Although IL17a has not been implicated in systemic reactions to vaccines, increases in systemic IL17a have been associated with disease severity in systemic auto-immune diseases in humans such as rheumatoid arthritis, systemic lupus erythematosus, and psoriasis and may be contributing to systemic adverse reactions to C. burnetii WCV as well (39, 41). This evidence concerns the gene IL17A and rheumatoid arthritis.