When working on laboratory animals to survey infectious and non-infectious diseases, especial rules should be considered. To achived this, labs, clinics, lab animal houses should be isolated, and specific factors for wtoking on Lab’s animals, immunity and…should be defined as biosafety levels. Level 1 of biosafety is suitable for experiments which are perfomed on known microorganism and are not harmful for human. In such places only qualified individuals are permited to inter. Also people should be informed about the dangers of microorganism. Level 2 of biosafety is peformed when one is engaged with infectious agents. These agents can penetrate into the body from different ways. All the people working in such sections must considered all the safety advices, and must be tested and vaccinated against infectious diseases. Level 3 of biosafety is suitable for working with animals that are infected by pathogens which are transferable by respiratory truct and can cause serious or even dead by diseases. Level 4 of biosafety is suitable by for working with external pathogens which is threatens the heath of people. Transfer of these agents is via respiratory truct of unknown agents with unknown transfer. In this article about biosafety levels of laboratory animals discussed in details.

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