protozoa_ intestinal and urogenital protozoa

7/27/2019 Protozoa_ Intestinal and Urogenital Protozoa

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OUTLINEPROTOZOA

General Introduction to protozoa

DefinitionDiversity and Medical importance of protozoa

General morphology protozoa

Size, Shape etc

Cellular structure and organization Basic properties

Locomotion

Reproduction

Feeding, Metabolism, Excretion and Encystment Classification

General characteristics of the five main groups


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What are

Protozoa?


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What are Protozoa?

proto = first

zoa = animals

=single-celled eukaryotic organisms=kingdom Protista

=Vary in size (3-2000 mm).


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=Unknown until the invention of the microscope in 1675

=First recognized by antony van leewenhoek in 1676

= He describe it as little animal or animacula

What.?


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=protozoa are extremely diverseorganisms and found in a variety ofniches

=>200,000 named species

= Most species are free-living in

= Freshwater= marine environments= decaying organic matter and soil=Some are beneficial to mankind by:

= being part of the food chain

= serving as experimental subjects.

Protozoan diversity


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= Few are adapted to a parasitic life butall plant and animal species have atleast one protozoan parasite

= ~10,000 are parasites in a wide range of hosts= Vertebrate= invertebrate

= Plants=~20 human pathogens= Adapted to life in a wide range of sites within the

host

Protozoan Diversity


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Ecological Niches in the Human Body:

Skin: Leishmania

Eye: Acanthamoeba

Mouth: Amoebae and flagellates (usually non-

pathogenic)

Gut: Giardia, Entamoeba (and invasion to liver),

Cryptosporidium, Isospora, Balantidium

G.U. tract: Trichomonas


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Ecological.

Bloodstream: Plasmodium, Trypanosoma

Spleen: Leishmania

Liver: Leishmania, Entamoeba

Muscle: Trypanosoma cruzi

CNS: Trypanosoma, Naegleria, Toxoplasma,

Plasmodium


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Importance of protozoa

Medical importance

Cause of more sickness and death, than any other

disease-causing organisms

reduced working capacity

Loss of productivity


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Veterinary importance Loss of productivity

Death

reduced meat and milk production,

reduced reproductive potential

reduced working capacity

Potential losses


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Protozoa

..eukaryote..has genetic materialencased in a nuclear membrane (unlike

bacteria and Viruses)

..Classified traditionally by:morphology(eg. organelles of

locomotion)

life cycle

mechanisms of reproduction etc.


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Taxonomy of Protozoan

Subkingdom Protozoa

Phylum Sarcomastigophora Subphylum Sarcodina

Ex. Entamoeba

Subphylum Mastigophora Ex. Giardia

Leishmania

Trypanosoma

Phylum Apicomplexa Ex Plasmodia (malaria) Toxoplasma gondii

Phylum Ciliophora Balantidium


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Mastigophora: movement with flagella

- e.g. Trichomonas, Giardia

Sarcodina: pseudopodia

e.g. Entamoeba histolytica

Apicomplexa: apical complex, nolocomotor apparatus

e.g. cryptosporidium, malaria, toxoplasma

Ciliophora: movement with cilia

e.g. Balantidium.


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Terms in protozoans

Trophozoite: any stage in a protozoans life cyclewhich can ingest food. In practice also refers to themotile form.

Cyst: the non motile form which is protected by a

distinct membrane or cyst wall. This is an infectivestage of the parasite.

Excystation: the process of emergence of thetrophozoite from the cyst (vs. encystation)

Pseudopod: literally means false foot; temporarycytoplasmic processes at the surface of thetrophozoite


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8/22/2013 Further reading 15


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Unlike their friend they do not lyse host tissue! Feed onbacteria, protozoa, yeasts and occasionally blood cells if available

VERY important to diagnose infection correctly or patient will

undergo unnecessary drug treatment


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Symptoms/Pathogenesis:Virulence factors: lectin, cysteine protease &

amoebaphore

The 1st stage invasive starts when adhesion to colonicmucins via parasite surface Gal/GalNAc lictin

The hallmark of amoebiais include:degradation extracellular matrix by amebicproteaseproduction of toxic factorsactivation of host cells from host immune systemkilling & phogocytosis human cells

E. histolyticainduces apoptosis and phagocytosis of thehuman target cells


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Persisting fever

Rarely diarrhea


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MECHANISMS OF CYTOTOXICITY

At least 5 mechanisms have been advanced to explain the pathogenicity of

virulent strains ofEntamoeba.

