Tom,
I spoke with Dr. Ross on several occasions back in the 1980's and did discuss some of his findings related to the WEI field study in Papua New Guinea. Out of the total set of all wild caught snake species tested, there were almost a third of them that tested positive for some species of pathogenic, gram negative bacteria. However, I think you are correct in that I don't believe any of the wild caught python specimens alone tested positive for P. aeruginosa, but a few did test positive for some of the other gram negative pathogenic bacteria species. It has been a long time since I've seen the data, but if my memory serves me correctly, I believe a few of the boa (Candoia) specimens did test positive for Pseudomonas. The study also showed that once the specimens were introduced to a captive environment at holding facilities, they shortly began testing positive for P. aeruginosa.
The fact that the wild caught python group only, showed no sign of P. aeruginosa, and that the vast majority of captive pythons are asymptomatic carriers, points to the conclusion that P. aeruginosa is an opportunistic pathogen in captive pythons. It is only when stress suppresses the immune system of the animal, that the organism is able multiply to cause a disease condition.
The big question that I don't believe Dr. Ross was ever able to completely answer was the source of these gram negative pathogens in wild snake populations. The question being, are they an artifact of the proximity of human populations, or are these pathogenic bacteria species naturally occurring in a wild, untouched environment.
There are probably other studies out there that I am not aware of, but I agree that Marzec would obviously be one of the best sources of information on this topic.
Kelly
