Why Contact Tracing Remains One of Infection Prevention's Most Powerful Tools: Lessons From the Ebola Outbreak in the DRC

Long before “contact tracing” became a news headline, infection preventionists (IPs) were already doing the quiet, meticulous work of defining, tracking, and containing infectious disease exposures. We have all gotten the call, 4:00 PM on a Friday before the holiday, as we are wrapping up our day. Patient A has positive test results for tuberculosis (TB), measles, Candida auris, and others.

After we take a deep breath, we determine if that test result meets the criteria for exposure. What was the source of the lab specimen? Was the patient on our campus during the contagious window? Where did the patient go? Finally, the one that often defines what the next few days are like was that the patient was placed on the appropriate transmission-based precautions.

After we confirm an infectious disease exposure in our facility, we build the line list, notify, monitor, and wait out the incubation period. In writing this article, I had to think back to the biggest outbreak I was part of, contact tracing, and it was in the hundreds. A patient who managed to test PCR (Polymerase Chain Reaction) positive for TB in the sputum while being seen in multiple clinics over the course of the week. The rest of the story, you have likely lived yourself.

The core workflow currently required in the Democratic Republic of the Congo (DRC) is identical to ours. Still, it is scaled to a population experiencing severe regional insecurity, armed conflict, and high mobility.¹ Bundibugyo virus disease (BVD) complicates it in a way that runs against intuition. There is no approved vaccine or treatment; it has a lower fatality rate than other Ebola strains. This less acute presentation may delay infected patients from seeking care, increasing the time they remain infectious in the community.¹ The reality of contact tracing for this outbreak presents an array of logistical challenges that offer no clear solution.

To see these challenges in action, look at the numbers: in the DRC, thousands of people have been identified as direct contacts and are being tracked each day. Since the outbreak was declared on May 15, the Africa Centers for Disease Control and Prevention (Africa CDC) has identified more than 35,000 people as contacts of confirmed cases.² Teams on the ground must maintain an up-to-date registry of these contacts, monitoring each daily for 21 days following their last known exposure to ensure the incubation period passes without symptoms.³ (Figure 1).

Reaching Beyond EMRs: Finding Contacts in a Conflict Zone

Before a contact can be followed, they must first be found. In the US health care environment, we have contact information for our patients and staff. When an exposure occurs, and contacts need to be identified, we conduct tracing searches in our electronic medical records (EMRs) and reach out to our clinical teams for the names of staff and potential visitors. This process is tedious and time-consuming. Now imagine conducting contact tracing during an active outbreak in a conflict zone. The surrounding humanitarian setting is filled with highly mobile and frequently displaced populations. To make matters worse, many of these individuals lack reliable access to food, clean water, shelter, or basic medical care.³

Safety concerns have escalated: security incidents at health facilities have constrained where response teams can operate, disrupted surveillance, and increased the likelihood that transmission continues out of sight.³ Mining draws workers in and out, and cross-border trade moves people across the region every day.⁴

The region's geography compounds it. Confirmed cases have reached 36 health zones across Ituri, North Kivu, and South Kivu.^3,5 Only 21 of those 36 have reported a new case in the past 21 days. A single infected traveler can surface hundreds of miles from the outbreak's center, handing tracers a fresh set of names to find.³ One case can generate dozens of contacts, and every one of them restarts a 21-day clock.

In its initial phase, BVD mirrors many other common infections by presenting with fever, fatigue, and body aches. This makes it incredibly challenging to rule out other prevalent diseases, such as malaria, based on symptoms alone. Ultimately, a definitive diagnosis requires a laboratory test. The reality is, the index case is often confirmed late, after the contact web has already widened.³

The Friction of Fear: Navigating Cultural Norms and Distrust

A contact list is only as valid as the names on it. It is only as complete as the index patient is willing to make it. In eastern DRC, the community has lived through years of conflict and deep distrust of outside authority. Effective contact tracing depends on a willingness to name household members, neighbors, and the people they cared for or buried. Knowing they will be subjected to weeks of monitoring, possibly asked to self-isolate.

The World Health Organization (WHO) has been consistent in the messaging that the response must be led by local leaders rooted in the communities. Outbreaks like this are contained only when communities are genuinely engaged.⁶ Before engagement comes trust. Telling a community, as an outsider, how to address generations of cultural norms and beliefs is not the way to go.⁷ The public health emergency declaration itself named the task of identifying and addressing the cultural norms and beliefs that keep people from taking part.⁷ The friction is sharpest around the dead; a body is most infectious after death. Asking a family to hand over a relative for a safe, supervised burial fundamentally alters how they grieve.⁴ When messaged successfully, contacts are traced for the full 21 days. When it is not, contacts are lost. Invariably, some of the lost contacts become new BVD cases.

The response’s own community feedback highlights exactly where the friction sits. By late June, the loudest complaints centered on issues that most directly affect people. These included burials delayed past what custom allows, the manner in which suspected cases are taken from their homes, and the quality of care waiting at the treatment centers. Although outreach had reached more than 1.7 million people and local leaders had opened doors, the trust gaps remained wide. If symptoms do appear, the contact is asked to enter isolation away from their home and family. This is a terrifying prospect for a disease currently killing roughly 31% of confirmed patients in this outbreak.³

Set that against how people are actually living. Isolating at home and reachable for 3 weeks is inherently at odds with the need to work, reach a market, or care for family. There is no vaccine for BVD. While candidate therapeutics and a post-exposure option are moving toward clinical trials, none is a resource that a tracer can offer.³ The true measure of this outbreak is the contact follow-up rate: the percentage of listed contacts a team successfully reaches each day.

