Elsevier

Acta Tropica

Volume 113, Issue 3, March 2010, Pages 234-240
Acta Tropica

Seroprevalence and risk factors for dengue infection in socio-economically distinct areas of Recife, Brazil

https://doi.org/10.1016/j.actatropica.2009.10.021Get rights and content

Abstract

Brazil currently accounts for the majority of dengue cases reported in the Americas, with co-circulation of DENV 1–3. Striking variation in the epidemiological pattern of infection within cities has been observed. Therefore, investigation of dengue transmission in small areas is important to formulate control strategies. A population-based household survey was performed in three diverse socio-economic and environmental areas of Recife, a large urban center of Brazil, between 2005 and 2006. Dengue serostatus and individual- and household-level risk factors for infection were collected in residents aged between 5 and 64 years. A total of 2833 individuals were examined, and their residences were geo-referenced. Anti-dengue IgG antibodies were measured using commercial ELISA. The dengue seroprevalence and the force of infection were estimated in each area. Individual and household variables associated with seropositivity were assessed by multilevel models for each area. A spatial analysis was conducted to identify risk gradients of dengue seropositivity using Generalized Additive Models (GAM). The dengue seroprevalence was 91.1%, 87.4% 74.3%, respectively, in the deprived, intermediate and high socio-economic areas, inversely related to their socio-economic status. In the deprived area, 59% of children had already been exposed to dengue virus by the age of 5 years and the estimated force of infection was three times higher than that in the privileged area. The risk of infection increased with age in the three areas. Not commuting away from the area was a risk factor for seropositivity in the deprived area (OR = 2.26; 95% CI: 1.18–4.30). Number of persons per room was a risk factor for seropositivity in the intermediate (OR = 3.00; 95% CI: 3.21–7.37) and privileged areas (OR = 1.81; 95% CI: 1.07–3.04). Living in a house, as opposed to an apartment, was a risk factor for seropositivity in the privileged area (OR = 3.62; 95% CI: 2.43–5.41). The main difference between the privileged and other areas could be attributed to the much larger proportion of apartment dwellers. Intensive vector control, surveillance and community education should be considered in deprived urban areas where a high proportion of children are infected by an early age.

Introduction

Dengue is a vector-borne disease considered a global public health threat in tropical and subtropical countries. Approximately 2.5 billion people – two fifths of the world population – are at risk of infection, mostly in urban regions given that the main vector (Aedes aegypti) is widespread and well adapted to such environments (Gubler, 1998, WHO, 2009). South-east Asia is one of the most affected regions, where dengue haemorrhagic fever (DHF) has been a leading cause of hospitalization and death among children (WHO, 2009). In the Americas, where all four serotypes (DENV 1–4) circulate, dengue incidence has increased dramatically in the last two decades (PAHO, 2008, Torres and Castro, 2007). From 2001 to 2008, more than 5 million cases of dengue were reported, including approximately 100,000 cases of dengue hemorrhagic fever and 1500 deaths (PAHO, 2008). Brazil currently accounts for the majority (∼80%) of the cases reported in Latin American, with co-circulation of three serotypes (DENV 1–3) in most of the country, with sporadic epidemic waves in several urban areas (Teixeira et al., 2009, PAHO, 2008, Siqueira et al., 2005).

Dengue has a broad spectrum of manifestations and the number of reported cases underestimates the number of infections, because most are asymptomatic and not all symptomatic ones are reported (Kyle and Harris, 2008). Hence, serosurveys and longitudinal studies are used to assess past and current dengue infection and transmission rates at the population level (Thai et al., 2005, Endy et al., 2010, Teixeira et al., 2002).

The spatial distribution of dengue infection can vary greatly between neighboring areas in urban settings (Vanwambeke et al., 2006, Reiter et al., 2003, Vallee et al., 2009, Almeida et al., 2007). Among possible individual and household risk factors, predictors of infection have included higher age (Yew et al., 2009), low socio-economic status (Vasconcelos et al., 1998, Siqueira et al., 2004), lower education level (Teixeira et al., 2002, Silva-Nunes et al., 2008) and lack of household protective measures such as unscreened houses or absence of air-conditioning (Ko et al., 1992, Reiter et al., 2003) In turn, this shows the importance of understanding small-scale variation in dengue infection when formulating control strategies.

The aim of the current population-based household study, conducted in the city of Recife in the Northeast of Brazil, was to estimate the prevalence of dengue infection between privileged and non-privileged areas and identify individual and area-level risk factors for infection in three urban areas. In addition, we describe the spatial distribution of risk of dengue infection to explore intra-urban variations in dengue infection that could be valuable in suggesting alternative control strategies.

