The infection has different stages:
Stage 1: Initial Infection
The virus acts like the flu or a cold, victims are the most infectious at this stage, often infecting their entire family and friends before the disease runs its course.
Stage 2: Gestation Period.
No further signs of infection are present during this stage, however infected can start to care less and less about wearing clothing. Infection is typically only done by coming in contact with body fluids at this point.
Stage 3: First Changes.
Infected start to grow fur and undergo other small transformations. They usually are small enough to not be noticeable if the infected wear clothing.
Stage 4: Changes Intensify.
The changes start to increase at this point, usually this is when genitalia, extremities, and other body parts transform. Tails will also grow during this period.