The epidemic spread of aquatic animal diseases is an increasing event in many regions of the world. In Asia, we have witnessed the devastating impacts of epizootic ulcerative syndrome (EUS) on freshwater fish during the 1980s and 1990s, viral nervous necrosis (VNN) in marine fish since the 1990s, white spot syndrome virus (WSSV) in penaeid shrimp from the early 1990s, and the emerging taura syndrome virus (TSV) in Penaeus vannamei. Since early 2002, Indonesia has been facing a serious epizootic, probably due to koi herpes virus (KHV), that is causing large-scale mortalities with significant economic losses among populations of cultured common and koi carp (Cyprinus carpio). More recently, during the last quarter of this year, an outbreak of KHV also occurred in common and koi carp in Japan. In Latin America, TSV and WSSV are still haunting the shrimp industry, while several new disease incursions have been recently reported from Europe and North America - Mikrocytosis in the United States of America, MSX disease (Haplosporidium nelsoni) in Canada and spring viraemia of carp (SVC) in Switzerland. There are also still a number of unresolved diseases, such as akoya pearl oyster mortalities in Japan, scallop mortalities in Mainland China, and abalone die-offs in Taiwan Province of China. These examples demonstrate the vulnerability of aquaculture systems to wide-scale infectious disease emergencies and the significant impacts that new diseases can have on local economies. Unless appropriate health management and biosecurity measures are continuously put in place and effectively implemented, the risks of major disease incursions and newly emerging diseases will continue to threaten the sector. Effective prevention and control measures complemented by extension, educational programmes and capacity building for farmers and producers are essential to reduce the risk of potential transboundary epizootics. Strong national approaches, along with well thought-out, concerted regional strategies, are required to ensure that operational capability is in place to respond effectively to disease emergencies. Equally important is that governments and the private sector see clearly the benefits from investing and participating in the development of emergency response systems. FAO, in collaboration with its partners, is currently taking action to find avenues for providing guidance and assistance for national and regional improvements.

Rohana Subasinghe
Chief Editor