Spatial analysis of dengue transmission in a medium-sized city in Brazil

Departamento de Epidemiologia e Saúde Coletiva, Faculdade de Medicina de São José do Rio Preto, São José do Rio Preto, SP, Brasil.
Revista de Saúde Pública (Impact Factor: 0.73). 07/2005; 39(3):444-51.
Source: PubMed


To perform spatial analysis on dengue transmission in a medium-sized city in the interior of the State of São Paulo, Brazil, covering the period from September 1990 to August 2002.
Autochthonous cases with confirmation by laboratory tests were utilized. Population data on the city of São José do Rio Preto were obtained from the Brazilian Institute for Geography and Statistics and the municipal authorities. The cases were georeferenced according to street addresses and clustered according to the 432 census tracts in the municipality, thus resulting in thematic maps.
A rising trend in annual incidence was noted, with a peak in 2000/2001. From 1990 to 1994 the length of the transmission period reached a maximum of five months per year. This period increased in length over subsequent years. In the final year investigated, transmission occurred in all twelve months, without interruptions. Analysis of the period of highest incidence showed that the transmission did not occur uniformly. While 29% of the tracts registered incidences of less than 1,000 cases per 100,000 inhabitants, 5% of them had more than 5,000 cases.
A process of increasing endemicity was observed, with transmission throughout the year, without the need for virus introducers. The endemic characteristic of the transmission and the differentiated occurrence according to areas need to be taken into account when developing strategies for dengue control.

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    • "World Health Organization defines dengue hemorrhagic fever as the manifestation of high fever, hemorrhagic phenomena with hepatomegaly, and signs of circulatory failure. The evolution to hypovolemic shock and plasma leakage is characterized as dengue shock syndrome and can be fatal to patient (WHO 1997) In Sã o José do Rio Preto City (northwest region of Sã o Paulo State, Brazil), cases of DENV-1 were initially identified after 1990 through 1995 (Mondini et al. 2005). In 1996, DENV-2 became the most important predominant agent of dengue (Brazilian Ministry of Health 2008), and in 2005 and 2006, Sã o José do Rio Preto City suffered from a large DENV-3 outbreak with more than 15,000 reported cases (Mondini et al. 2009). "
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    ABSTRACT: Arboviruses are frequently associated with outbreaks in humans and represent a serious public health problem. Among the Brazilian arboviruses, Mayaro virus, Dengue virus (DENV), Yellow Fever virus, Rocio virus, Saint Louis Encephalitis virus (SLEV), and Oropouche virus are responsible for most of human cases. All these arboviruses usually produce undistinguishable acute febrile illness, especially in the acute phase of infection. In this study we investigated the presence of arboviruses in sera of 519 patients presenting acute febrile illness, during a dengue outbreak in São José do Rio Preto City (São Paulo, Brazil). A multiplex-nested RT-polymerase chain reaction assay was applied to detect and identify the main Brazilian arboviruses (Flavivirus, Alphavirus, and Orthobunyavirus genera). The molecular analysis showed that 365 samples were positive to DENV-3, 5 to DENV-2, and 8 to SLEV. Among the positive samples, one coinfection was detected between DENV-2 and DENV-3. The phylogenetic analysis of the SLEV envelope gene indicated that the virus circulating in city is related to lineage V strains. These results indicated that during that large DENV-3 outbreak in 2006, different arboviruses cocirculated causing human disease. Thus, it is necessary to have an efficient surveillance system to control the dissemination of these arboviruses in the population.
    Vector borne and zoonotic diseases (Larchmont, N.Y.) 03/2011; 11(3):291-300. DOI:10.1089/vbz.2009.0200 · 2.30 Impact Factor
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    Cladistics 26. · 6.22 Impact Factor
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    ABSTRACT: The service currently uses for monitoring the Dengue’s vectors, two indexes, the Breteau’s Index and the building infestation Index, both basing in the larval stage. These indexes do not propitiate information to identify the strategical containers breeding, keys to Ae. aegypti surveillance, because they indicates only the larvae forms presence and not the productivity in these containers. This research objectified to study the spatial distribution of the Ae. aegypti’s containers breeding and the importance of these in the maintenance of their vector’s population in urban conglomerates with high infestation’s density. The indexes gotten in 2004 had been analyzed in two scales: wards and blocks. Later, in the period of December/2004 to April/2005, we proceeded the biweekly collection of all immature mosquitoes forms in containers breeding in blocks with larvae’s high density, identified in the spatial analysis. The container’s productivity in blocks was analyzed using the Kernel’s method, being also verified the potentials of the vector’s adult females production in these, according for the characteristics of them. The joint participation of containers in the adult specimen production was also evaluated. The Kernel’s analysis identified strategical urban conglomerates with high infestation’s densities, demonstrating to be an efficient method to Ae. aegypti surveillance. The containers with volumes between 1 and 1,000 liters had been more productive, also playing the function of feeders for the secondary containers breeding situated in the neighborhood of them. The containers with volume less than 50ml had not demonstrated capacity to produce adult forms. The containers with volumes between 50 and 100ml and that with volume above 5,000 liters had been much less productive not having importance for the surveillance. The methodology used in this research can easily be incorporated by the service, being necessary to adopt the use of the geo processing in the routine.
    03/2006, Degree: Master, Supervisor: Reinaldo Souza Santos
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