1. Coccidia characterized by thick-walled oocysts excreted in feces
In Humans
Cryptosporidium
Isospora
Cyclospora
Toxoplasma
Sarcocystis

2. GENERAL APICOMPLEXAN LIFE CYCLE

3. Cryptosporidium fecal-oral transmission (monoxenous)
wide range of animal hosts (C. parvum)?
several host-adapted species?
C. hominis for human species
first human case reported in 1976
self-limiting diarrhea in immunocompetent persons
profuse, watery diarrhea associated with AIDS (life threatening)

5. Extracytoplasmic Location
microvilli extend and fuse to enclose zoite
close association between parasite and host intestinal epithelial cell
called adhesive zone, feeder organelle, etc

8. Cryptosporidium Life Cycle
Merogony
= schizogony
produce merozoites
Gametogony
= gamogony or
= gametocytogenesis
produce micro- and macrogametes
Sporogony
produce sporozoites
completed on host cell
thin (autoinfection) or thick walled oocysts

9. Water Borne Outbreaks of Cryptosporidiosis in the USA
Modified from Graczyk et al, Parasitol. Today 13:348 (1997)

10. The Milwaukee Outbreak
NEJM 331:161 (1994)
massive cryptosporidiosis outbreak following spring thaw
>400,000 people may have been affected
based on clinical symptoms (acute watery diarrhea)
~100-fold higher prevalence of Cryptosporidium oocysts in stools than normal
other enterics (including Giardia, bacteria, viruses) were at ~normal levels
treated water had high levels of turbidity 3/23-4/5/1993
oocysts identified in ice made during this period

11. Waterborne Cryptosporidiosis
Factors Favoring
Waterborne Cryptosporidiosis
small size of oocysts (4-5 mm)
reduced host specificity and monoxenous development
close associations between human and animal hosts
large number of oocysts excreted (up to 100 billion per calf per day)
low infective dose (<30)
robust oocysts; resistant to chlorine

12. Human Cryptosporidiosis
associated with epidemic diarrhea in institutions and hospitals
highly transmissible (19% household members)

13. Molecular Epidemiology
2 major genotypes identified:
genotype 1
only human sources
non-infective for mice or calves
anthroponotic transmission
genotype 2
human and bovine sources
infective for mice and calves
zoonotic transmission
recently proposed genotype 1 = C. hominis
other genotypes (eg, C. felis, dog type, etc) rare
isolated only from AIDS patients

14. Symptoms of 205 patients with Confirmed Cases of Cryptosporidiosis During the Milwaukee Outbreak

15. Pathogenesis DIARRHEA enterocytes damaged or killed
villus atrophy (blunting)
 Na+ absorption
 intercellular permeability
crypt cell hyperplasia
 Cl- secretion
inflammation in lamina propria
cytokines and neurohormones?
enhanced secretion of antibodies (IgA)?
DIARRHEA
enterocyte malfunction (osmotic)
impaired absorption
enhanced secretion
inflammatory diarrhea
mucosal invasion
leukocytes in stools
secretory diarrhea
toxin associated
watery

17. Isospora belli
wide geographical distribution (higher prevalence in warmer climates)
monoxenous, probably not zoonosis
invades intestinal epithelial cells
often asymptomatic (seldom reported)
symptoms range from mild gastro-intestinal distress to severe dysentery
often self-limiting, but can become chronic (wasting, anorexia)
symptoms more severe in AIDS patients

20. Cyclospora cayetanensis
first human case in 1979
named in 1993
initially called ‘cyano-bacteria like body’ (CLB) or large Cryptosporidium
related to Eimeria
life cycle similar to Isospora
oocysts mature in environment (days-weeks)
no known animal reservoir
more common in tropical and sub-tropical areas

21. Cyclosporiasis Outbreaks in U.S. and Canada
Date
Location
Vehicle
Source
May-June 1995
New York
food? ?
May 1995
Florida
raspberries?
Guatemala?
May-June 1996
US, Canada
raspberries
Guatemala
March-April 1997
mesclun
Peru?
April-May 1997
June-July 1997
Wash., DC
basil
September 1997
Virginia
fruit plate
December 1997
Peru
May 1998
Ontario
Georgia
fruit salad?
May 1999
berry dessert
fruit (berry)
July 1999
Missouri
Mexico or US
June 2000
Pennsylvania

22. Transmission and Clinical Features
associated with food-borne outbreaks
luncheons, social events, weddings, etc.
possible source always involved foreign country and fresh fruit or vegetables
raspberries from Guatemala
salad from Peru
presumed source: contaminated water or human waste as fertilizer
symptoms similar to Cryptosporidium and Isospora
watery diarrhea/frequent stools
1-2 week duration typical
relapses over 1-2 months

23. Intestinal Coccidia Diagnosis Treatment
demonstration of oocysts in feces
acid-fast stain (all three)
autofluorescence (Isospora and Cyclospora)
direct observation (Isospora)
Treatment
paromomycin for Cryptosporidium
modest benefit
lowers parasitemia in AIDS
trimethoprim-sulfamethoxazole for Cyclospora and Isospora

24. Cryptosporidium Cyclospora Isospora belli 4-5 mm oocysts 4 sporozoites
no sporocysts
Cyclospora
8-10 mm oocyts
2 sporocysts
2 sporozoites each
Isospora belli
30 x 12 mm oocyts
4 sporozoites each

25. Cryptosporidium Cyclospora Isospora belli 4-5 mm oocysts 4 sporozoites
no sporocysts
Cyclospora
8-10 mm oocyts
2 sporocysts
2 sporozoites each
Isospora belli
30 x 12 mm oocyts
4 sporozoites each

26. Cryptosporidium Cyclospora Isospora belli 4-5 mm oocysts 4 sporozoites
no sporocysts
Cyclospora
8-10 mm oocyts
2 sporocysts
2 sporozoites each
Isospora belli
30 x 12 mm oocyts
4 sporozoites each