THE APICOMPLEXA (Sporozoa)

Intestinal Coccidia/Sporozoa in Human

Genera:1. Cryptosporidium2. Isospora3. Sarcocystis 4. Cyclospora

= these parasites demonstrate the classic sporozoan

alteration of asexual (schizogonic) and sexual (sporogonic) life cycle

Cryptosporidium

Specie:

Cryptosporidium parvum= only specie recognized recently to cause

human disease

= considered as natural parasite of animal causing

diarrheal diseases= infect variety of mammals, birds and

reptiles = cosmopolitan in distribution = first reported case in Philippines (1985)= associated with intractable diarrhea in

immunocompromised (AIDS) patient

Morphology:

= oocyst round or slightly oval-shaped, 4 –

6um

enclosing 4 spindle–shaped sporozoites

= no sporocyst

= found both in formed/watery stool

= highly resistant to chemicals used to treat

drinking

water (filtration important in water

treatment)

Disease: Cryptosporidiosis

= self – limiting diarrhea seen in healthy people= among immunocompromised individual (AIDS

patient) chronic persistent diarrhea with abdominal

pain, fever, anorexia are commonly seen and can

be life-threatening

= human infection usually waterborne and are acquired

by fecal-oral route= highest prevalence of disease in areas with

unreliable water and food sanitation = extraintestinal infection of the respiratory tract,

biliary tract and pancreas may occur.

= children more commonly infected than adult = clinically, cryptosporidiosis appears much like

giardiasis

L. C.: (both asexual & sexual development occurs in single host)Asexual: ingestion of oocyst intestine release of sporozoite from contaminated food and water with feces of man/animal invade the GIT microvilli

developed into tropozoite

schizont (each mature contains)

8 merozoite merozoite start with another schizogonic cycle schizogony

rapture of schizont

reinvade microvilli of merozoite release intestinal epithelial cell

Sexual: = Gametogenesis and Fertilization of male and female

gametocytes zygote development of oocyst

sporogony 4 sporozoites with in oocyst

passed out in feces

Pathogenesis:= development of the parasite usually occurs in

the brush border of the epithelial cell of the intestine

= intestinal biopsy of the ileum and jejunum reveals

mucosal changes like: 1. atropy of villous2. lengthening of the crypt and flattening of

intestinal epithelium 3. cellular infiltration of the lamina propia

= may also involve the epithelium of stomach, bile duct,

gall bladder and pancreatic duct

Diagnosis:1) Direct exam. of fresh fecal specimen to

demonstrate oocyst2) Microscopy – Modified Acidfast staining

demonstrating the oocyst (red color) in feces,

doudenal aspirates and doudenal biopsy

3) Sheater Sugar Floatation Technique/ Zinc Sulfate Centrifugal Floatation

Technique

Treatment: None - Supportive (Self – limiting)

Prevention:= Environmental and Personal Hygiene = boiling drinking water for 1-3 minutes = filter drinking water with device that can

remove particles 1um and larger

Isospora

Specie: Isospora belli

= intracellular parasite parasitic to human

= once considered a rare parasite

(very similar to Cryptosporidium)

Geog. Dist: Cosmopolitan

= often seen in warm region of the world

especially

N. America, Africa, Southeast Asia, rare –

U.S.

Morphology:= immature oocyst elongate/ovoidal-shape

with moderate constriction in one end giving

a charac. “bottle with short neck”

appearance = contains spherical mass of protoplasm which

divides to form sporoblast= cyst wall smooth, thin, colorless = mature oocyst contains 2 sporocyst and

each contains 4 cresent-shaped sporozoites

Habitat: = intestinal tract probably in the ileum and

cecum

Disease: Isosporosis/Intestinal coccidiosis = infection often symptomatic and self-limiting = charac. by mild gastrointestinal distress with

fever colicky abdominal pain, severe diarrhea, steatorrhea (fatty stool) and weight loss.

= predominantly and infection seen most often in patient with AIDS

= transmitted fecally in contaminated food and drink

with oocyst

Pathogenesis:= jejunal biopsy reveals: villous atrophy in the

intestinal mucosa associated with malabsorption syndrome

Lab. Diagnosis:1) Demonstration of oocyst in feces by

Formalin – Ether Conc.Technique (Unstained or Iodine stained)

2) Modified Acidfast staining of fecal material 3) Sheater Sugar Floatation Tech.

