Viruses are a string of dead proteins surrounded by a membrane. A virus can only replicate intracellularly, using the energy created by the infected cell. Viruses do not act—viruses react, and infect any available host, including intracellular bacteria.

When a virus infects intracellular bacteria, the damaging effect of the virus may be consistent with the predilection of the bacterial host. Pathogens can act synergistically to spread throughout the body with divergent effects, cause more severe disease in acute viral illnesses and influenza, and cause chronic disease.

Science often asks leading questions, such as did X cause Y, or does the patient have a specific pathogen, without identifying other potential infectious causes of Y, or other co-infections in the patient. Science could benefit by asking what causes Y, and what co-infections are present in patients, using modern diagnostic tools to test for a greater number of infectious pathogens.