Title: Human parasitology
1 Human Parasitology
Shandong University Department of Parasitology He
Shenyi (??? ) MD, Ph.D. Professor
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3Introduction to Human Parasitology
- Concept of Human Parasitology
- The Scope of Human Parasitology
- Terms of Parasitology
- Parasites Harms to Man
- Human Immunity against Parasites
- Characteristics of parasitic diseases
4Human parasitology
- Human parasitology is the study of those
organisms which parasitise humans. According to
the very broad definition of parasitology,
parasites should include the viruses, bacteria,
fungi, protozoa and metazoa (multi-celled
organisms) which infect their host species.
However, for historical reasons the first three
have been incorporated into the discipline of
Microbiology.
52. The Scope of Human Parasitology
- Parasitology claims those
protozoa (single celled animals), helminths
(worms) and arthropods whose existence depends on
the availability of host animals It is also
possible to argue about whether certain insects
and mites are "temporary parasites" or
"micro-predators", insects as a group belong to
the discipline of Entomology, while ticks and
mites are the concern of Acarology. The insects
that are of most interest in human parasitology
are those that are vectors of several parasitic
infections.
6- Class Lobosea
- Class Zoomastigophorea
- Class Sporozoa
- Class Ciliophora
Medical Protozoology
- Class Nematoda
- Class Trematoda
- Class Cestoda
- Class Metacanthocephala
Medical Helminthology
- Class Insecta
- Class Arachnida
- Class Crustacea
- Class Chilopoda
Medical Arthropodology
7Class Lobosea
Entamoeba histolytica Non-pathogenic amoeba
8Class Zoomastigophorea
Trichomonas vaginalis
Giardia
9Class Sporozoa
Toxopasma gondii Cryptosporidium Pneumocycstis
carinii
10Class Ciliophora
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12Class Nematoda
Trichuris trichiura Hookworm Enterobius
vermicularis Filaria Trichinella spiralis
13Nematoda
14Class Trematoda
Fasciolopsis buski Paragonimus westermani
Schistosoma japonicum
15Trematoda
16Class Cestoda
Taenia saginata Echinococcus granulosus
17Cestoda
18Class Metacanthocephala
Macracanthorhynchus
hirudinaceus
19Class Insecta
Lucilia sericata
Lice Sandflies , Fleas
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21Class Arachnida
Ticks Mites
follicle mite
22Class Crustacea
23Class Chilopoda
centipede
244. Terms of Parasitology
25Symbiosis
- (1)Symbiosis(????)Two different organisms live
together and interact, in this association one
partner lives in or on another ones body.
including 3 typesMutualism, Commensalism,
Parasitism.
26Symbiosis
- (2)Mutualism(????)is a permanent association
between two different organisms that life apart
is impossible, two partners benefit each other,
such as termites and flagellates. - The mutuals are metabolically dependent on one
another one cannot survive in the absence of the
other.
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28Symbiosis
- (3) 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 man. - (4) Parasitism(????)is the association of two
different organisms, in which one partner is
benefited while the other is injured, such as
Ascaris lumbricoides and man.
29Parasite
- (5) Parasite(???) In parasitism, it is the
benefited partner. It is an animal organism which
lives in or on the host in order to obtain
nourishment and shelter from the host as well as
does harms to the host.
30Parasite
- endoparasite
- ectoparasite
- temporary parasite
- permanent parasite
- obligatory parasite
- facultative parasite
- accidental parasite
- opportunistic parasite
31Endoparasite
32Ectoparasite
33Host
- (6) Host(??) In parasitism, it supplies the
parasite with nourishment and shelter, it is the
injured partner. - (7) Carrier(???) A person who harbours parasite
has no clinical symptoms, is an important source
of infection in epidemiology.
34- (8) Definitive (final) host(???)harbours adult or
sexually reproductive stage of a parasite. - (9) Intermediate host(????)harbours larval or
asexually reprodctive stage of a parasite,
according to priority they are classified into
first intermediate host, second intermediate
host, third intermediate host.
35- (10) Reservoir hosts(????)are the vertebrate
hosts which harbour the same species of parasite
at same stage as a human host. They are an
important source of infection in epidemiology.
36Zoonosis
- (11) Zoonosis(?????)refers to animals diseases
which can be transmitted to man. (These animals
infected with parasites are called reservoir
hosts.)
