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Published on: October 7, 2011
The impact of a physical geographic barrier on the dynamics of measles
A Vora1, D S Burke, D A T Cummings
1School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA.
Abstract:
Spatial-temporal patterns of measles incidence reflect the spatial distribution of human hosts. The heterogeneous spatial distribution of communities has been shown to introduce spatially dependent temporal lags in the timing of measles incidence. Incidence patterns reflect internal dynamics within a community and coupling of communities through the movement of infectious individuals. The central role of human movement in coupling dynamics in separate communities suggests that physical geographic barriers to movement should reduce spatial-temporal correlation. We examine measles dynamics in Maryland and Pennsylvania during the period of 1917-1938. The central feature of interest is the Chesapeake Bay, which separates Maryland into two distinct regions. We find that correlation of measles incidences in communities separated by the bay is reduced compared to communities not separated by the bay, suggesting the bay acted as a barrier to human movement during this time sufficient to decouple measles dynamics in Maryland counties.
Insights
Geographic barriers like the Chesapeake Bay can disrupt disease spread. Measles incidence patterns in Maryland and Pennsylvania showed reduced correlation across the bay, indicating its role in limiting disease transmission.
Area of Science:
- Epidemiology
- Spatial analysis
- Disease dynamics
Background:
- Measles incidence patterns are influenced by human host distribution and community interactions.
- Human movement connects separate communities, affecting disease transmission dynamics.
- Geographic barriers may impede movement and reduce spatial-temporal correlation in disease incidence.
Observation:
- The study analyzed measles dynamics in Maryland and Pennsylvania between 1917 and 1938.
- The Chesapeake Bay geographically separates Maryland into distinct regions.
- Measles incidence correlation was lower in communities separated by the bay.
Findings:
- The Chesapeake Bay acted as a significant barrier to human movement during the study period.
- Reduced human movement across the bay decoupled measles dynamics in Maryland counties.
- Spatial-temporal correlation of measles incidence was diminished by the geographic barrier.
Implications:
- Understanding geographic barriers is crucial for predicting and controlling infectious disease spread.
- Physical geography can influence disease transmission by limiting host movement.
- This research highlights the impact of landscape features on epidemiological patterns.
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