protozoa: 1. protozoa are unicellular (eukaryotic) or acellular organisms which are capable of...

Protozoa:1. Protozoa are unicellular (eukaryotic) or acellular organisms which are capable of performing all the vital functions of life.

2. Protozoan is measured in microns (size vary from 2-150 µ).

3. Cytoplasmic extension in form of pseudopodia, flagellae or cilia are responsible for locomotion.

4. Nucleus may be compact with diffuse chromatin or vesicular with central or eccentric karyosome (DNA) and peripheral chromatin (RNA).

5. Respiration is mostly anaerobic.

6. Secretion: Protozoa secrete digestive enzymes, toxins, cytolysin and antigenic substances.

7. Reproduction: may be asexual or sexual.

Parasitology: (Protozoa and Helminthes)

According to Mode of locomotion, protozoa are classified into the following groups: Class: Rhizopoda: Protozoa move by pseudopodia.

Entamoeba histolyticaClass: Mastigophora: Protozoa move by flagellae.

Gastrointestinal flagellates: Giardia intestinalis

Genitourinary flagellates: Trichomonas vaginalis

Blood and Tissue flagellates: Trypanosoma gambiense, Trypanosoma rhodesiense , and Leishmania species.

Class: Ciliophora: Protozoa move by cilia. Balantidium coliClass: Sporozoa: Protozoa have no motor organelles .

Plasmodium species, and Toxoplasma gondii.

Parasitology: (Protozoa)

Parasitology: (Protozoa)

A world wide in distribution

More often in tropical countries with poor sanitary conditions

A commensal protozoa when human has a normal immune function.

Invading host tissues and causing amoebiasis when human has a lower immune function

Entamoeba histolytica:

Protozoa: Entamoeba histolytica

Trophozoite No regular in shape, 20~60μm in size.

An active-moving trophozoite produce pseudopods (organelle)

A spherical nucleus. Nucleolus in the center.

peripheral chromatin

Erythrophagocytosis

Morphology:-

RBCs


Spherical in shape & 10~20μm in diameter. 1~4 nuclei (similar to that of the trophozoite).

Immature cyst (1 or 2 nuclei) has the glycogen vacuole & chromatoid body.

No inclusions disappear In mature cyst (4 nuclei)

---infective stage

Cyst

Microscopic characteristics of Entamoeba histolytica:



Basic model : cyst trophozoite cyst Parasitic location : large intestine (common) ; intestinal tissue or

other tissues (occasional) Infective stage : mature cyst Trophozoite in diarrhea or pus ; Cyst in formed feces Infection : by ingestion of mature cyst

Pathologic changes

Characteristic of life cycle

Colonic tissues : flask-shaped ulcers The destruction of trophozoites on mucosa may be shallow and small. While they enter the submucosa, they multiply and spread laterally give rise to extensive destruction. Extraintestinal tissues (liver) : abscess --- Anchovy-sauce type pus.


Clinical classification90% persons infected are carriers

Intestinal amoebiasis

Acute intestinal amoebiasis -- amoebic dysentery (bloody, mucus-

containing diarrhea) + lower abdominal discomfort + tenesmus

Chronic intestinal amoebiasis --- dyspepsia + weight loss + asthenia

(common) / diarrhea Extraintestinal amoebiasisLiver : amoebic hepatitis + amoebic liver abscess --- pain in right-

upper-quadrant + fever + marked tenderness of liverLung : amoebic pulmonary abscess --- pain in chest + cough + fever Sometimes,E.h can be carried to other organs. Such as brain, skin and

so on.


Fecal examination--- Wet mounts : Trophozoites in diarrhea feces.--- Wet mounts stained with iodine : Cyst in formed feces. Pus examination--- Trophozoites in aspirate pus from abscesses

Laboratory diagnosis

Protozoa: Giardia intestinalis

Worldwide distribution higher prevalence in tropical or developing countries (20%) 1-6% in temperate countries

Most common protozoa in stools: ~200 million cases/yr Giardiasis: -often asymptomatic OR -acute or chronic diarrhea

Fecal-Oral Transmission Factors Poor personal hygiene: -children (eg, day care centers) - food handlers Developing countries: -poor sanitation - endemic -travelers diarrhea Water-borne epidemics Male homosexuality: oral-anal contact

Giardia intestinalis:-


Trophozoite stage induces malabsorption of fats. Mechanism(s) unknown.

Pathogenesis:

Clinical Disease:Diarrhea (steatorrhea)

Weight loss

Constipation

Fatigue Histopathological correlate: Flattened villi


Diagnosis: Identify trophozoites and cysts by microscopic

examination of stool

Giardia intestinalis trophozoite:

Iron – hematoxylin stain.

Cyst

Protozoa: Trichomonas vaginalis

Worldwide in distribution The most common pathogenic protozoan of human in industrialized countries Transmission is by contact (by sexual intercourse). Sometimes, by indirect

contact, such as sharing damp washclothes / swimming clothes.

Morphology (trophozoite)

Trichomonas vaginalis

•Pear-like (teardrop), 7~32 X 5~12μm •One nucleus and a axostyle projected posterior out of the body.•Undulating membrane on one side (one-third the length of the body).•Basal body on anterior to nucleus and produce 4 anterior flagella and 1 posterior flagellum.

Protozoa: Trichomonas vaginalis

Clinical features : The incubation period is 5~28 days. In women, vaginitis with purulent discharge is prominent symptom, be

accompanied by vulva and cervical lesions, abdominal pain, dysuria. In men, asymptomatic (common) ; urethritis, epididymitis and prostatitis

(occasional)

Laboratory diagnosisMicroscopic examination of wet mounts : detect actively motile organisms.•In women, examination should be performed on vaginal and urethral secretions.•In men, anterior urethral or prostatic secretions should be examined.