37- (12) Paratenic host or transport host(????)is an
abnormal host in which some parasitic larvae can
survive but cant develop into adults. If the
larvae have a chance to enter their appropriate
hosts, they can continue to develop into adults
there.
38- (13) Larva migrans(?????)means that the larvae
living in their abnormal hosts in which they can
not grow into adults but can wander everywhere
and cause the local and systemic pathological
lesions of the hosts.
39Life cycle
- (14) Life cycle(???) is the process of a
parasites growth, development and reproduction,
which proceeds in one or more different hosts
depending on the species of parasites. - (15)Infective Stage(???)is a stage when a
parasite can invade human body and live in it .
40Life cycle
- (16) Infective Route(????)is the specific
entrance through which the parasite invades the
human body. - (17) Infective Mode(????) means how the
parasite invades human body, such as the
cercariae of the blood fluke actively penetrate
the skin of a swimming man and the infective
ascaris eggs are swallowed by man.
41Life cycle
- (18) Alternation of Generation
- In life cycles of some parasites, there are the
regular alternations of sexual and asexual
reproductions , this phenomenon is called
alternation of generation, such as the life cycle
of Plasmodium vivax.
42- (19) Mechanical Transmission Arthropods play a
role of the transportation of pathogens, which is
not indispensable for the disease transmission,
such as flies carry typhoid bacilli, ascarid eggs
and amoebic cysts.
43- (20) Biological Transmission Pathogens have to
spend a part of their life cycle in the vector
arthropods in which they multiply or develop into
the infective stage and then invade the human
body under the help of the arthropod, such as
Anopheles mosquitoes transmit malaria.
44Evolution of Parasitism
- endoparasite Free living
- ectoparasite
Commensalism(????) - temporary parasite Symbiosis
Mutualism(????) - permanent parasite
Parasitism - obligatory parasite
carrier - facultative parasite
parasite Host - accidental parasite
Patient - opportunistic parasite
-
- Final host Intermediate host Reservoir
host Paratenic host -
-
Zoonosis Larva migrans
454. Parasites Harms to Man
- Mechanical effects of parasites on host
tissues and organs e. g. , biliary ascariasis
and larva migrans. - Depriving nourishment from hosts e.g.
hookworms suck blood. - Toxic effect e. g., mosquitoes, spiders
and ticks introduce venom when they insert their
mouth parts into the skin. - Immuno-pathological lesion e.g. schistosoma
liver cirrhosis when hydatid fluid is released
from the rupture of a hydatid cyst anaphylaxis
often results.
465. Human Immunity against Parasites
- Its intensity and specificity are usually at a
lower level than those produced by bacteria and
viruses. It refers to Non-sterilizing immunity
(Premunition????Concomitant immunity????). The
host may be protected from superinfection????as
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.
47(WHO) - Priority Diseases
- 1. Schistosomiasis
- 2. Malaria
- 3. Filariasis
- 4. Trypanosomiasis
- 5. Leishmaniasis
- 6. Leprosy (replaced by HIV/AIDS)
48Why 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.
49General Characteristics
- 1. Chronic diseases
- 2. No effective vaccine
- 3. No practical chemotherapy
- 4. Affect young
- 5. Affect underprivileged
- 6. Vector-borne
50Geographic Distribution Factors (Endemicity)
- 1. Presence of a suitable host
- 2. Habits of the host
- 3. Escape from the host
- 4. Favorable conditions outside of host
- 5. Economic and social conditions
51Presence of Diseases in a Population
(Prevalence)
- Factors required
- 1. Source
- infected persons
- carriers
- animals
52Presence of Diseases in a Population
(Prevalence)
- 2. Mode of transmission
- direct
- indirect
- vectors
- 3. Susceptible host
- immunity
53- Three key links of disease transmission
- 1.Source of infection 2. Route of transmission
3. Susceptible people - excrement
mouth - secretion food, water, finger
skin or wound - blood direct or indirect contact
mucosa - focus of
placenta - infection blood transfusion, injection,
- intermediate host,
- insects sucking blood,
- congenital ,
- touch soil, water, grass
54Diagnosis of Parasitic Infections
- 1. Clinical diagnosis
- 2. Laboratory diagnosis
55Treatment of Parasitic Infections
- 1. Medical and surgical
- 2. Chemotherapy
- 3. Adequate nutrition
56Prevention and Control
- 1. Reduction in sources
- 2. Education
- 3. Destruction and/or control of reservoir hosts
and vector