Long-term Kinetics of Vibriocidal Antibody Responses After Vibrio cholerae Infection in the Democratic Republic of Congo

Abstract

Interpretation of seroepidemiology studies of cholera relies on knowledge of antibody kinetics, which are not well known in African populations. We performed vibriocidal antibody assays on 212 serum samples from 115 patients with culture-positive cholera (median age, 8 years) in Goma, Democratic Republic of Congo, which were collected at enrollment and 3 to 449 days after. Vibriocidal responses peaked at 7 to 40 days after symptom onset, with 89.5% waning to a titer ≤160 by 180 days. We used a bayesian exponential decay model to show an 88% probability of the posterior distribution supporting a faster decay in children ≤5 years of age.

Keywords: antibody kinetics; cholera; seroepidemiology; vibriocidal.

Figure 1.

Vibriocidal titer responses over time from culture-confirmed cholera cases. Vibriocidal titers by matching Vibrio cholerae O1 serotype from 101 participants with serotype information available, by (A) serotype and (B) age group, plotted on log₂-transformed scales. Hashed lines are LOESS smoothed data with 95% CIs in shade. LOESS, locally estimated scatterplot smoothing.

Figure 2.

Comparison of vibriocidal decay kinetics between age groups. 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 aged >5 years (left) and ≤5 years (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.