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Laboratory Animal Science (Fach) / Diseases and health monitoring (Lektion)
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Diese Lektion wurde von s7mnmart erstellt.
Diese Lektion ist leider nicht zum lernen freigegeben.
- Which diseases are relevant for lab animlas? Infectious diseases e.g. virus/bacteria/funghi Non-infectious diseases e.g. injury/trauma/genetic Combination of both e.g. secondary infection after injury
- Define infection „Infection is the active or passive invasion, persistence and subsequentreproduction of pathogenic agents (e.g. bacteria, fungi or parasites) orpathogenic molecules (e.g. viruses) in an organismand the reaction of host tissues to the infectious agents and the toxins theyproduce.“ •may cause no symptoms and be subclinical, or it may causesymptoms and be clinically apparent (=> infectious disease). • may remain localized, or it may spread through the blood orlymphatic vessels to become systemic (bodywide). • Microorganisms that live naturally in the body are not considered infectious(for example, bacteria that normally live on the skin, within the mouth, andintestine are not infections - we talk about the microbiom or microbiota of anorganism in this case) direct infection: transmission from animal to animal without any intermediate stages in an exogenous manner; direct contact, feces, secretions indirect infection: transmission from a host bymeans of different transmitters (vectors/vehicles)
- Why is it important to monitor the health and hygiene status of animals? Diseases, suffering of laboratory animals Influence on research: e.g. changes in the values of liver enzymes, infections lead to immuno-response Increase in number of animals: against 3 R Repetition of experiments: against 3 R Risk of ZOONOSES --> all are against the interest ofanimal welfare andresearch
- How can the hygenic status be determined? Diagnostic methods: Serology: viruses, some bacteria, parasites --> antibodies used in IFA or ELISA: Cautious remarks:In case of a positive result:• there is evidence of prior exposure to an agent• it is not indicative for the continuing presence of the agentIt is:• not a method to detect early infection (time is needed for seroconversion)• inadequate for immunodeficient animals and infant animals• possible that a cross-reactivity with related agents occurs exposition-seroconversion-B cell response PCR: viruses, bacteria, fungi, parasites--> genomic material • Benefits: high sensitivity and specificity (cave: contamination!) Cautious remarks:• Sampling: - correct organ / testing site- correct timingHygienic monitoring – diagnostic methods: PCR• Specificity: - mutation in a targeted sequence- genomic variations (not all strains isolated, only few sequenced)• False-Positive results: - transgene interference (expression of viral sequences) Culture: bacteria, dermatophytes-->agents ---> MALDI-ToFMicroscopy: parasites-->agents
- How is health monitoring documented? Hygienic monitoring is performed(results: IFA, ELISA, PCR, microscopy) and documented in house (lab book, positive, negative control and samples) and external (test protocol) any (new) positive result needs to be confirmedrepeated sampling and testing of resident animals/sentinelsif possible, positive results should be performed again by another testing laboratory Finally, generate a health reportthis can also be done in house or by the external lab
- How is health and hygiene managed? General work regulationsØ building measures, barriers, protective clothes…• Control of personnel, material, and animal flowØ controlled accessØ avoidance of switching between rooms/barriersØ working always from higher to lower hygienic levelsØ quarantine• Cleaning and disinfectant measuresØ rooms, floors, surfaces, equipment, hand hygiene• Regular intern controlsØ health monitoring, disease monitoring
- What are zoonoses? Zoonoses are infectious diseases that can be naturally transmitted betweenanimals (usually vertebrates) and humans.Zoonoses may be bacterial, viral, or parasitic, or may involveunconventional agents.• Anthropozoonosis: disease transmitted from humans to animals(e.g. S. aureus)• Zooanthroponosis: disease transmitted from animals to humans (e.g.rabies, Toxocara canis)
- what are sentinel animals and how are they used? used to detect risks to other animals by providing advance warning of a danger. In any case the dose applied is very important 1. Contact animals Keeping sentinels in the same cage as the animals to be examined (problem:sample size). 2. Bedding sentinelsKeeping sentinels on used bedding from several cages of the animals to beexamined (e.g. in IVCs; however, not all pathogens can be transferred thisway) 3. Exhaust air sentinelsKeeping sentinels in cages filled with the exhaust air of the cages of animals tobe examined (e.g. in IVCs; however, not all pathogens can be transferred thisway) criteria for sentinels • Animals should be free from all agents to be monitored (incl. parasites) andfree from antibodies to these agents (SPF or SOPF animals).• The animals should be of the same animal species like the one of thepopulation to be examined.• It should be young adult animals, which show a good immune reaction (=>serology)• Outbred or inbred animals?In general, outbred strains are prefered (cheap, fertile, robust, susceptible to awide range of pathogens, but: show less often clinical symptoms).In inbred animals, susceptibility to infectious agents differs between strains.S
- how can sampling for hygiene checking in IVC housing be performed? colony animals: - only a fraction of cages - diseased animals mouse samples: - swabs- tape test- feces- blood Environmental samples: - filter- exhaust dust- cage, bedding
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