introduction of parasitology

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GENERAL INTRODUCTION OF MEDICAL PARASITOLOGY

Bin YeProfessor, Ph. D.Email:[email protected]

weeklecturepractice1general introduction1roundworm, whipworm2pinworm, hookworm2filariae,trichinella 3trematode, liver flukebasic tech3lung & intestine fluke4schistosomes nematodes 4cestode, pork tapeworm5No class6beef & sheep tapeworm trematodes

weeklecturepractice7protozoa, amoebaecestodes

7giardia, trichomonas8leishmania,toxplasmaprotozoa8malaria

9arthropodes, mosqiuto, flylouse, flea, mite,arthropodes

9sumerrize

GENERAL INTRODUCTION OF MEDICAL PARASITOLOGY

Parasite

Parasite:an organism which obtains food and shelter from another organism and derives all benefits from association.

Traditionally, protozoa,arthropods,helminths are defined as parasites.

Within broad definition, parasites include microparasites: viruses, bacteria, fungi, protozoa.macroparasites: helminths, arthropods.

Microparasites & Macroparasites

Protozoamalaria parasite

helminths

arthropods

Medical Parasitology and Parasitic DiseaseParasitism and ParasiteInteraction of Parasites and HostsEpidemiology and Prevention of Parasitic DiseaseINTRODUCTION

Medical Parasitologyand Parasitic Disease

Parasitology : science that deals with the parasites of human and domestic animals.

interactions between a host and the population of parasites interactions between host populations and the parasites that infect them

Aspects of Parasitology :

parasites---morphology, biochemistry, physiology, life cycles

host---immunological, pathological, clinical responses

treatment and control

public health

Medical parasites and Parasitology:

Protozoasingle-celled parasites /Protozoology

Helminthsflukes, tapeworms,nematodes / Helminthology

Arthropodsinsects,ticks,mites /Arthropodology

Important Parasitic DiseasesMalariaFilariasisSchistosomaiasisLeishmaniasis Trypanosomiasis

Burden of Diseases in Developing WorldJuly2008Disability Adjusted Life Years (DALYs)

DiseaseEndemiccountriesDeaths/yr(million)DiseaseBurden(DALYs million)HIV/AIDS1802.886Malaria1011.244.7TB2111.635.4African tryps360.051.5Chagas Disease210.010.7Leishmaniasis880.052Filariasis805.8Schistosomiasis760.011.7Onchocerciasis360.5

Neglected Tropical DiseasesProtozoan InfectionsLeishmaniasis (VL, CL and MCL)Human African trypanosomiasis (sleeping sickness)Chagas diseaseHelminth InfectionsSoil-transmitted helminth infectionsAscariasis-Trichuriasis-HookwormLymphatic filariasis (elephantiasis)Onchocerciasis (river blindness)SchistosomiasisDracunculiasis (guinea-worm disease)Cysticercosis and other zoonotic helminthiasisViral InfectionsDengue & dengue haemorrhagic feverBacterial InfectionsLeprosyTrachomaBuruli ulcer

NTDs in poor populations

Soil transmitted helminthiasis SchistosomiasisLymphatic filariasis OnchocerciasisLeprosyTrachoma Leishmaniasis Buruli ulcerChagas diseaseHuman African trypanosomiasisDengue & DHFCysticercosis

EchinococcosisRabiesAnthraxBovine tuberculosisBrucellosisZoonotic trypanosomiasisImpact on povertymaking interventions cost-effectiveMalariaTBNeglected zoonoses or poor populations and (all) their (undermining) diseases ?HIV/AIDS Previously neglected diseasesNeglected tropical diseases

Global distribution of NTDs. Approximately 1 billion people are affected by more than one of NTDs

Elephantiasis of leg due to filariasis

Schistosomaiasis

Vector of African Trypanosomiasis

Trypanosomes

African Trypanosomiasis

Trypanosoma cruzi

Vectors of American Trypanosomiasis

American Trypanosomiasis

Other Parasitic Diseases

hookworm

A hookworm on mucosa of stomach Gastroscopy images

Whipworm adults

Whipworm adults embed in mucosa

pinworms

Trichinella spiralis larvae in muscles

Chinese liver flukes

lung fluke

Pork tapeworm adult

Beef tapeworm adult

Hydatid, sheep tapeworm larva

amoeba

giardiasis lamblia

Giardia lamblia

Toxoplasma gondii trophozoites

Brain damages caused by T gondii

follicle mite

Scabies, itch mite

Parasitism and Parasite

Parasitism

Symbiosis: An association in which both partners are so dependent upon each other that one cannot live without the other.

