Unraveling the Mystery in the DRC’s Disease Outbreak—Is It Disease X?

A recent outbreak of an undiagnosed illness in the Democratic Republic of the Congo is on the radar of public health professionals. Preparedness is key to mitigating the issue.

Published December 10, 2024

By Syra Madad, D.H.Sc., M.Sc., MCP, CHEP
Chief Biopreparedness Officer, NYC Health + Hospitals

A recent outbreak of an undiagnosed illness in the Panzi health zone of the Democratic Republic of the Congo (DRC) has captured global attention, spotlighting the challenges of outbreak investigations in resource-limited settings. Since late October, over 400 cases have been reported, predominantly among children under five years old. Symptoms such as fever, cough, and body aches have resulted in 31 deaths, with severe malnutrition compounding the crisis.

This outbreak highlights the critical need for strong global public health systems to detect and respond to emerging health threats. Although the cause remains uncertain, investigators are exploring various possibilities, including endemic diseases like malaria and respiratory infections such as acute pneumonia, influenza, COVID-19, and measles. Malnutrition is thought to play a significant role in worsening disease severity. Laboratory testing is ongoing, and health officials are evaluating whether multiple diseases may be contributing to the cases and fatalities reported.

Is This “Disease X”?

The term “Disease X” refers to a hypothetical, unknown pathogen with the potential to cause a global epidemic or pandemic. Coined by the World Health Organization (WHO) in 2018, Disease X represents the growing need to prepare for unforeseen infectious threats. In the 21st century, humanity has faced several emerging and re-emerging viral diseases, including SARS-CoV-1, MERS, and Zika, as well as the most recent Disease X, SARS-CoV-2, the virus responsible for COVID-19. These outbreaks underscore the importance of readiness, as novel pathogens like mpox have also spread beyond their endemic regions, creating widespread public health challenges.

While mysterious outbreaks like the one in the DRC often raise alarms, they are more frequently caused by endemic diseases in under-resourced areas than by new pathogens. Known diseases such as measles or influenza, exacerbated by malnutrition or poor vaccination coverage, are often the culprits. My husband often reminds me of the medical adage, “When you hear hoofbeats, think horses, not zebras,” which emphasizes prioritizing the most likely diagnosis. Yet, as someone who works in high-consequence infectious diseases, my mind often first goes to those zebras.

How Outbreak Investigations Work

Outbreak investigations follow a systematic approach to identify and control the source of illness:

1. Epidemiological Analysis: Investigators collect and analyze data to identify trends, clusters, and possible modes of transmission.

2. Clinical and Laboratory Testing: Samples from patients are tested to rule out suspected pathogens such as malaria, pneumonia, or influenza. In this case, samples have been sent to laboratories in Kinshasa for further testing.

3. Community Engagement: Teams work with local communities to identify additional cases, strengthen infection prevention, and provide treatment for the sick.

In the DRC, the investigation faces significant challenges, including remote locations, poor infrastructure, and a healthcare system strained by supply shortages. Despite these obstacles, international and national health teams are collaborating to identify the cause and strengthen the local response according to the latest WHO situation report.

Preparing for Future Threats

The DRC outbreak underscores the importance of global preparedness for both known and unknown diseases. Research shows that the risk of a pandemic with similar impact to COVID-19 is about 1 in 50 in any given year, with a lifetime probability of around 38%. This risk is amplified by environmental changes, which increase the likelihood of pathogens jumping from animals to humans.

To prepare for the next Disease X, scientists are studying the roughly 25 viral families most likely to harbor a novel pandemic threat. Efforts like CEPI’s 100 Days Mission aim to develop vaccines within three months of identifying a new pathogen, offering a proactive defense against future pandemics.

Lessons for the Present and Future

While it is unknown that the current outbreak in the DRC represents a new Disease X, it serves as a reminder of the need to strengthen health systems worldwide. Early investments in surveillance, laboratory capacity, and community engagement are critical to identifying and controlling outbreaks before they spread.

The ongoing investigation in the DRC is a testament to the dedication of public health professionals working in some of the world’s most challenging conditions. It also highlights the importance of global solidarity in addressing outbreaks, whether they stem from endemic diseases or novel pathogens.

Preparedness is our best defense against the unknown. By investing in science, supporting resource-limited health systems, and fostering international collaboration, we can mitigate the impact of today’s outbreaks and prevent the pandemics of tomorrow.

Read more from Dr. Madad on the Academy blog:

• The Rising Threat of Mosquito and Tick-Borne Illnesses: How to Protect Yourself
• The COVID-19 Pandemic at Year Four: The Imperative for Global Health Solidarity
• Crossing Species: The Rising Threat of H5N1 Bird Flu in the U.S.
• HPAI A(H5N1) Transmission Among Cattle in the U.S.
• Our Iceland Adventure Turned into a Climate Crisis Wake-Up Call
• Protecting Healthcare Workers: A Vital Imperative in Rwanda’s Marburg Virus Outbreak and Beyond