Marine shrimp farming started in Brazil only in the 1970s with Asian species Marsupenaeus japonicus. In the 1980s, the practice of shrimp farming emerged as an agribusiness following the introduction of exotic species Litopenaeus vannamei. Despite favorable conditions, it is only recently that Brazilian shrimp farming achieved a prominent place in the world [1,2]. Nevertheless, in 2004, the production of L. vannamei suffered a drastic drop due to various economic, environmental, and biological factors [3]. Among these, two viral epidemics caused great economic losses to Brazilian producers. The rst epidemic, designated as infectious myonecrosis (IMN), occurred in the Northeast region of Brazil in 2002, and the second epidemic, named white spot infection, occurred in the South in 2004 [3-6].