= most sensitive and accurate method to

detect Isospora in feces 4) Duodenal string test (Enterotest)

Treatment: = Combination of Sulfadiazine + Pyrimethamine

(very effective)= Combiantion of Cotrimoxazole (Trimethroprim)

+ Sulfamethoxazole (alternate drug)

Prevention:= Avoid drinking and eating contaminated food.

Genus Sarcocystis

Speices: S. hominis S. Suihominis S. lindemani

= parasite of human and domestic animals: cattle, swine, sheep

Geog. Dist.: Cosmopolitan

Morphology: = oocyst broadly oval or fusiform body with pointed

ends = contains 2 large sporocyst (rainy corpuscles)

inside tubular mass (Meischer tube) filled up with 4 mature cresent-shaped sporozoites

= banana-shape sporocyst with subspherical nucleus are found in the muscle thread extending from end to end

Disease: Sarcocystosis

= disease uncommon and rare in human = generally does not produced clinical symptoms= considered as zoonotic = domestic animals are intermediate host of the

parasite that pick up infective oocyst while grazing on grasses contaminated with human excreta

= human infection are acquired through ingestion of

uncooked meat (beef, pork, lamb) or contaminated

food and drink containing the infective sarcocyst

= clinical manifestation ncludes: diarrhea, nausea, vomiting, abdominal pain

which occurs 1 – 2 days after ingestion and may last

for 2 weeks

Lab. Diagnosis:1. Demonstration of oocyst in feces/duodenal aspirate 2. Biopsy of tissue of small intestine or colon

demonstrate Meischer tube

Treatment:= None for tissue infection (Supportive – self-

limiting) = For intestinal infection:

Trimethoprim + Sulfamethoxazole Pyrimethamine + Sulfadiazine (alternate

drug)

Prevention:= Avoid contact with infected animal host = Adequate cooking of all meat

Cyclospora

Specie: C. cayetanensis

= one of the medically important parasite

recognized today

= infect wide range of vertebrates including

reptiles, insect

and rodents

= established to cause human diarrhea in 1990

= 1st infection in human was diagnosed in 1977

= associated with cases of prolonged watery

diarrhea

among immunocompromised (AIDS) patient

Morphology:= unsporulated oocyst spherical-shaped 8-10um

dia. with greenish central morula containing membrane bound refractile granules, sporulation requires 5 - 10 days

= sporulated/mature oocysts contains 2 sporocyst 4um dia, each with 2 cresent-shaped

sporozoite = under UV illumination cyclospora appears

autofluoresce (bluish green circles)

(Cryptosporidium & Isospora do not fluoresce under UV light)

Sporozoite

Sporocyts

Disease: Cyclosporiasis

= clinically indistinguishable from cryptosporidiosis and

isosporiasis= charac. by a self-limiting persistent watery

diarrhea that tends to recur in a relapsing pattern and

last for 3-4 weeks followed by steatorrhoea

= associated with abdominal cramps, nausea, vomiting,

low grade fever, weight loss & anorexia = incubation is 2 - 11 days = among AIDS patient disease is usually severe

and recurrence rate high

Cyclospora cayetanensis (oocyst)Cyclospora cayetanensis (oocyst)

Pathogenesis:= infection typically is confined to the jejunum= tissue biopsy of the jejunum reveals:

inflammatory changes with villous atrophy and

hyperplasia of the jejunal tissue

Epidemiology:= first case of cyclospora infection was reported in

Papua New Guinea (1979)= subsequent cases has been reported from most

part of the world

= infection caused by cyclospora is acquired by drinking

water from contaminated water tank = outbreak of the disease occurs in Chicago U.S.A.

(1990)

Lab. Diagnosis: 1. Microscopic identification of oocyst in fecal

specimen = demonstrate unsporulated oocyst with

greenish central morula containing 6-9 refractile globules

2. Formalin - Ether Concentration technique 3. Modified Acidfast staining 4. Autofluorescence test

Treatment: Combination of Trimethoprim and

Sulfamethoxazole