Note: I'll be using the "Carrier" type a good deal. I would personally like to see Carriers be the default for the Infected (rather than Zombies) to distinct it from more generic zombie apocalypse horror and let us play with Carrier tribal synergies without worrying about cross-contamination with every other set's zombies. X Carrier for the less afflicted but still mechanically plaguey, just Carrier for those that are little more than macroscopic disease (essentially "Creature - Carrier" covers what would be "Creature - Carrier Horror")
Germ Archetype (Expected to be shared with Green). Essentially, consists of cards that create Germ tokens and cards that benefit from creating Germ tokens. Since germs are 0/0 by default they usually die to SBEs, and unlike Living Weapon germs are expected to, so the majority of synergy cards will trigger on germs entering and/or dying.
Vector Vermin


Creature - Rat Carrier {C}
When Vector Vermin enters the battlefield or dies, create a 0/0 black Germ creature token.
2/1
Blighted Infiltrator

Creature - Carrier {C}
Deathtouch
Whenever Blighted Infiltrator deals combat damage to a player, create a 0/0 black germ creature token.
1/1
Dying Wretch


Creature - Human Peasant {C}
When a germ enters the battlefield, you may sacrifice Dying Wretch. If you do, create two 0/0 black germ creature tokens
2/1
Pustule Pop


Instant {C}
Put a -1/-1 counter on target creature. Create a 0/0 black germ creature token
Delirious Victim


Creature - Human Peasant {U}
At the beginning of your upkeep, create a 0/0 black germ creature token
Plague Amalgam


Creature - Carrier {U}
Plague Amalgam enters the battlefield with 9 -1/-1 counters on it
Whenever a germ enters the battlefield, remove a -1/-1 counter from Plague Amalgam.
10/10
Diseased Gasp


Sorcery {U}
Destroy target creature with one or more -1/-1 counters on it. Create a 0/0 black germ creature token for each -1/-1 counter that was on that creature.
Master of Strains



Creature - Carrier {R}
Flying
Germs you control get +1/+1
4/4
Virulent Wind


Sorcery {R}
Virulent Wind costs

less to cast for each germ that entered the battlefield this turn.
Destroy all creatures you don't control.
Viropotence



Enchantment {MR}
Whenever a germ enters the battlefield you draw a card and lose 1 life.
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"Symptom" Auras - negative auras that return from the graveyard when something happens to indicate that a creature begins to "exhibit symptoms" (Yes, these are all drawn from the symptoms described on the original Carrier cycle)
Rash

Enchantment - Aura Symptom
Enchant Creature
Enchanted creature gets -1/-1
Whenever a -1/-1 counter is placed on a creature, you may return Rash from your graveyard to the battlefield, attached to that creature.
Vitriolic Nausea

Enchantment - Aura Symptom
Enchant Creature
Enchanted creature doesn't untap during its controller's untap step unless that player pays

or puts a -1/-1 counter on enchanted creature.
Whenever a creature becomes tapped except during combat, you may return Vitriolic Nausea from your graveyard to the battlefield, attached to that creature.
High Fever


Enchantment - Aura Symptom
Enchant Creature
Enchanted creature has "At the beginning of your upkeep, this creature deals 1 damage to you."
Whenever a creature deals damage to you, you may return High Fever from your graveyard to the battlefield, attached to that creature.
Muscle Aches


Enchantment - Aura Symptom
Enchant Creature
Damage is dealt to enchanted creature as though its source had wither.
Whenever a creature blocks, you may return Muscle Aches from your graveyard to the battlefield, attached to that creature.
Persistent Cough


Enchantment - Aura Symptom
Enchant Creature
At the beginning of your upkeep, put a -1/-1 counter on enchanted creature and create a 0/0 black germ creature token
Whenever a creature attacks or blocks with one or more other creatures, you may return Persistent Cough from your graveyard to the battlefield, attached to one of those creatures.
Plague Delirium


Enchantment - Aura Symptom
Enchant Creature
Enchanted creature can't attack or block unless its controller discards a card.
Enchanted creature's abilities cost an additional "discard a card" to activate.
Whenever a creature's power or toughness is changed by a spell or ability, you may return Plague Delirium from your graveyard to the battlefield, attached to that creature.
Convulsions


Enchantment - Aura Symptom
Enchant Creature
Enchanted creature attacks each combat if able
Enchanted creature blocks each combat if able
At the beginning of each player's upkeep, untap enchanted creature.
Whenever a creature becomes untapped except during an untap step, you may return Convulsions from your graveyard to the battlefield, attached to that creature.
Approaching Death


Enchantment - Aura Symptom
Enchant Creature
Enchanted Creature has "at the beginning of your upkeep, sacrifice this creature"
Whenever a creature's power or toughness becomes 1 or less, if that isn't its base power or toughness you may return Approaching Death from your graveyard to the battlefield, attached to that creature.
And a support card...
Asymptomatic Vector


Creature - Human Carrier
When Asymptomatic Vector enters the battlefield, search your library for any number of symptoms with different names and attach them to Asymptomatic Vector, then shuffle your library.
Symptoms attached to Asymptomatic Vector lose all abilities other than "Enchant Creature".
2/3