Symbiosis: association between animals of different species living together.

MutualismCommensalism Parasitism

symbiosis advantage advantagemutualism +cilliate +ox,sheepcommensalism +small fish - big fishparasitism+roundworm - human

Mutualism:In symbiosis, a special relationship that is beneficial to both partners.

Commensalism: An association in which the commensal only is deriving benefit without causing injury to its host. A commensal is capable of leading an independent life.

Parasitism:parasite derives benefit host always suffers some injury.A parasite has its power of independent life.

hookworms on small intestinal mucosa

Parasitism------important features involves two species, parasite and host. parasite receives nourishment and shelter from host parasite is always the beneficiary and host is always the provider. pathological changes in hosts that may result in disease. treatment and control of parasitic diseases requires information about parasite and its interactions with their hosts.

1. Types of parasites

Obligatory parasite, Facultative parasiteEndoparasite, EctoparasitePermanent parasite ,Temporary parasite Accidental parasite , Wandering parasiteOpportunistic parasite

1. Types of parasiteson selections of host, parasites are divided into:Obligatory parasite -- a parasite cannot exist without a parasitic life, it must live entirely or at least partially in or on the host to get food.Facultative parasite-- a parasite lives a parasitic life when opportunity arises,it can live without the host.

Obligatory parasite

Facultative parasite-Acanthamoeba

1.Types of parasites on living sites, parasites are divided into:

Endoparasite-- a parasite lives inside the body of the host; in the blood, tissues, body cavities, digestive tract and other organs.

Ectoparasite-- a parasite lives outside on the surface of the body of the host.

Endoparasite, hookworms on small intestinal mucosa

EEctoparasite

1. Types of parasiteson living time, parasites are divided into:Permanent parasite --must live in or on the host during the entire life time of the parasite.Temporary parasite-- may live on the host for a short period during its feeding, then leaves.

Permanent parasite

Temporary parasites

Nomenclature of Parasites: Phylum---Subphylum ---(Superclass)-Class-(Subclass) ---Order-(Suborder) ---(Superfamily)-Family-(Subfamily) ---Genus---Species

1. Types of parasitesOn if host or site is normal or abnormal, some parasites are divided into:Accidental or Occasional parasite a parasite enters or attaches to the body of an unusual host by a chance. Wandering or Aberrant parasite a parasite happens to reach a place where it cannot live.

myiasis caused by a fly larva.Accidental parasite

Accidental parasitemyiasis caused by fly larvae.

Aberrant parasiteascarid larva in brain

1. Types of parasiteson possibility of damage to host, some parasites are Opportunistic parasites can cause damage to the host when the host is under a susceptible condition,such as Toxoplasma gondii in AIDS patients .

Opportunistic parasites Toxoplasma gondii from an HIV infected patient.

2. Life cycle of parasites------ the whole process of parasite growing, developing and reproduction.

Some parasites have complex life cycles, others have simple life cycles.

Direct type: no intermediate host

Indirect type: need intermediate host

Life cycle of ascarid

Life cycle of Chinese liver fluke

Types of Life cycle

Multicellular Parasite: adults---- eggs----- larvae----- adults Unicellular Parasite (protozoa): sexual reproduction phase ------ asexual reproductive phase. Arthropods: adults--- eggs--- larvae--- pupa--- adult

3. Types of hostDefinitive host / Final hostIntermediate hostReservoir hostParatenic host / Transport host

Definitive /Final host harbors the adult stage of the parasite or where the parasite utilizes the sexual method of reproduction.

In majority of human parasitic infection, man is definitive host.

Intermediate host harbors the larval stages of the parasite or where the parasite utilizes the asexual method of reproduction.

Certain parasites have 2 intermediate host, known as the 1st and 2nd intermediate host respectively .

Definitive /Final hostharbors the adult stage of the parasite or where the parasite utilizes the sexual method of reproduction.

