**4. Conclusion: EHV-9 can induce encephalitis in primates, including humans**

In assessments of infectivity of EHV-9 in nonhuman primates, there were different results between new world and old world monkeys. While EHV-9 caused fulminant encephalitis, no infectivity was seen in cynomolgus macaques. It is still uncertain whether macaques have barriers to invasion of EHV-9 at the entrance, and this could apply to humans as well. Thus, it has not been determined that EHV-9 can cross the species barrier between new world and old world monkeys and humans. It is also uncertain whether EHV-9 can infect immunecompromised patients like AIDS patients, infants or elderly people. Ocular transmission of viruses to the CNS has been suspected in many viral diseases such as Cercopithecine herpes virus 1 (B-virus) in humans (CDC, 1999). Fatal infection by B-virus in humans via ocular exposure from biological fluid from macaque monkeys has been reported (CDC, 1999). Further studies using nonhuman primates may be needed to assess the risk to infants from the ocular route of infection.
