[Zbrafish] Re: Microsporidiosis

sarah via zbrafish%40net.bio.net (by sspinette from ric.edu)
Wed Jul 2 07:29:59 EST 2008

On Jun 30, 1:38 pm, Katy <kba... from gmail.com> wrote:
> On Jun 25, 10:32 am, sarah <sspine... from ric.edu> wrote:
> > I suspect that we may have some fish with Microsporidiosis infection.>From reading that I have done it seems that I should euthenize ALL of
> > the fish in the AHAB benchtop system and empty all water and clean all
> > tanks and resevoir. But I have also read that this parasite may not be
> > killed by common disinfection agents. How can I completely rid the
> > system of this agent? can things be taken apart and autoclaved? Has
> > anyone else encountered this and what did you do?  PLEASE HELP!!!
> Hi Sarah,
> First, I would confirm that you do in fact have microsporidiosis
> (Pseudoloma neurophilia) in your zebrafish.  Almost any pathogen can
> result in a skinny fish and there is no pre-mortem diagnostic for
> Pseudoloma in zebrafish.  You can diagnose microsporidiosis in H&E
> stained histological sections, wet mounts of the spinal cord and
> brain, or by PCR on spinal cord and brain tissue.
> Bleach concentrations used to sanitize eggs are not effective against
> Pseudoloma spores.  However, high concentrations of pH adjusted bleach
> will kill the spores.  See Ferguson et al. (2007), Dis Aquat Org, Vol.
> 76: 205-214.  Bleach is toxic to zebrafish, causing acute gill
> necrosis and asphyxiation.  Therefore, it's important to neutralize
> with sodium thiosulfate and rinse well.   Having said that, the most
> likely, and proven, mode of transmission is by cannibalism of dead,
> infected fish.  Therefore, removing dead, old, and sick fish from your
> population is the most effective way to break the cycle of
> transmission.  I am not aware of Pseudoloma being detected in biofilms
> and have not personally been able to detect it in water or debris
> samples from tanks with infected fish.
> UV is also an effective means of killing Pseudoloma spores.  Have you
> checked the efficacy of your UV bulbs?  I suspect that dead fish can
> get pulverized in the drains and filtration system, liberating
> infective spores.  However, UV will kill the spores and prevent
> circulation of Pseudoloma throughout your system.
> Katy Murray DVM, Ph.D.
> Zebrafish International Resource Center

Thank you very much. We do have UV but we are actually planning to
replace the bulb this week for that reason. We have been removing
symptomatic fish at the first detectable signs, but still we are
finding new sick fish each week. Yesterday, I was doing the bi-weekly
scouring of the resevoir and found a gritty fine sand-like substance
inside the bottom! My student claims that it was not there 2 weeks
ago. I have no idea where it could have come from aside from the water
we use for daily water exchanges (we used to use conditioned tap water
and now use conditioned filtered water). It was the color and feel of
the Siprax beads ...do these ever start to break down?

More information about the Zbrafish mailing list