Polio vaccine is usually provided in vials containing 10–20 doses of vaccine. A single dose of oral polio vaccine (usually two drops) contains 1,000,000 infectious units of Sabin 1 (effective against PV1), 100,000 infectious units of the Sabin 2 strain, and 600,000 infectious units of Sabin 3. The vaccine contains small traces of antibiotics—neomycin and streptomycin—but does not contain preservatives. In a generic sense, vaccination works by priming the immune system with an 'immunogen'. Stimulating immune response, by use of an infectious agent, is known as immunization. The development of immunity to polio efficiently blocks person-to-person transmission of wild poliovirus, thereby protecting
David Bruce (microbiologist) David Bruce (microbiologist) Major-General Sir David Bruce (29 May 1855 in Melbourne – 27 November 1931 in London) was a Scottish pathologist and microbiologist who investigated Malta fever (later called brucellosis in his honour) and African trypanosomiasis (sleeping sickness in humans and nagana in animals). He discovered a protozoan parasite transmitted by insects, later named "Trypanosoma brucei" after him. Working in the Army Medical Service and the Royal Army Medical Corps, his major scientific collaborator was his microbiologist wife Mary Elizabeth Bruce ("née" Steele), with whom he published more than thirty technical papers. Bruce was born in Melbourne, Australia to