1. GENERAL PARASITOLOGY (An introduction)
LECTURE NOTES ON
GENERAL PARASITOLOGY
(An introduction)
Dept of Parasitology, Fac. of Medicine Universitas Padjadjaran

2. Introduction to Medical Parasitology
Definition of Medical Parasitology
Conceptions related to medical parasitology
Relationships between parasite and host
The basic factors of transmission of parasitic diseases
The preventive measures of parasitic diseases

3. What are Parasites
This presentation was initially developed by Mary Dillenbeck, 3rd Year veterinary medical student at Texas A&M University.

6. WHO GETS PARASITES ?

7. Why Do Parasites Matter
Disease and Death
Zoonotic Potential
Wealth Loss

8. Definition of Medical Parasitology
Medical Parasitology Parasites Parasitic diseases
Morphology
Life Cycle
Pathogenesis
Diagnosis
Treatment
Transmission
Prevention

9. Conceptions related to medical parasitology
Symbiosis
Parasite and type of parasites
Host and common type of host
Life cycle and type of life cycle

10. Symbiosis
------The relationship beween two living things (animals). Two living things live together and involve protection or other advantages to one or both partner.
Commensalism
Mutualism
Parasitism*

11. Commensalism
Both partners are able to lead indepenent lives, but one may gain advantage from the association when they are together and least not damage to the other.
Fig. A female pea crab in the mantle cavity of its mussel host. The crab does not damage the mussel and uses its shell purely for protection

12. Mutualism
An association which is beneficial to both living things.
Fig. A selection of ciliates from the rumen. The rumen contains enormous numbers of ciliates that break down cellulose in the feed.

13. Parasitism
An association which is beneficial to one partner and harmful to the other partner. The former that is beneficial to is called parasite, the latter that is harmful to is called host. Human / Hookworm

14. Types of Parasites Ectoparasites
Live on the outside or skin of the host
Usually insects or arachnids (ticks, mites, or spiders)
Endoparasites
Parasites found within the body of the host
Can be in blood, tissue, or gastro-intestinal tract
Nematodes, Trematodes, Cestodes and Protozoa

15. Ecto- & Endoparasitism
Ectoparasites live on, but not in their hosts (they can nevertheless cause severe illness). Ich a protozoan ectoparasite of the skin of a fish.
Endoparasite live within the body and tissues of their hosts. Trypanosomes (which cause sleeping sickness) within the blood of an infected animal.

16. Infection & infestation
Infectious diseases are caused by transmittable parasitic agents including bacteria, viruses, fungi, protozoa and a variety of metazoans commonly referred to as helminths or worms
Infection usually implies replication of the agent resulting in a growing number of pathogens
Infestation are characterized by a constant number of pathogens. Severity of disease often depends on infection dose.

17. Is a mosquito a parasite?
The border between parasitism and micro-predation is blurry
Parasites usually live in a very intimate relationship with their host depending on more than food from it
The host is food source and more or less permanent habitat at the same time
Many parasites show strict specificity for a single host

18. METHOD OF/PORT OF PARASITE ENTRY
Mouth
Skin penetration
Insect bite
Inhalation
Transplacental (Congenital)
Transmammary
Sexual
Blood Transfusion
Tissue Transplantation

19. Hosts and life cycles
The definitive host is by definition the one in which the parasite reproduces sexually
Additional hosts are then designated intermediate hosts
Host which actively transmit parasites to humans are often called vectors
In paratenic or transport hosts no parasite development occurs
Reservoir host are alternate animal host from which the parasite can be transmitted to humans (zoonosis) or domestic animals
Accidental host, not suitable for parasite development, but severe disease might ensue nonetheless

20. Parasite life cycle
Many animal parasites also have the potential to infect humans
Pass out brochures for zoonotic parasites. This is the hookworm lifecycle. People can be infected through fecal-oral ingestion of the eggs and skin penetration of the larvae from the soil it is common to see the tracts of the migrating worms on extremities such as the hands and feet.

21. Life cycle and type of life cycle
Life cycle : The whole process of parasite growing and developing.
The direct life-cycle : Only one host (no intermediate host).
The indirect life cycle : Life cycle with more than one host (intermediat host and final host).

