Surveillance of Vibrio cholerae in a non-sewered sanitation refugee camp setting using culture methods: Dzaleka camp, Malawi

Abstract

Refugees living in camps may be particularly vulnerable to infectious disease outbreaks because of factors such as overcrowding, inconsistent preventive healthcare, and limited water, sanitation, and hygiene services. Due to the endemicity of cholera, Malawi provides a suitable setting for a wastewater and environmental surveillance feasibility study in a refugee camp. We conducted a study in the Dzaleka camp in Malawi during a nationwide cholera outbreak. Incentivized refugee volunteers collected samples for 19 weeks from seven high-use public pit latrines and from a vacuum pump truck used to remove fecal sludge. The National Microbiological Reference Laboratory of the Public Health Institute of Malawi used culture methods, with confirmation using VITEK MS or Analytical Profile Index, to detect Vibrio cholerae. Academic partners provided technical input, training, and quality assurance throughout the study. The results were reviewed weekly at partner-coordination meetings. No V. cholerae were detected in regular samples (n = 147), in concordance with clinical data from the same period. The paired pit latrine and pump truck samples also had consistent negative results for V. cholerae. Other noncholera, pathogenic Vibrio species were identified in seven samples, namely, V. alginolyticus, V. parahaemolyticus, and V. metschnikovii. Here, we discuss the unique challenges of conducting wastewater and environmental surveillance in refugee camp settings, including our operational framework. This study provides a framework for scaling wastewater and environmental surveillance efforts in other humanitarian contexts through robust partnerships, clear protocols for non-sewered sanitation systems, and in-country resources.