[Adaptability of Nippostrongylus brasiliensis (Travassos, 1914) to lead contamination].

It was investigated whether toxicity of lead (Pb) is so high that its effect on Nippostrongylus brasiliensis larvae could be transferred into subsequent (3) generations of the nematode. Wistar rats were infected with a dose of 1000 N. brasiliensis larvae contaminated with Pb (9 days at 200 ppm in solution). The number of larvae in lungs after 24 and 42 hours and the number of adult nematodes in the small intestine after 90, 114 and 236 hours after infection were examined. To determine reproduction of the N. brasiliensis the number of eggs was determined. Eggs of the first generation subjected to Pb (P generation) were used to culture a subsequent generation of invasive larvae (F1) which were used to infect rats. Eggs from that generation were used to culture the next invasive larvae generation (F2) used again to infect rats. Lungs dissection after 24 hours has shown that the P generation produced 12 times less larvae than the control, while generations F1 and F2 produced 4,9-5 times less larvae than the control. Dissection data for the small intestine show the highest loss in invasive capability of this nematode in generation F1. The dynamics of eggs excretion is the lowest in F1 and excretion period is shorter by 1 day. In F2, the number of eggs excreted is 5.8 times higher than in the control group. It seems that in F2 generation mechanisms enabling the species to survive under unfavorable environmental conditions were started.