Hallmarks of amoebiasis include: degradation of the extracellular matrix (ECM)by amoebic proteases, production of toxic factors, activation of cells from thehost immune system, killing and phagocytosis of human cells,

1. Direct contacts with the host tissues.Example: adherence to the host cell by the release of adhesin molecules.

2. Release of soluble toxic metabolites.Example: amoebapore are capable of forming a hole in a target cell.

3. High enzymatic activities of the amoebasExample: enzymes released by the parasite damaging the host cell. .4. Interfering with the immune response of the host. Example: Antigensreleased by the amoeba cell can lead to:

inflammatory reaction allergies Immunodepression over stimulation of cytokines

formation of immune complexes formation of autoantibodies

5. E. histolytica induces apoptosis of the host cells during tissue invasion


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E. histolytica vs E. dispar

Brumpt 1949, proposed to establish a newspecies ofEntamoeba amoebae that are notpathogenic.

In 1993, it was decided that the invasionform will be called called E. histolytica.

The non-invasive invasive form will be calledE. dispar.

The 2 amoebae cant be distinguished bymicroscopic observation.


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Phylum: Sarcomastigophora

Flagellates Amebas

Giardia, Trichomonas Entamoeba Early-diverging Eukaryotes

Facultative Anaerobes

Carbohydrate metabolism is anaerobic

Lack mitochondria Extracellular parasites

Do not invade host cells

Adhere to plasma membrane of host cells

Contact-dependent cytotoxicity

Mechanical damage to host tissues

Replicate and divide within the host by binary fission

All are killed by treatment with Metronidazole, a drug that

selectively kills anaerobic cells


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GIARDIASISInfection with the protozoan parasite Giardia lamblia

Giardia duodenalis most common name

used. G. intestinales and G. lamblia are

also used.

Giardia spp. can parasitize the intestinal

tract of a wide range of vertebrates,

including humans.

Disease is prevalent in children attendingday care centers.

In addition the domestic dog and certain

wild animals serve as hosts.

Most common protozoan disease in the

United States.The distribution is cosmopolitan.

Transmission ofGiardia is predominantly

by ingestion of food or water

contaminated with cyst


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EPIDEMIOLOGY

Worldwide distribution

Common in areas with poor sanitary conditions

Seasonal with peak during late summer in UK, USA

and Mexico

Prevalence: 2-5% in industrialized countries

20-30% in developing countriesTravelers, hikers, campers are at risk. Swallowing

water while swimming, drinking tap water, eating

lettuce.

Risk groups in the US: travelers, children in daycares and homosexual men


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TRANSMISSION

Reservoir-human and possibly other

mammals (zoonotic?)

Infective cysts in feces: 10-25 cysts sufficient

Fecal contamination of water Feces for fertilizer

Defective piping

Flies Soiled hands


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CLINICAL FEATURES

Incubation period : 1-2 weeks

Majority of infected individual are asymptomatic

SYMPTOMS:

Diarrhea with loose, foul-smelling stools

FlatulenceAbdominal cramps and bloating

Nausea

Anorexia

MalaiseWeight loss

Prolonged symptoms

Malabsorption

DIAGNOSIS


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DIAGNOSIS

Identification of cysts or trophozoites in fecal

specimens

May need to be repeated Detection ofGiardia antigens in feces.

Serodiagnosis is not useful

TREATMENTMetronidazole:

Quinacrine-

Tinidazole-

Furazolidone- approved by the FDA for giardiasisParanomycin- used for pregnant women

Nitazoxanide: recently approved for giardiasis and

cryptosporidosis in children

T i h i i


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Trichomoniasis

Trichomonas


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Trichomonas

Life cycle of T vaginalis


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Life cycle of T. vaginalis


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Morphology ofT. vaginalis


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Epidemiology T. vaginalis

Clinical symptoms T vaginalis


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Clinical symptoms T. vaginalis


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22 August 2013 53Yellow vaginal discharge due to T. vagin alis

Treatment of Trichomoniasis


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Treatment of Trichomoniasis

I t ti l idi


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Intestinal coccidianCryptosporidium,Isospora,Cyclospora

General characteristics

Considered as opportunistic parasite in

immunocompromissed person

Complete entire life cycle in single host

Within the intestinal epithelial cells

of the host

Characterized by a thick walled oocyst

excreted in feces

Are transmitted by the fecal-oral route

Cryptosporidium


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Cryptosporidium

Species:

C. parvumA coccidean parasite implicated in intestinal Disease primarily among immune-compromised patient

1985 first reported case in philippines associated with

intractable diarrhea in immune-compromised (AIDS)patient

Self-limiting diarrhea in immuno-competent persons

Profuse, watery diarrhea associated with AIDS (life

threatening)


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1976 considered as natural parasite of animal especially

calves causing diarrheal diseases

Infect wide range of animal hosts (fish-humans)

