Tuesday, September 06, 2011

Tracking Cholera Outbreaks in Post-Earthquake Haiti

  • Cholera has recently returned to Haiti, where it poses a deadly threat. A new computer-forecasting tool is enabling researchers to predict how the disease is spreading in order to contain it.Technological tools have recently helped track epidemics of influenza and tropical diseases such as dengue fever. With a new project, researchers are using computer forecasting to predict outbreaks of cholera, a highly contagious and deadly disease.
    In earthquake-damaged Haiti, cholera, spread by both human contact and contaminated water, is on the rise. But its multiple means of transmission make the disease difficult to track and contain.

    In Haiti, cholera is spread both by contaminated water and human contact, making the disease difficult to track. (Source: Ohio State University)
    A team of researchers from Ohio State University and the Centers for Disease Control and Prevention (CDC) are working on a computer-modeling tool to help track where and how the disease is spreading.
    With the tool, researchers have already identified several patterns in cholera outbreaks. New strains of the disease, for example, usually cause a small outbreak of cases in the fall and then a larger epidemic in the summer.
    “Before the earthquake, cholera hadn't been reported in Haiti in decades, so we're in new territory as far as what the disease will do there in the coming months and years,” said Joseph Tien, professor of mathematics at Ohio State, in a statement. “There are lots of different factors to consider -- environmental conditions affecting the ability of the cholera bacteria to persist in water bodies, variation in water quality and sanitation in different locales, infection-derived immunity, seasonal drivers such as rainfall.  We're hoping to use mathematics to help piece the puzzle together.”
    Tien, along with other Ohio State researchers, including Marisa Eisenberg, has made several trips to Haiti, where cholera is currently rampant.
    “Two neighbors may both get cholera, but they didn’t necessarily get it from the same source,” Eisenberg explained in a statement. Even if one source is contained, another source can continue to spread the disease.
    One problem in creating an accurate prediction tool is the different types of data reported by various organizations. Local hospitals, UNICEF and the United Nations all provide information at different scales, such as by country or by city. Eisenberg is working on algorithms that help align and analyze different data at once.
    By identifying sources of cholera and then tracking the movement of that source, the forecasting tool can help predict and prevent outbreaks of the disease. It is able to predict the likelihood of cholera based on various factors, including population, water sources, travel and weather.
    As many organizations begin to run out of relief funds, the computer program should enable groups to use resources in optimized ways.
    A paper about the research was recently published in Annals of Internal Medicine. The National Science Foundation is providing funding for the team.

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