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New model for calculating the global spread of epidemics
Avian flu, swine flu, SARS, EHEC - New human pathogens often present the risk of a pandemic in view of global networking. "The global spread of pathogens can have serious health, social and economic consequences and is a major challenge for the health of the population", report the Robert Koch Institute (RKI) and the Humboldt University in Berlin in a joint press release. In order to determine possible propagation paths of such global waves of infection, the researchers led by Dirk Brockmann, Professor at the Humboldt University in Berlin and project group leader at the RKI, have developed a new method of epidemiological modeling, which is published in the current issue of the science magazine "Science" The hidden geometry of complex, network-driven contagion phenomena ”is presented.
With the support of scientists from the ETH Zurich (Eidgenössische Technische Hochschule Zürich), a new mathematical theory had emerged "that improves the understanding of global spread of epidemics," according to the RKI and the Humboldt University. In this way, the “hidden geometry of global epidemics” becomes visible. The model enables both retrospective statements and forecasts of the propagation paths. For example, the place of origin of diseases can be determined more precisely in the future and at the same time predicted when an epidemic is likely to reach certain places in the world. In general, computer simulations that predict the spread of epidemics - similar to modern weather forecasts - "are extremely complex and require precise knowledge of disease-specific properties, which are not yet known, especially with new types of pathogens," report the Humboldt University and the RKI.
Effective removal is crucial for the spread of disease
The previous models for the spread of epidemics have a major weakness, since they generally work with geographical distances, but according to Brockmann and colleagues, these are no longer relevant today. "From the perspective of Frankfurt, for example, other metropolises like London or New York are effectively no further away than geographically close places like Bremen or Leipzig," says the scientists. In their model, they therefore replaced the geographical distance with the “effective distances”, which in the case of air traffic result directly from the travel flows of the air traffic network. “When many people travel from A to B, the effective distance from A to B is small, only a few people travel, and the effective distance is large,” the researchers explain. According to the scientists, the global air traffic network connects more than 4,000 airports worldwide through more than 25,000 direct connections. Over three billion passengers are transported every year, covering more than 14 billion kilometers a day, according to Brockmann and colleagues.
Predict the spread of epidemics and determine the place of origin
Today's mobility conditions often result in an extremely rapid global spread of pathogens. While the plague spread in Europe as a uniform wave front from south to north at a speed of four to five kilometers per day in the 14th century, modern epidemics reach between 100 and 400 kilometers per day, Brockmann explained. However, the model had shown that "contrary to all appearances, modern epidemic spread does not differ fundamentally from historical spread patterns." The spread is only obscured by the changed mobility patterns. A look at the geographical distribution patterns of SARS (2003) and swine flu (H1N1; 2009) with the help of their newly developed theory showed that the "complex spatiotemporal distribution patterns (become) regular, circular wave fronts that are easy to describe mathematically "The rates of disease spreading could thus be calculated relatively easily and it could be determined" at what point in time a wavefront is likely to reach any place in the world or where an infection has started ", according to the scientists' conclusion. (fp)
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