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Microbiology: Ditch the term pathogen

The term pathogen started to be used in the late 1880s to mean a microbe that can cause disease. Ever since, scientists have been searching for properties in bacteria, fungi, viruses and parasites that account for their ability to make us ill. Some seminal discoveries have resulted — such as the roles of various bacterial and fungal toxins in disease. Indeed, our oldest and most reliable vaccines, such as those for diphtheria and tetanus, work by prompting the body to produce antibodies that neutralize bacterial toxins.

Yet a microbe cannot cause disease without a host. What actually kills people with diphtheria, for example, is the strong inflammatory response that the diphtheria toxin triggers, including a thick grey coating on the throat that can obstruct breathing. Likewise, it is the massive activation of white blood cells triggered by certain strains of Staphylococcus and Streptococcus bacteria that can lead to toxic-shock syndrome.