1. Cystoisospora 2. Cyclospora 3. Cryptosporidium 4. Toxoplasma 5. Sarcocystis

MIDTERM: COCCIDIANS Flashcards by Sunwoo's Berry

 Phylum Apicomplexa (The coccidian parasites are
the LARGEST GROUP of apicomplexan protozoa falling under Class Conoidasida.)
 Spore forming, microscopic, single-celled parasites
(withstand extreme conditions of starvation, acidity,
temperature, and desiccation by producing resistant
forms called “spores.”)
 OBLIGATE INTRACELLULAR (which means they strictly need host cell in order to reproduce)
 Intracellular parasites are microparasites that are
capable of growing and reproducing inside the
cells of a host.
 Order Eucoccidiorida Suborder
Eimeriorina

COCCIDIANS

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MEMBERS

Cystoisospora
Cyclospora
Cryptosporidium
Toxoplasma
Sarcocystis

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ALL MEMBERS OF COCCIDIANS ARE HOST SPECIFIC EXCEPT for?

Toxoplasma gondii

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3 sequential stages:

SPOROGONY
SCHIZOGONY/MEROGONY
GAMETOGONY

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produces oocysts containing trophozoite

Sexual or Sporogony

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production of merozoites (meronts)

Asexual or Schizogony or Merogony

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Development of micro (male), macro (female)
gametocytes (gamonts)

Gametogony

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a dormant stage of protozoa which facilitates the
survival during unfavourable environmental conditions

CYST

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reproductive cell): Present in the life cycle of protozoa which contains a zygote within it. A reproductive structure that is formed by a protozoa to aid in transmission to a new host.

OOCYST

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a nucleated and long asexual stage of coccidians.

MEROZOITES (MERONTS)

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motile, spore-like stage in the life cycle of
a protozoan

SPOROZOITES

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activated, feeding stage in the life cycle of
protozoan parasite

TROPHOZOITES

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a cell that divides by schizogony to form daughter
cells; multinucleate sporozoan that reproduces by schizogony.

SCHIZONT

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 all stages of development completed in
gastrointestinal tract
 found mainly in humans
 causes CRYPTOSPORIDOSIS
 oocysts found in the human and animal feces
 attach to epithelial cells:
- outside cytoplasm (within brush
borders)
- located intracellular but
extracytoplasmic
 Mode of transmission: WATERBORNE (common)

Cryptosporidium hominis

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Only specie that infect mammals is the __________
MOT: zoonotic and anthroponotic

Cryptosporidium parvum

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 roundish (4 to 6 Um)
 contains 4 sporozoites present in feces
o Turns to small trophozoite then divided
by schizogony producing merozoites
(micro and macrogamete)

Cryptosporidium hominis OOCYST

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Cryptosporidium hominis OOCYST Merozoite type 1 contains how many nuclei?

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Cryptosporidium hominis OOCYST Merozoite type 2 contains how many nuclei?

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o Burst inside the small intestine and releases
sporozoite
o INTERNAL AUTOINFECTION

Cryptosporidium hominis OOCYST THIN - WALLED

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o 1-6 dark granules may be viable
o Passed in the feces
o EXTERNAL AUTOINFECTION

Cryptosporidium hominis OOCYST THICK - WALLED

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INFECTIVE STAGE OF Cryptosporidium hominis

OOCYST

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CLINICAL MANIFESTATION
 SELF - LIMITED DIARRHEA lasting for 2 to 3
weeks
 Other manifestation: abdominal pain, anorexia, fever, nausea, and weight loss

CRYPTOSPORIDIOSIS on Immunocompetent Host

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CLINICAL MANIFESTATION
 MORE SEVERE DIARRHEA, progressive and may become life threatening
 Acute and Gangrenous cholecystitis
 Dyspnea, chronic cough, bronchiolitis, pneumonia
 Blunted intestinal Villi: malabsorption and excessive fluid loss

CRYPTOSPORIDIOSIS on Immunocompromised Host

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Commonly used technique to detect oocyst in Cryptosporidium hominis

A. Acid-fast staining
B. Sheather’s sugar flotation
C. Kinyoun’s modified acid fast stain
D. Formalin ether/acetyl concentration test (FECT)

B & D
- Sheather’s sugar flotation
- Formalin ether/acetyl concentration test (FECT)

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Cryptosporidium hominis DIAGNOSIS - Routinely used with the oocysts (appear as RED PINK) - appearing red-pink doughnut-shaped circular organisms in blue background A. Acid-fast staining B. Sheather’s sugar flotation C. Kinyoun’s modified acid fast stain D. Formalin ether/acetyl concentration test (FECT)

C. Kinyoun’s modified acid fast stain

Cryptosporidium hominis DIAGNOSIS - probably the quickest and cheapest method of diagnosis A. Acid-fast staining B. Sheather’s sugar flotation C. Kinyoun’s modified acid fast stain D. Formalin ether/acetyl concentration test (FECT)

