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Questions and Answers
What is the primary location of the sexual cycle in the life cycle of Sarcocystis?
What is the primary location of the sexual cycle in the life cycle of Sarcocystis?
Which of the following symptoms is most commonly associated with muscular infection of Sarcocystis?
Which of the following symptoms is most commonly associated with muscular infection of Sarcocystis?
Which preventative measure is recommended to avoid Sarcocystis infection?
Which preventative measure is recommended to avoid Sarcocystis infection?
In which year did more than 100 European tourists experience muscular sarcocystosis while visiting Pulau Tioman?
In which year did more than 100 European tourists experience muscular sarcocystosis while visiting Pulau Tioman?
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What type of infection results from the ingestion of improperly cooked beef or pork containing the sarcocyst?
What type of infection results from the ingestion of improperly cooked beef or pork containing the sarcocyst?
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What is the primary mode of transmission for Isosporiasis in humans?
What is the primary mode of transmission for Isosporiasis in humans?
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Which of the following species is commonly associated with Isosporiasis?
Which of the following species is commonly associated with Isosporiasis?
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What is the primary morphological feature of a sporulated oocyst in Isospora?
What is the primary morphological feature of a sporulated oocyst in Isospora?
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What defines the life cycle of Isospora as homoxenous?
What defines the life cycle of Isospora as homoxenous?
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Which symptoms indicate a clinical illness related to this parasitic infection?
Which symptoms indicate a clinical illness related to this parasitic infection?
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During the asexual reproduction phase of Isospora in the intestinal mucosa, which form is produced?
During the asexual reproduction phase of Isospora in the intestinal mucosa, which form is produced?
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What is the significance of prolonged diarrhea in immunocompromised individuals?
What is the significance of prolonged diarrhea in immunocompromised individuals?
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What happens to the zygote formed during the sexual cycle of Isospora?
What happens to the zygote formed during the sexual cycle of Isospora?
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What is a major characteristic of Isosporiasis infection in most cases?
What is a major characteristic of Isosporiasis infection in most cases?
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Which stain is used to identify the presence of the parasite in smears?
Which stain is used to identify the presence of the parasite in smears?
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In which group of patients is Isosporiasis most frequently observed as a significant health concern?
In which group of patients is Isosporiasis most frequently observed as a significant health concern?
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Which of the following pairs correctly identifies human hosts for Sarcocystis species?
Which of the following pairs correctly identifies human hosts for Sarcocystis species?
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What is the primary method of prevention for infections caused by Sarcocystis species?
What is the primary method of prevention for infections caused by Sarcocystis species?
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Which Sarcocystis species is responsible for muscular sarcocystosis in humans?
Which Sarcocystis species is responsible for muscular sarcocystosis in humans?
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Which characteristic of the diarrhea associated with the infection makes it stand out?
Which characteristic of the diarrhea associated with the infection makes it stand out?
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Which animal acts as an intermediate host for S.hominis?
Which animal acts as an intermediate host for S.hominis?
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What is the primary site of infection for a definitive host when infected with Sarcocystis species?
What is the primary site of infection for a definitive host when infected with Sarcocystis species?
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Which morphological form of Sarcocystis is considered the infective form to the intermediate host?
Which morphological form of Sarcocystis is considered the infective form to the intermediate host?
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In which types of hosts can Sarcocystis be found according to its life cycle?
In which types of hosts can Sarcocystis be found according to its life cycle?
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Where are sarcocysts generally located within the intermediate host?
Where are sarcocysts generally located within the intermediate host?
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What is the main method of infection for the intermediate host with Sarcocystis?
What is the main method of infection for the intermediate host with Sarcocystis?
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What unique characteristic is typical of the sarcocyst morphology?
What unique characteristic is typical of the sarcocyst morphology?
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Which oocyst characteristic is true regarding its structure?
Which oocyst characteristic is true regarding its structure?
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What type of infection occurs in the striated muscles of the intermediate host?
What type of infection occurs in the striated muscles of the intermediate host?
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Study Notes
Isospora and Sarcocystosis
- Isosporiasis: A diarrhoeal disease, a significant cause of diarrhoea in immunocompromised patients, especially those with AIDS. Previously used as an indicator for AIDS.
- Two species exist: Isospora belli (common) and Isospora natalensis.
- Naturally occurring in animals (e.g., dogs).
- Cosmopolitan distribution, but often underdiagnosed.
- Transmission occurs via ingestion of mature oocysts from human or animal sources.
- Spread through contaminated food or water, faecal-oral route.
Morphology of Oocyst
- Sporulated oocysts are oval/elliptical.
