MỘT SỐ ĐẶC ĐIỂM DỊCH TỄ CỦA BỆNH DO Lates calcarifer HERPES VIRUS (LCHV) GÂY RA TRÊN CÁ CHẼM (Lates calcarifer Bloch, 1790)

This study investigated epidemiological features of disease caused by LCHV,is a new emerging virus in barramundi. Sick barramundi was collected monthly fromthe field through-out a year and diagnosed for the presence of LCHV using realtimePCR. The virus was detected in farmed barramundi in the Central region (KhanhHoa) and Southern region (Vung Tau) of Vietnam. Positive samples were foundevery month with an average prevalence up to about 62.5% (27 - 100%) at the totalsamples showed signs at disease. Fish were more sensitive to the disease in rainyseason, especially during the transition period from July to November, with the peakin July, August and November with an infection rate of 100%. Large fluctuations intemperature and rainfall were associated with the outbreak of the disease. Fishweighing at less than 250 g, especially when first transferred from the hatchery tothe cage, were more sensitive. Horizontal transmission was confirmed in controlledexperiments. These epidemiological features were critical for prevention andmanagement of this disease.