22. To study the parasite life cycle, there is need to know :
Source of infection (reservoir)
Site/method of entry of parasite into the host
Physical changes of parasite occurring inside the host

23. The knowledge on life cycle is needed in relation to :
PARASITE LIFE CYCLE
The knowledge on life cycle is needed in relation to :
Treatment
Prevention
Control/eradication

24. PARASITE LIFE CYCLE Reproduction may occur two ways : Sexual Asexual
In term of sexual organ, parasite may be :
Hermaphrodite, or
Sexually separate (male and female)

25. Parasite and the type of parasites
Parasite: It is an animal that is dependent
on another animal (host) for its
survival.
Type of parasites
Protozoa
Nematodes
Parasites Helminths Trematodes Endo-
Cestodes
Arthropods Ecto-

26. Endoparasite and ectoparasite
----A parasite which lives in or on the body of the host is called endoparasite (protozoa and heminthes) or ectoparasite (arthropods).

27. Host and type of host
Host : An organism that harbors the parasite usually larger than the parasite.
Intermediate host : The host harboring the larvae or asexual stage of parasite.
Final host : The host harboring adult or sexual stage of parasite.
Reservoir host : Animals harboring the same species of parasites as man. Potential sources of human infection.

28. Relationship (Effect) between parasite and host
injure to
Parasites harbour in Host (animal or human)
to response immune produce
Effects of the parasites on the host
Effects of the host on the parasites

29. Effects of parasites on the host
Depriving the host of essential substance
Hookworm Suck blood Anemia
Mechanical effects of parasites on the host
Ascaris Perforate/Obstruction
Toxic and allergy effect
E.h Proteolytic enzyme Necrosis
Parasite antigen Immune system
e.g Anaphylaxix
Immune response
Allergy/ Hypersensitivity

30. Effects of the host on the parasites
----The host can produce certain degree resistance to parasites in human body or re-infection. The resistance (Immunity) is not very strong. In general, It don’t wipe out parasites completely, but may limit the number of parasites and establish balance with parasites.
Innate immunity
Acquired immunity

31. Innate immunity
Barrier : Prevent parasites to invade in certain degree. Skin/Mucous membrance/Placenta.
Acid in skin or stomach can cause damage of the parasites.
Phagocytosis of phagocyte.
----Non-specific/effective against a wide range of parasitic infection/controlled by genetical factors. But not very strong!

32. Acquired immunity Mechanism : cellular and humoral immunity.
Sterilizing immunity : Wipe out the parasites completely, meanwhile get a long-term specific resistance to re-infection. Rare!
Non-sterilizing immunity : Wipe out most of the parasites, but not completely. Common! No parasite, no immunity!

33. The basic factor of transmission of parasitic diseases
Parasitic diseases Infectious diseases Transmission
The source of the infection
The routes of transmission
The susceptible host
----The combined effect of those factors determine the dipersibility and the prevalence of the parasites at a given time and place and regulate the incidence of the parasitic diseases in certain local population.

34. The source of the infection
Patient : Persons who have parasites in their body and show clinical symptoms.
Carrier : Persons who have parasites in their body, not show symptoms.
Reservoir host : Animals that harbors the same species of parasites as man. Sometimes, the parasites in animals can transmit into human.

35. The routes of transmission I
Congenital transmission : From mother to infant. Toxoplasmosis
Contact transmission : Direct contact---Trichomonas vaginalis; Indirect contact---Ascaris lumbricodes
Food transmission : The infectious stage of parasites contaminated food / The meat of the intermediate hosts containing infectious stage of parasites.

36. The routes of transmission II
Water transmission : Drink or contact the water contaminated the infectious stage of parasites.
Soil transmission : Contamintion of the soil by feces containing the certain stage of parasites and this stage can develop into stage.
Arthropod transmission : Vectors of certain parasitic diseases.

37. The susceptible host
----In general, most people is the susceptible host (Why?). The parasite reaching a susceptible host must gain entrance and set up a favorable residence in order to complete its life cycle and cause the transmission of parasitic diseases.

38. The avenues of invasion
Digestive tract : Most common avenue of entrance. (Food/ Water transmission)
Skin : Infective larvae perforate skin and reach to body and establish infection. (soil/ water transmission)
Blood : Bloodsucking insects containing infective parasites bite the skin and inject parasites into human blood. (Arthropod transmission---malaria).

39. The prevention measures of the parasitic diseases
Controlling the source of the infection.
----Treatment of the patients, carriers and reservoir hosts.
Intervention at the routes of transmission
----Managing feces and water resource,controlling or eliminating vectors and intermediate hosts.
Protecting the susceptible hosts.
----Paying attention to personal hygiene, changing bad eating habit, taking medicine.

40. Diagnosing Parasite Infection
Direct observation
Blood antigen tests
Direct blood smears
Skin scraping
Fecal exam
Biopsy of tissues
Pictures right to left hook worm egg on a fecal float, babesia on a blood smear, and sarcoptic mange on a skin scraping. If available bring in a heartworm or giardia test to show the students.

41. Terima kasih atas perhatiannya ......
April
2005