This project constitutes a study to compare diagnostic procedures (faecal examination and
biopsies) for the detection of Cryptosporidium infection in the host.
The infectivity of oocysts of Cryptosporidium parvum was examined. Oocysts, obtained
from faecal samples of infected cattles, were purified using sucrose gradients. Oocysts in the
study were four to six weeks old when they were used for the UV disinfection and infectivity
experiments. The oocysts were suspended in deionized water and exposed to well-defined
doses of ultraviolet (UV) light (254 mm). The experiments were carried out under laboratory
conditions in a specially constructed apparatus. Oocyst concentrations of 1 x 106 per
ml in a total volume of 30 ml in Petri dishes were used and four selected UV dosages (300, 150, 75, 30
J/m2) were applied. The oocyst survival rate was measured after in vivo infectivity assay
using the SCID mice model and compared to the infectivity rate by unexposed controls. SCID
mice (C.B-17-SCID/IcrCrl, male and female, 4 weeks old) were supplied by Charles River
GmbH, Germany. Several groups were used with usually five animals in each group. Each mouse
of the group was orally administered an aliquot of 0,5 ml of the appropriate inoculum between
2,5 . 10 x 105 (250,000, 450,000 and 500,000, 1,000,000) oocysts from the exposed sample as
have been previously described. Each inoculated animal was kept in a separate cage.
Two diagnostic techniques have been applied for the detection of Cryptosporidium oocysts:
faecal samples from inoculated mice were collected between 5 to 18 days post inoculation (dpi), diluted in distilled water, and oocysts were separated using discontinuous sucrose gradient and were then detected by Direct Immunofluorescence (DIF), (Crypto-
CELL, Cellabs Pty.); and,
mice were sacrificed 15-18 days after inoculation by cervical dislocation. Intestinal
manifestations and histopathology of the small intestine in comparison to the uninfected
animals and to the results from the faecal examinations are also described. Pieces of the
small intestine (duodenum, jejunum, and ileum) of each mouse from each experiment have
been prepared for histopathology analysis. Tissues were fixed in formaldehyde, embedded
in paraffin and thins sections (3-5 um) stained with HE-method. Hematoxylin was used for
nuclear-staining (10-12 min) and azophloxin for cytoplasma-staining (7 min). The sections
are collered in violet-red. Cryptosporidium oocysts are stained violet-blue. The sections were observed by x100 and x400 magnification. Includes 10 references, tables.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 150 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 9 |
| Published : | 09/22/2002 |
