Study of the relationship between Aedes (Stegomyia) aegypti egg and adult densities, dengue fever and climate in Mirassol, state of São Paulo, Brazil

Abstract

The purpose of this study was to examine the relationship between Aedes aegypti egg and adult density indices, dengue fever and climate in Mirassol, state of São Paulo, Brazil, between November 2004-November 2005. Weekly collections of adults and eggs were made using, respectively, manual aspirators and oviposition traps that produced four entomological indices (positivity and average of females and eggs). Weekly incidence coefficients were calculated based on dengue cases. Each week, the data obtained from entomological indices were related to each other, dengue, and climate variables. The first index to show an association with dengue transmission was the female average, followed by female positivity and egg average. Egg positivity did not show a relationship with risk for dengue, but was sensitive to identifying the presence of the vector, principally in dry seasons. The relationship between climatic factors, the vector and the disease found in this study can be widely employed in planning and undertaking dengue surveillance and control activities, but it is a tool that has not been considered by the authorities responsible for controlling the disease. In fact, this relationship permits the use of information about climate for early detection of epidemics and for establishing more effective prevention strategies than currently exist.

A ocorrência da dengue e variações meteorológicas no Brasil: revisão sistemática

“…This fact has also been described by Dos Reis et al 42 , who used oviposition traps in 3 districts of the city of Rio de Janeiro, in the summer (January to March) and in the winter (June to September) of 2007; although the captures did not differ, a higher number of eggs and female adults was verified during the summer. Dibo et al 43 , by means of weekly collections of eggs and larvae in the city of Mirassol, state of São Paulo, Southeastern region of Brazil, from November 2004 to November 2005, confirmed the results that have already been described here about Ae. aegypti proliferation, which shows that the number of eggs, larvae and mosquitoes is larger in periods of higher temperatures and rainfall indexes 25,26,37,44 .…”

“…The number of collections did not follow one single distribution pattern over the period. It could occur during the whole year, as it has been shown in other studies 28,43,49 .…”

Hot temperatures can force delayed mosquito outbreaks via sequential changes in Aedes aegypti demographic parameters in autocorrelated environments

“…Moreover, several long-term studies on Ae. aegypti abundance have shown the abundance of this mosquito species to be correlated with different environmental factors, primarily rainfall and temperature (Barrera et al 2011;Dibo et al 2008;Foo et al 1985;Ho et al 1971;Oo et al 2011;Schultz 1993;Scott et al 2000;Tonn et al 1970), but also with "socio-ecological" factors such as unreliable water supply (Barrera et al 1993;Padmanabha et al 2010) or lack of community engagement in proper water container disposal (Predescu et al 2007). Similar patterns of association between mosquito abundance and weather fluctuations have been observed in other Aedes spp.…”

Incidence of Dengue in Ozamiz City, Philippines

“…A study by Chowell and Sanchez (2006), found a correlation between temperature, precipitation or evaporation with the number of dengue cases. The possible relationship between dengue incidence and climatic factors encourages the use of information about climate for early detection and for establishing more effective prevention strategies (Dibo et al, 2008). However, preventive measures against dengue are not limited only about data on weather factors because climate change is not the sole culprit of dengue epidemics but from complex interactions between ecology, environment, vector and virus serotypes (Chandy et al, 2013).…”