Correlation between Aedes Aegypti Larval Indices and Dengue Epidemics in Jeddah, Saudi Arabia
Jeddah had experienced increasing dengue fever outbreaks since 2006. The largest epidemic of dengue fever was reported in 2013. Manmade artificial water containers are important environmental risk factor for dengue outbreaks. Aedes aegypti is the primary vector in Jeddah city. Ongoing indoor larval surveys and larval source management are part of the national dengue control program.
This study aims at characterizing the main indoor breeding premises for Aedes aegypti and their abundance during the pre-epidemic and epidemic period.
METHODS:
Data from door to door larval survey program were analyzed for the period from the begening of the 10th till end of the 27thInternational weeks. Breeding premises were identified as large (≥50 L), medium (20-50L), and small (≤20 L) indoor containers. The relation between Container Indices and dengue cases were determined.
RESULTS:
A total of 124794 houses were surveyed and 7175 larva positive water-holding containers were identified. The mean house index was 6.2. The most frequently infested indoor premises were the large type containers Container Index=36.5 (SD=6.4), followed by the small type Container Index=15.5 (SD=4.5) and the medium type containers Container Index= 13.2 (SD=5.7). A statistically significant positive correlation was found between dengue cases and indoor container indices with a gap of four international weeks.
CONCLUSIONS:
Stegomyia indices may be used as an early warning for dengue outbreaks. Control measures should target indoor larval source reduction.