This project aims to fill this essential knowledge gap by assessing the impact of oral cholera vaccine mass campaigns in 2 sites (urban and rural) in DRC, described in this protocol. The evidence generated from this project will be key to develop future strategies regarding cholera vaccine use in endemic settings, including places with higher burden in terms of cholera mortality.

The project will comprise three different components:

1. Clinical cholera surveillance to measure cholera diseases incidence in selected African hotspots targeted by vaccination.
2. Serial serological surveys to measure the prevalence of recent cholera infection (within the last 12 months).
3. Identification and follow up of individuals with positive V. cholerae shedding (symptomatic or asymptomatic) among sero-survey participants and among household members of cholera confirmed cases.

The present protocol relates to the setup of clinical surveillance and the follow up of individuals with positive V. cholerae shedding identified through clinical surveillance, in DRC.

This protocol will allow us to assess if a large vaccination campaign reaching high coverage in cholera hotspot in Africa can allow sustained control of cholera for at least two years, by fulfilling the following specific objectives:

• To measure cholera incidence rates following the mass vaccination campaign in two cholera hotspots in Africa.
• To assess the duration of shedding among vaccinated and unvaccinated individuals and the duration of viable V. cholerae in the peri-household environment.
• To measure the secondary cholera attack rates (symptomatic and asymptomatic) at household level among vaccinated and unvaccinated individuals following the identification of an index case in a given household.
• To describe the global genetic diversity of V. cholerae strains in the study areas and within households affected by cholera.
• To develop sustainable surveillance methods that could be applied in other hotspots in Africa and elsewhere aiming to monitor the impact of the cholera control program.

For Surveillance in study CTCs

Inclusion Criteria:

• All patients presenting at the time of the study to any selected Cholera Treatment Center/Cholera Treatment Unit (CTC/CTU), matching the case definition and giving his/her consent (or assent for children 8 to 17 years old) to participate in the study will be eligible.

Exclusion Criteria:

• Patients who decline to participate will be excluded from the study.

Follow up of individuals with active cholera shedding:

Inclusion Criteria:

1. present to any selected CTC/CTU, match the case definition, participate to the clinical surveillance activity and test positive to RDT OR
2. Be a household member of a person respecting inclusion criteria 1. AND for whom the head of the household has provided verbal consent to participate AND giving his/her consent (or assent for children 8 to 17 years old) to participate in the study will be eligible.

Exclusion Criteria:

- Individuals who decline to participate will be excluded from the study, as well as households for whom the head of the household (and his or her representative) decline the participation of his/her household.

All patients presenting to a CTC/UTC with a watery diarrhoea (≥ 3 watery stools per day), with or without vomiting, with or without dehydration.

For the follow-up of individuals with active cholera shedding:

This activity will take place in the community at included patient's households. Patients will be identified through CTC/CTUs and will therefore be conducted in the catchment area of these structures.

Datasets gathered during this study are susceptible to be made available to other research groups which are currently actively collaborating with Epicentre in the cholera research projects. In that case, data sharing agreements will be made with the relevant research groups.