Morphological changes of Ascaris spp. eggs during their development outside the host

Area of Science:

• Parasitology
• Developmental Biology
• Environmental Science

Background:

• Limited information exists on early embryonic development and the extra-host life cycle of Ascaris lumbricoides.
• Ascaris suum eggs serve as a reliable model for studying A. lumbricoides development outside the host.

Purpose of the Study:

• To describe morphological changes during in vitro embryonic development of Ascaris spp. at 28°C.
• To investigate Ascaris egg viability throughout the incubation period.
• To expand the known stages of Ascaris development outside a host.

Main Methods:

• Ascaris suum eggs were incubated in 0.1N H2SO4 at 28°C in the dark for 21 days.
• Daily microscopic evaluation of approximately 100 eggs was performed.
• Morphological changes and viability of developing embryos were documented.

Main Results:

• Twelve distinct embryonic developmental stages were identified, including two previously unreported stages.
• By day 7, most embryos reached the late-morula stage (72.5%).
• By day 14, 90% developed to larva-1, and by day 21, 100% reached larva-2. Egg viability showed no significant difference from day 5 to day 21.

Conclusions:

• This study expands the documented stages of Ascaris spp. development outside the host.
• The findings suggest early developmental stages of Ascaris can indicate the safety of treated environmental materials like sewage sludge and compost.
• Consistent egg viability supports the reliability of these developmental markers.