- Contains two sporocysts, each with four sporozoites.
- Surrounded by a thin, smooth, two-layered cyst wall.
Life Cycle (Isospora)
- Infection occurs by ingestion of contaminated food or water containing sporulated oocysts.
- Homoxenous (needs only one host).
- Sexual and asexual life cycle stages occur in the intestinal mucosa.
- Immature oocysts are passed in faeces.
Life Cycle (Isospora)
- Infection via ingestion of sporulated oocysts or food/water.
- Sporozoites released from oocysts penetrate intestinal epithelial cells.
- Sporozoites transform into trophozoites which multiply asexually into merozoites.
- Merozoites invade adjacent cells, continuing the asexual cycle.
- Some trophozoites transition to sexual cycle (gametogony) forming macro and microgametocytes in enterocytes.
- Fertilisation results in a zygote, which develops into an immature oocyst.
- Immature oocysts are excreted in faeces.
- Oocysts mature in the environment.
Clinical Features (Isospora)
- Often asymptomatic.
- Symptoms include abdominal discomfort, mild fever, diarrhoea (watery, without blood or pus) and malabsorption.
- Protracted diarrhoea can be seen in immunocompromised individuals (especially HIV-positive).
- Extra-intestinal infections can involve the biliary tract.
Diagnosis (Isospora)
- Stool examination (wet mount, acid-fast stain) for oval oocysts.
- Molecular methods (PCR).
- Histopathology of small bowel tissue sections.
- Fluorescent staining (auramine rhodamine) and autofluorescence (330-380 nm UV).
Treatment and Prevention (Isospora)
- Usually not required for mild cases.
- Cotrimoxazole for severe cases.
- Prevention: good personal hygiene, adequate sanitation.
Sarcocystosis
- Sarcocystosis: A zoonotic parasite that infects a wide range of animals but transmission to humans is relatively rare. More serious in animals.
- Two types; intestinal and muscular.
-
Intestinal Sarcocystosis:
- Caused by S. hominis (cattle) and S. suihominis (pigs).
- Humans are the definitive host.
- Cattle/pigs serve as the intermediate hosts.
-
Muscular Sarcocystosis:
- Caused by S. lindemanni.
- Humans serve as intermediate hosts.
- Dogs/cats are the definitive hosts.
Life Cycle (Sarcocystosis)
- Infection via ingestion of sporulated oocysts in undercooked meat (e.g., beef, pork).
- Obligatory two-host (prey-predator) system for life cycle completion.
- Sexual cycle in the intestine of the carnivorous/predator host.
- Asexual cycle in the muscles and other tissues of the herbivorous/prey host.
- Humans (can be both definitive and intermediate host depending on the species of parasite).
Clinical Features (Sarcocystosis)
- Intestinal Infection: Often asymptomatic or mild (abdominal discomfort, nausea, diarrhoea).
- **Muscular Infection: ** Asymptomatic; painful muscular and subcutaneous inflammatory swellings (various parts of body) and eosinophilia.
Diagnosis (Sarcocystosis)
- Intestinal: Stool microscopy (wet mount) for sporocysts.
- Muscular: Histological examination of muscle biopsy (detect sarcocysts).
- Serum antibodies (Western blot).
Treatment and Prevention (Sarcocystosis)
- No specific treatment.
- Symptomatic relief or cotrimoxazole.
- Prevention: Avoid eating raw or undercooked meat and avoiding contamination of food/water with the feces of affected animals.
Morphology (Sarcocystosis)
- Three forms: Oocysts, Sporocysts, Sarcocysts.
- Oocysts: Found in the intestine of the definitive host . Their sporulation takes place within the lamina propria of the intestinal epithelium. Typical oval and elongated in appearance; a thin-walled structure. It contains 2 elongated sporocysts and each sporocyst contains 4 elongated sporozoites.
- Sporocysts: Released from the oocysts and excreted in feces of the definitive host. They are considered the infective form for intermediate hosts. They are elliptical in shape; oval with a size ranging from 9-16µm. Contains 4 elongated sporozoites.
- Sarcocysts; also referred to as muscle cysts and found in the cardiac and skeletal muscles of the intermediate host. Elongated cysts, found longitudinally along the muscle fibre and covered in a thick cyst wall. They are divided into numerous compartments that contain numerous banana-shaped braduyoites/metrocytes.
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Description
This quiz delves into the details of Isospora, a significant cause of diarrhoea in immunocompromised individuals, particularly those with AIDS. Explore the life cycle, morphology of oocysts, and transmission methods of Isospora belli and Isospora natalensis. Test your knowledge on these important parasitic infections.
