Opportunistic Intestinal Parasites - Coccidian Parasites

major cause of endemic and epidemic diarrhea in developing countries

Cryptosporidium parvum

how to kill Cryptosporidium parvum?

• resistance to chlorination

• use ozonation - use O₃ gas to disinfect water, air, food

• use desiccation - removal of water

where does Cryptosporidium parvum excyst?

• small intestine

• enters brush border of epithelial cells

• remains extra cytoplasmic

Cryptosporidium parvum causes—

• persistent watery diarrhea with cramps

• weight loss

• fever

• nausea/vomiting

Cryptosporidium parvum infectious dose

as few as 10 oocysts - low infectious dose

Cryptosporidium parvum lab diagnosis

• modified Kinyoun on fecal concentrate

• diarrheal stools tested with EIA Ag detection kits

• DFA microscopy morse sensitive

• PCR

Cryptosporidium parvum oocyst

• oocyst contains sporocysts with sporozoites

• may have white clearing around sporocyst

• honestly idrk how to describe this one

oocyst

infectious, sexual reproductive stage of coccidian parasites

sporocyst

protective sac within an oocyst containing the sporozoites

sporozoites

infective stage of a parasite that proliferates asexually within the sporocyst

Cyclospora cayetanensis is more prevalent at these locations

widespread in tropical or subtropical areas

• US cases related to contaminated raspberries and strawberries from Central America

Cyclospora cayetanensis transmission

• no direct fecal-oral spread

• oocysts that are shed are non-infectious for day-weeks

• oocysts release sporocysts in GI tract, invade mucosal cells

incubation period and duration of infection for Cyclospora cayetanensis

• incubation for 1 week

• duration 10-12 weeks if untreated

Cyclospora cayetanensis causes—

often severe watery diarrhea, anorexia, weight loss, abdominal pain, nausea/vomiting, myalgia, low fever, fatigue

• frequent relapses

Cyclospora cayetanensis laboratory diagnosis

• collect stool >3 at 2-3 day intervals because of small amounts of oocysts in stool and intermittent shedding

• fix in 10% formalin (mod AFB staining)

Cyclospora cayetanensis oocyst

• oocysts auto-fluoresce blue

• 8-10 um

Cystoisospora bellii is more prevalent at these locations

• worldwide mostly in tropical/subtropical areas

• institutional outbreaks in the US

Cytoisospora belli invades —

villous epithelial cells in more commonly immunosuppressed people

Cystoisospora belli causes —

acute, non-bloody diarrhea with cramping and abdominal pain

• severe presentation in infants and children and immunosuppressed

• eosinophilia is often present (not for other coccidians)

• lasts for several weeks

laboratory diagnosis of Cystoisospora belli

• stool O&P with 2-3 specimen because of intermittent shedding

• wet mount, modified AFB stain, or autofluorescence

Cystoisospora belli oocysts

• spindle shaped

• 20-33 um

• immature cysts have a single sporoblast

• mature cysts have two sporoblasts/cysts

distribution of Microsporidia spp.

worldwide with emergence as opportunist agent on all continents

infectious particle of Microsporidia spp is —

the spore

Microsporidia spp. sizes —

vary by species

Microsporidia spp. causes —

diverse manifestations dependent on species

• Enterocytozoon bieneusi - diarrhea

• Encephalitozoon intestinalis - diarrhea, dissemination to eye, genitourinary, and respiratory

lab diagnosis of Microsporidia spp.

separate order, so it will not be picked up on stool O&P (special order test)

• chromotrope 2R stain

• quick-hot gram chromotrope technique

• calcofluor white

Microsporidian spp. in chromotrope 2R stain

• pink/red spore walls with visible central belt-like stripe