INTRODUCTION TO MEDICAL INTRODUCTION TO MEDICAL PARASITOLOGYPARASITOLOGY

Learning outcomesLearning outcomes

By the end of this section, you should be able to:By the end of this section, you should be able to:Define Parasitology.Define Parasitology.Mention kinds of parasitism.Mention kinds of parasitism.Mention kinds of hosts.Mention kinds of hosts.Classify human parasites.Classify human parasites.Mention transmission of parasitic infectionMention transmission of parasitic infectionMention Host – Parasite relationshipMention Host – Parasite relationshipDefine infection, infestation, incubation period, and Define infection, infestation, incubation period, and ConvalescenceConvalescenceClassify Medical ProtozoalogyClassify Medical ProtozoalogyDefine and Classify medical Helminthology.Define and Classify medical Helminthology.

MEDICAL PARASITOLOGY MEDICAL PARASITOLOGY

The science that deals with parasites that live The science that deals with parasites that live in or on other organisms called their hosts and in or on other organisms called their hosts and causing injury to them. causing injury to them. A parasite may be:A parasite may be:Endo-parasite Endo-parasite which lives inside the host which lives inside the host (parasitic infection).(parasitic infection).Ecto-parasiteEcto-parasite which lives on the surface of the which lives on the surface of the host (parasitic infestationhost (parasitic infestation).).

General Types of ParasitesGeneral Types of Parasites

A. A. Obligatory parasiteObligatory parasite: One that is entirely : One that is entirely dependent upon a host for its survival.dependent upon a host for its survival.

B. B. Facultative parasiteFacultative parasite: : Free-living Free-living organisms, but can become parasitic upon organisms, but can become parasitic upon another organism another organism

C. C. Accidental parasitesAccidental parasites:: The parasite infect The parasite infect unsuitable host, so cannot complete its life unsuitable host, so cannot complete its life cycle cycle

KINDS OF HOSTKINDS OF HOSTDefinitive hostDefinitive host: A host in which the adult : A host in which the adult stages of the parasite developstages of the parasite develop ((It is the host It is the host in which sexual reproduction takes place)in which sexual reproduction takes place)

Intermediate hostIntermediate host:: A temporary host for the A temporary host for the parasite, in which the immature stage of the parasite, in which the immature stage of the parasite developparasite develop ((It is the host in which It is the host in which asexual reproduction takes place).asexual reproduction takes place).

Reservoir hostReservoir host: : An animal host which can be An animal host which can be infected with the parasite and act as a source infected with the parasite and act as a source for human infection for human infection

VectorVector:: An arthropod, that serves as an An arthropod, that serves as an intermediate host as well as transmitting a intermediate host as well as transmitting a pathogen from host to hostpathogen from host to host..

Accidental hostsAccidental hosts: : These are hosts in These are hosts in which the parasite cannot successfully which the parasite cannot successfully develop, but can still cause disease develop, but can still cause disease

Transmission of parasitic infectionTransmission of parasitic infection 1- Mouth: most common: 1- Mouth: most common: Ingestion of infective stage, e.g. protozoan cysts & Ingestion of infective stage, e.g. protozoan cysts & embryonated nematode eggs. embryonated nematode eggs. Intimate oral kissing, e.g. Intimate oral kissing, e.g. Entamoeba gingivalis.Entamoeba gingivalis.

2- 2- Skin penetration of infective larval stage to skinSkin penetration of infective larval stage to skin Directly: e.g. Cercaria of Directly: e.g. Cercaria of SchistosomaSchistosoma & filariform larva of & filariform larva of hookworm. hookworm. Indirectly (through insect vectors), e.g. infective stage of Indirectly (through insect vectors), e.g. infective stage of trypanosome trypanosome

3- 3- AirborneAirborne..Parasite inhaled Parasite inhaled nose nose nasopharynx nasopharynx intestine, e.g. intestine, e.g. E. E. vermicularis.vermicularis.Parasite inhaled Parasite inhaled nose nose blood or lymphatic blood or lymphatic specific specific tissues, e.g. tissues, e.g. T. GondiiT. Gondii & free living amoeba. & free living amoeba.

4-4- TransplacentaTransplacentall: Parasite from mother to foetus: Parasite from mother to foetus

Host – Parasite RelationshipHost – Parasite Relationship

1.1. CommensalismCommensalism:: 2 animals of different 2 animals of different species live together without species live together without

metabolically dependent on the other, metabolically dependent on the other, although one organism may receive although one organism may receive

some benefit but does not harm the some benefit but does not harm the other.other.

2.2. MutualismMutualism:: Where shared benefits are Where shared benefits are present; one cannot survive in the present; one cannot survive in the

absence of the other absence of the other

ParasitismParasitism:: where an organism living in or where an organism living in or on another living organism, causing some on another living organism, causing some degree of damage to its host degree of damage to its host

DISEASE TERMINOLOGYDISEASE TERMINOLOGY

InfectionInfection: : Term applied to invasion of the Term applied to invasion of the body by pathogenic organisms and the body by pathogenic organisms and the reaction of the body to their presence and reaction of the body to their presence and to the toxins .to the toxins .

