September 10, 2010
I got this article from a closed linked in group I belong to (the Zebrafish Husbandry Association) at:
Most people probably can't get to it, but I can send people copies of the pdf.
This article is specifically about zebrafish in laboratories and makes use of modern biological techniques, including molecular biological techniques. Nevertheless, there is up to date information of some diseases and the general ideas here can be applied (in less extreme form) by other fish keepers. The same diseases and the techniques should apply to most or all species of fish.
Zebrafish culture in labs is a lot like monoculture crops. There is always a concern of a disease ripping through a facility and killing a lot of fish. For a large zebrafish facility, this would be a threat to the established genetic resource of hundreds of different genetic lines that has taken lots of researchers many years to establish there. Another concern is that individual experiments may have their results affected by an undiagnosed disease condition, resulting in false conclusions.
Thus, there is an emphasis on strict quarantining, identifying sick fish, and taking actions to prevent disease from spreading.
Because there is a lot of government money going into research using zebrafish, there is a lot of bureaucratic oversight in an attempt to prevent the loss of the investment in research.
Glossary of terms in the paper:
subclinical infection: an infected animal that is not yet showing any obvious symptoms
zoonotic: an infection of an animal that can also infect humans
Pseudoloma neurophilia: an infectious organism similar to neon tetra disease. It’s a small cell that lives inside of fish cells. It is injected into fish cells from its spore. This is a very widespread disease, but is often subclinical (undiagnosed). It can infect many danio species.
Pleistophora hyphessobryconis: neon tetra disease.
Mycobacterium sps: mycobacteria, AKA fish TB. People can get it and its difficult to treat, but it’s not really tuberculosis.
Edwardsiella ictaluri: An infection causing problems on some fish farms.
Piscinoodinium pillulare: velvet disease
Obligate parasite: requires a host to survive. Remove the potential hosts and wait a while and the parasites should die off. This is like Ich.
Opportunistic parasite: can survive and make a living without having a host, but given the opportunity it will infect a host. Mycobacteriosis is an example of this. It can survive in biofilms on tank sides and in filters.
Sentinel animals are ones which are killed and tested in detail for disease. Using fish that would be more susceptible to disease than normal makes them a more sensitive test animal.
Vertical spread of disease: from an infected mother to its offspring via the not yet fertilized egg (or sperm).
Horizontal spread of disease: from an infected animal to another animal, but not via the not yet fertilized egg (or sperm).
Histopathology: using a microscope to look at sections (very thin slices) of tissue to see if parasites can be visually identified. Expensive and labor intensive.
Microbiological techniques usually involve growing things (like bacteria) on culture plates or in liquid media.
September 10, 2010
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