Studies on the survival of Ascaris suum eggs under laboratory and simulated field conditions.

A series of four experiments was carried out to study the survival of Ascaris suum eggs: in a pig slurry unit on a farm, in the laboratory under anaerobic conditions and different relative humidities (rH), and under simulated field conditions. Survival of eggs in the pig slurry unit was 20% after four weeks and 0% after 16 weeks. Anaerobic conditions had only a minor influence on survival: after 12 weeks, more than 80% of the eggs could still develop. At high relative humidities (100% and 75%), survival was respectively 96% and 62% after 12 weeks. At 47.5% rH, survival dropped to 0% after 10 weeks and at 7.5% rH in 8 weeks. A. suum eggs kept in pig slurry under dry and sunny outdoor conditions survived for 2-4 weeks, whereas under wet and shady conditions, 90% of the eggs were still viable after 8 weeks.