General Discussion

MIERS. Do you get any regional differences in the infection rate of possums?

HATHAWAY. I have only sampled in the southern half of the North Island. However we have differentiated between different habitats such as pastoral, forest margin and deep forest. We found leptospiral infection in forest up to 5 miles from the forest margin so it seems capable of residing in the deep forest populations.

B.D. BELL. Have you examined isolated populations, such as the possums on Kapiti Island?

HATHAWAY. Mr A.J. White has been collecting urine from possums in the Orongorongo Valley forest and the organisms appear to occur through the year at a rate of about 10–20% of the possums examined.

KEBER. Could you speculate on how this serotype has become so infective in the possum in New Zealand?

HATHAWAY. I can speculate. In New Zealand all our ground mammals were introduced, and these included species in which the infection could have evolved. So you could speculate that the organism was introduced to possums after European settlement in New Zealand, or was introduced with the brushtail possum from Australia and that in New Zealand we have a specific ecological situation which has allowed balcanica to become endemic.