History of Emerging Infectious Diseases - Factors Impairing Identification of Pathogens

Factors Impairing Identification of Pathogens

Factors which have been identified as impeding the identification of pathogens include the following:

1. Lack of animal models: Experimental infection in animals has been used as a criterion to demonstrate a disease-causing ability, but for some pathogens (such as Vibrio cholerae, which cause disease only in humans) animal models do not exist. In cases where animal models were not available, scientists have sometimes infected themselves or others to determine an organism's disease causing ability.

2. Pre-existing theories of disease: Before a pathogen is well-recognized, scientists may attribute the symptoms of infection to other causes, such as toxicological, psychological, or genetic causes. Once a pathogen has been associated with an illness, researchers have reported difficulty displacing these pre-existing theories.

3. Variable pathogenicity: Infection with pathogens can produce varying responses in hosts, complicating the process of showing a relationship between infection and the pathogen. In some infectious diseases, the severity of symptoms has been shown to be dependent on specific genetic traits of the host.

4. Organisms that look alike but behave differently: In some cases a harmless organism exists which looks identical to a disease causing organism with a microscope, which complicates the discovery process.

5. Lack of research effort: Slow progress has been attributed to the small numbers of researchers working on a pathogen.