Lymphocytic encephalitis

For other uses of the concept of viruses in Battlestar Galactica, see Virus.

Lymphocytic encephalitis is a viral infectious disease caused by the Lymphocytic Choriomeningitis Virus (LCMV). Originally carried by rodents, primarily rats, LCMV is not lethal to humans, who developed immunity to the virus several hundred years ago.

A beacon, believed to have been left by the Thirteenth Tribe on their way to Earth, was contaminated by LCMV. When a basestar discovers the beacon while exploring the Lion's Head Nebula, the Cylons bring the device on board and unleash the virus. Some time later, a team of Colonial marines discovers the drifting basestar and boards the vessel, finding everything save for a small group of humanoids dead. They take the ill Cylons (a Five, a Six, an Eight, a Leoben, and a Simon) prisoner and return to Galactica just as the basestar's self-destruct mechanism activates and destroys the ship.

Though humans are immune, the virus is highly lethal to Cylons because there is a bio-electric feedback component to the pathogen. It corrupts how the brain of a humanoid Cylon manages the immune system, eventually killing it. Furthermore, the Cylons speculate that if an infected host is resurrected, the disease will follow, afflicting the Resurrection Ship and eventually the entire Cylon fleet.

This theory forms the basis of a plan devised by Lee Adama to eradicate the Cylon race. By killing the infected Cylons prisoners near a Resurrection Ship, the aforementioned bio-electrical effect would be spread to all Cylons upon download. Ultimately, the plan is thwarted when Karl Agathon kills the prisoners before Galactica can penetrate the Resurrection Ship's upload radius. Agathon does this despite the risk of being executed for treason, as he feels that the genocide of the Cylon race, despite the fact that they had tried to do the same to mankind, is morally wrong.

Dr. Cottle creates a simple vaccine that can dramatically reverse the effect on the Cylons. However, an antibody in their blood breaks down the vaccine's RNA backbone, rendering the treatment useless. Because of that, they need regular close interval injections of the vaccine or they will die. If regular injections are provided, an infected Cylon could be kept alive indefinitely.

Unlike the other Cylons Sharon Agathon displays immunity; although she is exposed to LCMV, the pathogen does not adversely affect her. Cottle postulates that during her pregnancy with her half-human daughter Hera, human antibodies were transferred over to Sharon and that these antibodies are subduing the virus.

Notes

• Lymphocytic choriomeningitis (of which encephalitis is one form) is an actual disease. As in the episode, the illness was spread through rodents on the real-world Earth. The effects on the Cylons appear similar to the symptoms in this CDC document.
• Arguably, the plan to kill all Cylons by exposing the Resurrection ship to the disease is ill-conceived; there is nothing to stop the Cylons from destroying the vessel after it is infected. Additionally, the plan seems to hinge on the idea that once in the Resurrection Ship the disease would spread throughout the Cylon fleet and perhaps even the whole of Cylon-inhabited space.