Salmonella Typhi Contamination of Water in Liberia

Assessing Salmonella Typhi Contamination of Water in Urban Settings of Liberia

Objectives

To evaluate the contribution of commonly used water sources on typhoid transmission in urban settings of Liberia.

Rationale

Typhoid fever disproportionately impacts underserved, pediatric populations in low- and middle-income countries globally. In population dense settings, such as Kathmandu, Nepal, municipal water has previously been implicated in the causal pathway of typhoid transmission. Liberia is a country undergoing rapid population growth, is estimated to have a high burden of typhoid, and recently became the first African country to roll out a pediatric typhoid conjugate vaccine (TCV) immunization program – a relatively new, more effective vaccine that is approved for younger age groups as compared to prior typhoid vaccines. However, data on the true burden of typhoid in Liberia is limited. Additionally, in certain areas with high TCV coverage, typhoid incidence remains high suggesting vaccination alone is not enough to interrupt transmission. We will evaluate whether commonly used water sources, including municipally supplied water and hand pump wells, are contributing to typhoid transmission in urban settings of Liberia via typhoid contamination surveillance. Previous techniques utilized, such as direct culture (i.e., Moore Swabs) or PCR, may be time consuming, have sensitivity and specificity issues, and can be resource intensive. We will instead characterize the presence or absence of typhoid-specific bacteriophage, a surrogate marker for typhoid presence. In collaboration with the National Public Health Institute of Liberia and Ministry of Health, these data will be presented to Liberian government authorities and serve to focus typhoid surveillance and control efforts, and support the evaluation of TCV introduction in Liberia and globally.

Project Dates

2022-2023

Stage of Work

Explication of causal pathways that generate the problem.

1) What’s been accomplished: National Public Health Institute team member training of sample collection and bacteriophage plaque assay techniques.

2) What we’re focusing on now: starting sample collection!

To Learn More About This Work

CIGH Interview: 5 Questions with Dr. Seth Ari Sim-Son Hoffman, Global Health Postdoctoral Affiliate

People

Primary Contact: Seth Hoffman

Stanford University

. Stephen Luby