Tishk International University - PowerPoint Presentation

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Tishk International UniversityFaculty of Science Medical Analysis Dep.Medical parasitology Ilec-2-Grade -3- fall semester By:Dr.Hemdad Hawez Mawlood

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2ZoonosisThis term is used to describe an animal infection that is naturally transmissible to humans either directly or indirectly via a vector.

Examples of parasitic diseases that are zoonotic include: - Leishmaniasis, - South American trypanosomiasis, - Rhodesien trypanosomiasis.

-

Japonicum

schistosomiasis

,

- Trichinosis,

fascioliasis

,

-

Hydatid

disease

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3VectorA vector is an agent, usually an insect, that transmits an infection from one human host to another. The term mechanical vector is used to describe a vector which assists in the transfer of parasitic forms between hosts but is not essential in the life cycle of the parasite e.g. a housefly that transfers amoebic cysts from infected food that is eaten by humans.Biological Vector: Is the vector in which the parasite undergo development.

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4HOST-PARASTTE RELATIONSHIPS1.Symbiosis An association in which both host and parasite are so dependent upon each other that one can not live without the help of the other.2.Commensalism

An association in which only parasite derives benefit without causing any injury to the host.3.Parasitism Parasitism is a relationship in which a parasite benefits and the host provides the benefit. The host gets nothing in return and always suffers from some injury. The degree of dependence of a parasite on its host varies

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Crocodile Plover bird a large predatory semiaquatic reptile with long jaws, long tail, short legs, and a horny textured skin.5

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6SOURCES OF INFECTIONParasitic infections originate from following sources:1. Contaminated soil Soil polluted with human excreta acts as a source of infection with - Ascaris lumbricoides,

- Trichuris trichiura, - Ancylostoma duodenale, - Necator americanus and - Strongyloides stercoralis Before acquiring infectivity for man, eggs of these parasites undergo certain development in the soil.  These are known as soil transmitted helminthes

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72.Water polluted with human excreta which may contain viable cysts of Entamoeba histolytica

, Giardia lamblia, Balantidium coli, eggs of - Taenia solium, - Hymenolepis nana,

and the

infective

cercarial

stage

of

-

Schistosoma

haematobium

,

- S.

mansoni

- S.

japonicurn

.

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83. Freshwater fishes constitute the source of Diphylobothrium latum and Clonorchis sinensis.4. Crab and crayfishes are the sources of Paragonimus westermani

.5. Raw or undercooked pork is the source of Trichinella spiralis, T. solium, and Sarcocystis suihominis.6. Raw or undercooked beef is the source of T. saginata, Toxoplasma gondii, and Sarcocystis hominis.

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107. Watercress is the source of Fasciola hepatica.8. Blood-sucking insects transmit Plasmodium spp., Wuchereria bancrofti, Brugia malayi, Onchocerca volvulus, T. brucei, T. cruzi, Leishmania spp. and

Babesia spp.9. Housefly (mechanical carrier) is the source of E. histolytica.10. Dog is the source of Echinococcus granulosus and Toxocara canis (visceral larva migrans).

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1111. Cat is the source of T. gondii,12. Man is the source of E. histolytica, Enterobius vermicularis, and H. nana.13. Autoinfection

may occur with E. vermicularis and S. stercoralis, leading to hyperinfection,

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12PORTAL OF ENTRY INTO THE BODY1. Mouth The commonest portal of entry of parasites is oral, through contaminated food, water, soiled fingers or fomites. This mode of transmission is referred to as faecal-oral route. e.g. E. histolytica, G lamblia, B. coli. E. vermicularis, T. trichiura, A. lumbricoides, T. spiralis, T. solium, T. saginata,

D. latum, F. hepatica, C. sinensisFasciolopsis buski, P. westermani

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132. SkinInfection with A. duodenale, N. americanus and S. stercolaris is acquired when filariform larvae of these nematodes penetrate the unbroken skin of an individual walking over faecally contaminated soil. Schistosomiasis caused by S. haematabium, S. mansoni and S. japonicum

is acquired when the cercarial larvae, in water, penetrate the skin. A large number of parasites e.g, Plasmodium spp., W. bancrofti, B. malayi, Onchocerca . volvulus, T. brucei, T. cruzi, Leishmania spp. and Babesia spp. are introduced percutaneoursly when blood-sucking arthropods puncture the skin to feed.

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143. Sexual contact Trichomonas vaginalis is transmitted by sexual contact, E. histolytica and G. lamblia may also be transmitted by anal-oral sexual practices among male homosexual4. Kissing

E. gingivalis is transmitted from person-to-person by kissing or from contaminated drinking utensils.5. Congenital Infection with T. gondii and Plasmodium spp. may be transmitted from mother to fetus transplacentally

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156. Inhalation Airborne eggs of E. vermicularis may be inhaled into posterior pharynx leading to infection.7. latrogenic infection - Malaria parasites  transmitted by transfusion of blood from the donor with malaria containing asexual forms of erythrocytic schizogony  This is known as trophozoite-induced malaria or transfusion malaria.

- Malaria parasites may also be transmitted by the use of contaminated syringes and needles  This may occur in drug addicts.

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16LIFE CYCLE OF HUMAN PARASITESOn the basis of their life cycles human parasites can he divided into three major groups:NO INTERMEDIATE HOST

Protozoa Entamoeba histolytica  G. lamblia



Chilomastix

mesnili



T.

vaginalis



B. coli

Helminths



E.

vermicularis



T.

trichiura



Ascaris

lumbricoides



A.

duodenale



N.

americanus

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17ONE INTERMEDIATE HOST

INTERMEDIATE HOSTPARASITE

INTERMEDIATE HOST

PARASITE

pig

T.

solium

T.

Spiralis

Mosquito

W. bancrofti

B. malayi

Cow

T

saginata

Snail

Schistosoma spp.

Man

E. granulosus

Plasmodium spp.

Copepod

Dracunculus

medinensis

Flea

H. nana

Fly: -

Sandfly

- Tsetse

-

Chrysops

(deer fly)

-

Simulium

(black fly)

Leishmania

Trypanosoma

spp.

Loa

loa

O. volvulus

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18TWO INTERMEDIATE HOSTSINTERMEDIATE HOSTS

PARASITE

Snail, crustacean

Paragonimus westermani

Cyclops, fish

Diphyllobothrium latum

Snail, fish

Clonorchis sinensis

Snail, plant

Fasciola

spp.

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1-Simplelife cycle Cysts predominate in formed stool Is highly resistant to environmental conditions Is killed by boiling, not killed by chlorination of water supplies.Entamoeba histolytica life cycle

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2-Complicated life cycle eg.Trypanosoma, require transmitting vector

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Heterophyidae life cycle, complicated with 2 intermediate hosts

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