Table 1.
Phenotypic features of C. parvum experimental infection observed in severe combined immunodeficiency (SCID) mice after inoculation with different isolates: IOWA, TUM1, DID and CHR.
| C. parvum (IOWA) | C. parvum (TUM1) | C. parvum (DID) | C. parvum (CHR) | |
|---|---|---|---|---|
| Length of time between Cryptosporidium isolation and mice infection | <1 month | <1 month | <1 month | 5 months |
| Oocyst viability | > 95% | > 95% | > 95% | > 95% |
| Infection dose | 105 | 105 | 105 | 5.103 |
| Log10 of oocysts/mg of feces | 4.32a | 6.53b | 6.15c | NA |
| Clinical manifestations | Rare and late onset: spiky hair, lethargy, prostration | Frequent: bloody diarrhea, spiky hair, lethargy, prostration | Frequent: bloody diarrhea, spiky hair, lethargy, prostration and one case of rectal prolapse | Frequent: spiky hair, lethargy, prostration |
| Time of onset of digestive neoplastic lesion (Days Post-Infection, PI) | 45 | 20 | 40d | 15 |
| The most severe observed neoplastic lesion gradee | 5 | 4f | 5 | 4f |
| Localization of the most severe lesion | Antropyloric region | Ileocaecal region | Ileocaecal region and biliary tree | Ileocaecal region |
| Extra gastro-intestinal lesions | No | Intraepithelial neoplasia in the biliary tree | Cholangiocarcinoma and vascular tumor emboli | Pancreatitis |
| Mortality rate at 60 days PIg | 0% (0/80) | 29% (7/24) | 41% (10/24) | 29% (4/14) |
| Maximum score of severityh | 11 | 32.5 | 35 | 40 |
aQuantification before euthanasia at 57 days PI.
bQuantification before euthanasia at 35 days PI.
cQuantification before euthanasia at 60 days PI.
dFor this animal experiment onset of neoplastic lesions before 40 days PI was not explored. This time corresponds to the first date of planned euthanasia. Thus, it is not excluded that the lesion appeared before.
e0, no lesion; 1, inflammation and/or regenerative changes; 2, low grade intraepithelial neoplasia (LGIEN); 3, High grade intraepithelial neoplasia (HGIEN); carcinoma in situ (limited to the epithelium) or intramucosal adenocarcinoma (invasion into the lamina propria through the basement membrane of glands); 4, submucosal adenocarcinoma when glands penetrate through the muscularis mucosae; 5, invasive adenocarcinoma with the invasion through the muscularis into the subserosa.
fThis grade corresponds to the most severe lesion observed in mice that were alive at the time of euthanasia. It is not excluded that the ones who died before had a more severe lesion.
gThis mortality concerned animals that died before planned euthanasia.
hThe degree of severity of histological damage for each mouse was calculated by the sum of neoplastic lesions scores over five organs (stomach, liver, duodenum, ileocecal region and colon). In order to include the mortality as a factor of disease severity, each mouse which died before planned euthanasia was assigned a number of points equivalent to: 25 + ((60 – day of death)/2), where 25 corresponded to the maximum score of severity that can be reached by animals euthanized as planned, and 60 days corresponded to the end time of the experiment (slightly modified from Certad et al., 201018).
NA: Not applicable