The Summary Index of Malaria Surveillance (SIMS): a stable index of malaria within India
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RESEARCH
Open Access
The Summary Index of Malaria Surveillance (SIMS): a stable index of malaria within India Alan A Cohen1*, Neeraj Dhingra2, Raju M Jotkar3, Peter S Rodriguez1, Vinod P Sharma4, Prabhat Jha1
Abstract Background: Malaria in India has been difficult to measure. Mortality and morbidity are not comprehensively reported, impeding efforts to track changes in disease burden. However, a set of blood measures has been collected regularly by the National Malaria Control Program in most districts since 1958. Methods: Here, we use principal components analysis to combine these measures into a single index, the Summary Index of Malaria Surveillance (SIMS), and then test its temporal and geographic stability using subsets of the data. Results: The SIMS correlates positively with all its individual components and with external measures of mortality and morbidity. It is highly consistent and stable over time (1995-2005) and regions of India. It includes measures of both vivax and falciparum malaria, with vivax dominant at lower transmission levels and falciparum dominant at higher transmission levels, perhaps due to ecological specialization of the species. Conclusions: This measure should provide a useful tool for researchers looking to summarize geographic or temporal trends in malaria in India, and can be readily applied by administrators with no mathematical or scientific background. We include a spreadsheet that allows simple calculation of the index for researchers and local administrators. Similar principles are likely applicable worldwide, though further validation is needed before using the SIMS outside India.
Background Malaria in India has a long and tumultuous history. Apparently not widespread before British agricultural projects created ideal breeding conditions for the mosquito vectors, by the end of the 19th century, malaria had become a severe public health concern: a constant endemic problem in northeastern regions such as Bengal and a periodically ravaging epidemic in the northwestern states such as Punjab, where a single epidemic killed in excess of 300,000 people in late 1908 [1-3]. During this time, falciparum malaria - substantially more severe and deadly than the other species - became widespread. After independence, a control program nearly succeeded in eliminating malaria entirely, but in 1965, on the verge of success, funding was cut, and there was a substantial rebound of the disease in the following years[4,5]. Currently, malaria is much less severe than before the control program, but it continues to be * Correspondence: [email protected] 1 Centre for Global Health Research, Li Ka Shing Knowledge Institute, St Michael’s Hospital, Toronto, Ontario, Canada
a major public health concern, accounting for perhaps 1-2% of all deaths in India (AAC and PJ, unpublished data). In some states, particularly Orissa, disease burden is much worse[5]. As part of the National Malaria Eradication Programme (which became the National Vector-born Disease Control Program, or NVBDCP), a surveilla
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