Outbreak investigation of Pseudomonas aeruginosa in tilapia grow-out farms in Minalin, Pampanga, Philippines

Abstract

This study was conducted in order to investigate the outbreak of Pseudomonas aeruginosa in tilapia grow-out farms in Minalin, Pampanga, Philippines and to identify the possible risk factors in the occurrence of the bacterium. Majority of the collected tilapia samples showed various signs of bacterial infection such as lesion, fin/skin rot, eye opacity and/or abnormal body coloration. The computed attack rate of P. aeruginosa in the whole municipality was 51.04%. Lower attack rate of P. aeruginosa was recorded in male tilapias (male = 50.70%; female = 52.00%). The temporal pattern of P. aeruginosa depicts that tilapias were continuously exposed over a long period of time to a common disease-causing factor. The top three identified risk factors for the occurrence of P. aeruginosa in grow-out tilapia were the pond preparation (relative risk = 1.53), source of water (relative risk = 1.45) and temperature (relative risk = 1.38). The occurrence of bacterial diseases in tilapia is caused by the interplay of various risk factors such as presence of pathogenic organism and source of contamination, and a susceptible host due to stressful environment.