Mathematical tools for planning effective intervention scenarios for sexually transmitted diseases.
BACKGROUND
We studied the dynamics of sexually transmitted diseases in structured populations, deriving analogies from the theory of metapopulations.


OBJECTIVE
The goal was to study the impact of potential interventions, such as reducing the probability of transmission (e.g., by condom use), reducing the duration of infectiousness (e.g., by early diagnosis and treatment), or reducing the number of new contacts.


METHODS
A structured SIS model was used for the study.


RESULTS
We extended the concept of core groups to the concept of nodal epidemiologic contribution (NEC) by considering the contribution that an individual in a particular (social, spatial, or other such) group makes to a target quantity, such as the threshold condition for disease persistence, the equilibrium prevalence, or the number of disease transmissions in the long term. The measures for NEC derived here are analogous to patch values in metapopulation theory, which measure the contributions of particular habitat patches to various-aspects of metapopulation dynamics.


CONCLUSIONS
Our results highlight that intervention measures should be targeted especially promptly if the goal is the complete eradication of the disease, as the variance in the contributions made by the individuals is the highest for this case.
Ovaskainen
Otso T
OT
Metapopulation Research Group, Department of Ecology and Systematics, P.O. Box 65, Viikinkaari 1, FIN-00014 University of Helsinki, Finland. otso.ovaskainen@helsinki.fi
Grenfell
Bryan T
BT
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D011157:Population Dynamics; D012307:Risk Factors; D012725:Sexual Behavior; D012749:Sexually Transmitted Diseases / Q000453:epidemiology / Q000517:prevention & control / Q000635:transmission*