Longterm kinetics of vibriocidal antibody responses after V. cholerae infection in the Democratic Republic of Congo

Abstract

Interpretation of sero-epidemiology studies of cholera relies on knowledge of Vibrio cholerae antibody kinetics, which thus far have been lacking in African populations. We performed vibriocidal assays on 212 serum samples from 116 culture-positive cholera patients (median age 8 (IQR 4-18)) in Goma, DRC, collected at enrollment and again 3-449 days after. Vibriocidal responses peaked 7-40 days after symptom onset, with nearly all samples declining to a titer of 160 or lower by day 180. We used a Bayesian exponential decay model to show an 88% probability of a faster decay in children under 5.

Figure 1:. Post-infection vibriocidal titer responses from confirmed cholera cases.

Vibriocidal titers by matching V. cholerae O1 serotype from 101 participants, by (A) serotype, and (B) age group. Days since symptom onset on the x-axis, and vibriocidal titer on the y-axis, are plotted on log2-transformed scales. Hashed lines are LOESS smoothed data with confidence intervals in shade.

Figure 2.

Estimated average titer value and 95% posterior credible interval for serotype-matched vibriocidal titers from the exponential decay equation plotted against days since symptom onset, by participants over 5 years of age (left) and under 5 (right). Each line represents the vibriocidal titer decay of a participant with at least 2 paired samples, fitted to a Bayesian model to estimate exponential decay parameters describing the amplitude of titers and the rate of decay.