Questions and Answers
What are the general biological features of cyst-forming coccidia?
Cyst-forming coccidia have a heteroxenous life cycle requiring one host for sexual reproduction and another for asexual reproduction.
Which of the following genera are discussed in relation to cyst-forming coccidia?
What is the primary feature that differentiates the Family Sarcocystidae from Eimeriidae?
The life cycle is heteroxenous, requiring different hosts for sexual and asexual reproduction.
What is the infective form of Sarcocystis for the final host?
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The majority of clinical cases of Cystoisosporosis are diagnosed in animals less than ______ months old.
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Cystoisospora is a genus that was formerly classified under Sarcocystis.
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Which species of Sarcocystis is most pathogenic in cattle?
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Which of the following are species affecting dogs?
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What is the main clinical sign of Cystoisosporosis in affected animals?
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What clinical sign is NOT associated with a heavy infection of cruzi in calves?
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Which clinical sign reflects the impact of S.tenella infection in lambs?
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Which of the following conditions is NOT a clinical sign of infection caused by cruzi?
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What is a significant clinical effect of heavy infection of S.gigantea in sheep?
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Which clinical sign indicates a severe infection in cattle caused by cruzi?
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Which option does NOT describe a clinical symptom of S.tenella infection in lambs?
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What pathological sign may be observed in cows infected with cruzi?
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What symptom is commonly associated with S.gigantea but NOT with cruzi?
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Which of the following statements about the clinical signs of S.gigantea is FALSE?
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Which of these symptoms is specifically attributed to heavy infections in calves caused by cruzi?
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Study Notes
Lecture Overview
- Focus on cyst-forming coccidia within veterinary entomology.
- Key organisms include Cystoisospora, Sarcocystis, Toxoplasma gondii, Neospora caninum, Besnoitia, and Hammondia.
Family Sarcocystidae
- Life cycle is heteroxenous, requiring two types of vertebrate hosts for sexual and asexual reproduction; final hosts are carnivores, intermediate hosts are typically prey animals.
- Oocysts may sporulate inside the final host or in the environment.
- Sporulated oocysts contain two sporocysts, with four sporozoites in each.
Cystoisospora
- Previously classified under Isospora, now reclassified as a separate genus.
- Lacks Stieda bodies within the sporocyst.
- Common infection route for dogs and cats: ingestion of sporulated oocysts from the environment or through predation.
- Species affecting dogs: C. canis, C. ohioensis, C. burrowsi, C. neorivolta; species affecting cats: C. felis, C. rivolta.
- Usually subclinical, but puppies and kittens (3-8 weeks old) are more susceptible; most clinical cases occur in animals under four months.
- Clinical signs include diarrhea, sometimes bloody in severe cases.
- Diagnosis through fecalysis with sporulation of oocysts for differentiation from Eimeria.
- Recommended treatments include toltrazuril, diclazuril, oral sulfadimethoxine, and trimethoprim-sulfonamide.
Sarcocystis
- Sarcocysts containing bradyzoites develop in striated and cardiac muscles, and occasionally the brain of the intermediate host, serving as the infective form for the final host.
- Two types of cysts: macrocysts and microcysts. Metrocytes are present in immature cysts.
- Oocysts sporulate within the final host, and sporulated oocysts are excreted in feces.
- Intermediate hosts, such as ruminants, pigs, and rodents, are infected by consuming sporocysts.
Pathogenesis of Sarcocystis
- Generally low pathogenicity; infections in final hosts are usually non-pathogenic.
- Pathogenic effects in intermediate hosts arise from tachyzoites and merozoites affecting endothelial cells.
- Intact sarcocysts may release toxins like sarcocystin.
- Pathogenic species for cattle: S. cruzi (bovicanis), causing fever, anemia, lymphadenopathy, diarrhea, and reduced milk yield; severe cases can lead to hemorrhages.
- In sheep, S. tenella is highly pathogenic for lambs, while S. gigantea produces notable macroscopic cysts.
Toxoplasma gondii and Neospora caninum
- Both are important protozoan parasites with significant veterinary implications.
- Understanding their life cycles, pathogenic features, diagnosis, treatment, and control measures is essential for managing infections in various animal species.
Besnoitia and Hammondia
- Additional protozoan parasites of interest; details on life cycles and pathogenesis should be reviewed for comprehensive understanding.
Lecture Overview
- Subject: Veterinary Entomology and Protozoology, focusing on cyst-forming coccidia.
- Key speaker: Dr. Remil L. Galay, DVM, DVSc, Associate Professor.
Lecture Objectives
- Understand biological features of cyst-forming coccidia.
- Explain the life cycles of Cystoisospora, Sarcocystis spp., Toxoplasma gondii, and Neospora caninum.
- Identify pathological features associated with these organisms.
- Discuss different methods for the diagnosis, treatment, and control of infections.
- Explore aspects relating to Besnoitia and Hammondia.
Family Sarcocystidae
- Characterized by heteroxenous life cycles, necessitating two host types for reproduction (sexual in definitive hosts, asexual in intermediate hosts).
- All hosts are vertebrates: definitive hosts typically carnivores, intermediate hosts often prey animals.
- Oocysts can sporulate inside the definitive host or in the environment.
Cystoisospora
- Each sporulated oocyst contains two sporocysts with four sporozoites each.
- Most infections occur in puppies and kittens aged three to eight weeks; clinical cases predominantly seen in animals under four months.
- Clinical signs: diarrhea, sometimes with blood, due to cystoisosporosis.
- Diagnostic method: fecalysis for oocysts, necessitating sporulation for Eimeria differentiation.
- Treatment options: Toltrazuril, diclazuril, oral sulfadimethoxine, and trimethoprim-sulfonamide.
Sarcocystis
- Sarcocysts, containing bradyzoites, primarily develop in striated and cardiac muscles, and sometimes in the brain of intermediate hosts.
- Types of cysts: macrocysts and microcysts; mature cysts may contain rapidly dividing metrocytes.
- Life cycle: Merozoites form sarcocysts in muscles post-schizogony in endothelial cells; sexual reproduction in the intestines of definitive hosts leads to oocyst formation.
- Infection occurs when intermediate hosts ingest sporocysts.
Sarcocystis Pathogenesis
- Generally low pathogenicity for most Sarcocystis spp.; infections in definitive hosts are typically non-pathogenic.
- Pathogenic effects primarily involve tachyzoites and merozoites affecting endothelial cells in intermediate hosts.
- Intact sarcocysts may release an endotoxin known as sarcocystin.
Sarcocystis in Domestic Animals
- S. cruzi (bovicanis) is notably pathogenic for cattle, causing a range of symptoms including fever, anemia, and hypersalivation.
- Heavy infections in calves may lead to petechial hemorrhages and generalized lymphadenopathy.
- In sheep, S. tenella and S. gigantea are significant; S. tenella is highly pathogenic in lambs, and clinical signs include fever and anemia.
- S. gigantea causes rounded macroscopic sarcocysts in the esophagus and tongue.
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Description
Test your knowledge on the Coccidia, focusing specifically on heteroxenous and cyst-forming species. This quiz is designed for students of VPAR 131, Veterinary Entomology and Protozoology, and will challenge your understanding of these important organisms in veterinary science.
