Parasitology

Question 1

1. Define what is a parasite?

Answer 1

A parasite is an organism that lives on or in a host organism and gets its food from or at the expense of its host.

Question 2

2. What are the three main classes of parasites that cause disease in humans?

Answer 2

1. Protozoa
2. Helminths
3. Ectoparasites.

Question 3

3. What is a protozoa?

Answer 3

• Protozoa are microscopic, single-celled organisms that can be free- living or parasitic in nature.

Question 4

4. What feature of a protozoa parasite allows it to cause serious infections in humans?

Answer 4

They are able to multiply in humans allowing serious infections to develop from a single organism.

Question 5

5. How are protozoa transmitted in humans?

Answer 5

• Protozoa living in the human intestine can be transmitted by the fecal-oral
route

• Protozoa living in blood or tissues are transmitted by an arthropod vector

Question 6

6. What feature of protozoa are they classified by?

Answer 6

There mode of movement

Question 7

7. Give the five classifications of protozoa

Answer 7

1. Amoeba
2. Flagellates
3. Ciliates
4. Sporozoa

Question 8

8. Give an example of an Amoeba protozoa?

Answer 8

Entamoeba

Question 9

9. Give two examples of a flagellate protozoa?

Answer 9

1. Giardia

2. Leishmania

Question 10

10. Give an example of a ciliate protozoa?

Answer 10

Balantidium

Question 11

11. What are Sporozoa protozoa and give two examples?

Answer 11

• Sporozoa – organisms whose adult stage is not motile e.g. Plasmodium, Cryptosporidium

Question 12

12. List three medically important protozoa infections?

Answer 12

Any three out of :
• Entamoeba histolytica
• Giardia lamblia
• Trichomonas vaginalis
• Malaria (Plasmodium spp.) • Toxoplasma gondii
• Cryptosporidium
• Leishmania spp.
• Trypansoma cruzi
• Trypansoma brucei (gambiense/rhodesiense)

Question 13

13. What are Helminths?

Answer 13

Helminths are large, multicellular organisms (worms) generally visible to the naked eye in their adult stages.

Question 14

14. In their human form can Helminths multiply in humans?

Answer 14

NO

Question 15

15. What are the three main groups of Helminths in the human parasite?

Answer 15

1. Nematodes (roundworms)
2. Trematodes (flukes)
3. Cestodes (tapeworms)

Question 16

16. What are three types of medically important Helminths that are nematodes? Give an example for each

Answer 16

1. Soil transmitted Helminths eg Hookworm spp
2. Filarial parasites eg Loa Loa
3. Others eg Trichinella Spiralis

Question 17

17. Give an example of a medically important Helminths that is a trematode?

Answer 17

Paragonimus Spp

Question 18

18. Give an example of a medically important Helminths that is also a cestode?

Answer 18

Taenia Solium

Question 19

19. What are ectoparasites - give some examples?

Answer 19

• Blood-sucking arthropods such as ticks, fleas, lice, and mites that attach or burrow into the skin and remain there for relatively long periods of time (e.g., weeks to months).


Question 20

20. What are four types of medically important ectoparasites?

Answer 20

1. Mites
2. Ticks
3. Lice
4. Flies

Question 21

21. What types of mites are there?

Answer 21

Scabies or Trombiculid

Question 22

22. What types of ticks are there?

Answer 22

Hard or soft

Question 23

23. What types of lice are there?

Answer 23

• Pediculus humanus capitis

* Pediculus humanus humanus

Question 24

24. Whats an example of the flies ectoparasites?

Answer 24

Botflies

Question 25

25. Approx. how many people does malaria kill each year?

Answer 25

660,000 people each year

Question 26

26. What is an NTD and give some examples of parasitic diseases that are NTDs?

Answer 26

The Neglected Tropical Diseases (NTDs) include parasitic diseases such as lymphatic filariasis, onchocerciasis, and Guinea worm disease

Question 27

27. What are two types of host that parasites can infect?

Answer 27

• Intermediate – host in which larval or asexual stages develop
• Definitive – host in which adult or sexual stage occurs

Question 28

28. What are two types of vectors parasites can have?

Answer 28

• Mechanical when no development of parasite in vector

* Biological when some stages of life cycle occur

Question 29

29. What is the primary determinant of the distribution of parasite infection in humans?

Answer 29

relative wealth

Question 30

30. What are 5 determinants of parasite infections?

Answer 30

• > Depends on mode of transmission and opportunities for transmission
• > Faeco-oral
• > Complex life cycle
• > Others

Question 31

31. What determines if there will be faeco-oral transmission?

Answer 31

• > Household Sanitation
• > Access to clean water
• > Personal hygiene behaviours

Question 32

32. How could food be a way of transmission?

Answer 32

• > Animal Husbandry
• > Surveillance
• > Regulations and government controls

Question 33

33. How might complex life cycles be a way of transmission?

Answer 33

Distributions of vectors and intermediate/definitive hosts

Question 34

34. What are some examples of other determinants of the distribution of parasitic infections?

Answer 34

• Government resources and level of human development/per capita income • Education
• Country-level and regional control programmes
• Availability of cheap and efficacious treatments
• Construction and building regulations(eg Chagas)
• Urban vs. rural residence
• Environmental sanitation