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Study details distribution of dengue cases in Campinas

Research finds that groups that have worse socioeconomic and environmental conditions are more susceptible to the disease

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The combination of factors such as the high number of properties occupied by tire shops, recycling material depots and mechanical workshops with the intense mobility of the population comprises a potential risk for the occurrence of dengue in Campinas. The finding is part of Igor Cavallini Johansen's doctoral thesis in Demography, defended at the Institute of Philosophy and Human Sciences (IFCH) at Unicamp. The work was supervised by professor Roberto Luiz do Carmo and co-supervised by professor Luciana Correia Alves.

In his research, Johansen investigated the socio-environmental factors that contributed to the occurrence of dengue epidemics in Campinas between 2007 and 2015. In that period, the three largest dengue epidemics faced by the municipality were recorded (2007, 2014 and 2015 ). In the nine years considered, more than 123 thousand cases of the disease were reported in the city. “Dengue is a multicausal disease. Factors related to the virus, the vector and the characteristics of the population may eventually favor the emergence of epidemics. The purpose of the thesis was to verify, in the face of historical epidemics, whether all groups of the population and all regions of the municipality were affected equally or whether there were certain population segments, residing in specific spaces, that were more affected by the disease”, explains the author of the work.

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One of the “strategic points” identified during fieldwork: locations act as potential breeding grounds for Aedes aegypti

At the end of the analyses, the demographer found that groups that have worse socioeconomic conditions and that live in places with worse environmental quality are at greater risk of contracting the dengue virus. In other words, people who live in places with a greater number of “strategic points”, as properties occupied by tire shops, recycling material depots, mechanical workshops, etc., are more susceptible to the disease; who have lower per-capita income; who live in neighborhoods with a higher proportion of unpaved streets; and who live in single-story houses instead of apartments. “It is also worth pointing out that data analysis indicated that women are the ones who most report dengue cases. Furthermore, the most affected groups are between the ages of 15 to 19 and 30 to 34 years old”, points out Johansen.

The work also found that Campinas presents epidemic peaks in line with other municipalities in the Metropolitan Region, especially Sumaré and Hortolândia, to which it is linked by intense daily population exchanges. According to data from the 2010 Demographic Census, close to 113 thousand people travel daily from other cities to Campinas, for work or study purposes. At the same time, around 33 thousand people leave Campinas towards municipalities in the region.

The demographer explains that he decided to incorporate this aspect into the study because, if infected, a person could be bitten in a location other than where they live by the dengue vector, Aedes aegypti, transmitting the virus to the mosquito, which in turn could infect others. people in that locality. “This process explains part of the dynamics of dengue distribution, which begins in a certain location and tends to spread to others. In the case of the three municipalities mentioned, dengue from Campinas can be redistributed to Hortolândia and Sumaré, and the opposite is also possible”, points out Johansen.

Photo: Disclosure
Intense movement of people between Campinas and neighboring cities favors the distribution of dengue

A reality that makes dengue control in Campinas difficult, according to the doctoral thesis, is the large number of closed houses and residents who refuse to open the doors of their homes to inspect possible breeding grounds for Aedes aegypti. According to the research, more than half of the homes (50,5%) in the Northern Region of the municipality, where the district of Barão Geraldo and neighborhoods such as Jardim Santa Mônica and Jardim Aurélia are located, were not inspected by health agents. The lack of inspection of these units, observes the demographer, generates two problems. “On the one hand, it leads to the production of incomplete data on the real level of infestation in the municipality. On the other hand, it prevents so-called mechanical control, that is, the elimination or treatment of breeding sites found, which is very serious,” he considers.

The study also found that the common period for epidemic processes in the interval considered occurred especially between the end of March and the end of April of each year, with a concentration in populations residing in the South, Southwest and Northwest regions of Campinas. “What we were able to verify was that the distribution of dengue cases is not random. It focuses especially on areas that present worse socioeconomic and environmental conditions. The population in the central region of the municipality, generally more affluent, in addition to living predominantly in buildings [Aedes has difficulty reaching high floors], is less affected by epidemics, regardless of their size. Thus, due to specific conditions, these groups were not heavily affected even in the biggest dengue epidemics that the municipality faced, in 2007, 2014 and 2015, which presented more than 11 thousand, 42 thousand and 65 thousand cases, respectively”.

On the other hand, continues the author of the thesis, there are populations that are systematically affected by the disease, as is the case of those who live in the aforementioned South, Southwest and Northwest regions, which generally have worse socioeconomic and environmental conditions. These regions include neighborhoods such as Jardim Campo Belo, Jardim Fernanda and Parque Oziel (South); Jardim Campos Elíseos, Industrial Districts of Campinas (DICs) and Vila União (Southwest); and Florence, Ipaussurama and Satélite Íris gardens (Northwest). “These locations still have important deficiencies in terms of environmental sanitation. In the field research I carried out, I was able to verify that these conditions are different from the rest of the municipality”, assures Johansen.

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Demographer Igor Cavallini Johansen, author of the thesis: “Dengue control needs to be carried out from the perspective of shared responsibilities”


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In the methodology adopted by the demographer, the geocoding technique was applied, which can be explained as the location of an address on the map. With the residential addresses of the approximately 123 thousand cases of dengue officially reported in Campinas during the period taken for analysis, the researcher sought to locate them with the aim of establishing the coordinates (latitude and longitude) of each of them. After a series of attempts, Johansen achieved a success rate of 93,4%, quite significant given that studies that used the same tool achieved rates between 80% and 90%. “With the exact location of the cases, we were able to verify where and when there were the highest concentrations of dengue in Campinas in the selected period, and then compare with the characteristics of the population and environment in these locations. This investigation was carried out using spatial analysis techniques and classical statistical modeling”, explains the researcher.

Last but not least, the research analyzed the main types of containers that favor the development of Aedes aegypti in Campinas. “In addition to the strategic points, which are important factors for the vector and the occurrence of the disease, at home, the main breeding sites identified, representing 64,8% of the total containers, were mobile deposits such as plant pots, buckets, trays of refrigerator/air conditioning and construction materials. This means that most of the breeding sites found in the municipality's homes are avoidable. It is important to emphasize this issue because, to be effective, dengue control needs to be carried out from the perspective of shared responsibilities. In other words, if on the one hand the public administration has the fundamental role of offering adequate environmental sanitation and urban planning to avoid the production of environmental conditions favorable to Aedes aegypti, on the other hand the population also needs to mobilize to help control the vector within the scope residences”, ponders the author of the thesis.

Johansen's expectation is that the results of his work can contribute to the development of public policies focused on certain population segments and specific locations, promoting the rationalization of public resources and the enhancement of activities already developed. The demographer received a grant from the National Council for Scientific and Technological Development (CNPq) and funding from the Coordination for the Improvement of Higher Education Personnel (Capes), the latter to pay for studies carried out at the School of Public Health at Harvard University, in the States Unidos, where the researcher completed his sandwich doctorate.

 

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