Ebola 2018

Approximately two years after Liberia, the hardest hit and last of the 6 countries to be affected in the largest Ebola outbreak since discovery of the disease in 1976, was declared Ebola-free, the virus has again reared its head. This time, its in the Democratic Republic of the Congo (DRC).

Timeline of the Outbreak:

  • May 3, 2018: a district in the Province of Equateur, DRC, reported 21 cases of undiagnosed illness with 17 deaths. Samples from 5 of these cases were sent to the Institute National Recherche Biomedicale in Kinshasa.
  • May 7: Ebola virus was confirmed by RT-PCR.
  • May 8, 2018: Ebola outbreak declared.
  • May 21: 628 contacts of confirmed or suspected cases listed.
  • May 25: 58 cases and 27 deaths.
  • June 1: the outbreak is contained in the Province of Equateur. This Province covers an area of 130442 km2 and has a population of 2,543,936. Equateur as 16 health zones and 284 health centers – this works out as 1 health center for every 9,000 people! The WHO warns that this outbreak has the potential to expand, and while at the moment there is no international spread, the Congo’s neighbors have been placed on alert. The WHO has distributed personal protective equipment, infrared thermometers, and rapid diagnostic tests to health centers in Equateur as well as neighboring countries.

The WHO considers laboratory diagnostics on of the pillars of the Ebola response. They recommend “strengthening diagnostic capabilities” as part of a strategic approach to the prevention, detection, and control of Ebola. In fact, laboratory diagnostics might be a key to how this epidemic plays out, versus the previous outbreak in West Africa wherein six African countries were affected and over 11,000 patients died. This time, there are rapid tests tests available ranging from lateral flow to molecular.

As part of the DRC’s National Laboratory Strategy developed in response to the outbreak, the GeneXpert confirmatory Ebola PCR test is being used a key sites in mobile laboratories. As of June 1, the WHO has deployed four mobile labs through out Equateur including the epicenter of the outbreak. Government Health Centers are equipped with rapid lateral flow tests: the ReEBOV Antigen Rapid Test released under Emergency Use Approval in 2015. According to WHO documents, this test has a sensitivity of 91% and specificity of 84.6%. Both positives and negatives should be confirmed with RT-PCR. The following is the guidance for the use of rapid tests:

Special settings where rapid antigen for Ebola may be beneficial:

  1. In the investigation of suspected Ebola outbreaks in remote settings where PCR tests are not immediately available. While awaiting confirmatory testing, action can be taken to: a) isolate test-positive patients, b) repeat daily testing on patients who initially tested negative but remain symptomatic, c) mobilize transport of samples for confirmatory testing and initiate outbreak-management procedures.
  2. In settings where the number of cases and suspects arriving for triage and care cannot be managed with the existing health staff and laboratory facilities.

Example situations where rapid antigen detection tests should NOT be used:

  • Individual case management – including for establishing definitive diagnosis or making therapeutic decisisions
  • Certification of Ebola virus-free status prior to medical care for other illnesses
  • Release of Ebola patients from Ebola Treatment Centers
  • Pooled blood samples for community-based testing
  • Testing blood before transfusion
  • Active case finding without confirmatory PCR
  • Any setting where action (quarantine, referral, care) based on results is not possible
  • Airport screening

So to summarize, currently in the Province of Equateur, suspected cases are tested by rapid test for initial triage, then samples are sent to the nearest lab for confirmation (positive or negative) by PCR. A suspected case cannot be released until there is a negative test by PCR. Suspected cases that initially negative by the rapid test are isolated from cases that are initially positive.

What about outside Equateur? I talked to Dr. Tim Rice, a friend and colleague serving as a missionary physician in Vanga, Congo. Vanga is the in Province of Bandundu, the northern neighbor of Equateur. While this province has not had a reported case of Ebola, they are getting ready. I asked him about their readiness plan and any laboratory capabilities they had. They have a rapid test: Ebola rapid lateral flow test from STADA Diagnostik (Germany). This assay detects the Ebola virus antigen VP 40 with a sensitivity of 92% and specificity of 98% (according to the package insert). Serum and throat swabs are acceptable specimens, although it is not clear which matrix was used to determine the performance characteristics. The package insert states that the performance characteristics are still being evaluated. Dr. Rice said they use the rapid test with patients with potential exposure and severely ill with fever.  Someone arriving from the Equatorial province with a fever, even if not severely ill, would be tested and isolated. They are to call the local health department for help in obtaining the correct confirmatory samples, properly storing the sample, alerting the regional and national leaders, and transporting the sample properly protected the 10 hours overland to Kinshasa for confirmatory PCR testing at the Institute National Recherche Biomedicale.

The response to the 2018 Ebola outbreak has been impressive and I sincerely hope that with the benefits of laboratory diagnostics and a vaccine, the world will be spared the devastation experienced in the previous outbreak.

 

Sarah Brown Headshot_small

Sarah Riley, PhD, DABCC, is an Assistant Professor of Pediatrics and Pathology and Immunology at Washington University in St. Louis School of Medicine. She is passionate about bringing the lab out of the basement and into the forefront of global health.  

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