Which is a known risk factor for a person to be a carrier of CJD or its variant?

The identified risk factor that relates to being a carrier of Creutzfeldt-Jakob disease (CJD) or its variant is family history. CJD is a prion disease, which means it can be inherited in some cases due to genetic mutations. If a family member has CJD, especially in its hereditary form, other family members are at increased risk of carrying the same genetic predisposition that could lead to developing the disease.

While other factors like recent blood transfusions and consumption of beef may relate to specific risks of transmission—particularly with variant CJD, which has been linked to Bovine Spongiform Encephalopathy (BSE)—the strong genetic component of CJD makes family history the most significant risk factor in determining whether someone might be a carrier of the disease.

Also, traveling to endemic areas and recent blood transfusions are indeed separate risk factors but do not directly apply to the potential hereditary aspect that can be conveyed through family lineage.