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Type of publication: Diploma Thesis
Type of document:

Year: 2010

Authors: Tischlinger, Michaela

Title: Isospora suis: Methodenevaluierung zur Koproskopie und retrospektive Analyse von Infektionsmodellen.

Other title: Isospora suis: evaluation of coproscopical methods and retrospective analysis of infection models

Source: Diplomarbeit, Vet. Med. Univ. Wien, pp. 47.


Advisor(s):

Joachim Anja

Reviewer(s):
Ritzmann Mathias

Vetmed Research Units:
Institute of Parasitology


Abstract:
Isospora suis is a widespread pathogen of neonatal piglets. The diagnosis is usually based on the detection of oocysts in faeces; however, validated methods are not available. Furthermore, different infection models are available which mimic the course of infection and disease. The present study had two aims. First, two different coproscopical methods were compared with respect to their reproducibility and correlation of results. Secondly, data for the retrospective analysis from various infection models were compared with regards to faecal consistency and oocyst excretion. The validation of methods was carried out with 2 examiners testing 168 samples each by McMaster counting to determine the number of oocysts per gramme of faeces – OPG – and autofluorescence. From these a further 50 were selected and re-examined. For the retrospective analysis, data were evaluated from 4 infection trials under highly standardized conditions using different infection doses and infection days. The parameters were quantitative and qualitative excretion of oocysts and faecal score. The agreement of negative McMaster results in the category 0 between two examiners was 98.8 %. In category 5 (>16650 OPG) a mean difference of 2751 OPG (standard deviation 4881 OPG) between the two examiners was found. When a sample was compared by autofluorescence microscopy usually differed in the grade of positivity from the McMaster counting. A low infection dose (1000 oocysts) and infection on the fourth day of life lead to a medium diarrhea prevalence of > 80 % on days 8 - 10 post infection (dpi). A comparison of mean OPG values showed that a low infection dose and an early infection (first day of life) reduced the excretion to 0 OPG on dpi 9 and 10. The correlation between faecal consistency and OPG was calculated in the infection model with a low dose and a late infection (1000 oocysts on the fourth day of life); the result was high faecal scores on dpi 8 - 10 while excretion decreased during that time.


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