Age at Occurrence of Mycobacterium avium Subspecies paratuberculosis in Naturally Infected Dairy Cows

Survival probability plot of age at the occurrence of antibodies in cows: average; cows without detected shedding of Mycobacterium avium ssp. paratuberculosis (Never FC+, where FC refers to fecal culture); cows with a low level of shedding (FC_Low); and cows with high levels of shedding (FC_High). For each FC group, vertical lines are drawn at the age at which 50% of the group tested positive. For each survivor function, the 95% confidence interval is shown by shaded areas around the graph.

Survival probability plot of DIM at the occurrence of antibodies against Mycobacterium avium ssp. paratuberculosis (Map) in cows by parity and by shedding group. Survival functions in black show cows with high levels of Map (FC_High, where FC refers to fecal culture); survival functions in dark gray show cows with low levels of Map (FC_Low); and survival functions in light gray show cows whose FC were always negative (FC_Neg).

Survival probability plot of age at detection of Mycobacterium avium ssp. paratuberculosis in cows: average; cows testing ELISA-positive; and cows testing ELISA-negative. For each group, vertical lines are drawn at the age at which 50% of the group tested positive. For each survivor function, the 95% pointwise confidence interval is shown by shaded areas around the curve.

Survival probability plot of DIM at detection of Mycobacterium avium ssp. paratuberculosis in cows: average and by ELISA group. For each survivor function, the 95% confidence interval is shown by shaded areas around the curve.

Effect of sampling interval on the probability of testing positive for Mycobacterium avium ssp. paratuberculosis (Map; 1 – survivor probability function) in the milk ELISA with repeated sampling. Sampling frequency varied from 2 to 24 mo (see legend). The top 6 lines are from cows testing Map-positive by fecal culture, whereas the lower 6 lines in the graph are from cows testing Map-negative.