Participatory Disease Surveillance for the Early Detection of Cholera-Like Diarrheal Disease Outbreaks in Rural Villages in Malawi: Prospective Cohort Study

"Traditional surveillance systems can have limitations in detecting early signals of outbreaks....PS [participatory surveillance] has been proposed as an additional approach that leverages the local knowledge and resources of communities to identify early outbreak signals."

Participatory surveillance (PS) has proven to be valuable for the early detection of epidemics. This system engages the community in a bidirectional manner, capturing strategic data from the community, processing the acquired knowledge, and providing nearly real-time information back. PS empowers communities to take ownership of their health and well-being, allowing for more comprehensive and timelier case reporting. This study aims to evaluate the feasibility and outcomes of PS using interactive voice response (IVR) technology for the early detection of cholera-like diarrhoeal disease (CLDD) outbreaks in Malawi. IVR is a cost-effective and easy-to-use technology that requires minimal training and can reach a wide range of people, including those in remote and rural areas, where access to health care and traditional disease surveillance methods may be limited.

This longitudinal prospective cohort study followed 740 rural households in Salima District, Malawi, for 6 months. It was conducted as part of a larger study: the Child Development Study, which is an initiative to leverage high-frequency data collection and novel technologies for understanding child development in low-income settings. The survey tool for the PS cohort study was designed to collect answers weekly to 10 symptom questions related to CLDD (here defined as cases where reports indicated diarrhoea combined with either fever or vomiting/nausea). Participants could use all types of phones, as they needed to simply type, press, or dial the numbers indicated by the voice message to respond with "yes" or "no" (e.g., "Have you or anybody in your house experienced fever in the last 7 days?"). Calls were conducted from July 18 2022 to January 8 2023 in Chichewa, the primary language spoken in Malawi.

Prior to the official start of the IVR calls, the research team conducted sensitisation campaigns at community-based childcare centres (CBCCs) to raise awareness among participants and to ensure widespread engagement. (Based on the eligibility criteria, all households involved in the study had at least 1 child who regularly attended the CBCCs.) The awareness-raising events were held at various times and on different days at the CBCCs to reach as many people as possible. At the events, study personnel addressed participants' concerns or questions about technical issues related to using mobile phones in this specific context and discussed the importance of preventive health measures.

Data show that, during the study period, there were 16,280 observations, with an average weekly participation rate of 35%. Maganga Traditional Authority (TA) had the highest average of completed calls, at 144.83 (standard deviation (SD) 10.587), while Ndindi TA had an average of 123.66 (SD 13.176) completed calls. Participation rates were slightly higher at the beginning of the study and decreased over time.

The findings demonstrate that this method might be effective in identifying CLDD with a notable and consistent signal being captured over time. The signal showed a significant increase coinciding with cholera outbreaks in the region. This pattern was observed with the first cholera case in the Salima District, detected shortly after a spike in the PS strategy's CLDD data. Despite limited official reporting, this outbreak was confirmed through hyperlocal media sources. A subsequent analysis highlighted a peak in cholera cases in the Maganga TA area, preceded by a rise in CLDD reports of diarrhoea-like symptoms, underscoring the potential of CLDD in early outbreak detection and response facilitation.

Based on these findings, the researchers suggest that PS using IVR can be particularly useful in preventing CLDD outbreaks for several reasons:

• IVR allows for the timely detection of cases by rapidly identifying suspected CLDD cases within communities, providing public health officials with real-time data to respond promptly and contain potential outbreaks.
• By using a standardised set of questions, the IVR system ensures that data collected across different participants and time points are consistent and comparable, thus improving the surveillance system's reliability.
• The use of phone-based surveys enables data collection from geographically dispersed and hard-to-reach populations, overcoming logistical barriers typically encountered in low-resource settings.
• By longitudinally monitoring the same set of participants over 6 months, the IVR-based PS system can capture temporal trends and identify emerging risk factors, enabling targeted and context-specific interventions to prevent and control disease outbreaks.

Reflecting on the experience, the researchers stress that the successful implementation of PS must consider the site's geolocation, epidemiological profile, seasonality, and available telecommunication infrastructure. For example, reports from 2022 showed that almost 80% of Malawi's population remained offline, with internet access being particularly low in areas away from cities. Bearing that in mind, models of PS conducted through mobile apps (requiring smartphones) would likely not achieve significant engagement in the most remote areas of Malawi.

In conclusion: "By leveraging the IVR design, it is possible to establish a less expensive, flexible, scalable, and reliable system that captures data voluntarily and provides information that is not possible to capture using traditional surveillance methods. This approach can empower communities to take an active role in anticipating disease outbreaks, even in settings where internet coverage is limited..."