Closing the Distance: Turning the Tide on the Map

The reach tells its own story (Figure 2). In late May, teams in Ituri were reaching 21% of the people on their lists, with insecurity and movement restrictions keeping the rest out of view.⁸ By July 1, that reach had climbed to 83% in Ituri.³ That is a hard number to move a mobile population living in a high-conflict zone, and it moved.

The shift from 21% to 83% represents the response finally catching up to the outbreak.³ Early follow-up efforts were severely crippled by weak surveillance, security threats, movement restrictions, and funding shortages that left too few teams on the ground.⁸ Through June, however, testing capacity scaled up and moved closer to the affected communities. The Africa CDC and WHO launched a unified continental response plan to secure new resources. At the same time, a health-zone risk analysis allowed teams to target areas where transmission was most active.

Ultimately, reach rose because more tracers were covering more of the map, backed by stronger community engagement.⁵ Yet, one sober number keeps that progress honest: tracking efficiency climbed even as confirmed cases in the DRC rose to 1,460.³ Better tracing has successfully brought more of the epidemic into view, but it has not yet turned the curve.

Regional contrast sharpens the picture. In Uganda, tracing did exactly what it is supposed to do. Of the 831 contacts listed by late June, 821 successfully completed their 21-day monitoring by July 2. With no new cases appearing after June 21, the country recorded zero community transmission.³

The response was equally efficient when France confirmed an imported case in a doctor returning from Ituri. He reported his own symptoms upon arrival and went straight into isolation. In response, 107 of his DRC contacts were immediately listed and monitored in Kinshasa, while French authorities traced the remaining exposures.³

One Missed Link: The Fragile Science of Risk Mitigation

While significant traction is being made, there is additional work to do. WHO sets the target for daily contact follow-up at 90% to 95%.⁹ The containment of this outbreak rests on a short list: find cases fast, isolate and care for them, bury the dead safely, engage the community, and trace every contact.³ Without successful tracing, there is no way to get ahead of the infected. One missed link can surface a province or a continent away.

For IPs, the resonance is direct even where the setting is not. The follow-up rate in a WHO situation report is the same metric we use to report our success: the number of contacts we followed through the incubation period, divided by the total number identified. This tells us in real time whether we have contained and mitigated the risk. When it falls, a contact we missed is walking through our facility's doors, still in the incubation window. The next cluster is already being written.

References

1. Bangelesa F, Akilimali P, Hosner R, Buckee C, Shoemaker TR, Kaba D. Population mobility and Ebola case containment in Ituri, DR Congo. Lancet. Published online July 2, 2026. doi:10.1016/S0140-6736(26)01253-5

2. Getachew S, Musambi E. Africa CDC chief says the continent needs to invest its own funds in Ebola response, vaccine. AP News. June 19, 2026. Accessed June 23, 2026. https://apnews.com/article/congo-ebola-africa-cdc-ituri-a5bfda53dbef567146cc1b39cce6f3f3

3. Ebola disease caused by Bundibugyo virus, in the Democratic Republic of the Congo and Uganda. World Health Organization. Disease Outbreak News. July 3, 2026. Accessed July 3, 2026. https://www.who.int/emergencies/disease-outbreak-news/item/2026-DON612

4. Ebola disease outbreak in the Democratic Republic of the Congo and Uganda. CDC. Health Alert Network Health Advisory. May 16, 2026. Accessed July 3, 2026. https://www.cdc.gov/han/php/notices/han00530.html

5. Ebola disease caused by Bundibugyo virus, Democratic Republic of the Congo and Uganda. World Health Organization. Disease Outbreak News. June 13, 2026. Accessed July 3, 2026. https://www.who.int/emergencies/disease-outbreak-news/item/2026-DON607

6. Ongoing outbreak of Ebola disease caused by Bundibugyo virus in the Democratic Republic of the Congo. World Health Organization Regional Office for Africa. Accessed July 3, 2026. https://www.afro.who.int/health-topics/ebola-disease/outbreak-drc-26

7. Epidemic of Ebola disease caused by Bundibugyo virus in the Democratic Republic of the Congo and Uganda determined a public health emergency of international concern. World Health Organization. May 17, 2026. Accessed July 3, 2026. https://www.who.int/news/item/17-05-2026-epidemic-of-ebola-disease-in-the-democratic-republic-of-the-congo-and-uganda-determined-a-public-health-emergency-of-international-concern

8. Ebola disease caused by Bundibugyo virus, Democratic Republic of the Congo. World Health Organization. Disease Outbreak News. May 21, 2026. Accessed July 3, 2026. https://www.who.int/emergencies/disease-outbreak-news/item/2026-DON603

9. Bundibugyo virus disease outbreak: Democratic Republic of the Congo, Uganda, France. World Health Organization Regional Office for Africa. Weekly External Situation Report 07. Data as of June 28, 2026. Accessed July 4, 2026. https://reliefweb.int/report/democratic-republic-congo/ebola-bundibugyo-virus-disease-outbreak-democratic-republic-congo-uganda-weekly-external-situation-report-07-data-28-june-2026.