With the purpose of standardising techniques for the laboratory study of Ascaris lumbricoides, faeces were collectedfrom children parasitised by A. lumbri- coides, during a 24 hour period. The fecal samples were sieved and resuspended several times in water. The se- diment containing the eggs was cultivated in H2SO4O. IN in tissue culture flasks, at 28°C. The culture of embryonated eggs was determined every ten days starting from the 20th day of culture achieving around 98.0% embryogeny on the 80th day of culture. The best day to recover larvae from mice was determined by infecting 9 groups of 5 mice per os with 200 embryonated eggs/mouse. Each mouse was sacrificed by cervical rupture starting on the 4 day up to the 12 day of infection. On the 8 day after the infection 0.45% of the larvae were recovered from the lungs. The inoculum determination was performed by using 5 groups of 10 infected mice with 200, 400, 800, 1.600 and 3.200 embryo eggs/mouse. The best age for recovery of infection was achieved by using 4 groups animals, with 5 mice/group, with age varying from 20 to 50 days and an inoculum of3.200 eggs. The best recovery (1.9% was obtained from the group of 20 days of age.
Ascaris lumbricoides; Egg culture; Larval recovery