Intermediate hostharbors the larval stages of the parasite or where the parasite utilizes the asexual method of reproduction.

larvae In Suitable hostIn UnSuitable hostHuman ??? hostvertebrate Animal ??? host

vertebrate Animal-- ??? hostadultlarve

Reservoir host a normal vertebrate animal host that harbors the parasites of human. ensure continuity of the parasite's life cycle and act as additional sources of human infection. Domestic animals are chief reservoir hosts.

Paratenic / Transport hostan abnormal vertebrate host which harbors the larvae of helminths, the larvae remains viable without further development, but is infective to their normal hosts. Usually,an insect transmitting the parasitic infection known as the vector, not as a transport host.

Reservoir host a normal vertebrate animal host that harbors the parasites of human, act as additional sources of human infection. Paratenic / Transport hostan abnormal vertebrate host which harbors the larvae of helminths, the larvae remains viable without further development, but is infective to their normal hosts.

life cycle of Spirometra mansoni

larvae In Suitable hostIn UnSuitable hostHuman definitive hostvertebrate Animal reservoir host

vertebrate Animal-- Transport hostadultlarve

InteractionbetweenParasites & Hosts

1.Effects of Parasites on HostsDepend upon parasite species, strain, amount of parasites, parasitic sites, secretion and excretion of parasites.Proliferation, multiplication and metastasis in protozoal infection are important.

Pathogenic Factors of a parasite

migratory pathway in host anatomical site where parasite develops feeding habits suitable living site stimulate hyperactive immunological responses in host that may lead to immunopathological changes (fibrosis, granulomas, autoimmuine reactions, allergic reactions and splenomegaly.) transmit other infectious agents. ( relevant to arthropods. )

1.Effects of Parasites on HostsCompetition for hosts nutrients Physical Damages to Tissues or Organs Toxic and Allergic Effect on Host

1.Effects of Parasites on HostsCompetition for hosts nutrients roundworm,tapeworm gets nutrition from intestine of man.

1.Effects of Parasites on HostsCompetition for hosts nutrients Physical Damages to Tissues or Organs roundworms can block intestine, invade appendix or bile duct.

1.Effects of Parasites on HostsCompetition for hosts nutrients Physical Damages to Tissues or Organs Toxic and Allergic Effect on Host toxin of arthropods; proteolytic enzyme secreted by amoeba; metabolite, secretions, excretions from parasites or dead parasites act as antigen, induce hypersensitive immune response or allergy, damage tissues.

1.Effects of Parasites on HostsCompetition for hosts nutrients roundworm,tapeworm gets nutrition from intestine of man.Physical Damages to Tissues or Organs roundworms can block intestine, invade appendix or bile duct.Toxic and Allergic Effect on Host toxin of arthropods; proteolytic enzyme secreted by amoeba; metabolite, secretions, excretions from parasites or dead parasites act as antigen, induce hypersensitive immune response or allergy, damage tissues.

2.Effects of Hosts on Parasites

host offers some resistance to injury done by the parasite,

there may be some adaptation (tolerance) between parasite and host


Every species of animals is naturally resistant to infection of many different parasites.


Every species of animals is naturally resistant to infection of many different parasites.Diet or nutritional status of host is major important in outcome of parasitic infection. High protein diet is unfavorable for many intestinal protozoa. Carbohydrate-rich diet favors some tapeworms.

Resistance to parasites----

Innate Immunity

Acquired Immunity

(1) Innate Immunity/Innate Barrier Skin, mucous membrane, placenta. Phagocytosis of phagocytes.

innate immunity features: natural heritage, non-specific, not very strong.

(2) Acquired Immunityestablished by previous infection. Sterilizing Immunity Non-Sterilizing Immunity

Sterilizing Immunity can wipe out the parasite radically,the clinical symptoms disappear completely, can acquire long-time specific resistance to the reinfection of this parasite. E.g. Leishimania tropical. absolute sterilizing immunity to reinfection is rare in protozoa, probably never in helminths.

Non-Sterilizing Immunity

can wipe out most of the parasite, but not completely, host can acquire certain degrees of resistance to the reinfection. If all of the parasites cleared radically, the resistance would disappear completely.

It is a common immunity caused by many protozoa and helminths.

