Infectivity

The infectivity describes the ability of a pathogen to infect a host. It is thus dependent on the pathogenicity and thus on the ability of a pathogen to invade a host and a reproduction in him. The infectivity is determined, inter alia by the determined in the laboratory number of newly formed pathogens per cell ( engl. burst size, resulting in a dose occasionally instead in a titer ), the minimum infectious dose and the epidemiological R0 value (see also basic reproduction number ) of the pathogen.

The term describes contagiousness, however, how easy or difficult a pathogen can be transmitted on the different, each pathogen infection typical ways. However, the terms of contagiousness (English contagiosity ) and infectivity (English infectivity ) in English usage are equivalent.

The knowledge of the infectivity and contagiousness of the person responsible for a disease pathogen is important in order to estimate how a disease may behave at the outbreak and whether any hygienic measures or disease - hygienic measures are necessary (eg, quarantine, etc.. ).

Examples

• Leprosy:

The pathogen of leprosy ( Mycobacterium leprae ) has low infectivity, that is, there is usually a long contact with sufferers necessary to become infected.

• Ebola virus:

The contrast Ebola virus has a high infectivity, ie it is enough a short contact with patients or infectious material to become infected.