African Trypanosomiasis American TrypanosomiasisSleeping sickness Chagas disease Transmitted by tsetse fly Transmitted by kissing bug

Large and aggressive fly Painful bites Triatomid insect

Protozoa: Trypanosoma

Trypanosomiasis: Diseases

Trypanosoma


Local lesion (chagoma, palpebral edema) at the site of inoculation Acute phase (2 -3 months)

Usually asymptomatic Fever, anorexia Lymphadenopathy Mild hepatosplenomegaly Myocarditis

Asymptomatic chronic stage (years- decades) Symptomatic chronic stage

Cardiomyopathy (the most serious manifestation) Megaesophagus Megacolon Weight loss Can be fatal

Chagas disease:


Blood smear Patient antibodies

Indirect fluorescence assay ELISA

Xenodiagnosis To detect low levels of parasitemia Laboratory-raised non-infected vectors (triatomids or kissing

bug) feed on patient Triatomids are later dissected and examined for trypanosoma

via microscopy or PCR

Diagnosis:

Large kinetoplast

Protozoa: Leishmania:

Caused by: L. tropica.

Cutaneous leishmaniasis :

MORPHOLOGYIntracellular parasites..Shape: oval..Length: 2-6μ,, wide 1-3μ..Amastigote and promastigote forms

Promastigote

Amastigote

L.tropica


Sensitive animal Dog,, rat,, cat,, rabbit and guinea pig.. Source of infection: human and above animals.. Transmission: direct and indirect.. Direct transmission: from ulcer Indirect transmission: sand fly.

PATHOGENICITY►Incubation period: 2-5 months..►Primary furuncle (hand,, foot,, face,, neck)►Progress to ulceration or health..►Duration: 6 – 24 months..►Complications: with other microbes produce permanence mark ( one or more )


Diagnosis: Direct diagnosis: Giemza or leishman stain off biopsy or fluid (amastigot form).. Culture off pus or blood..

Balantidium coli:

Protozoa: Balantidium coli:

Morphology:• Shape: oval, measure 50-80μ long and 40-60μ wide• Inferior cytostome and posterior cytopyge• Double nucleus (micro and macro nucleus)• Cilia , vacuole and some RBC• Cyst : oval or circleTransmission -Natural host pigs -Accidental host human.


Pathogenesis:• Cases dysentery• Use intestine tissue , RBC , and bacteria as a food• Mixture: Appendicitis , liver and intestine abscess , intestine ulcer and its perforation.

Diagnosis:- Detection of trophozoit and cystic form of parasites in stool.

B.coli cyst

B.coli trophozoit

Microscopic characteristics of protozoa:


Four species of Plasmodium can infect humans: P. falciparum

P. vivax Hypnozoites in liver cells

P. ovale Relapse

P. malariae

Plasmodium:-

Fatal malaria

Protozoa: Plasmodium:-

Plasmodium: Vector:•Anopheles mosquitoes

430 Anopheles species, only 30-40 transmit malaria (i.e., are "vectors")

•Human malaria is transmitted only by females of the genus•Need blood for the development of eggs


Fever Chills Malaria quartana

3-day cycle P. malariae

Malaria tertiana 2-day cycle P. ovale/vivax (P. falciparum)

Malaria: Symptoms:-

Headache Flu-like symptoms Muscle aches Fatigue AnemiaJaundiceEnlarged spleenEnlarged liver


Malaria: Diagnosis:-Microscopy

RingTrophozoiteSchizontGametocyte

Molecular PCR

Patient antibodies


Plasmodium falciparum: Ring form and gametocyte : The causative agent of Malaria. The Mosquito species of the genus Anopheles.

Helminthes:Helminthes can be classified into the following:

1- Trematodes (flukes): are members of Platyhelminthes.

Trematoda are flattened- leaf shaped non-segmented hermaphrodites except Schistosoma species.

Schistosoma :

Schistosomes are unisexual blood flukes that have worldwide distribution.

Three species arc known to affect man:

1- Schistosoma hematobium: It causes urinary bilharziasis.

2 - Schistosoma mansoni: It causes intestinal bilharziasis.

Parasitology: Helminthes:-

MORPHOLOGY:

Male: 10-20 x I mm with short anterior cylindrical pan

and posterior flattened part which incurved

ventrally to form the gynaeccphoric canal. It has well developed oral and

ventral suckers.

Female: 15-25 x 0.25 mm:, cylindrical, ovary may "be central, anterior

or posterior, uterus may be short

or long containing eggs.


2-CestodaFlattened-segmented Platyhelminthes, hermaphroditic worms (Tapeworm) with body differentiated into:Scolex: 1-2 mm, carries, organ of fixation in the form of suckers or bothria. Neck actively dividing parts which gives rise to segmentsSegments start with immature segments followed by mature segments with well-developed reproductive organs and then by gravid segments with well gravid uterus.


TAENIA WORMS:Two Taenia species are known to affect man:

1- Taenia saginata (beef tapeworm)

2- Taenia solium

(pork tapeworm)


3- Nematoda:Nematodes are cylindrical non-segmented unisexual worms.They have body cavity containing fluids in which organs float. Anal and genital opening are separate in female and united in male (Cloaca). Mouth may be provided with lips, papillae and teeth.

Ascaris lumbricoides : Distribution: worldwide Habitat: Free in small intestine Morphology:

Whitish yellow cylindrical worms: male 15-25 cm x 3 mm with posterior

curved end, female 20 -40 cm x 5mm

with tapering posterior end. it lays around 200000 eggs per day.

Parasitology: Helminthes :-

protozoa: 1. protozoa are unicellular (eukaryotic) or acellular organisms which are capable of...

Documents