Presentation of the NosoSim platform

NosoSim is an agent-based platform which simulates pathogen transmission in a geographically realistic hospital ward. Human agents such as patients and health-care workers circulate in the ward; their actions are reproduced at all times.

An executable version of the model is downloadable here.

    The hospital ward in NosoSim

Geographical description

The hospital ward is composed of corridors, patient rooms and staff rooms, among which human agents may move. Any geographical combination of these elements may be entered into NosoSim and used for simulations.

Example 1 : corridor-like hospital ward

Example 2 : hospital ward based on observations in Henri Mondor hospital in Paris, France

Health-care workers (HCWs)

A given number of patients (or patient rooms) are assigned to each HCW.

All HCWs have a profile, which determines their daily timetable, and the duration and nature (in terms of time spent in direct contact) of their patient visits. For each HCW profile present in the ward, the HCW to patient ratio is entered as a parameter.

Examples of HCW profiles in a 18-bed ICU :

 ProfilePresence in the ward
No. of assigned patients
No. of visits per patient
 Duration of patient visits
 Portion of visits spent in direct  contact
 Day nurse
 7AM-7PM 2 3 25 minutes
 Physician 9AM-6PM 6 1 25 minutes
 Therapist 9AM-6PM18
 1 15 minutes


Patients do not move from the room they are allocated, except for entering or leaving the ward. Rooms are supposed to be single. The bed occupancy may be fixed in simulations.

        Pathogen circulation in NosoSim

One or several pathogens may circulate in the ward.

For each simulation, users may either select circulating pathogens from a built-in library, or define a new pathogen. For each pathogen, the duration of colonization is entered, as well as the transmissibility and the duration of natural immunity following decolonization.

Image : capture d'écran de l'interface de contrôle des bactéries en présence

Colonization of patients and HCWs

NosoSim simulated human colonization with these pathogens, rather than infection.

Patients are colonized until they are detected and isolated, or effective antibiotics are prescribed to them, or they leave the ward. A temporary immune period follows their decolonization.

HCWs may only be transiently colonized for a short duration, which is provided for each pathogen. No immune period follows the end of transient colonization.

Transmission of colonization

Colonization is transmitted from a patient to another via the hands of HCWs. During all patient-HCW contacts, there is a chance of colonization transmission; the transmission probability per minute of contact depends on the involved pathogen as well as on the profile of the HCW. However, the probability of patient-to-HCW transmission is the same as that of

HCW-to-patient transmission.