Cryptosporidium parvum Benjamin Harris

Cousins, Grandpa, Sisters

Navi

Epidemiology Found on all six continents. Distributed through fecal-oral route from infected hosts. Most commonly transmitted through contaminated water.

Hosts Definitive Host: non-specific (terrestrial mammals) Intermediate Host: None Infects: – Humans – Livestock – Pets – Almost any domesticated mammal. – First confirmed human case was 3-year-old girl from rural Tennessee in 1976

Lifecycle Sporulated oocyst (containing four sporozoites) are ingested or inhaled by infected host. Excystation occurs and sporozoites are released attaching to intestinal or respiratory walls. Undergo asexual multiplication (schizogony or merogony) or sexual multiplication (gametogony).

Lifecycle Continued Sexual multiplication yields: – Microgamonts (male) – Macrogamonts (female) Upon fertilization of zygote, two types of oocysts can be produced. – Thick-walled (typically excreated) – Thin-walled (primarily for autoinfection)

Transmission Fecally contaminated food and water – Swimming pools, public drinking water, lakes, rivers. Animal-person (zoonotic) – Approximately 50% of calves discrete oocysts. Person-Person High frequency in day-care centers, bathrooms, urban. Fecal-oral route. Small contamination required: – Infective dose (132 oocysts for healthy persons)

Symptoms Nausea Vomiting Abdominal Cramps Low-grade fever Frequent watery diarrhea Much more severe in all respects for immunocompromised persons (HIV/AIDS). CD4 <180 cell/cubic mm.

Pathogenesis After excystation, sporozoites adhere to the surface of intestinal mucosa. Epithelial mucosa cells release cytokines to activate resident phagocytes which in turn release factors to bring about a specific response elements. – T cell response causes inflammation and can damage or kill cells. – Cell death directly caused by parasite invasion.

Diagnosis Identification of oocysts from stool sample or salvia. – Acid-fast stain most reliable. Secondary tests Enzyme-linked immunoabsorbent assay (ELISA) Immunofluorescence (IFA) PCR (Polymerase Chain Reaction)

Diagnosis Continued Real time PCR. CDC technique using specific primers to detect highly sensitive rRNA gene sequences.

Treatment Immediate fluid and electrolyte replacement. Immunocompetent patient disease progression is self-limited. Immunocompromised patients: – Nitazoxanide (antiprotozoal) – Anti-retroviral therapy

Prevention Common Sense! – Wash food, especially fruits and vegtables. – Don’t drink and avoid using questionable water. – Don’t part-take in risky sexual practices with infected partner. – Wash hands frequently after coming in contact with infected patients. – Avoid swimming in contaminated water.

Water Treatment Between six major outbreaks have been documented. – 1993 Milwaukee outbreak caused over 400,000 cases via municipal water utilities. 84 of which had HIV and 85% of deaths a year after the incident were HIV postive. 240,000 times more resistant to chlorination than Giardia Smallest cysts are 4 microns in diameter making micro filtration effective. Boiling water for 1 minute is also effective.

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