Combining Routine Health Survey Data and Geographic Information Systems to Assess Stunting after the 2001 Earthquake in Peru

PLOS | One, Published Online 19 June 2015

By Henny Rydberg, Gaetano Marrone, Susanne Strömdahl, and Johan von Schreeb

“Background: Research on long-term health effects of earthquakes is scarce, especially in low- and middle-income countries, which are disproportionately affected by disasters. To date, progress in this area has been hampered by the lack of tools to accurately measure these effects. Here, we explored whether long-term public health effects of earthquakes can be assessed using a combination of readily available data sources on public health and geographic distribution of seismic activity.

ShakeMap image of the 2001 southern Peru earthquake.

“Methods: We used childhood stunting as a proxy for public health effects. Data on stunting were attained from Demographic and Health Surveys. Earthquake data were obtained from U.S. Geological Survey’s ShakeMaps, geographic information system-based maps that divide earthquake affected areas into different shaking intensity zones. We combined these two data sources to categorize the surveyed children into different earthquake exposure groups, based on how much their area of residence was affected by the earthquake. We assessed the feasibility of the approach using a real earthquake case – an 8.4 magnitude earthquake that hit southern Peru in 2001.

GIS-based map of the areas affected by the 2001 southern Peru earthquake.

“Results and conclusions: Our results indicate that the combination of health survey data and disaster data may offer a readily accessible and accurate method for determining the long-term public health consequences of a natural disaster. Our work allowed us to make pre- and post- earthquake comparisons of stunting, an important indicator of the well-being of a society, as well as comparisons between populations with different levels of exposure to the earthquake. Furthermore, the detailed GIS based data provided a precise and objective definition of earthquake exposure. Our approach should be considered in future public health and disaster research exploring the long-term effects of earthquakes and potentially other natural disasters.”

• Read the paper

Scientific Reports 5, Published 02 June 2015

By Kai Chen, Lei Huang, Lian Zhou, Zongwei Ma, Jun Bi, and Tiantian Li

“To examine the spatial variation of stroke mortality risk during heat wave, we collected 418 stroke mortality cases with permanent addresses for a severe heat wave (July 28–August 15, 2010) and 624 cases for the reference period (July 29–August 16, 2009 and July 27–August 14, 2011) in Nanjing, China. Generalized additive models were used to explore the association between location and stroke mortality risk during the heat wave while controlling individual-level risk factors. Heat wave vulnerability was then applied to explain the possible spatial variations of heat-wave-related mortality risk.

(1) Using reference period 1 (A2); (2) Using reference period 2 (A3). Maximum of daytime land surface temperatures (Terra/MODIS, 1 km resolution) in each period (19 days) was used as the temperature exposure indicator. White areas indicate that land surface temperatures were not available due to cloud cover. Maps were generated using ArcGIS (version 10.0; ESRI, Redlands, CA).

“The overall risk ratio (95% confidence intervals) of stroke mortality due to the heat wave in Nanjing was 1.34 (1.21 to 1.47). Geolocation was found to be significantly associated with the heat-wave-related stroke mortality risk. Using alternative reference periods generated similar results. A district-level risk assessment revealed similar spatial patterns. The highest stroke mortality risk observed in Luhe district was due to the combination of high heat exposure and high vulnerability. Our findings provide evidence that stroke mortality risk is higher in rural areas during heat waves and that these areas require future interventions to reduce vulnerability.”

• Read the paper