ReHeal

In 2167 NextLife™ announced plans to create a virus that could restore lost limbs, organs and even revive human beings. They called it ReHeal as it only worked on people with RH+ in their blood.

Early testing on chimpanzees showed that the virus only helped the body so that it could spread to other hosts by disabling the Claustrum, also known as what makes primates conscious. The test subjects did not regain consciousness after being revived and started attacking all living primates.

Before the problem was fixed, a terrorist attack struck the NextLife Mars Labs site releasing the virus. It didn't take long before most of the population was infected and the Martian society collapsed.

Characteristics
The virus is spread through direct contact with the blood. This could be through a bite, ingestion of bodily fluids or similar ways. Once infected, people with RH+ will experience dizziness and fevers. It's all over when they show signs of sudden anger and dilated pupils much like how dogs become after getting rabies.

The infected can not be killed unless shot in the head. Shooting anything else will not do anything because they heal. People with RH- also get attacked by the infected. Although they will not get infected, they can still get wounded and/or killed.

Locations

 * The infected roam mostly in and around Mars Capital as well as around the NextLife Mars Labs.
 * Some of the infected may roam in large groups on Mars.
 * ReHeal darts can be obtained and shot through a tranquilizer gun to turn enemies against one another.