Re: more glugea queations (was Re: plague)

["Barry J. Cooper" <bjc3 at cornell_edu>]

>Hello
>
>Here are a few questions regarding glugea I would very much like
>answers to.
>
>1) Are only nothos susceptable. From the barrage of posts I get the
>impression that SAA are also effected. (I'm ignoring the
>unsubstantiated Aplocheilus incident.)


No, Nothos as a group seem to have had the most problems, but SA annuals are definitely susceptible and I have seen the disease (in a preserved specimen sent to me) in at least one Fundulopanchax species.

>
>2) Can other fish act as carriers without contrecting the disease?


I have no direct evidence, but I would assume that the answer is yes. It is pretty certain that some fish can be infected with a small load of the organism, thus not causing visible signs or lesions. In fish that I have studied microscopically I have seen fish with just a small number of xenomas (the enlarged infected cells), which are typically in the lining epithelial cells of the gut. I assume these can shed organisms and spores into the water, which could infect other fish.

>
>3) Can the disease organism survive in a free swimming state? If so
>for how long?


I don't think it has a free swimming state. However, spores are shed either in the feces or from ruptured superficial lesions. They could also be released from decaying dead fish. Fish picking on the bodies of dead fish would also obviously be exposed. How long the spores can survive is not known, at least to me, but it is obviously a long time, because fish hatched from contaminated peat can become infected. I surmise that the reason that Nothos and SA annuals have been the most susceptible is that the newly hatched fry are exposed to a potentially high parasite load early in life. This has two effects, one being the heavy infection load and the second being the length of time that the disease has to develop. The resistance of young fish is likely also less than that of adults, due to immature host defense mechanisms (immunity, in the broadest sense of the word).

>
>4) Are the spores produced in response to stress or are they
>continually pumped out?


Probably the latter, or at least intermittently when xenomas rupture.

>
>5) If adult nothos are infected would the disease move rapidly or
>still take 2 or 3 months to kill?

Not certain. Most people have problems when they hatch fry from contaminated peat and signs usually develop within about two months. My impression, and it is only that, is that adult fish may not develop signs for a long time, if at all, for the reasons given above. However, they could become sources of infection and contamination of the peat.

I can tell you that I am currently investigating a treatment method and I hope to be able to report on it by convention time.

Barry
-- 
Barry J. Cooper
Department of Biomedical Sciences		Home address:
College of Veterinary Medicine		27505 Riggs Hill Rd.
Cornell University				Sweet Home, OR 97386
(607)253-4273				(541)367-2568
---------------
See http://www.aka.org/AKA/subkillietalk.html to unsubscribe
Join the AKA at http://www.aka.org/AKA/Applic.htm