Receptivity conditions of the domicile and occurrence of severe dengue fever in a endemic area of Brazil

INTRODUCTION:  The potential influence of high vector density environments where people are supposedly more exposed to mosquito bites may have a relation with clinical severity of dengue fever, an association that has been poorly discussed in the literature. This study aimed at analyzing the association between anthropic environmental factors, particularly those related to the conditions domicile and peridomicile, and occurrence of severe dengue cases during the 2008 epidemic in the state of Rio de Janeiro. 

METHODS: We conducted a retrospective case-control study with a sample of 88 severe patients aged 2 to 18. They were selected through chart review in four children's tertiary care centers. The 367 controls were neighbors of the cases, paired by age.  Data were collected through interviews and systematic assessment of house conditions as well as peridomicile area conditions and later analyzed by conditional logistic regression. 

RESULTS: The presence of three or more reservoirs, without a lid or that were inadequately sealed (water tanks, barrels, wells/cisterns and cement tanks and pools) was significantly more frequent in households with severe cases when compared with households of controls (OR= 1.6; CI95%= 1.36-20.01; p- value=0.015). The presence of such larger reservoirs that could potentially produce more adult forms of the vector is consistent with a situation in where people are more exposed to mosquito bites and consequently are more prone to have multiple infections over a short period of time.

CONCLUSIONS: The emergence of severe dengue cases in high-transmission context underpins the importance of constant vigilance and interventions in those types of reservoirs, which result from precarious household structures and irregular water supply services.