3rd

• Coccidian Parasites


  Microscopic, spore-forming, single-celled obligate intracellular parasites of phylum Apicomplexa

  
• Coccidian Parasites

  • Defining characteristic: Apical Complex (Apicoplast)
  • No locomotory organelle
  • Sporulation: non-infective to infective oocyst development
  • Reproduction: alternating asexual and sexual phases

  
• Reproduction - Life Cycle of Coccidian Parasites

  1. Sporulation (Sporogony)

  2. Merogony (Schizogony)

  3. Gametogony (Gamogony)

  
• Sporulation (Sporogony)


  Produce sporulated oocyst, Release sporozoites

  
• Merogony (Schizogony)


  Produce meront / schizont, Release merozoites
• Gametogony (Gamogony)


  Produce gamonts (microgametocyte and macrogametocyte), Release unsporulated oocyst
• Intestinal Coccidian Parasites

  • Cryptosporidium spp.
  • Cyclospora cayetanensis
  • Cystoisospora belli

  
• Cryptosporidium spp.


  Intracellular location: epithelial cells (enterocytes) of small intestinal lining

  
• Cryptosporidium spp.


  • Common name - Crypto
  • Infects a wide range of vertebrate hosts, including birds, reptiles, and mammals
  • Zoonotic and Non-Zoonotic Cryptosporidium spp.
  • Cryptosporidium hominis and Cryptosporidium parvum

  
• Cryptosporidium spp. Oocyst


  • 4.2 - 5.4 um in diameter
  • Spherical or oval in shaped
  • Contains 4 sporozoites
  • Sexual and Asexual Reproduction
  • Highly resilient and can survive for long periods in the environment

  
• Cryptosporidium spp. Life Cycle


  1. Infective Stage: Thick-walled oocyst

  2. Definitive Host: Vertebrate hosts, including birds, reptiles, and mammals

  3. Mode of Transmission: Mouth/Ingestion

  4. Source of Infection: Ingestion of fecally contaminated water or Direct contact with infected animal or human

  5. 2 Life Cycle Stages: Asexual and Sexual Reproduction

  
• Cryptosporidiosis


  • Symptoms show: 2-10 days (average 7 days) after infection
  • Symptoms last: 1-2 weeks
  • May also affect other areas of the digestive tract or the respiratory tract

  
• Cryptosporidiosis Easy Targets

  • Young children
  • Immunocompromised patients
• Cryptosporidiosis Diagnosis Methods

  • Microscopic Techniques (Acid-fast Staining, Direct Fluorescent Antibody, Immunofluorescence Microscopy, Enzyme Immunoassays)
  • Molecular Method (Polymerase Chain Reaction)
• Cryptosporidiosis Treatment

  • Patients may recover without treatment
  • Nitazoxanide (Adult: 500 mg, BID (3 days); Children 1-3 years: 100 mg, BID (3 days); Children 4-11 years: 200 mg, BID (3 days))
  • Fluid Replacement Therapy
  • For immunocompromised patients, antiretroviral therapy will decrease symptoms
• Cryptosporidiosis Prevention & Control

  • Stay out of the water if you are sick with diarrhea
  • Don't swallow the water
  • Take kids on bathroom breaks
  • Wash your hands
  • Water, Sanitation, Hygiene, and Education (WASH-E)
• Cystoisospora belli

  • Formerly known as Isospora belli
  • Only species belongs to genus Cystoisospora that can infect humans
  • Least common to infect humans

  
• Cystoisospora belli Oocyst

  • 25 to 30 µm by 10-19 µm
  • Oval or Ellipsoidal in shape
  • Two types: Immature Oocyst (contains one or two sporoblast), Mature Oocyst (Sporulated, contains 2 sporocyst that has 4 sporozoites inside)

  
• Cystoisospora belli Life Cycle

  1. Diagnostic Stage: Immature Oocyst

  2. Infective Stage: Mature Oocyst

  3. Definitive Host: Humans

  4. Mode of Transmission: Mouth/Ingestion (Fecal-Oral Route)

  5. Source of Infection: Contaminated food and water with mature sporulated oocyst

  6. 2 Life Cycle Stages: Asexual (Schizogony) and Sexual Reproduction

  
• Cystoisosporiasis

  • Generally, asymptomatic
  • More common in children and immunocompromised patients (AIDS, cancer like lymphoma, leukemia, and organ transplant patients)
• Cystoisosporiasis Diagnosis Methods

  • Visualization of oocyst in fecal specimens (DFS, Concentration Technique, Modified Acid-Fast Staining)
  • Entero-test (String Capsule)
  • Duodenal aspirate
  • Eosinophilia
  • Charcot-Leyden crystals in stool
• Cystoisosporiasis Treatment

  • Trimethoprim-sulfamethoxazole (TMP-SMX) (160/800 mg QID x 10 days)
  • Pyrimethamine and sulfadiazine
• Cystoisosporiasis Prevention & Control

  • Proper hygiene
  • Food and water precaution
  • Proper human waste disposal
• Cyclospora cayetanensis

  • Referred to as cyanobacterium-like body (CLB) / coccidia-like bodies
  • Phylogenetically closely related to the genus Eimeria
  • Common to certain tropical or subtropical regions
• Cyclospora cayetanensis Oocyst

  • 7.5 to 10 µm
  • Spherical in shape
  • Two types: Immature Oocyst (unsporulated, undifferentiated cytoplasm), Mature Oocyst (Sporulated, contains 2 sporocyst that has 4 sporozoites)

  
• Cyclospora cayetanensis Life Cycle

  1. Diagnostic Stage: Immature Oocyst

  2. Infective Stage: Mature Oocyst

  3. Definitive Host: Humans

  4. Mode of Transmission: Mouth/Ingestion (Fecal-Oral Route)

  5. Source of Infection: Contaminated food and water with sporulated oocyst

  6. 2 Life Cycle Stages: Asexual (Schizogony) and Sexual Reproduction

  
• Cyclosporiasis Symptoms

  • Initial symptoms = malaise, low grade fever (12-24 hrs post exposure)
  • Chronic = intermittent watery diarrhea alternating w/ constipation (6-7 weeks, ≥ 6 stools/day)
  • D-xylose malabsorption
  • Other symptoms are fatigue, anorexia, weight loss, nausea, vomiting, abdominal pain, flatulence, bloating, and dyspnea
  • No deaths are reported
• Cyclosporiasis

  • Generally, self-limiting (resolves without treatment)
  • With repeated infection = IMMUNITY
• Cyclosporiasis Diagnosis Methods

  • Direct microscopic examination (DFS, Concentration Technique, Modified Acid-Fast Staining, Fluorescent Microscopy)
  • Polymerase chain reaction
• Cyclosporiasis Treatment

  • Self-limiting: treatment is NOT necessary if symptoms are mild
  • Trimethoprim-sulfamethoxazole (TMP-SMX) (160/800 mg 1 tab BID x 7 days, only proven drug if treatment is warranted)
• Cyclosporiasis Prevention & Control

  • Good sanitary practices
  • Adequate water treatment (Boiling water, Chlorination is NOT effective)
  • Proper washing of fruits and vegetables