Dr. Hamdy  Badie M. El-Wakil

Prof. of Parasitology & Public Health .

Faculty of Allied Medical Sciences.Pharos University In Alexandria,Egypt

Human parasitology is the study of those organisms which parasitize humans. According to the very broad definition of parasitology, parasites should include the viruses, bacteria, fungi, protozoa (protista) 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. 

After completing this course, you should be able to: Discuss how important parasites can be classified

according to kingdom and phylum State the meaning of commonly-used terms Describe how parasitic infections affect communities in

poor countries and that knowledge of their life cycle is necessary for effective prevention and control

Discuss the epidemiology, basic life cycle, clinical presentation, management and control of some important parasitic infections

Note: This course will contain many unfamiliar terms. You are NOT expected to remember the classifications and names of all of the different parasite species. The emphasis is on understanding basic concepts and being able to illustrate these with some important examples.

After completing this course, you will associated a quiz to assess your learning.

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Parasite Diseases No. people infected Deaths/yr

Plasmodium malaria 273 million 1.12 million

Soil transmitted helminthes:

• Roundworm (Ascaris)

• Whipworm (Trichuris)• • Hookworm

(Ancylostoma and Necator)

Pnemonitis, intestinal obstruction

Bloody diarrhoea, rectal prolapse

Coughing, wheezing, abdominal pain and anaemia

2 billion 200,000

Schistosoma Renal tract and intestinal disease

200 million 15,000

Filariae Lymphatic filariasis and elephantiasis

120 million Not fatal but 40 million disfigured or incapacitated

Trypanasoma cruzi Chagas disease (cardiovascular)

13 million 14,000

African trypanosomes African sleeping sickness 0.3 – 0.5 million 48,000

Leishamania Cutaneous, mucocutaneous and visceral leishmaniasis

12 million; 2 million new cases/yr

50,000

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Phylum: Sarcomastigophora:Phylum: Sarcomastigophora:

Subphylum: Sarcodina e.g. Subphylum: Sarcodina e.g. AmoebaAmoeba

Subphylum:Mastigophora e.g. Subphylum:Mastigophora e.g. TrypansomaTrypansoma

Phylum: Ciliphora: Class: Ciliates e.g. Phylum: Ciliphora: Class: Ciliates e.g. Balantidium coliBalantidium coli

Phylum: Apicomplexa: Class: Sporozoa e.g. Phylum: Apicomplexa: Class: Sporozoa e.g. PlasmodiumPlasmodium Sp. Sp.

Classification of parasites and vectorsClassification of parasites and vectors

Animal KingdomAnimal Kingdom

Sub-KingdomSub-Kingdom(Metazoa)(Metazoa)

Multicellular animalsMulticellular animals

Sub-KingdomSub-Kingdom(Protozoa) Unicellular (Protozoa) Unicellular

parasites=kingdom parasites=kingdom

ProtistaProtista

Phylum Helminthes : Phylum Arthropods :Phylum Phylum Helminthes : Phylum Arthropods :Phylum MolluscsMolluscs

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Sub kingdom =kingdom =kingdom ProtistaProtista

Phylum Sub-phylum Genus- examples

Species- examples

Unicellular Unicellular Protozoa

Sarcomastig-ophorafurther divided into

Sarcodina-- - move by pseudopodia

Entamoeba E. histolytica

Mastigophoramove by flagella

Giardia G. lamblia

Apicomplexano organelle of

locomotion

Plasmodium P. falciparum,

P. vivax,

P. malariae,

P. ovale

Ciliophoramove by cillia

Balantidium B. coli

MicrosporaSpore-forming

Enterocyto-zoa

E. bieneusi

Sub kingdom

Phylum Class Genus – examples

Metazoa

Multicellular Multicellular animalsanimals

NematodesRound worms; appear round in cross section, they have body cavities, a straight alimentary canal and an anus

Ascaris (roundworm)

Trichuris (whipworm)

Ancylostoma (hookworm)

Necator (hookworm)

Enterobius (pinworm or threadworm)

Strongyloides

Platyhelminthes or PlathelminthesFlat worms; dorsoventrally flattened, no body cavity and, if present, the alimentary canal is blind ending

CestodesAdult tapeworms are found in the intestine of their host

They have a head (scolex) with sucking organs, a segmented body but no alimentary canal

Each body segment is hermaphrodite

Taenia (tapeworm)

TrematodesNon-segmented, usually leaf-shaped, with two suckers but no distinct head

They have an alimentary canal and are usually hermaphrodite and leaf shaped

Schistosomes are the exception. They are thread-like, and have separate sexes

Fasciolopsis (liver fluke)

Schistosoma (not leaf shaped!)