A Acid-fast staining

Cryptosporidium hominis treatment that is reported effective in preliminary/clinical trials

Nitazoxanide

Used to treat severe diarrhea

o Bovine colostrum o Paromomycin o Clarithromycin * Azithromycin

 Causes CYCLOSPORIASIS  originally called a CYANOBACTERIUM-LIKE body (CLB)  Showed organelle that undergoes photosynthesis and autofluorescence.  Acid-fast variable resembling “wrinkled cellophane-unstained”  invades the epithelial cells of the small intestines o site of predilection: jejunum  MODE OF TRANSMISSION: Ingestion of sporulated oocyst

Cyclospora cayetanensis

 7 – 10 um in diameter  Ingestion, contains two sporocysts with two sporozoites each then invades the small intestine  Multiple fissions of these sporozoites take place inside the cells to produce meronts

Cyclospora cayetanensis OOCYTS

Cyclospora cayetanensis OOCYST First generation contains how many merozoites?

8 - 12

Cyclospora cayetanensis OOCYST second generation contains how many merozoites?

only 4

infective stage of Cyclospora cayetanensis

Cyclospora cayetanensis SPORULATED OOCYST/OOCYTE

Cyclospora cayetanensis OOCYST undergo complete sporulation within ____ days in a _____ environment.

7 to 12 , warm

malaise, low grade fever (12-24 hours post exposure)

Initial Symptoms

proximal small intestine malabsorption

D-xylose malabsorption

Cyclospora cayetanensis DIAGNOSIS: Recommended diagnostic test?

Direct microscopic examination (HPO) of DFS

Cyclospora cayetanensis DIAGNOSIS: - Differentiates Cyclospora from Eimeria spp.

Polymerase chain reaction

Cyclospora cayetanensis other diagnostic test:

 Acid fast staining (Kinyoun's stain)  Oocyst: auto fluorescent o Fluorescent microscopy: blue or green circles  Safranin staining and microwave heating

treatment for CYCLOSPORIASIS

Trimethoprim-sulfamethoxazole o 160/800 mg twice daily for 7 days

- causes Cystoisosporiasis - Humans are the only host - sporulated oocysts contains 2 sporocysts each containing 4 sporozoites - Sporulation usually occurs within 48 hours after passage with the stool. - Habitat: small intestine - MODE OF TRANSMISSION: Ingestion of a MATURE OOCYST

Cystoisospora belli

- 25 -35um long, 10 – 15 um wide; TRANSPARENT; oval; - cell wall is 2 layered, colorless and smooth - developing sporoblast is unicellular with granular cytoplasm

Cystoisospora belli OOCYST

o is elongated and ovoidal (20-33u x 10-19u) o Has 2 sporoblast

Cystoisospora belli IMMATURE OOCYST

 2 sporocysts with 4 long and slender (sausage shaped) sporozoites each  Total of 8 sporozoites

Cystoisospora belli MATURE SPORULATED OOCYST

Cystoisosporiasis is more common on ____and ____________________

children,immunocompromised patients

o Generally ASYMPTOMATIC or self-limiting gastroenteritis o Stools contain undigested food, mucus, and Charcot-Leyden crystals IMMUNOCOMPETENT OR IMMUNOCOMPROMISED?

IMMUNOCOMPETENT

o Self-limiting enteritis to severe diarrheal illness o Mucosal bowel biopsy may reveal flattened mucosa and damaged villi IMMUNOCOMPETENT OR IMMUNOCOMPROMISED?

IMMUNOCOMPROMISED

Prolonged Mild diarrhea, Abdominal pain may lead to _________ with weight loss

Malabsorption syndrome

Oocysts of C. belli may be detected in feces through:

Direct microscopy/FECT

Other concentration:

Zinc sulphate, Sugar floatation, Enterotest

oocysts can be seen in a fecal smear stained by a _________________ (granular red color against a green background)

Modified Ziehl-Neelsen method

Help visualize the organism:

o Phenol-auramine o iodine staining

FOR BLOOD EXAMINATION?

peripheral eosinophilia

Asymptomatic infections:

bed rest and bland diet

Symptomatic infections:  For AIDS patient

- Trimethoprim- sulfamethoxazole 160/800 mg (4/day for 10 day) then (2/day for 3 weeks) - Combination therapy with pyrimethamine and sulfadiazine for 7 weeks

- coccidian that belongs to the Phylum Apicomplexa - has worldwide distribution - causes TOXOPLASMOSIS, CONGENITAL TOXOPLASMOSIS, CEREBRAL TOXOPLASMOSIS - Infects humans and many species of animals.  Hosts: - Definitive host: Cat family (Felidae) - Intermediate host: other animal like mouse, bird, rodents, pigs, cows, sheep - Accidental host: Humans

Toxoplasma gondii

infective stages of Toxoplasma gondii

- Sporulated oocyst - Encysted bradyzoites - Motile tachyzoites

Toxoplasma gondii unsporulated oocyst undergo sporulation for how many days?

