What is the main challenge faced by
biologists researching infectious diseases?

The main challenge faced by a microbiologist researching infectious disease is to prevent the spreading of infectious disease to itself and others.  

So to prevent the spreading of infectious disease microbiologist takes a lot of precautions like they work in an area which has negative pressure that do not allow the infectious particles to move out from that area.

They wear protective clothing that protects them from any spillage during the research work but even then it is a great challenge to scientists to prevent the spreading of these infectious diseases.

Some scientists and doctors working on ebola virus are killed by the disease ebola because they came in contact with this virus during their work.

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