C. hominis & C. parvumare species mostly causing

disease in humans

C. hominisinfects only humans but C. parvumalso

infects many other mammals

C. felis, C. meleagridis, C. canis, and C. murisinfections have also been reported


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Geog. Dist.: = Worldwide distribution

Morphology: = oocyst round or slightly oval-shaped,


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Transmission

Mainly through the ingestion and possibly inhalation ofsporulated oocysts

mainly through contaminated water &

Occasionally food sources, such as chicken salad

fecal-oral transmission (monoxenous)

anthroponotic transmission

autoinfection

zoonotic transmission


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Waterborne Cryptosporidiosis

human infection usually waterborne and acquired by

fecal-oral route

highest prevalence of disease in areas with unreliable

water and food sanitation

Factors Favoring


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Factors FavoringWaterborne Cryptosporidiosis

Small size of oocysts (4-5 mm)

Reduced host specificity and monoxenous development

Close associations between human and animal hosts

Large number of oocysts excreted (up to 100 billion per calf per day)

Low infective dose (


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Disease: Cryptosporidiosis

= human infection usually waterborne and acquired by

fecal-oral route= highest prevalence of disease in areas with unreliable water and foodsanitation= extraintestinal infection of the respiratory tract, biliary

tract and pancreas may occur.


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Clinical Features

Varry from asymptomatic to severe, life-threatening

illness; infection usually self-limiting diarrhea of 1-2 weeks

duration charactrized by copious watery diarrhea,

vomiting, intense abdominal pain, anorexia and

weakness

among immunocompromised patient (AIDS) develops

severe chronic diarrhea which may last for months

malabsorption

Cyclospora


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y p

Specie: C. cayetanensis

= was established to cause human diarrhea in 1990

=1986 cases of prolonged watery diarrhea among

immunocompromised (AIDS) patient has been reported

worldwide

=Species Name C.Cayetanensiswas given in 1993

=Initially called cyano-bacteria like body (CLB) or large cryptosporidium


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Epidemiology:

= More common in tropical and sub-tropical areas

= case of cyclospora infection was reported in

papua, new guinea= Subsequent cases has been reported from most

part of the world


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Epidemology

= Infection caused by cyclospora can be acquired by

drinking contaminated water (fecal-oral)

=

More associated with food-borne outbreaks ( socialevents, weddings, etc)

= Parasite infect vertebrates including reptiles, insect

& rodents


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Disease:Cyclosporiasis

= disease is clinically indistinguishable from

cryptosporidiosis and Isosporiasis

= self-limiting, characterized by persistent watery diarrhea

that ends to recur in a relapsing pattern and last for

3-4 wks,

= associated with abdominal cramps, nausea, vomiting,

low grade fever, weight loss and anorexia

Clinical Features


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Isospora

Specie:Isospora belliEpidemiology

wide geographical distribution (higher prevalence in warmer

climates)

the least common of the three intestinal coccidia that infecthumans

transmitted through intake of fecally contaminated food and

drink with oocyst

Cli i l f t


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Clinical feature Disease: Isosporosis/Intestinal coccidiosis

often asymptomatic (seldom reported)

symptoms range from mild gastro-intestinal distress

to severe dysentery

mild self-limiting infection charac. by fever, colicky

abdominal pain, severe diarrhea, steatorrhea (fatty

stool) and weight loss.

often self-limiting, but can become chronic (wasting,

anorexia)

symptoms more severe in AIDS patients


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Pathology

intracellular development occurs in the intestinal

mucosa mucosal atrophy

chronic diarrhea (months to years) abdominal

discomfort, low grade fever

Intestinal Coccidia


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Intestinal CoccidiaTreatment paromomycin for Cryptosporidium

modest benefit lowers parasitemia in AIDS

trimethoprim-sulfamethoxazole for Cyclosporaand Isospora

l d


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Intestinal coccidian

Summary are opportunistic parasite in

immunocompromissed person

Have both sexual and asexual reproduction

Require single host to comlete their entire life cycle characterized by a thick walled oocyst excreted in

faeces

Are transmitted by the fecal-oral route

Laboratory diagnosis is by finding the oocyst infaeces


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Intestinal Coccidia- Summary

Got medical attention after the emergence of HIV/AIDS

Fecal-oral or contaminated food and water are means oftransmission

Simple lifecycle and reproduce Sexually and asexually

infection leads to acute, watery diarrhea; self limiting in

immunocompetent individuals but significant, chronicillness in the immunosuppressed may occur

characterized by a thick walled oocyst excreted infaeces

oocyst stage :Infective and diagnostic stage

Laboratory dx; finding oocyct in stool specimen

protozoa_ intestinal and urogenital protozoa

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