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Ebola detection and testing rapidly expands in Uganda and US

A presentation slide showing the location of the 2022 Sudan ebolavirus outbreak. The speaker is shown to the right.

Ebola detection and testing rapidly expands in Uganda and US

By Melanie Padgett Powers, writer

A partnership between Uganda and US public health professionals was instrumental in responding to the 2022 Ebola outbreak in Africa. Furthermore, lessons learned from that response helped update guidance on how the US would respond to suspected Ebola cases arriving on US shores.

Ebola is a highly transmissible disease with a mortality rate of 50 to 90 percent without treatment. When people hear “Ebola,” it’s usually referring to the Zaire ebolavirus, explained Trevor Shoemaker, PhD, MPH, at the 2023 APHL Annual Conference May 23 session, “Preparedness and Response Domestically and Abroad—the 2022 Ebola Outbreak” in Sacramento, CA. Shoemaker is team lead, epidemiology, surveillance, clinical and health education, Viral Special Pathogens Branch, US Centers for Disease Control and Prevention (CDC).

The Zaire virus has been responsible for the majority of Ebola outbreaks in recent years and is one of four ebolaviruses known to cause human infection. However, when Ebola broke out in Uganda in September 2022, it was the Sudan ebolavirus.

For the past 12 years, the CDC has been supporting Uganda’s Viral Hemorrhagic Fever (VHF) Surveillance System. “But we’ve been engaged in Uganda ever since the first Sudan virus outbreak detected in the year 2000,” Shoemaker said. For the VHF program, the CDC assisted Uganda’s Ministry of Health, through the Uganda Virus Research Institute, to establish a laboratory to perform in-country diagnostics and enhance the epidemiological and clinical surveillance in the country.

“Most of the things we helped implement were to improve reporting capability, improve the laboratory capacity, detect incident cases very rapidly and report those to the national level so they could take action,” Shoemaker said. “We improved the capability to respond, so this would be quick outbreak investigation and containment.”

They also trained Ugandan health workers on how to properly don personal protective equipment, take a blood specimen for testing, fill out the case report form and safely ship samples to the national laboratory.

The program, which has tested over 20,000 clinical samples, has greatly increased the detection of VHF outbreaks in Uganda and the region, Shoemaker said. Since the program began, it has detected more outbreaks than in the previous 10 years. “It has also reduced the time between initial report of suspected outbreaks and laboratory confirmation by quite a number of days,” he said. The laboratory can provide results within six to 12 hours of receiving the sample and can do confirmatory testing within 24 hours.

In the 2022 Ebola outbreak, there were 164 total cases in nine Ugandan districts, with 77 deaths, which is a 47 percent case fatality rate.

Ebola preparation in the US

Although the risk of Ebola being imported to the US last year was considered low, Shoemaker said, the CDC activated its emergency response structure. CDC Ebola Response Teams were ready to travel to states if needed. CDC updated its guidance for health care workers in the US for suspected Ebola cases. The APHL Biosafety and Biosecurity Committee also updated its Ebola guidance, which was from 2015.

In the US, the CDC oversees the Laboratory Response Network (LRN), a system of approximately 120 US laboratories—including all 50 state public health laboratories—that detect and respond to biological threats.

Before the 2022 Uganda Ebola outbreak, only eight LRN laboratories had the capability to test for the Sudan ebolavirus. Within a month, that was expanded to 27 LRN laboratories, as well as 10 regional emerging special pathogen treatment centers, Shoemaker said. Now, there are 34 laboratories able to test for Sudan virus (as well as the Marburg virus, another severe viral hemorrhagic fever).

To test for the Sudan ebolavirus, the LRN laboratories use the commercial product BioFire FilmArray and the Warrior Panel, which was approved by the US Food and Drug Administration in 2017. CDC uses a real-time reverse transcription–polymerase chain reaction (RT-PCR) assay, similar to what many LRN laboratories already have to test for the Zaire virus. The CDC’s Sudan test is currently undergoing approval to send out to LRN laboratories.

In 2022 in the US, the CDC had clinical consultations for 35 ill returning travelers from the outbreak region and performed tests on three people. All were negative. Compare that to January 2017 to December 2021, Shoemaker said, when there were seven Ebola virus outbreaks and the US performed testing on only nine ill travelers.

Melanie Padgett Powers is a freelance writer and editor specializing in health care and public health.

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