Parasitic Infections

Question 1

what is a PARASITE

Answer 1

An organism that lives in (or on) (infects) the host and is dependent on it for nutrition, often causing damage or disease

Question 2

What are protozoa

Answer 2

are single-celled eukaryotic organisms whose pathogenesis is varied and many are carried by insect vectors
- They do not produce eosinophilia in the host

Question 3

What are metazoa

Answer 3

• Helminths/worms are complex multicellular organisms known as metazoa which can be free living or transmitted by vectors and their lifecycle involves an intermediate host – humans are the definitive host
• Adult worms lay eggs or produce microfilariae but cannot themselves multiply in man, so they’re a cause of morbidity rather than mortality
• Forms which invade the blood often cause eosinophilia

Question 4

Do protozoa evoke eosinophilia

Answer 4

No

Question 5

Do metazoa evoke eosinophilia

Answer 5

Yes

Question 6

What are ectoparasites

Answer 6

Parasites that live externally

Question 7

What are endoparasites

Answer 7

Parasites that live internally

Question 8

4 types of protozoa?

Answer 8

Amoeba, coccidiae, ciliae, flagellates

Question 9

3 examples of metazoa?

Answer 9

roundworms, flatworms, flukes

Question 10

Difference between protozoa and metazoan?

Answer 10

Protozoa: single celled, no eosinophilia, can cause mortality

Metazoa: multicellular, eosinophilia, cause morbidity rather than mortality

Question 11

2 examples of ectoparasites?

Answer 11

Scabies, live

Question 12

Example of an amoeba?

Answer 12

Entamoeba histolyca

Question 13

What does Entamoeba histolyca cause?

Answer 13

bloody diarrhea (dysentery) when it infects the colon and can also lead to abscess formation in the liver – these amoebae can ingest red cells

Question 14

Example of an coccidiae? (3)

Answer 14

• Plasmodium species e.g. P. falciparum, ovale, vivax, knowlesi and malariae cause malaria – the lifecycle involves the invertebrate (Anopheles mosquito) and the vertebrate (man)
• Toxoplasma gondaa
• Cryptosporidium

Question 15

What type of parasite is Entamoeba histolyca

Answer 15

Amoeba

Question 16

What type of parasites are plasmodium

Answer 16

Coccidiae

Question 17

Pathophysiology of malaria? (5)

Answer 17

febrile illness, paroxysm, cerebral malaria, respiratory distress and severe anaemia

Question 18

What type of parasite is Toxoplasma gondaa

Answer 18

coccidia

Question 19

What type of parasite is Cryptosporidium

Answer 19

coccidia which can infect the small bowel and produces severe diarrhea – infection is commonly waterborne/faeco-oral

Question 20

What does cryptosporidium cause

Answer 20

coccidia which can infect the small bowel and produces severe diarrhea – infection is commonly waterborne/faeco-oral

Question 21

How do you diagnose malaria? (2)

Answer 21

Blood films are used to diagnose, rapid test is also available via antigen detection test

Question 22

Example of Flagellate? (4)

Answer 22

• Giardia
• Trichomonas
  Lieshmania
  Trypanosoma (Tsetse flies)

Question 23

Giardia is example of what type of protozoa?

Answer 23

Flagellate

Question 24

Trichomonas is example of what type of protozoa?

Answer 24

Flagellate

Question 25

Lieshmania is example of what type of protozoa?

Answer 25

Flagellate

Question 26

Trypanosoma is example of what type of protozoa?

Answer 26

Flagellate

Question 27

What does giardia infect

Answer 27

the upper small bowel (jejunum)

Question 28

What does giardia cause

Answer 28

giardiasis (prolonged diarrhea, sometimes causing malabsorption

Question 29

What does trypanosoma cause

Answer 29

febrile illness with lymphadenopathy

Question 30

What does trichonomonas cause (3)

Answer 30

vaginitis Causes an offensive odour, can cause abdominal pain

Question 31

Example of a ciliate and what it causes?