Non-Sterilizing Immunity includes premunition

concomitant immunity

Premonition --- specific immunity to some protozoa infection,which can wipe out most of the parasites, results in clinical recovery and resistance to the challenge from same parasites.

concomitant immunity --- specific immunity to some helminths infection, which can resist the subsequent challenge infection of the larvae of same parasites, whereas the adults that induce the response can survive.

Premunition--a specific immunity to some protozoa infection,which can wipe out most of the parasites,results in clinical recovery and resistance to the challenge from same parasites.

Concomitant immunity-- a specific immunity to some helminths infection, which can resist the subsequent challenge infection of the larvae of same parasites,whereas the adults that induce the response can survive.

3. Interaction of Parasites and HostsAB, parasitic disease.resist (B)harm (A)HOST

Epidemiology & Prevention of Parasitic Disease

1. Basic Factors of Transmission Infective source: patients, carriers, reservoir hosts(dog, pig, cat, cattle, rat, etc.).

1. Basic Factors of Transmission Infective source: patients, carriers, reservoir hosts(dog, pig, cat, cattle, rat, etc.).Susceptible hosts: common people without specific immunity.

1. Basic Factors of Transmission Infective source: patients, carriers, reservoir hosts(dog, pig, cat, cattle, rat, etc.).Susceptible hosts: common people without specific immunity.Pathways of transmission: path from infective source to susceptible hosts.It includes contaminated food and water, polluted soil, direct contact, biting of arthropods, congenital infection from pregnant mother to fetus in the uterus.

2. Infection of ParasitesStage of infection: a stage of a parasite, which can invade the human body and establish infection.


Method of infection: methods by which a parasite invades the human body.Such as by ingesting of contaminated food and drink water, flesh, aquatic plants; by invading of the skin or mucous membrane; by the biting of insects vectors.


Method of infection: methods by which a parasite invades the human body.Such as by ingesting of contaminated food and drink water, flesh, aquatic plants; by invading of the skin or mucous membrane; by the biting of insects vectors.

Entry of infection: the avenue through which a parasite enters human body. E.g., mouth, skin, placenta, respiration duct, genital canal, blood vessel, etc.

3. Epidemiological featuresEndemic Climate factors (temperature, humidity ), Biologic factors (vectors and intermediate hosts), Living habits and modes or conditions of working.

helminth

3. Epidemiological featuresEndemic Climate factors (temperature, humidity ), Biologic factors (vectors and intermediate hosts), Living habits and modes or conditions of working.Seasonal Distribution and population of vectors and of intermediate hosts vary with different seasons. Different modes of working at different seasons.

3. Epidemiological featuresEndemic Climate factors (temperature, humidity ), Biologic factors (vectors and intermediate hosts), Living habits and modes or conditions of working.Seasonal Distribution and population of vectors and of intermediate hosts vary with different seasons. Different modes of working at different seasons.Zoonosis A parasite can live in animal and human body. Reservoir hosts is the source of infection to man.

4. Prophylaxis Principles (1) Eradicate infective sources therapy patients and carriers, therapy or kill reservoir hosts

4. Prophylaxis Principles (1) Eradicate infective sources therapy patients and carriers, therapy or kill reservoir hosts (2) Block transmission routes proper dispose of feces, mange water resource. control vectors and intermediate hosts.

4. Prophylaxis Principles (1) Eradicate infective sources therapy patients and carriers, therapy or kill reservoir hosts (2) Block transmission routes proper dispose of feces, mange water resource. control vectors and intermediate hosts. (3) Protect susceptible individuals improve personal hygiene change bad eating and working habits, improve working modes and conditions, drug prophylaxis.

1.Habitat inside the human host.2.Morphology and life cycle(staining methods and cultivation).3.Modes of infection: Reservoir host, sources of infection, portal of entry, vehicle of transmission.4.Effects of the parasite; Pathogenic lesions, Clinical manifestations.5.Immunological responses.6.Methods for specific diagnosis.7.Approved therapy for eradication of the parasitic infection. 8. Geographical distribution. Prophylactic measures for the prevention of parasitic infection of the individual as well as of the community. Scheme Followed in Parasitological Studies

* *World Health Organization***World Health Organization***World Health Organization**

introduction of parasitology

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