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The model epidemic fights against a real one

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12.10.2007

There exist quite a lot of mathematical models, which describe the infectious diseases spreading process, but they do not take into account the demographic structure of a megapolis, its inhabitants’ complicated contact system. A new model developed by joint effort of researchers from the N.E. Zhukovsky Central Aerohydrodynamics Institute (TsAGI) and the Institute of Mathematical Modelling, Russian Academy of Sciences, is individual-oriented.

The new model takes everything into account - the quantity of inhabitants in the city, their sex and age, social status and family status, place of employment and relaxation: how spacious the premises are and if all employees have turned up to work today. The model also requires the data about the disease: its duration, clinical course options, if the persons who have been ill with it forms the immunity, if the persons are inoculated against the disease, what the probability of infection is in different situations. For example, at school or in public transport.

In essence, the model reproduces the day by day life of a big city to the minutest detail. How many persons have fallen ill and stayed at home, how many mothers stay with sick children but go shopping during the day and may get infected or can infect others. Out of the persons who came to work some are virus carriers. Some will bring the virus to a small-scale enterprise, but others – to a large-scale entity. The person who avoided infection during the day will go to the cinema in the evening, and there is probability that he/she will come across a virus carrier there. Some quantity of people will consult the doctor, but others – will take a sip of Coldrex – and will return to work thus infecting their colleagues. All these complicated and multiple contacts determine disease spreading and they all are taken into account by the new model.

Based on statistical data on Dresden, presented by Doctor W. Schmidt, head of statistical department of Dresden, and statistical data on Moscow, the researchers have developed a “model epidemic”. Having reviewed it in the minutest detail, they made some conclusions.

The most active part in disease spreading is played by children – schoolchildren and children in kindergartens. At that, the more children are vaccinated, the less citizens will fall ill. An important role is played by the family, which serves as an infectious bridge between various institutions of the city.

Breaking the well-known rule “once fallen ill – stay at home” leads to noticeable increase in the number of sick persons. And the custom to provide additional vacation during the epidemic does not tell on the quality of the diseased individuals, this leads only to increase in epidemic duration. Admittedly, well-chosen time for vacation will allow to assign more evenly the load on polyclinics, avoiding the peaks typical of epidemic.

The persons dealing with epidemiology will say that these are well-known facts confirmed by medical statistics. We can exclaim, “It means that the model works!” Having made sure of its capacity for work, one can model the influence of various antiepidemic measures and choose the most efficient measures.

The only “but” is that the model’s operation needs reliable demographic and statistical data per each city.

Nadezda Markina | Source: alphagalileo
Further information: www.informnauka.ru

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