Occupational Health & Safety

Lymphocytic Choriomeningitis Virus Infection

Human infection with lymphocytic choriomeningitis (LCM) associated with laboratory animal and/or pet contact has been recorded on several occasions. LCM is widely distributed among wild mice throughout most of the world, and presents a zoonotic hazard. Many laboratory animal species are infected naturally, including mice, hamsters, guinea pigs, nonhuman primates, swine and dogs.

But the mouse has remained the primary concern in the consideration of this disease. Athymic, severe-combined-immunodeficiency (SCID), and other immunodeficient mice can pose a special risk by harboring silent, chronic infections, which present a hazard to personnel.

The LCM virus produces a pantropic infection under some circumstances, and can be present in blood, cerebrospinal fluid, urine, nasopharyngeal secretions, feces, and tissues of infected natural hosts. Bedding material and other fomites contaminated by LCM-infected animals are potential sources of infection, as are infected ectoparasites.

In endemically infected mouse and hamster colonies, the virus is transmitted in utero, or early in the neonatal period, and produces a tolerant infection characterized by chronic viremia and viruria, without marked clinical disease.

Humans can be infected (PDF) by parenteral inoculation, inhalation, contamination of mucous membranes or broken skin with infectious tissues or fluids from infected animals or congenitally (PDF).

Humans develop an influenza-like illness characterized by fever, myalgia, headache, and malaise after an incubation period of 1-3 weeks. In severe cases of the disease, patients might develop meningoencephalitis. Central nervous system involvement has resulted in several deaths.

On August 19, 2005, the Centers for Disease Control (CDC) published an updated report that provides background information on LCM virus and interim guidelines for the public in reducing risk for LCM virus infection from pet rodents.