Foto taken of Benson L, Kar S, McLaughlin G, Ihler G. Entry of Bartonella bacilliformis into erythrocytes. Infect Immun 1986; 54: 347-353

- The first step in the process is bacterial adhesion, interacting through multiple surface-exposed membrane proteins.
- The second step is the production of the extra cellular protein, termed deformin, that produces deep invaginations within the erythrocyte membrane.
- Motility of the multiple unipolar flagella is the next step.
- Finally, the red blood cell surface becomes markedly deformed with trenches, conic depressions and hole-like depressions.

An important genetic determinant is the invasion-associated locus (ial) which is a putative virulence determinant implicated in the invasion process.