3. Yellow-head virus (YHV)
Thai work onMBVwas interrupted by the arrival of the
first really serious viral pathogen of shrimp in Thailand in
1992. In retrospect, we know that this virus first began to
cause problems in Thailand in 1990 (Limsuwan, 1991), but
it was not discovered as a new pathogen until 1992
(Boonyaratpalin et al., 1993; Chantanachookin et al.,