The pathogenic potentials of two sibling nematodesAnisakis simplexsensu stricto (s.s.) andA. pegreffiiwere compared byin vitroandin vivostudies. Live third-stage larvae of each species were subjected to agar blocks made using PBS or RPMI-1640, overlaid with different supernatants (artificial gastric juice, PBS, and RPMI-1640), and their penetration ability was compared. Their tolerance of artificial gastric juice was also tested. Further, they were introduced into rats by gastric intubation, and thein vivolocations of them were investigated.A. pegreffiishowed higher penetration ability thanA. simplex(s.s.) in most of the experimental conditions, except for the RPMI-1640 agar block overlaid with artificial gastric juice. In an acid tolerance test, the mean survival times were 6.1 days forA. simplex(s.s.) and 4.2 days forA. pegreffii. In an animal experiment,A. simplex(s.s.) stayed for a shorter time in the stomachs of rats thanA. pegreffii. SomeA. pegreffiiandA. simplex(s.s.) were embedded in the gastric mucosa or freely existed in the abdominal cavity. All of these results suggest thatA. pegreffiihas the pathogenic potential to cause anisakidosis in humans when ingested, as doesA. simplex(s.s.).

Megalocytivirus was detected from paradise fish Macropodus opercularis imported from Indonesia. Four of 11 fish (36%) in 2006 and 40 of 117 fish (34%) in 2008 were found to be PCR-positive for megalocytivirus. Phylogenetic analysis based on partial major capsid protein (MCP) gene nucleotide sequences revealed that the sequences detected in paradise fish were classified as Genotype II, which includes freshwater fish isolates from Southeast Asian countries, closely related to infectious spleen and kidney necrosis virus (ISKNV), Murray cod iridovirus (MCIV), and dwarf gourami iridovirus (DGIV-2004). Paradise fish was added as a new host for megalocytivirus based on this study.