Persistence of Ebola virus after the end of widespread transmission in Liberia: an outbreak report

Dokubo, E. Kainne; Wendland, Annika; Mate, Suzanne; Ladner, Jason T.; Hamblion, Esther; Raftery, Philomena; Blackley, David J.; Laney, A. Scott; Mahmoud, Nuha; Wayne-Davies, Gloria; Hensley, Lisa E.; Stavale, Eric; Fakoli, Lawrence; Gregory, Christopher J.; Chen, Tai Ho; Koryon, Augustine; Allen, Denise Roth; Mann, Jennifer; Hickey, Andrew C.; Saindon, John; Badini, Mehboob; Baller, April; Clement, Peter; Bolay, Fatorma K.; Wapoe, Yatta; Wiley, Michael R.; Logue, James; Dighero-Kemp, Bonnie; Higgs, Elizabeth; Gasasira, Alex; Williams, Desmond E.; Dahn, Bernice; Kateh, Francis; Nyenswah, Tolbert; Palacios, Gustavo; Fallah, Mosoka

doi:10.1016/s1473-3099(18)30417-1

Cited by 49 publications

(37 citation statements)

References 19 publications

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“…Despite clearance of viraemia, some male survivors continue to shed live EBOV in the semen, thereby posing a public health risk of sexual transmission and reignition of outbreaks 40,41,68,123,229,[254][255][256][257] . Studies have investigated clusters of EVD cases that occurred sporadically after the peak of the 2013-2016 Western African EVD outbreak, each cluster thought to be initiated by a transmission event involving viral persistence in survivors of EVD, typically in semen 68,258,259 .…”

Section: Mechanisms Of Evd Sequelaementioning

confidence: 99%

Ebola virus disease

Jacob

Crozier

Fischer

et al. 2020

Nat Rev Dis Primers

374

345

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To date, 12 distinct filoviruses have been described 1. The seven filoviruses that have been found in humans belong either to the genus Ebolavirus (Bundibugyo virus (BDBV), Ebola virus (EBOV), Reston virus (RESTV), Sudan virus (SUDV) and Taï Forest virus (TAFV); Fig. 1) or to the genus Marburgvirus (Marburg virus (MARV) and Ravn virus (RAVV)) 2. The WHO International Classification of Diseases Revision 11 (ICD-11) of 2018 recognizes two major subcategories of filovirus disease (FVD): Ebola disease caused by BDBV, EBOV, SUDV or TAFV, and Marburg disease caused by MARV or RAVV. Ebola virus disease (EVD) is defined as a disease only caused by EBOV. This subcategorization of FVD is largely based on the increasing evidence of molecular differences between ebolaviruses and marburgviruses, differences that may influence virus-host reservoir tropism, pathogenesis and disease phenotype in accidental primate hosts 2. Since the discovery of filoviruses in 1967 (reF. 3), 43 FVD outbreaks (excluding at least five laboratoryacquired infections) have been recorded in or exported from Africa 4. The epidemiological definition of outbreak is one or more cases above the known endemic prevalence. For example, the single case of TAFV infection recorded in a setting in which FVD had never been reported before (Côte d'Ivoire) 5 is still considered an outbreak. All FVD outbreaks, with the exception of that caused by TAFV, were characterized by extremely high case-fatality rates (CFRs, also known as lethality). Until 2013, the most extensive outbreak, caused by SUDV, involved 425 cases and 224 deaths (CFR 52.7%) 6. The overall limited numbers of FVD cases (1967-2013: 2,886 cases including 1,982 deaths 4), the typical remote and rural locations of outbreaks and the often delayed announcement of new outbreaks to the international community 7 have prevented the systematic study of clinical FVD in humans. Thus, the commonly used description of FVD was derived either from observation of small groups of patients in care settings that were not well-equipped for diagnosis, treatment and disease characterization, or from observations of even smaller samples, such as individuals who were transferred from Equatorial Africa to Europe and the USA or who fell sick in Europe or the USA after contracting the virus elsewhere. Pathological characterization of FVD via autopsies has been rare 7,8. In the absence of extensive human clinical data, FVD could only be defined further via the use of experimental animal infections 9,10 .

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Section: Mechanisms Of Evd Sequelaementioning

confidence: 99%

Ebola virus disease

Jacob

Crozier

Fischer

et al. 2020

Nat Rev Dis Primers

374

345

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“…The use of this criterion to declare the EO, especially in the context of EVD, has been questioned. Firstly, this criterion ignores the possible recrudescence of EVD cases through uncommon transmission routes and persistence of the virus in survivors (sexual transmission, immunocompromised women, and migration) (13)(14)(15)(16)(17).…”

Section: Introductionmentioning

confidence: 99%

A quantitative framework to define the end of an outbreak: application to Ebola Virus Disease

Djaafara

Imai

Hamblion

et al. 2020

Preprint

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Declaring the end of an outbreak is an important step in controlling infectious disease outbreaks. An objective estimation of the probability of cases arising in the future is important to reduce the risk of post-declaration flare-ups. We developed a simulationbased model to quantify that probability. We tested it on simulated Ebola Virus Disease (EVD) data and found this probability was most sensitive to the instantaneous reproduction number, the reporting rate, and the delay between symptom onset and recovery or death of the last detected case. For EVD, our results suggest that the current WHO criterion of 42 days since the outcome of the last detected case is too short and very sensitive to underreporting. The 90 days of enhanced surveillance period after the end-of-outbreak declaration is therefore crucial to capture potential flare-ups of cases. Hence, we suggest a shift to a preliminary end-of-outbreak declaration after 63 days from the symptom onset day of the last detected case. This should be followed by a 90-day enhanced surveillance, after which the official end-ofoutbreak can be declared. This corresponds to less than 5% probability of flare ups in most of the scenarios examined. Our quantitative framework could be adapted to define end-of-outbreak criteria for other infectious diseases.

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“…The key question is whether these unidentified Ebola virus infection contact persons had any role in transmission chains. This issue was highlighted by Dokubo and colleagues, 12 who reported a familial cluster occurring in Liberia 1 year after an undiagnosed Ebola virus infection in a female contact, probably due to viral persistence. This potential transmission risk should be balanced against the risk of further stigmatisation of both survivors and household contacts.…”

Section: Unrecognised Ebola Virus Infection In Contact Persons: What mentioning

confidence: 99%

Unrecognised Ebola virus infection in contact persons: what can we learn from it?

Fletcher

Bower

2019

The Lancet Infectious Diseases

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be the goal. Rather, we need to offer everyone access to the best diagnostic services possible-including highquality drug susceptibility testing-and treat them with individualised regimens containing the strongest and safest drugs to which their strains are susceptible and avoiding drugs to which there is resistance. Wishful thinking about a scenario in which drug susceptibility testing is not necessary for tuberculosis treatment has no place in the modern approach to tuberculosis. Universal access to drug susceptibility testing will, no doubt, require substantial work, but we must commit ourselves fully to achieving this goal. As the study by Zürcher and colleagues shows, people's lives depend upon it.

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Persistence of Ebola virus after the end of widespread transmission in Liberia: an outbreak report

Cited by 49 publications

References 19 publications

Ebola virus disease

Ebola virus disease

A quantitative framework to define the end of an outbreak: application to Ebola Virus Disease

Unrecognised Ebola virus infection in contact persons: what can we learn from it?

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