Dynamic Processes Underlying Persistent Polio Transmission in India

Principal Investigator

Joseph Eisenberg

Co-Principal Investigator

James Koopman

Additional Personnel

CJ Henry

Funding Sources

Michigan State University - Center for Advancing Microbial Risk Assessment (CAMRA)

About this Project

Polio transmission in northern India has been persistent despite high levels of vaccination of children. To explore the dynamics behind this, we analyzed a polio transmission model that explains the persistent transmission in northern India in the face of high vaccination as well as a wide variety of polio eradication experiences elsewhere. Our model based explanation of polio transmission dynamics captures important dynamics that should be considered in conducting the end game of polio eradication. Also, our model shows that under high transmission conditions circulation of wild poliovirus can be sustained by adults if two conditions are met: 1) childhood vaccination efforts are effective enough so that reinfection does not continually boost adult immunity to the levels it used to, and 2) the build up to high levels of childhood vaccination takes long enough so that adult immunity falls to levels that can sustain virus circulation. We further show that where lack of sanitation allows high levels of transmission, the time that it takes for adult immunity to fall to critical levels is shortened and the time a vaccination program has to eliminate transmission before transmission between partially immune adults can sustain transmission is also shortened.