How do infectious diseases spread if there is no direct contact between hosts?

Despite complete movement bans and other bio-security measures, transmission of infectious animal diseases occurred during the last epidemics of, for example, foot-and-mouth disease, classical swine fever and avian influenza in the Netherlands and abroad.

Promovendus drs. BAD (Bram) van Bunnik
Promotor MCM (Mart) de Jong
Copromotor dr. TJ (Thomas) Hagenaars
Copromotor Dr. G Nodelijk
Organisatie Wageningen University, Quantitative Veterinary Epidemiology

ma 23 juni 2014 13:30 tot 15:00

Locatie Auditorium, building number 362
Generaal Foulkesweg 1
6703 BG Wageningen

With the aid mathematical modelling it has been shown that the transmission between spatially separated animals  as observed in transmission experiments does not take place via direct (airborne) transmission, but rather through slow contamination of the environment between sending and receiving animals (via a combination of transport processes). This process is characterised by a build-up of infectious material in the environment until enough infectious material is accumulated at the receiving animal to cause infection. 

Decay rate of the pathogen

The duration of this delay before first transmission occurs proved to be highly dependent on the decay rate of the pathogen in the environment. This form of transmission was shown to play an important role in intensive care units of hospitals too. Another important conclusion from the research is that transmission of pathogens with a low decay rate can occur at distant locations and long after an infectious source is removed.