In the current discussion on viability of Toxocara eggs, the point has
been made that Toxocara eggs survive a "long time" in soil. However, I
think it is also important to take into consideration quantitative
aspects. Key information must be the rate of death of eggs with time.
So even if viable eggs could be found for years, what proportion of the
initial inoculum survives 1 wk, 1 mth, 1 yr, etc. I have not yet made
the effort to chase this up, but it is important. Do any subscribers
have good data on this?
Remember that the zoonotic hazard is probably dose related. One of the
key factors in the risk of disease to a person will be inoculating dose.
(Apart from a range of host factors as well). Without quantitative
considerations, a qualitative argument may serve to make the situation
appear much worse than it is.
Also dog faeces does not equal Toxocara eggs. Has the soil been checked
for Tozocara eggs?
Department of Public Health and Tropical Medicine
James Cook University
email: Richard.Speare at jcu.edu.au