Background: Influenza is a respiratory infection caused by influenza viruses. It spread from person-to-person by contact with respiratory secretions. Worldwide, annual influenza epidemics result in an estimated 3–5 million cases of severe illness and 250,000-500,000 deaths every year. Influenza outbreak occurred in Kallu district, due to this; we had assessment and identify associated risk factors with the diseases. Methods: Unmatched Case-control studies with the case to control the ratio of 1:1 were conducted in Kalu district Amhara region, Ethiopia in the period of January 2016. Data was collected by face to face interview through semi-structured questionnaires. Data analysis was done using Epi-Info 2. Adjusted odds ratio with its 95% confidence interval was used as a measure of association and to assure statistical significance. Result: One Hundred forty respondents were included; 70 cases and 70 controls. An Attack Rate of 333:100,000 and 300: 100,000 populations were males and females respectively. The analysis of the study shown that people who had close contact with ill person were 3.79 (95% CI= (1.76- 8.24), people who have traveled to an epidemic area in the last 7 days were 2.7 (95% CI= (1.17- 6.31) and peoples who live in one house which have less or equal to one window were 2.7 (95% CI= (1.47-6.65) times more likely to develop influenza-like illness. Conclusions: History of close contact with the primary case and having a travel history to an epidemic area were identified risk factors for the current epidemic. We recommend community health awareness on the importance of close contact and travel history would be highly important interventions in the similar epidemic situation.

Keywords: Influenza, outbreak investigation, Amhara region, Ethiopia