[Seasonal fluctuation of Aedes aegypti in Chaco Province, Argentina]. / Fluctuación estacional de Aedes aegypti en Chaco, Argentina.

ABSTRACT

OBJECTIVE: To study the seasonal fluctuation of Aedes aegypti and to correlate its abundance with climate conditions. METHODS: Samples were weekly collected in ovitraps in the city of Resistencia, Chaco Province, Argentina, between October 2002 and November 2003. The number of eggs collected was correlated with temperature, relative humidity, evaporation and rainfalls recorded. Pearson's correlation test with the respective weekly climate data was used in single and multiple correlation analyses. RESULTS: The first record of eggs took place in the last week of October 2002 and continued irregularly up to the last week of June 2003, when no more eggs were seen until November 2003. The highest peak of abundance (70%) was observed in November-December 2002, which coincided with the season of high temperatures and rainfalls. A second less important peak was seen in April coinciding with autumn rainfalls. Significant correlations were found only for monthly accumulated rainfall (r=0.57; p<0.05). No ovipositions were recorded during the winter when temperature dropped below 16.5 degrees C. CONCLUSIONS: The results show a correlation between oviposition and rainfall, as the periods of high activity of Aedes aegypti were in the end of spring-beginning of summer, and beginning of fall. These are periods of major epidemiological risk if an infected person gets to Resistencia.