1. Human Parasitology
Dai xiaodong

2. Ⅰ. Definition and components of Human Parasitology
Human parasitology is the study of those organisms which parasitize humans. It describes the external morphology, internal structure, life cycle, pathogenesis, diagnosis, prevention and control of parasite. It also deals with the relationship between parasites and hosts, parasites and external environment.

3. The components of Human Parasitology Medical Protozoology: single celled animals Medical Helminthology: worms Medical Arthropodology: insects and arachnoid

4. Plasmodium.vivax

5. Ascaris

6. mosquito
fly

7. Ⅱ.The seriousness and harmfulness of parasitic diseases:
“Five main parasitic diseases” in the world:
Malaria, Schistosomiasis, Filariasis, Trypanosomiasis,
Leishmaniasis.
“Five main parasitic diseases” in China:
Malaria, Schistosomiasis, Filariasis,
Hookworm disease, Kala-azar.

8. Why were they selected?
Schistosomiasis - 200,000,000 infected 500,000-1,000,000 deaths/year Malaria - 500,000,000 infected 2,500,000 deaths/year Filariasis - 250,000,000 infected Trypanosomiasis - 25,000,000 infected 65,000 deaths/year Leishmaniasis - 1,200,000 infected Leprosy - 1,300,000 infected Approximately 25% of world's population infected by one of these.

9. Ⅲ. Parasitic relationship and parasitic life :
（Ⅰ）Terminology in parasitic relationship:
1.Symbiosis:
Two different organisms live together and interact, in this association one partner lives in or on another one’s body.
2. Sub-categories of symbiosis to describe the different associations：
Commensalism
Mutualism
Parasitism

10. Commensalism:
is the association of two different organisms, in which one partner is benefited while the other neither benefited nor injured, such as E. coli and human.

11. Mutualism: is a permanent association between two different organisms
that life apart is impossible, two partners benefit each other, such as termites and flagellates.

12. Parasitism:
is the association of two different organisms, in which
one partner is benefited while the other is injured, such as
Ascaris lumbricoides and human.

13. （Ⅱ） Parasite and Host:
1. Parasite:
In the relationship of parasitism, the organism which lives on or in another and gets its food from it.
2. Host:
In the relationship of parasitism, the organism which serves as an origin of food and a shelter for parasites.

14. （Ⅲ） The clssification of parasites:
1. The zoological classification of parasites：
The classification of parasites according to the rules
of zoological classification :

15. Human Parasitology Class Lobosea Class Zoomastigophorea Medical
Class Sporozoa
Class Ciliophora
Medical
Protozoology
Human Parasitology
Class Nematoda
Class Trematoda
Class Cestoda
Class Metacanthocephala
Medical
Helminthology
Class Insecta
Class Arachnida
Class Crustacea
Class Chilopoda
Medical
Arthropodology

21. 2. Different types of parasites ： (1) Ectoparasites: Parasites live on the outer surface of the host in this kind of association. (2) Endoparasites: Parasites live inside the host in this kind of association.

22. (3) Obligate Parasites:
are those where the organism cannot survive and reproduce in the absence of the partner.
(4)Facultative Parasites:
are organisms those may exist in a free-living state as a commensal and those ,if opportunity presents themselves, may become parasitic.

23. （Ⅳ）Sorts of Host: 1. Definitive Host :
It is the host where the parasite reaches its adult stage or undergoes sexual reproduction.
2. Intermediate Hos:
It is the host where the parasite undergoes larva stage or non-sexual multiplication.
First intermediate host
Second intermediate host

24. 3. Reservoir Host:
It is the vertebrate host other than human where the parasite undergoes the same development as that in human, and it serves as the source of infection.

25. 4. Paratenic Host：
It is an abnormal host in which some parasitic larvae can survive but can’t develop into adults. If the larvae have a chance to enter their appropriate hosts, they can continue to develop into adults there.

26. （Ⅴ）The Life-cycle of parasites:
1. Definition:
The whole life or a complete generation including the growth, development and reproduction of a parasite, which proceeds in one or more different hosts depending on the species of parasites..
2. Four phases in the life cycle of parasites:
The route of leaving human body
The development outside human body
The route of invading (entering) human body
The development inside human body

28. (1) The route of leaving human body:
passed in feces
passed in sputum
with the aid of a blood sucking vector
(2) The development outside human body:

29. (3) The route of invading (entering) human body:
per-oral: Ascaris
per-cutanous: Hookworm
per-contact: Trichomonas
via arthropod vector: Malaria parasite
per-placenta: Toxoplasma
(4) The development inside human body:

30. (Ⅵ)The Infective Stage of the parasite:
Definition:
The particular stage of a parasite which is able to invade human body and continue to develop is called ~.
for example: the infective Ascaris eggs

31. Ⅳ. The reciprocal effects between the parasite and the host
(Ⅰ) Effects of parasites on hosts:
1. Depriving the host of essential substances:
e. g. biliary ascariasis
2. Mechanically injuring to the host:
during invading human body:
during migrating in human body:
during parasitizing in parasitic positions:

32. 3. Antigenic effect and toxic (or chemical) effect:
Induced through the action of secretions, excretions or other products by parasites.
Example: E.histolytica erodes the intestinal wall by means of the secretion of proteolytic enzyme.

33. （Ⅱ） Human Immunity against Parasites
It refers to Non-sterilizing immunity (premunition；concomitant immunity).
The host may be protected from superinfectionas long as the parasites remain in the body. This situation is known as premunition.
This may be of great importance in endemic areas in limiting the severity of infection with Plasmodium, Schistosome, hookworms and other parasites.

34. Evasion of Immunity Definition：
Many parasites appear not to elicit or not to be affected by their hosts' immune response, this phenomenon is called ~.
The evasion strategies can include:
loss or masking of surface antigens,
antigenic variation,
the occupation of immunologically incompetent sites
immunosuppression.

35. （Ⅲ）The result of the reciprocal effects between parasites and hosts:
The damage effects of the parasite on the host < The immune
response of the host on the parasite:
No parasitic infection
The damage effects of the parasite on the host = The immune
Parasitic infection
The damage effects of the parasite on the host ＞The immune
Parasitic disease

36. schistosomiasis

37. Ⅴ. The Transmission and Control of parasitic diseases:
（Ⅰ）The transmission of parasitic diseases：
1. Three key links in the transmission of parasitic diseases ：
（1）The source of infection：
　　　It means those which can carry pathogens and transmit them to another new host or the environment. It includes the definitive host, the carrier and the reservoir host.

38. Definition of The Carrier:
A person, without apparent symptoms, harbours parasites and may serve as an important source of infections to others.
（2）The route of transmission：
The same as The route of entering human body
（3）The susceptible population：
It means those who are absent or have a low level of the capacity of the immune response to a parasite.

39. 2. Two factors influencing the dissemination of parasitic diseases :
(1) Natural factors:
(2) Social factors:

40. （Ⅱ）The control of parasitic diseases:
Comprehensive measures of parasitic disease control must be adopted:
The treatment of the source of infection
The blockade of the route of transmission
The protection of the susceptible population

41. Diagnosis of Parasitic Infections:
1. Clinical diagnosis 2. Laboratory diagnosis

42. Treatment of Parasitic Infections:
1. Medical and surgical 2. Chemotherapy 3. Adequate nutrition

43. Prevention and Control:
1. Reduction in sources 2. Education 3. Destruction and/or control of reservoir hosts and vector