Answer 31

- Balantidium is an unusual pathogen in man causing balantidiasis, which involves diarrhea in immunocompromised patients

Question 32

What is a vector

Answer 32

A vector is an organism that acts as an intermediary host for a parasite.

Question 33

4 examples of roundworms?

Answer 33

- Ascaris - Filaria - Hookworm - Strongyloides

Question 34

What does ascaris cause? What does this lead to?

Answer 34

ascariasis in the bowel, they live in the intestines – worms can cause obstruction of the bile duct or the bowel, and have no intermediate host, abdominal pains, or malnourishment

Question 35

What does hookworm cause?

Answer 35

Iron deficiency

Question 36

How does hookworm enter the body

Answer 36

via the skin

Question 37

examples of a metazoa with no intermediate host?

Answer 37

Ascaris

Question 38

What do filaria cause?

Answer 38

Aedes mosquitoes, blackflies and mango flies and can cause lymphatic filariasis (elephantiasis), cutaneous filariasis (onchoceriasis) and loaiasis (Loa Loa) (eyeworm)

Question 39

What does the aedes mosquito act as a vector for and cause?

Answer 39

filaria and can cause lymphatic filariasis (elephantiasis)

Question 40

What do blackflies act as a vector for and cause?

Answer 40

filaria and cutaneous filariasis (onchoceriasis)

Question 41

What do mango flies act as a vector for and cause?

Answer 41

filaria and loaiasis (Loa Loa) (eyeworm)

Question 42

What does Strongyloides worm cause

Answer 42

severe illness especially when the host is immunocompromised – cause of diarrheal illness in the tropics

Question 43

Example of a flatworm?

Answer 43

- Taenia (tapeworm) - pork (taenia solium) or beef (taenia saginata)

Question 44

what does taenia infectation cause and what does it lead to the acquisition of?

Answer 44

can invade host tissues especially the brain leading to cysticercosis with fits and neurological signs - Commonest cause of acquired epilepsy

Question 45

Example of a fluke?

Answer 45

- Schistosoma

Question 46

what do schistosoma do to the human?

Answer 46

Adult worms live in the urinary bladder or bowel where they lay eggs which may spread to the liver and cause inflammation leading to fibrosis and obstruction of the HPV – this results in esophageal varices and hemoptysis

Question 47

Example of a lice?

Answer 47

Pediculus humanus capitis, pediculus humanus corporis and pthirus pubis

Question 48

What can lice serve as a vector for (3)

Answer 48

Rickettsia prowazekii (epidemic typhus), Bartonella Quintana (trench fever) and Borrelia recurrentis (louse-borne relapsing fever)

Question 49

What is the vector for leishmania

Answer 49

sandflies

Question 50

Difference between leismania in the human vs in the sandfly host?

Answer 50

No longer has flagella in the human

Question 51

3 forms of leishmaniasis and what are the defining features?

Answer 51

Visceral: most severe, irregular fever, weight loss, swelling of liver and spleen, anaemia Cutaneous: skin lesions on exposed body parts, can create serious disability and scars Diffuse cutaneous: disseminated lesions, resembles leprosy, no spontaneous healing, frequent relapses mucocutaneous: disfiguring, destroys mucous membranes

Question 52

what are the defining features of visceral lieshmaniasis? (4)

Answer 52

irregular fever, weight loss, swelling of liver and spleen, anaemia

Question 53

what are the defining features of cutaneous lieshmaniasis? (3)

Answer 53

skin lesions on exposed body parts, can create serious disability and scars

Question 54

what are the defining features of diffuse cutaneous lieshmaniasis? (4)

Answer 54

disseminated lesions, resembles leprosy, no spontaneous healing, frequent relapses

Question 55

what are the defining features of mucocutaneous lieshmaniasis? (2)

Answer 55

disfiguring, destroys mucous membranes