It depends on the host species, natural vs. experimental infections, tissue or organ, etc..., so ti may vary from undetectable to 10^13 (in bovine placenta).

CFU in placenta around 10^14, while in expermental study with non mamalian host 10^12 is leathal dose to the host 

You got  already the answers,  regarding host,  tissues etc,  inclusive if you do experimental infection sometimes CFU can vary from same organs in different animals,  beside ruminants,  many years ago we inoculate guinea pigs with Brrucella wildtype and CFU differ from spleen and limphonodes among animals.

Brucellae are intracellular bacteria that cause brucellosis, a chronic disease which affect target organs, such as the pregnant uterus and the udder, allantoic fluid contains 1.01 × 1013 CFU/g of tissue /bovine placenta.