Sarcocystosis

Essentials of Diagnosis

• Acute diarrhea, especially in children in developing countries

• Outbreaks of diarrhea secondary to contaminated water or food

• Prolonged diarrhea in immunocompromised persons

• Diagnosis mostly by identifying organisms in specially stained stool specimens

General Considerations

• Causes of coccidiosis

  • Cryptosporidium spp, particularly C parvum and C hominis

  • Isospora belli

  • Cyclospora cayetanensis

  • Sarcocystis species

• Sarcocystis infects many species

• Humans are intermediate hosts (infected by ingestion of fecal sporocysts) for some species

• Humans are definitive hosts for Sarcocystis bovihominis and Sarcocystis suihominis (infected by ingestion of tissue cysts in undercooked beef and pork, respectively)

Demographics

• Occurs worldwide, particularly in tropics and in regions where hygiene is poor

• Clustering of cases occurs in households, day care centers, and among sexual partners

Symptoms and Signs

• Usually asymptomatic

• Gastrointestinal symptoms (eg, diarrhea)

• Cysts in muscle may cause

  • Myalgias

  • Fever

  • Bronchospasm

  • Pruritic rash

  • Lymphadenopathy

  • Subcutaneous nodules

Differential Diagnosis

• Infections caused by I belli, C cayetanensis, and Cryptosporidium species

• Giardiasis

• Viral gastroenteritis, eg, rotavirus

• Other traveler's diarrhea, eg, Escherichia coli

• Cryptosporidiosis

• Other causes of diarrhea in AIDS, eg, cytomegalovirus colitis

• Trichinosis

• Eosinophilia

• Elevated creatine kinase

• Diagnosis is by identification of acid-fast organisms in stool or by identification of trophozoites or bradyzoites in tissue biopsies

• No specific treatment is established

• Patients may respond to albendazole or trimethoprim-sulfamethoxazole

Prevention

• Water purification

• Immunocompromised patients should boil or filter drinking water and should consider avoidance of lakes and swimming pools

• Routine precautions (handwashing, gloves, disinfection) should prevent institutional patient-to-patient spread