P3 - Entomological, epidemiological, and climatological investigation of the 2019 Dengue Fever outbreak in Gewane District, Afar Region, North-East Ethiopia

Dengue Fever (DF) is an important arthropod-borne viral infection, which has repeatedly occurred as outbreaks in eastern and northeastern Ethiopia since 2013. A cross-sectional epidemiological outbreak investigation was carried out from September - November 2019 on febrile patients (confirmed malaria negative) who presented with suspected and confirmed DF at both public and private health facilities in Gewane District, Afar Region, northeastern Ethiopia. Entomological investigation of containers found in randomly selected houses belonging to DF positive patients was undertaken, to survey for the presence of Aedes larvae or pupae. A total of 1,185 DF cases were recorded from six health facilities during the 3-month study period. The mean age of DF cases was 27.2 years and 42.7% of the cases was female. The most affected age group was 15-49 years (78.98%). However, the attack rate (AR) was highest in the 49+ age group (134.2), though this should be interpreted cautiously, as this is likely a function of the small denominator, (only 2.9% of the total population), and is not necessarily an indication of increased risk among this group per se. A total of 162 artificial containers were inspected from 62 houses, with 49.4% found positive for Aedes larva/pupae. Aedes mosquitoes were mostly found breeding in buckets/bowls, clay jars, plastic tanks, and tires. World Health Organization entomological indices classified the study site as high risk for dengue outbreaks (House Index=45.2%, Container Index=49.4% and Breteau Index=129). Timeseries climate data, specifically rainfall, was found to be predictive of attack rate (p = 0.035). Study findings highlight the importance of vector control to prevent future DF outbreaks in the region. The long-term storage of uncovered, stagnant drinking water by community members and changing climactic conditions may have also contributed to the occurrence of this outbreak.