The Influence of Urbanization Modes on the Spatial Circulation of Flaviviruses within Ouagadougou (Burkina Faso)

Abstract

Dengue is an emerging infectious disease of global significance. Although this virus has been reported for a long time, its significance within the burden of diseases in West Africa is not obvious, especially in Burkina Faso. Our objective was to evaluate flavivirus presence in Ouagadougou (Burkina Faso) and the link between anti-flavivirus antibody seroprevalence and urbanization modes. A population-based cross-sectional survey was conducted and 3015 children were enrolled from Ouagadougou districts with different types and degrees of urbanization (with/without equipment and high/low building density). Flavivirus (FLAV) IgM MAC-ELISA and FLAV indirect IgG ELISA were performed. Associations between FLAV IgG presence (sign of past infection) and various independent variables were assessed using the chi-square test and a multivariate logistic regression analysis. The apparent prevalence of past flavivirus infections among the enrolled children was 22.7% (95% CI: 22.4–26.7) (n = 685). Eleven children (0.4%; 95% CI: 0.61–2.14) were positive for FLAV IgM, indicating active transmission. Factors associated with flavivirus infection were identified among the enrolled children (age, sex), householders (educational level, asset index) and in the environment (building density, water access, waste management and house appearance); however, they showed great variability according to the city districts. The water access modality did not significantly influence FLAV IgG positivity. Conversely, apparently good practices of waste management had unexpected consequences (increased risk related to municipal dumpsters). Given the scale of ongoing urbanization and the spread of arboviral diseases, close collaboration between health and city stakeholders is needed.

Seroprevalence and factors associated with IgG anti‐DENV positivity in blood donors in Burkina Faso during the 2016 dengue outbreak and implications for blood supply

“…Donors living in rural areas were 50% less likely to have a positive IgG anti‐DENV test than those living in Ouagadougou (OR = 0.47; IC = 0.33–0.65, P = 0.000). Vairo et al . in Zanzibar, reported that donors living in urban areas were three time more likely to be infected.…”

“…Second, we did not perform an antibody neutralising assay to rule out cross‐reactions with other circulating flaviviruses. Indeed, as previous studies indicate regarding the circulation of other flaviviruses, the plaque reduction neutralisation test (PRNT) could have allowed us to determine antibody and serotype specificity. Moreover, it would have been necessary to perform a nucleic acid test (NAT) or at least serological tests for NS1Ag and IgM anti‐DENV to attempt to identify recent (primary or secondary) infections that are the most important concern for blood safety.…”

“…Previous studies showed that the presence of waste in the environment is a significant risk factor for flavivirus infections because empty plastic containers constitute peri‐domestic breeding sites for Aedes aegypti during the rainy season. In addition, dumpsters, where they exist, are not regularly emptied, providing breeding sites for vectors …”

“…Ouagadougou, the country and central region's capital city, with around 2.8 million inhabitants is the largest city of the country. Its population increased from 282 000 inhabitants in 1985 to 709 000 inhabitants in 1996 and to 2 637 303 inhabitants in 2016, concomitant with spectacular spatial growth . The major part of this spatial expansion can be described in terms of “peripheral urbanisation”.…”

“…Its population increased from 282 000 inhabitants in 1985 to 709 000 inhabitants in 1996 and to 2 637 303 inhabitants in 2016, concomitant with spectacular spatial growth. 33,37 The major part of this spatial expansion can be described in terms of "peripheral urbanisation". Indeed, next to the planned urbanisation with the parcelled neighbourhoods, there are nonparcelled neighbourhoods ("non-lotis") that lack basic supply infrastructures (water supply, sanitation, etc.).…”