Survival of Ancylostoma caninum on bare ground, pea gravel, and concrete.

Studies were done to determine the survival of infective Ancylostoma caninum 3rd-stage larvae on 3 ground covers commonly used in dog run construction: bare ground, pea gravel, and concrete. Changes in numbers of recovered larvae were compared to meterologic data and the most significant weather variables were determined. Larvae were recovered 1 to 7 days on bare ground. Larvae survived longer in the fecal mass (mean of 3 days) than on the bare ground (mean of 2 days). Rain was the most significant variable, in that it was positive in its effects (higher larval count) early in the experiment (causing fecal mass breakdown and release of larvae) and negative (lower larval count) later in the experiment (spreading larvae away from test site). Larvae were also recovered 1 to 7 days on pea gravel. They were recovered for a mean 2.6 days from the fecal sample, a mean of 1.5 days from the rocks directly below the fecal mass, and a mean of 1.3 days from the remaining rocks. Here also, rain was the most significant weather factor. It was negatively significant (lower larval count) for the fecal mass (spreading of the larvae) and positive for those in the pebbles (increasing the moisture in the pebbles). Survival time of larvae on concrete was shorter than that on the other 2 substrates: from 0 to 2 days. Larvae were recovered a mean of 1.3 days from the fecal mass and a mean of 0., days from the surrounding concrete. Rain was positively significant early in the experiments in that it released trapped larvae from the fecal mass. Sunlight consistently was negatively significant (lower larval count) due to its lethality to the unprotected larvae.