Yes, like all plagues, the Necroa Virus must have symptoms.
Meet the Symptoms
Insomnia- Slows future research speed
Fever- Slows future research speed, increases severity
Photophobia- Sensitivity when exposed to sunlight, slows future research speed
Delirium- Causes paranoia, can be fatal, and slows future research speed
Coma- Slightly reduces infectivity and greatly slows future research speed
Psychosis- Causes random bursts of violence, can be fatal, quite hard to cure
Acute Encephalitis- Very lethal brain lesions, don't evolve until late-game
Hyper Salivation- Makes people spit, a lot, great with Saliva transmissions
Polyphagia- Makes people eat, a lot, increasing infectivity
Gastroenteritis- Makes people puke, a lot, increasing infectivity and severity, of course
Cannibalism- Makes people want to bite or eat others, increases infectivity and is lethal
Autophagia- Makes people want to bite or eat parts of their body, increasing infection rates
Cytopathic Reanimation- Makes the dead turn into zombies
Anaerobic Resuscitation- Very lethal for living hosts, and destroyes personality
Enhanced Sensory Integration- Enhanced senses makes zombies more effective
Encanced Motor Control- Zombies move better, allowing more people to be killed
Masticatory Tension- Severity greatly increased
Peptide Surge- Better strength, severity increased
Acidic Reflux- Zombie saliva gets acidic, gives zombies combat advantage
Naja Mortis- Allowes zombies to projectile puke, pretty much, at people, giving them advantage
Autothysis- KAMIKAZE ZOMBIES! Allowes zombies to explode!
Dermal Calcification- Causes parts of skin to harden, gives zombies advantage
Cranial Elephantitis- Makes zombies' skulls bigger, giving them an advantage
Bone Dysplasia- Gives zombies great advantage, bones thickened
Adrenal Surge- Increases aggression of zombies
Hyperosmia- Makes zombies smell better
Temporal Lobe Manipulation- Makes zombie prey more likely to be zombified
Anabolic Boost- Beefy, hulking zombies appear, muscle growth enhanced
Cathemeral Shift- Improved vision in bright light, makes zombies more effective
Vampiric Hunger- VAMPIRE ZOMBIES! Zombies prefer to suck blood rather than eat, increasing zombification