InfestationInfestation: Some parasites do not : Some parasites do not multiply within the host and this situation is multiply within the host and this situation is at times referred to as infestation.at times referred to as infestation.

Incubation periodIncubation period: : The incubation period The incubation period is the time between infection and the is the time between infection and the development of symptoms and signs of development of symptoms and signs of diseasedisease..

ConvalescenceConvalescence: : Convalescence is the Convalescence is the period of healing and describes a phase in period of healing and describes a phase in which balance is regained and damage which balance is regained and damage repaired. repaired.

Life cycle of parasitesLife cycle of parasitesStudy of life cycle of parasites is following up Study of life cycle of parasites is following up

the pathway of its development, starting by the pathway of its development, starting by one stage ending to where the cycle one stage ending to where the cycle repeats.repeats.

HostsHosts:: Definitive – Intermediate – Reservoir Definitive – Intermediate – Reservoir Habitat:Habitat: The organ inside the definitive host where The organ inside the definitive host where

adult stages of the parasite liveadult stages of the parasite live Infective Stage: Infective Stage: The stage of the cycle that infect The stage of the cycle that infect

manman Mode of Infection:Mode of Infection:

IngestionIngestionInjectionInjectionInhalationInhalationPenetration of skinPenetration of skinBite of insectBite of insectOrgan transplantationOrgan transplantationBlood transfusionBlood transfusionCongenitalCongenital

Diagnostic Stage: Diagnostic Stage: The stage from the cycle which The stage from the cycle which can be seen under microscopy or by naked eyecan be seen under microscopy or by naked eye

DiagnosisDiagnosis Clinical DiagnosisClinical Diagnosis

Clinical Picture – Symptoms - SignsClinical Picture – Symptoms - Signs Laboratory DiagnosisLaboratory Diagnosis

- - Direct Methods: Direct Methods: Demonstration of the Demonstration of the diagnostic parasitic stage, in urine or stool or diagnostic parasitic stage, in urine or stool or blood or sputum, under microscopyblood or sputum, under microscopy- - Indirect Methods:Indirect Methods:

*Detection of Antibodies (Abs) by *Detection of Antibodies (Abs) by serological tests [IHAT- IFAT-ELISA]serological tests [IHAT- IFAT-ELISA]

*Detection of Antigens (Ags)*Detection of Antigens (Ags) Imaging MethodsImaging Methods

X-Ray – Ultrasonography – Ct Scan - MRIX-Ray – Ultrasonography – Ct Scan - MRI

MEDICAL PARASITOLOGYMEDICAL PARASITOLOGY

1- Medical Helminthology.1- Medical Helminthology.

2- Medical Protozoology.2- Medical Protozoology.

3- Medical Entomology 3- Medical Entomology

Human ParasitesHuman Parasites

Parasites infect human fall into 2 categories:Parasites infect human fall into 2 categories:

1- 1- Unicellular Parasites (Protozoa).Unicellular Parasites (Protozoa).

2- Multicellular Parasites (Metazoa).2- Multicellular Parasites (Metazoa). Flat worms.Flat worms. Round worms.Round worms. Ticks.Ticks. Mites.Mites. Insects.Insects.

Each Parasite is classified into:Each Parasite is classified into:

• Phylum Phylum الشعبةالشعبة• Class Class الطائفةالطائفة• Order Order الرتبةالرتبة• Family Family العائلةالعائلة• Genus Genus الطبقةالطبقة• Species Species الصنفالصنف

Classification of human parasitic protozoaClassification of human parasitic protozoa

kingdom: kingdom: Protozoa Protozoa 1- Phylum: 1- Phylum: RhizopodaRhizopoda

EntamoebaEntamoeba

2- Phylum: 2- Phylum: CiliophoraCiliophora BalantidiumBalantidium

3- Phylum: 3- Phylum: Euglenozoa (Mastigophora Euglenozoa (Mastigophora or Flagellatesor Flagellates)) TrypanosomaTrypanosoma LeishmaniaLeishmania

4- Phylum: 4- Phylum: Apicomplexa Apicomplexa ((SporozoaSporozoa)) ToxoplasmaToxoplasma PlasmodiumPlasmodium

MEDICAL HELMINTHOLOGYMEDICAL HELMINTHOLOGY

HelminthsHelminths are a general term meaning are a general term meaning worms. This part deals with the study of worms. This part deals with the study of helminths that parasitize man.helminths that parasitize man.

CLASSIFICATION of MEDICAL CLASSIFICATION of MEDICAL HELMINTHOLOGYHELMINTHOLOGY

I-Platyhelminthes (Flatworms):I-Platyhelminthes (Flatworms): They They include; include;

Trematoda (Flukes)Trematoda (Flukes):.:.

Cestoda (Tapeworms)Cestoda (Tapeworms)

II) Nemathelminthes (Nematoda) II) Nemathelminthes (Nematoda) (Roundworms)(Roundworms):: The medically The medically important worms have separate sexesimportant worms have separate sexes. .