Section snippets

Study settings

Recife (1.5 million inhabitants) lies on the Atlantic coastal plain (8°03′S 34°52′W) at a mean altitude of 5 m above sea, level and is relatively flat. The city's area of 217 km2 is divided in 94 neighborhoods (IBGE, 2009) as shown in Fig. 1. Its climate is tropical humid, with average temperature of 25 °C and rainfall of around 2000 mm per year, with no major variation between neighborhoods (ITEP, 2009). Dengue vector surveillance and control covers the whole city and relies on premise visits for

Results

A total of 2819 individuals, approximately half of them aged 5–14 years, were analyzed in the three areas. Participants living in the high and intermediate socio-economic status areas were, on average, more highly educated and more likely to commute outside their home area (Table 1). Around 90% of people lived in houses in the deprived and intermediary areas, compared to more than 40% in apartment buildings in the high socio-economic area. Around 25% of the dwellings in the high socio-economic

Discussion

This household survey of a Northeastern Brazilian city found dengue seroprevalence ranging from 74% to 91%, with the risk being inversely associated with socio-economic status. This variation in prevalence is unlikely to be explained by climate, because local temperature, rainfall, humidity and altitude are similar among these three areas of the city. Further, entomological research found that infestation rates of Aedes aegypti are similarly high in the three study areas (Regis et al., 2008).

In

Acknowledgments

The authors acknowledge the support of the National Institute of Allergy and Infectious Diseases (NIAID/NIH), Grant U19 AI56541 and PDTIS RVR09-FIOCRUZ. Martelli CMT, Albuquerque MFP and Souza WV were partially supported by Conselho Nacional de Desenvolvimento Científico e Tecnológico -CNPq (scholarships 307963/2004-7, 305947/2006-0, respectively)

References (38)

  • P.F. Vasconcelos et al.

    Dengue epidemic in Fortaleza, Ceara: randomized seroepidemiologic survey

    Rev. Saude Publica.

    (1998)
  • M.C. Almeida et al.

    Intra-urban dynamics of dengue epidemics in Belo Horizonte, Minas Gerais State, Brazil, 1996–2002

    Cad. Saude Publica.

    (2008)
  • M.C.M. Almeida et al.

    Spatial vulnerability to dengue in a Brazilian urban area during a 7-year surveillance

    J. Urban Health

    (2007)
  • R. Barrera et al.

    Stratification of a hyperendemic city in hemorrhagic dengue

    Rev. Panam. Salud Publica.

    (2000)
  • D. Collett

    Modelling Binary Data. Text in Statistical Science

    (2002)
  • J.R. Egger et al.

    Reconstructing historical changes in the force of infection of dengue fever in Singapore: implications for surveillance and control

    Bull. World Health Organ.

    (2008)
  • T.P. Endy et al.

    Spatial and temporal circulation of dengue virus serotypes: a prospective study of primary school children in Kamphaeng Phet, Thailand

    Am. J. Epidemiol.

    (2002)
  • T.P. Endy et al.

    Prospective cohort studies of dengue viral transmission and severity of disease

    Curr. Top. Microbiol. Immunol.

    (2010)
  • H. Gomez-Dantes et al.

    Dengue in the Americas: challenges for prevention and control

    Cad. Saude Publica.

    (2009)
  • D.J. Gubler

    Dengue and dengue hemorrhagic fever

    Clin. Microbiol. Rev.

    (1998)
  • J.E. Kelsall et al.

    Spatial variation in risk: a nonparametric binary regression approach

    Appl. Statist.

    (1998)
  • Y.C. Ko et al.

    The predisposing and protective factors against dengue virus transmission by mosquito vector

    Am. J. Epidemiol.

    (1992)
  • B. Koh et al.

    The 2005 dengue epidemic in Singapore: epidemiology, prevention and control

    Ann. Acad. Med. Singapore

    (2008)
  • G. Kuno

    Review of the factors modulating dengue transmission

    Epidemiol. Rev.

    (1995)
  • J.L. Kyle et al.

    Global spread and persistence of dengue

    Annu. Rev. Microbiol.

    (2008)
  • C.W. Lian et al.

    Spatial, environmental and entomological risk factors analysis on a rural dengue outbreak in Ludun District in Sarawak, Malaysia

    Trop. Biomed.

    (2006)
  • PAHO

    Number of reported cases of dengue and Dengue Hemorrhagic Fever (DHF). Region of the Americas (by country and subregion)

    EID Updates: Emerging and Reemerging Infectious Diseases, Region of the Americas

    (2008)
  • L. Regis et al.

    Developing new approaches for detecting and preventing Aedes aegypti population outbreaks: basis for surveillance, alert and control system

    Mem. Inst. Oswaldo Cruz

    (2008)
  • P. Reiter et al.

    Texas lifestyle limits transmission of dengue virus

    Emerg. Infect. Dis.

    (2003)
  • Cited by (0)

    View full text