New strategies area unit being tried to spot biological agents and analyze them, however these technologies area unit still in their early stages. Most micro-organisms area unit harmless to humans however some have evolved mechanisms that modify them to infect and cause illness. Infectious agents area unit biologically numerous and embrace viruses, bacteria, fungi, protozoa and parasites. Biological agents, or pathogens, area unit present within the surroundings and most area unit either harmless or useful to humans. However, some might cause health hazards for the subsequent reasons, eg the biological agents have evolved special characteristics that modify them to cause illness, or people exposed to the biological agents area unit vulnerable to sick effects caused by organisms or their merchandise. A biological hazard, or biohazard, could be a biological substance that poses a threat to the health of living organisms, primarily humans. this might embrace a sample of a organism, virus or poisonous substance which will adversely have an effect on human health. A biohazard might even be a substance harmful to different animals.