Survival assays show C. burnetii infection results in a significantly reduced lifespan of C. elegans concurrent with progressively increased Dar pathology. (a) Kaplan–Meier survival plots of N2 nematodes fed live/dead E. coli OP50 or live/dead CCB and observed every 24 h. Worms were classified as live if motile or responsive to touch. Dead worms were non-motile and non-responsive to touch. Worms that left NNGM plates were censored from the assay. Median life spans of nematodes were not significantly different (P =0.9014 by pair-wise log-rank test comparison) when fed dead E. coli or dead C. burnetii. However, a significant difference (P <0.0001 by pair-wise log-rank test comparison) was observed between worms fed live E. coli or live C. burnetii, with mean survival times of 15 d and 8 d, respectively. (b) Initially, Dar pathology (dashed line) was not evident, but, over time, progressively greater Dar pathologies (c, Dar-1 (weak); d, Dar-2 (moderate); e, Dar-3 (severe), were observed. (f) Percentage of worms with Dar pathologies as a function of days post-infection. All nematodes exhibited ≥Dar-2 by 4 d. By 8 d 59% of nematodes exhibited Dar-3. Images were acquired by differential interference microscopy. Bar =20 μM.