Effect of Temperature on Embryonation of Ascaris suum Eggs in an Environmental Chamber

Abstract

The influence of temperature on the development and embryonation of Ascaris suum eggs was studied using coarse sand medium in an environmental chamber with 50% humidity. The time required for development and embryonation of eggs was examined under 3 different temperature conditions, 5℃, 25℃, and 35℃. A. suum eggs did not develop over 1 month at the temperature of 5℃. However, other temperature conditions, 25℃ and 35℃, induced egg development to the 8-cell-stage at days 5-6 after incubation. All eggs examined developed to the 8-cell stage at day 6 after incubation in the sand medium at 25℃. The higher temperature, 35℃, slightly accelerated the A. suum egg development compared to 25℃, and the development to the 8-cell stage occurred within day 5 after incubation. The formation of larvae in A. suum eggs at temperatures of 35℃ and 25℃ appeared at days 17 and 19 after incubation, respectively. These findings show that 35℃ condition shortens the time for the development of A. suum eggs to the 8-cell-stage in comparison to 25℃, and suggest the possibility of accelerated transmission of this parasite, resulting from global warming and ecosystem changes.

Comparison of multi-parallel qPCR and double-slide Kato-Katz for detection of soil-transmitted helminth infection among children in rural Bangladesh

“…However, fertilized eggs undergo multiple cellular divisions during the process of embryonation, meaning that a single egg may contain many copies of the genome. Typically, under permissive environmental conditions, embryonation occurs over the course of approximately 2-3 weeks following fecal shedding, generally requiring approximately 5 days for eggs to reach the 8-cell stage [73]. When stored at colder temperatures approaching 5˚C, such development is arrested [73].…”

“…Typically, under permissive environmental conditions, embryonation occurs over the course of approximately 2-3 weeks following fecal shedding, generally requiring approximately 5 days for eggs to reach the 8-cell stage [73]. When stored at colder temperatures approaching 5˚C, such development is arrested [73]. Given that all stool samples collected as part of this study were placed on ice within 18 hours of sample production, it is extremely unlikely that significant embryonic development could have occurred prior to DNA extraction and qPCR testing.…”

Changes in the viability of the eggs of Ascaris suum under the influence of flavourings and source materials approved for use in and on foods

“…At a temperature of +43.6 °C and relative humidity of 43% the viability of A. suum eggs was no higher than 5%, and only 0.004% of eggs developed to the larval stage. The influence of temperature on the development of A. suum eggs was described by Kim et al (2012). A. suum eggs were unable to develop for a month at a temperature of 5 °C.…”

A multilevel study of the environmental determinants of swine ascariasis in England

“…Contrarily, our results do not suggest any biological advantage of A. suum in fine-textured soils and, indeed, reveal the limited impact of soil characteristics on the epidemiology of the disease. Although extremely resistant in the environment, the eggs of A. suum do not develop at temperatures below 5°C and its life cycle is highly dependent on humidity (Arene, 1986;Kim et al, 2012). This has been suggested as a possible reason for seasonal patterns of milk spots.…”

“…In England and other countries, strong spatial inequalities in the distribution of swine ascariasis were observed, which suggests that the geographical location may act as a latent variable encapsulating several biogeophysical and socioeconomic factors (Roepstorff and Nansen, 1998;Sanchez-Vazquez et al, 2010). Accumulated evidence suggests that climatic and soil characteristics might also be possible determinants of the disease (Beaver, 1953;Arene, 1986;Kim et al, 2012;Schüle et al, 2014). For instance, it has been accepted for a long time that A. suum eggs do not develop under the temperature of 5°C and the optimum temperature for cleavage seems to be between 25 and 30°C (Arene, 1986;Kim et al, 2012), which might explain the comparatively higher incidence of the disease in summer months (Sanchez-Vazquez et al, 2012;McCormick et al, 2013;Neumann et al, 2014).…”