Ginny (Virginia) Pitzer

My research focuses on using mathematical modeling and statistical methods to examine heterogeneities in the transmission and distribution of emerging infectious diseases.

Specific interests include:

Factors associated with heterogeneity in the transmission of SARS

Heterogeneity in transmission, such as the presence of “superspreaders”, played an important role in the emergence and subsequent spread of severe acute respiratory syndrome (SARS). A major challenge is to disentangle the factors contributing to this heterogeneity, which include:

• the number of contacts
• the duration of infectiousness (or exposure of a given contact)
• biological factors that determine the infectiousness of a SARS case and the susceptibility of his/her contacts

Building on earlier work that I did examining the transmission of SARS to household contacts during the 2003 outbreak in Hong Kong, I hope to focus on the biological factors (e.g. age, gender, markers of disease progression) that correlate with individual variation in infectiousness and/or susceptibility, and determine whether there is evidence for additional heterogeneity beyond these factors.

The role of incomplete immunity in the spatio-temporal dynamics of rotavirus

While much of the focus has been on respiratory transmitted infections such as influenza, it may be that the next important emerging pathogen is one with an alternative route of transmission. The dynamics of enterically transmitted infections with imperfect immunity are relatively poorly understood.

Rotavirus is one such pathogen which causes a considerable burden of diarrheal disease in both human and animal populations, and for which widespread implementation of vaccination is on the horizon. By developing a transmission model that incorporates specific information on the dynamics of rotavirus infection such as the incomplete nature of immunity to re-infection, I hope to:

• Examine the relative contributions of intrinsic versus extrinsic factors in determining the spatio-temporal pattern of rotavirus incidence in the U.S.
• Explore the potential impact of vaccination on the incidence of rotavirus-associated severe diarrhea