Use of Capture–Recapture to Estimate Underreporting of Ebola Virus Disease, Montserrado County, Liberia

Gignoux, Etienne; Idowu, Rachel; Bawo, Luke; Hurum, Lindis; Sprecher, Armand; Bastard, Mathieu; Porten, Klaudia

doi:10.3201/eid2112.150756

Cited by 33 publications

(36 citation statements)

References 7 publications

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“…Extrapolating the EVD mortality rate observed in the study to the population of Monrovia (1,144,806 individuals [20]) indicates an estimate between 1,254 and 4,596 EVD deaths in one year in Monrovia, which is in keeping with the 2,300 EVD deaths notified to MOHSW in Monrovia up to March 2015 [21]. Thus, underestimation of EVD case notification data in Monrovia does not seem to be as high as previously estimated [5]. …”

Section: Discussionsupporting

confidence: 77%

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Mortality, Morbidity and Health-Seeking Behaviour during the Ebola Epidemic 2014–2015 in Monrovia Results from a Mobile Phone Survey

Kuehne

Lynch²,

Marshall³

et al. 2016

PLoS Negl Trop Dis

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Between March 2014 and July 2015 at least 10,500 Ebola cases including more than 4,800 deaths occurred in Liberia, the majority in Monrovia. However, official numbers may have underestimated the size of the outbreak. Closure of health facilities and mistrust in existing structures may have additionally impacted on all-cause morbidity and mortality. To quantify mortality and morbidity and describe health-seeking behaviour in Monrovia, Médecins sans Frontières (MSF) conducted a mobile phone survey from December 2014 to March 2015. We drew a random sample of households in Monrovia and conducted structured mobile phone interviews, covering morbidity, mortality and health-seeking behaviour from 14 May 2014 until the day of the survey. We defined an Ebola-related death as any death meeting the Liberian Ebola case definition. We calculated all-cause and Ebola-specific mortality rates. The sample consisted of 6,813 household members in 905 households. We estimated a crude mortality rate (CMR) of 0.33/10,000 persons/day (95%CI:0.25–0.43) and an Ebola-specific mortality rate of 0.06/10,000 persons/day (95%-CI:0.03–0.11). During the recall period, 17 Ebola cases were reported including those who died. In the 30 days prior to the survey 277 household members were reported sick; malaria accounted for 54% (150/277). Of the sick household members, 43% (122/276) did not visit any health care facility. The mobile phone-based survey was found to be a feasible and acceptable alternative method when data collection in the community is impossible. CMR was estimated well below the emergency threshold of 1/10,000 persons/day. Non-Ebola-related mortality in Monrovia was not higher than previous national estimates of mortality for Liberia. However, excess mortality directly resulting from Ebola did occur in the population. Importantly, the small proportion of sick household members presenting to official health facilities when sick might pose a challenge for future outbreak detection and mitigation. Substantial reported health-seeking behaviour outside of health facilities may also suggest the need for adapted health messaging and improved access to health care.

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Section: Discussionsupporting

confidence: 77%

“…A capture-recapture study conducted in August 2014 suggested that actual case numbers could be three times higher than the number of notified EVD cases [5]. …”

Section: Introductionmentioning

confidence: 99%

Mortality, Morbidity and Health-Seeking Behaviour during the Ebola Epidemic 2014–2015 in Monrovia Results from a Mobile Phone Survey

Kuehne

Lynch²,

Marshall³

et al. 2016

PLoS Negl Trop Dis

Self Cite

View full text Add to dashboard Cite

show abstract

“…Those subsequently classified as asymptomatic contacts may therefore have been true survivors. Gignoux et al (2015) used a statistical comparison of two databases of patients covering Montserrado, Liberia, from June to August 2014 to estimate that the true number of clinical EVD cases was threefold higher than the reported number. It is unclear, however, whether this is due to administrative deficiencies or deliberate under-reporting.…”

Section: Hypothesis 1: Evd Outbreaks Have Been Misidentified As Othermentioning

confidence: 99%

The serology of Ebolavirus – a wider geographical range, a wider genus of viruses or a wider range of virulence?

Formella

Gatherer

2016

Journal of General Virology

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Viruses of the genus Ebolavirus are the causative agents of Ebola virus disease (EVD), of which there have been only 25 recorded outbreaks since the discovery of Zaire and Sudan ebolaviruses in the late 1970s. Until the west African outbreak commencing in late 2013, EVD was confined to an area of central Africa stretching from the coast of Gabon through the Congo river basin and eastward to the Great Lakes. Nevertheless, population serological studies since 1976, most of which were carried out in the first two decades after that date, have suggested a wider distribution and more frequent occurrence across tropical Africa. We review this body of work, discussing the various methods employed over the years and the degree to which they can currently be regarded as reliable. We conclude that there is adequate evidence for a wider geographical range of exposure to Ebolavirus or related filoviruses and discuss three possibilities that could account for this: (a) EVD outbreaks have been misidentified as other diseases in the past; (b) unidentified, and clinically milder, species of the genus Ebolavirus circulate over a wider range than the most pathogenic species; and (c) EVD may be subclinical with a frequency high enough that smaller outbreaks may be unidentified. We conclude that the second option is the most likely and therefore predict the future discovery of other, less virulent, members of the genus Ebolavirus.

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“…The first step is estimating the key outbreak parameters: instantaneous reproduction number, reporting rate, and serial interval distribution. These can be estimated from outbreak data using widely available and established methods which increasingly account for sparse data (34)(35)(36)(37). The next step is to implement the method developed in this study to determine the day when the probability of cases arising in the future is deemed acceptable (in this study < 5%), and an outbreak can be declared over.…”

Section: Discussionmentioning

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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Use of Capture–Recapture to Estimate Underreporting of Ebola Virus Disease, Montserrado County, Liberia

Cited by 33 publications

References 7 publications

Mortality, Morbidity and Health-Seeking Behaviour during the Ebola Epidemic 2014–2015 in Monrovia Results from a Mobile Phone Survey

Mortality, Morbidity and Health-Seeking Behaviour during the Ebola Epidemic 2014–2015 in Monrovia Results from a Mobile Phone Survey

The serology of Ebolavirus – a wider geographical range, a wider genus of viruses or a wider range of virulence?

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

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