The organism is commonly found in dry and dusty soil and can be important for diseases of domesticated animals (horses and goats).

[2] R. equi can infect immunocompromised people, such as HIV-AIDS patients or organ transplant recipients.

Rhodococcus equi infection in these populations resemble the clinical and pathological signs of advanced pulmonary tuberculosis.

The internal environment of the phagolysosome contains nucleases and proteases, which are activated by the low pH of the compartment.

This allows R. equi to multiply within the phagosome where it is shielded from the immune system by the very cell that was supposed to kill it.

[8] Necrosis is pro-inflammatory, attracting additional phagocytic cells to the site of infection, eventually resulting in massive tissue damage.

[citation needed] The variable region of the virulence plasmid contain genes that are highly expressed following phagocytosis of R. equi by macrophages.

All foals infected with R. equi produce high levels of antibodies specific for vapA, the first vap gene to be characterised.