3 - 4 days

Toxoplasma gondii mot for accidental host (human)

- Consuming contaminated food or water - eating raw/undercooked meat - blood transfusion - trans placental infection - transplantation

Diagnostic specimens and stages of Toxoplasma gondii

- Tissue biopsy showing encysted bradyzoites - Blood smear showing tachyzoites - Serum or CSF for serologic testing

FORMS OF Toxoplasma gondii - Found in the stool of definitive host - ovoidal, thin wall - 10 - 13 um by 9 to 11 um - Contain 2 sporocysts, each sporocysts contains 4 sporozoites

Toxoplasma gondii OOCYST

FORMS OF Toxoplasma gondii - ACTIVELY multiplying morphologic form - 3-7 um x 2-4 um - Crescent – shaped, often more rounded on one end - Single central nucleus - Contains a variety of organelles that are not readily visible - found during the initial and acute stage of the infection

Toxoplasma gondii TACHYZOITE

FORMS OF Toxoplasma gondii - SLOW-GROWING morphologic form - Smaller than tachyzoites, appearance is similar to that of the tachyzoites - single nucleus is located posteriorly - Hundreds or thousands of bradyzoites enclosed themselves to form a cyst that may measure 12-100 um in diameter

Toxoplasma gondii BRADYZOITE

CLINICAL MANIFESTATION of Toxoplasma gondii o commonly asymptomatic as long as the immune system of the patient is functioning well. o recognized as an important disease associated with AIDS.

TOXOPLASMOSIS

CLINICAL MANIFESTATION of Toxoplasma gondii - most common manifestation among the immunocompromised patients

Encephalitis:

DIAGNOSTIC TEST used to detect antibodies against T. gondii (positive titer or a four-fold increase in titers)

Serodiagnostic methods:

very sensitive and specific but it requires the maintenance of live organisms in the laboratory

Sabin-Feldman methylene blue dye test

o successfully used in the diagnosis of toxoplasmosis o Samples taken: serum, amniotic fluid, cerebrospinal fluid, and bronchoalveolar lavage

Polymerase chain reaction

Used in combination for 1 MONTH, keeps Toxoplasma under control but DO NOT KILL IT:

PYRIMETHAMINE (25 – 100 mg daily) and SULFADIAZINE (1 – 1.5 g 4 times daily)

o can lower blood counts o given together with leucovorin (folic acid)

Pyrimethamine

o cause serious allergic reactions like fever and rash o can be substituted with clindamycin

Sulfadiazine

given to prevent occurrence of hypersensitivity reactions

Corticosteroids

given for the immunocompromised:

Prophylaxis with trimethoprim-sulfamethoxazole

- Causes Sarcosporidiosis or Sarcocystosis - Definitive host: Humans  Intermediate host: cattle (S. hominis) and pigs (S. suihominis)

Sarcocystis spp.

- Oval, transparent o Contains 2 sporocysts (10-18 um long) - Each sporocysts contains 4 sausage-shaped sporozoites - Cell wall: Clear, colorless, double-layered

Sarcocystis spp. MATURE OOCYST

o first reported this parasite in 1843 o described it as a white thread like cyst in striated muscles of a house mouse

Miescher

Sarcocystis spp. referred to as ________ until 1899

Miescher’s tubules

Sarcocystis spp. 1st proposed name:

Sarcocystis miescheriana

Sarcocystis spp. Infective Stage:

OOCYST or FREE SPOROCYST (sarcocyst containing bradyzoites)

Sarcocystis spp. MOT?

consumption of uncooked or undercooked meat of intermediate host that contains sarcocysts

Sarcocystis spp. in the PHIL. - in backyard cattles, has type 7 sarcocyst wall

S. cruzi

Sarcocystis spp. in the PHIL. - in water buffaloes, has type 7 sarcocyst wall, with similarities to S. cruzi

S. levinei

Sarcocystis spp. in the PHIL. - in domestic pigs, has type 10 sarcocyst wall

S. miescherenia

Sarcocystis spp. in the PHIL. - in domestic goats, has type 14 sarcocyst wall

S. capracanis

* Simplest form of Sarcocystis * Banana-shaped cell * Has a pointed anterior end * Hosts: pigs, ducks, birds

Sarcocystis spp. ZOITE

* Size: 15-19um by 8-10um * Contains 4 sporozoites and a discrete refractile residual body * Capable of surviving on the ground and infecting intermediate hosts

Sarcocystis spp. SPOROCYSTS

CLINICAL MANIFESTATION OF Sarcocystis spp. o presents with vasculitis and myositis o involve a wide variety of tissues (lymph nodes, muscles, and the larynx)

Rare Invasive Form

CLINICAL MANIFESTATION OF Sarcocystis spp. o presents with nausea, abdominal pain, and diarrhea o normally mild and lasting under 48 hours o occasionally be severe or even life threatening

Intestinal form

DIAGNOSIS OF Sarcocystis spp.

- Fecal floatation wet mount - Biopsy of an infected muscle