Applied Epidemiology in Cambodia.

Abstract

In meeting the Master of Philosophy in Applied Epidemiology (MAE)'s, I completed two of my core projects at the Institute Pasteur of Cambodia (IPC), a non-governmental organization. The other two core projects I completed at the Ministry of Health's Cambodian Communicable Disease Control Department (CCDC), where I was later deployed to support Coronavirus Disease 2019 (COVID-19) contact tracing and surveillance. In this thesis, I demonstrate how I met the core competencies of the MAE program.

In late November and early December 2019, a provincial health department notified CCDC about what they called a food poisoning event that had affected more than 200 people, and resulted in two deaths in a residential facility in a province of Cambodia. We conducted a case-control study. We found a strong association between eating cucumbers and illness. However, laboratory analysis failed to detect a causative agent. Toxicology testing was not conducted, and therefore we were unable to rule out contamination of the cucumbers. This project is described in chapter two, "An outbreak of unknown etiology associated with fresh cucumbers in a residential facility in Cambodia, 2019".

We aimed at describing how malaria has evolved spatially from 2006 to 2019. We undertook a secondary analysis of existing malaria data from all public health facilities in Cambodia between 2006 and 2019 in combination with metadata. Overall, incidence fluctuated between 1.5 and 7.4 cases/1000 inhabitants per year. Malaria clusters were detected in seven northern provinces, along borders. We recommended that interventions aimed at preventing new infections of Plasmodium vivax and relapses should be prioritized. All confirmed malaria cases should be reported to Health Management Information System to avoid misleading trends. This project is detailed in chapter three, "Malaria in Cambodia: retrospective analysis of a changing epidemiology 2006-2019."

I implemented and evaluated the RAI2 surveillance system as part of activities associated with a funded malaria project. Nine attributes, adapted from the US CDC guideline 2001, were used to assess the performance of the system. Usefulness was described based on the outcome of the evaluation of the other eight attributes. Simplicity, flexibility, acceptability, and stability were assessed using a short online survey with health center staff. Sensitivity, positive predictive value, data quality, and timeliness were assessed using document review and data from the RAI2 surveillance system. Findings suggested that the RAI2 surveillance system was simple, flexible, stable, timely but did not meet its primary objective. We recommended that the RAI2 surveillance system should be integrated into the national malaria information system and moved to be a real-time data collection. Additional exposure variables should be captured. I placed this project in chapter four, "Using Kobo Toolbox as a malaria project-based surveillance system in Cambodia: surveillance evaluation."

My final project was to estimate the proportion of COVID-19 cases that were asymptomatic and understand how the asymptomatic transmission may occur. I analyzed data from 22 cases as part of a cluster of returned travelers, with what was believed to be a common exposure site. Their 491 uninfected contacts and ten infected contacts were also included in the analysis. The findings suggested asymptomatic cases made up a larger proportion of total cases within the cluster. This project is described in chapter five, "Coronavirus Disease 2019 asymptomatic transmission: A cluster review in Cambodia, 2020."

Finally, other required activities presented in this thesis include an oral presentation, a scientific manuscript submitted to a peer-review journal, a literature review, a summary for a layperson, lessons learned from the field, and teaching. Show more