The Blood Baby is a disease/abomination found in Deadlands Classic. It infests the waters of the Rio Grande, and so can be found in any area that the river passes through, from Texas to Mexico.
The Blood Baby, also known as the Texas Blood Baby, is detailed on pages 84-85 of the "South o' The Border" sourcebook.
A close relative of the Texas Tummy Twister, the Blood Baby has a fundamentally identical nature and MO; infesting water, it attempts to colonise the body of people who drink it in its microscopial larval state and grow to maturity. It differs from the Tummy Twister in that it can only infect women and it has a different end-game; while the Tummy Twister hijacks the host's body, the Blood Baby parasitises its host, emerges once grown, lays eggs to start the process over again, and begins a normal life of hunting.
Fully matured, a Blood Baby looks like a horribly twisted, malformed human infant with blood-red skin that oozes gore-colored slime. Its mouth brims with needle-sharp fangs and its fingers and toes end in vicious claws.
The best way to avoid being infected by a Blood Baby is to boil the water beforehand if one must drink from the Rio Grande. Only women are vulnerable to Blood Baby infection.
Upon infection, the Blood Baby remains in the host's stomach until it reaches roughly the size of a finger, whereupon it bores its way from the stomach to the uterus. There, it gestates over a period of 3-4 weeks before tearing its way out through the abdomen, attacking any living creature in sight to feed upon their meat.
The initial "migration" inflicts a Light wound to the Guts. Whilst gestating, the mother suffers a permanent (that is, uncurable so long as they are hosting the Blood Baby) Heavy wound to the Guts. Finally, the "birth" inflicts a Critical wound to the Guts. In all cases, this damage cannot be migated by using Fate Chips.
An infected woman can be saved by means of surgical intervention, but it requires a Hard (9) Medicine: Surgery roll and is only possible after the Blood Baby has entered the host's womb, which exposes the doctor to attack by the still-juvenile abomination, though its stats are lowered depending on how long it has had to mature.
The Blood Baby's profile is as follows:
Corporeal: D: 3d6, N: 3d6, S: 2d8, Q: 3d10, V: 2d8
Dodge: 5d6, Fightin': Brawlin' 5d6
Mental: C: 2d6, K: 1d6, M: 1d6, Sm: 1d6, Sp: 1d4
Claws: Strength +1