results in inflammation and causes what 4 things

Answer 64

1. Further loss of parietal and chief cells 2. Mucous neck cell hyperplasia 3. Parietal and chief cells are replaced by mucous neck cells (metaplasia) 4. Increased vascular permeability, loss of serum proteins, diarrhea

Question 65

In ostertagia ostertagi Parietal cells are replaced by mucous neck cells, what is this an example of

Answer 65

Metaplasia- parasite replaces cell types **other example was trichniella spiralis in skeletal muscle

Question 66

Overall ostertagia ostertagi Results in what 3 things

Answer 66

1. Impaired protein digestion 2. Bacterial overgrowth 3. Diarrhea