Human infections by lymphocytic choriomeningitis virus (LCMV) have been recognized since 1933. LCMV is an RNA virus that belongs to the family Arenaviridae, and its reservoir in nature is rodents such as mice and hamsters. Pregnant wild mice that become viremic can transmit LCMV transplacentally. Mice infected in utero are unable to
mount an effective immune response to the virus and they remain asymptomatically infected. LCMV is shed in their nasal secretions, saliva, milk, urine, semen, and feces. Horizontal transmission to other rodents such as hamsters further spreads the virus. Humans acquire LCMV by inhaling aerosolized virus or by direct contact with contaminated fomites (888). Although arenaviruses are generally not very pathogenic for rodents, they are capable of causing serious or fatal infections such as aseptic meningitis, liver disease, and hemorrhagic fever in humans, primates, and guinea pigs (888,889,890).