Influence of Incubation Time for Correctness of Viability Assessment of Ascaris suum Eggs – Attempts to Optimise the Parasitological Examination

The aim of this study was to determine the optimal incubation time for accurate assessment of parasitic nematode eggs viability, an important step in improving parasitological diagnostics. The experiment used Ascaris suum eggs were collected from three sources: adult roundworms uteri (U), pig faeces (F) and sewage sludge (S), then incubated at 27°C and monitored weekly. Eggs were classified as dead (with clear deformations), viable (with motile larvae) or of uncertain viability (retaining structural integrity but undeveloped). The results showed that eggs from group U had the highest viability (96%) and developed larvae within 3 weeks. In contrast, group F (52% viability) and S (3% viability) showed delayed development, requiring up to 8-12 weeks for a conclusive viability assessment. These results indicate significant differences in egg viability depending on the sample source and emphasise the need for longer incubation times, particularly for environmental samples such as sewage sludge. The study also highlights the limitations of single time point assessments based solely on egg structure, which can lead to misclassification. In conclusion, prolonged incubation improves diagnostic accuracy by allowing a clearer distinction between viable and non-viable eggs, especially in samples with initially uncertain viability.