New Insights From Tracking Dengue Incidence In Thailand

Researchers tracking the incidence of dengue fever in Thailand over a period of almost 40 years have uncovered new insights about the disease.

Asian Scientist (Jul. 9, 2013) – Researchers tracking the incidence of dengue fever in Thailand over a period of almost 40 years have uncovered new insights about the disease.

In their study, published in the Journal of the Royal Society Interface, the researchers worked with a large database that tracked a total of over 12,000 dengue infections, from 1973 to 2010, at the Queen Sirikit National Institute of Child Health in Bangkok.

“This dataset from Bangkok is unique, we don’t know of any other data like this in the world,” said Nicholas Reich, a biostatistician who led the study.

“It provided us with a unique opportunity to analyze long-term disease patterns in ways that we are not able to do with datasets of shorter duration.”

By using a statistical model developed specifically for the purpose, the researchers estimated that after an initial dengue infection, a person is protected from infection with other strains for between one and three years.

Researchers knew that a person’s immune response to infection with one dengue strain offered some protection against future infection with others. But this is the first time that this important clinical and epidemiological feature, known as cross-protection, has been characterized for dengue.

This is also the first explicit quantitative evidence that short-term cross-protection for dengue exists since human experimental infection studies performed in the 1940s and 1950s by Albert Sabin.

By extending existing methods for analyzing infectious disease time-series data, the researchers created and applied a new framework for estimating the duration and strength of cross-protection between multiple strains of an infectious disease.

Many multi-strain diseases such as dengue confer at least partial short-term cross-protection to people who come down with one. However, cross-protection introduces significant challenges to researchers trying to create an accurate model of disease transmission or to evaluate vaccine effectiveness.

Knowing how long cross-protection may last can help in planning well-controlled and more effective vaccine studies.

“Dengue is a unique and convenient disease for studying these dynamics of cross-protection,” said Reich.

“Many diseases either evolve too rapidly, like influenza, or have too many circulating subtypes, like malaria, for us to gain good traction on studying cross-protection.”

“But dengue is sort of a ‘goldilocks’ virus in this way. It has four circulating strains, which means that it’s in sort of a genetic diversity ‘sweet spot.’ There are not too many strains and not too few, which provides us with fertile ground for such study.”

The article can be found at: Reich et al. (2013) Interactions Between Serotypes Of Dengue Highlight Epidemiological Impact Of Cross-Immunity.

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Source: UMass; Photo Credit: James Gathany (jentavery)/Flickr.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.

Yew Chung is a postdoctoral research fellow at the Duke-NUS Graduate Medical School, Singapore.

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