February 15-18, 2009 Washington State Convention Center Seattle ...

DETECTION OF YELLOW HEAD DISEASE IN INTENSIVE FRESHWATER PRODUCTION
SYSTEMS OF Litopenaeus vannamei
Liñán-Cabello Marco A., Sánchez-Barajas Maximiliano and Mena-Herrera Alfredo
Facultad de Ciencias Marinas
Universidad de Colima
Km. 19.5 Carretera Manzanillo-Barra de Navidad
Manzanillo Colima México CP 28860
linanmarco@hotmail.com
The culture of penaeid shrimps in inland well waters with low salinity represents an important development in aquaculture.
Yellow head disease of shrimps has been reported in many countries in Asia and Latin America, but, in most cases, the etiologic
agents have not been clearly defined. In the present study, we used reverse transcription-nested polymerase chain reaction (RT-n
PCR) to detect yellow head virus (YHV), white spot syndrome virus (WSSV), and gill-associated virus (GAV), during single
culture cycles of Litopenaeus vannamei on two farms (F1 and F2), located in Colima, Mexico.
The shrimps were intensively cultured in freshwater, with densities of 70 organisms org m -2 and 25 org m -2 and hardness values
of 390 and 450 mgL-1 (as CaCo3), respectively. The average salinities throughout the year were 0 ppm. The results obtained
indicated that the samples were negative to WSSV and GAV. YHV was present on each farm, with a prevalence of 13%, over
60 d of observation. During this time, the growth of shrimps decreased on F1. The infections obeyed the principles of horizontal
transmission, and we discuss various factors, such as increases in shrimp density, and consequent lower levels of oxygen, that
could increase the effects of YHV on the health of shrimps on farm F1. We consider that the observed infection obeyed the
principles of horizontal transmission. It is important to determine if the YHV we detected is a product of dissemination from
other farming areas, or if it corresponds to an endemic variety. If the latter, our virus would be considered a member of the
YHV complex.
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