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Although parasitic infections occur globally, the majority occur in tropical regions, where there is poverty, poor sanitation and personal hygiene

Often entire communities may be infected with multiple, different organisms which remain untreated because treatment is neither accessible nor affordable

Effective prevention and control requires "mass intervention strategies” and intense community education. Examples include:◦ General improved sanitation: pit latrines, fresh water

wells, piped water◦ Vector control: insecticide impregnated bed nets, spraying

of houses with residual insecticides, drainage, landfill◦ Mass screening and drug administration programmes

which may need to be repeated at regular intervals

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Parasite transmissionParasite transmission

IndirectIndirect(with intermediate hosts)(with intermediate hosts)

DirectDirect

(without intermediate host)(without intermediate host)

(2) Immediately(2) Immediately

infectiveinfective Entamoeba histolyticaEntamoeba histolytica

Giardia lambliaGiardia lamblia

Balantidium coliBalantidium coli

Trichomonas Trichomonas spsp

.. Hymenolepis nanaHymenolepis nana

Enterobius vermicularisEnterobius vermicularis

Sarcoptes scabieiSarcoptes scabiei

Pediculus huminusPediculus huminus

Phthirus pubisPhthirus pubis

(1)Taking a (1)Taking a period to period to become become

infectiousinfectiousAscaris lumbricoidesAscaris lumbricoides

Trichuris trichiuraTrichuris trichiura

Ancylostoma duodenaleAncylostoma duodenale

Necator americanaNecator americana

Strongyloides stercoralisStrongyloides stercoralis

(2) Requiring (2) Requiring oneone

intermediate intermediate hosthost

Wuchereria bancroftiWuchereria bancrofti

Onchocerca volvulusOnchocerca volvulus

Loa loaLoa loa

Dracunculus medinensisDracunculus medinensis

Dipylidium caninumDipylidium caninum

Taenia Taenia sppspp

.. Schistoma Schistoma sppspp

.. Leishmania Leishmania spp.spp.

Fasciola spp.Fasciola spp.

((1) Requiring 1) Requiring TwoTwo

intermediate intermediate hostshosts

• H. HetrophyesH. Hetrophyes

Clonorchis sp.Clonorchis sp.

Fasciolopsis buskiFasciolopsis buski

Paragonimus Paragonimus westermaniwestermani

Diphyllobothrium Diphyllobothrium L.L.

Eukaryote: a cell with a well-defined chromosome in a membrane-bound nucleus. All parasitic organisms are eukaryotes

Prokaryotic organelles Prokaryotes are not as structurally complex as eukaryotes,

and were once thought not to have any internal structures enclosed by lipid membranes.

Protozoa: unicellular organisms, e.g. Plasmodium (malaria)

Metazoa: Multicellular organisms, e.g. helminths (worms) and arthropods (ticks, lice)

An endoparasite: “a parasite that lives within another living organism” – e.g. malaria, Giardia

An ectoparasite: “a parasite that lives on the external surface of another living organism” – e.g. lice, ticks

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Definitive host: “the organism in which the adult or sexually mature stage of the parasite lives”

Intermediate host: “the organism in which the parasite lives during a period of its development only”

Zoonosis: “a parasitic disease in which an animal is normally the host - but which also infects man”

Vector: “a living carrier (e.g.an arthropod) that transports a pathogenic organism from an infected to a non-infected host”. A typical example is the female Anopheles mosquito that transmits malaria

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Parasitology :Is the science which deals with parasitism, in other hand, it studies the host parasite relationships.Medical parasitology: Deals with the study of parasites of animal origin, belonging to the animal kingdom, and affecting man, the disease they produce, the various methods of their diagnosis, their treatment and finally prevention and control.

Parasite :Any organism is considered as a parasite when it lives either on or in another organism to obtain food and shelter without compensation.

Host :Is the living organism which harbours the parasites.

Habitat :Is the site in the host where the parasite lives.Parasites vary according to their biological habits.

Commensal :

If the parasite derives benefit from its host without harming it, it becomes, known as a commensal.

Symbiosis:If on the other hand the association between them is so that one cannot live without the help of the other, then this relationship becomes known as symbiosis, but usually a parasite causes injury to its host.

Definitions: What is ….?

Endemic parasite:

Maintains a relatively moderate steady level of parasitism in man in a certain area. Also, a parasite is called hyperendemic when its prevalence or incidence is relatively high.

Epidemic parasite:

When these exist a sharp rise in the prevalence of infection or infestation culminating in an intense outbreak of the disease.

Define the following:

Definitive host: Intermediate host Zoonosis: Vector: Commensal:

Group of students will be selected for an assignment topic ,one of the parasites that are studied in your course.

The following points should be covered in your assignment sheets:

(1) Classification Position:(2) Name of the parasite;(3)Description ( Morphological Characters in vivo): (4) Definitive (Final) Host:(5) Intermediate Host:(6) Mode Of Infection:(7) Infective Stage:-.(8) Habitat:- (9) Diagnostic Stage:- (10) Disease:- (11) life cycle

Giardia lamblia.

Should be prepared by the following students Ahmed Hassan Hameda Ahmed Raslan Ahmed Farghaly Ahmed Mahfouz Amr Abdel Attey Amr Salah Al Dein khalaf Amr Youness Ghaly Moursy

Ahmed Mohamed Abdel Hameed Ahmed Abdel Naby Akhlas Khalil Esraa Farhat Faten Lotfy Fatma Soubhy Fatma Mohamed Khalil Kareem Zeddan