Identifying Paucisymptomatic or Asymptomatic and Unrecognized Ebola Virus Disease Among Close Contacts Based on Exposure Risk Assessments and Screening Algorithms.

BACKGROUND: There is limited evidence to evaluate screening algorithms with rapid antigen testing and exposure assessments as identification strategies for paucisymptomatic or asymptomatic Ebola virus (EBOV) infection and unrecognized EBOV disease (EVD). METHODS: We used serostatus and self-reported postexposure symptoms from a cohort study to classify contact-participants as having no infection, paucisymptomatic or asymptomatic infection, or unrecognized EVD. Exposure risk was categorized as low, intermediate, or high. We created hypothetical scenarios to evaluate the World Health Organization (WHO) case definition with or without rapid diagnostic testing (RDT) or exposure assessments. RESULTS: This analysis included 990 EVD survivors and 1909 contacts, of whom 115 (6%) had paucisymptomatic or asymptomatic EBOV infection, 107 (6%) had unrecognized EVD, and 1687 (88%) were uninfected. High-risk exposures were drivers of unrecognized EVD (adjusted odds ratio, 3.5 [95% confidence interval, 2.4-4.9]). To identify contacts with unrecognized EVD who test negative by the WHO case definition, the sensitivity was 96% with RDT (95% confidence interval, 91%-99%), 87% with high-risk exposure (82%-92%), and 97% with intermediate- to high-risk exposures (93%-99%). The proportion of false-positives was 2% with RDT and 53%-93% with intermediate- and/or high-risk exposures. CONCLUSION: We demonstrated the utility and trade-offs of sequential screening algorithms with RDT or exposure risk assessments as identification strategies for contacts with unrecognized EVD.

Simplifying the estimation of diagnostic testing accuracy over time for high specificity tests in the absence of a gold standard.

Many different methods for evaluating diagnostic test results in the absence of a gold standard have been proposed. In this paper, we discuss how one common method, a maximum likelihood estimate for a latent class model found via the Expectation-Maximization (EM) algorithm can be applied to longitudinal data where test sensitivity changes over time. We also propose two simplified and nonparametric methods which use data-based indicator variables for disease status and compare their accuracy to the maximum likelihood estimation (MLE) results. We find that with high specificity tests, the performance of simpler approximations may be just as high as the MLE.

A Longitudinal Study of Ebola Sequelae in Liberia.

BACKGROUND: Multiple health problems have been reported in survivors of Ebola virus disease (EVD). Attribution of these problems to the disease without a control group for analysis is difficult. METHODS: We enrolled a cohort of EVD survivors and their close contacts and prospectively collected data on symptoms, physical examination findings, and laboratory results. A subset of participants underwent ophthalmologic examinations. Persistence of Ebola virus (EBOV) RNA in semen samples from survivors was determined. RESULTS: A total of 966 EBOV antibody-positive survivors and 2350 antibody-negative close contacts (controls) were enrolled, and 90% of these participants were followed for 12 months. At enrollment (median time to baseline visit, 358 days after symptom onset), six symptoms were reported significantly more often among survivors than among controls: urinary frequency (14.7% vs. 3.4%), headache (47.6% vs. 35.6%), fatigue (18.4% vs. 6.3%), muscle pain (23.1% vs. 10.1%), memory loss (29.2% vs. 4.8%), and joint pain (47.5% vs. 17.5%). On examination, more survivors than controls had abnormal abdominal, chest, neurologic, and musculoskeletal findings and uveitis. Other than uveitis (prevalence at enrollment, 26.4% vs. 12.1%; at year 1, 33.3% vs. 15.4%), the prevalence of these conditions declined during follow-up in both groups. The incidence of most symptoms, neurologic findings, and uveitis was greater among survivors than among controls. EBOV RNA was detected in semen samples from 30% of the survivors tested, with a maximum time from illness to detection of 40 months. CONCLUSIONS: A relatively high burden of symptoms was seen in all participants, but certain symptoms and examination findings were more common among survivors. With the exception of uveitis, these conditions declined in prevalence during follow-up in both groups. Viral RNA in semen persisted for a maximum of 40 months. (Funded by the National Institute of Allergy and Infectious Diseases and the National Eye Institute; PREVAIL III ClinicalTrials.gov number, NCT02431923.).

SARS-CoV-2 Sequence Analysis during COVID-19 Case Surge, Liberia, 2021.

In June 2021, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) cases surged in Liberia. SARS-CoV-2 sequences from patients hospitalized during March-July 2021 revealed the Delta variant was in Liberia in early March and was dominant in June, irrespective of geography. Mutations and deletions suggest multiple SARS-CoV-2 Delta variant introductions.

Phase 2 Placebo-Controlled Trial of Two Vaccines to Prevent Ebola in Liberia.

BACKGROUND: The safety and efficacy of vaccines to prevent Ebola virus disease (EVD) were unknown when the incidence of EVD was peaking in Liberia. METHODS: We initiated a randomized, placebo-controlled, phase 3 trial of the chimpanzee adenovirus 3 vaccine (ChAd3-EBO-Z) and the recombinant vesicular stomatitis virus vaccine (rVSV∆G-ZEBOV-GP) in Liberia. A phase 2 subtrial was embedded to evaluate safety and immunogenicity. Because the incidence of EVD declined in Liberia, the phase 2 component was expanded and the phase 3 component was eliminated. RESULTS: A total of 1500 adults underwent randomization and were followed for 12 months. The median age of the participants was 30 years; 36.6% of the participants were women. During the week after the administration of vaccine or placebo, adverse events occurred significantly more often with the active vaccines than with placebo; these events included injection-site reactions (in 28.5% of the patients in the ChAd3-EBO-Z group and 30.9% of those in the rVSV∆G-ZEBOV-GP group, as compared with 6.8% of those in the placebo group), headache (in 25.1% and 31.9%, vs. 16.9%), muscle pain (in 22.3% and 26.9%, vs. 13.3%), feverishness (in 23.9% and 30.5%, vs. 9.0%), and fatigue (in 14.0% and 15.4%, vs. 8.8%) (P<0.001 for all comparisons); these differences were not seen at 1 month. Serious adverse events within 12 months after injection were seen in 40 participants (8.0%) in the ChAd3-EBO-Z group, in 47 (9.4%) in the rVSV∆G-ZEBOV-GP group, and in 59 (11.8%) in the placebo group. By 1 month, an antibody response developed in 70.8% of the participants in the ChAd3-EBO-Z group and in 83.7% of those in the rVSV∆G-ZEBOV-GP group, as compared with 2.8% of those in the placebo group (P<0.001 for both comparisons). At 12 months, antibody responses in participants in the ChAd3-EBO-Z group (63.5%) and in those in the rVSV∆G-ZEBOV-GP group (79.5%) remained significantly greater than in those in the placebo group (6.8%, P<0.001 for both comparisons). CONCLUSIONS: A randomized, placebo-controlled phase 2 trial of two vaccines that was rapidly initiated and completed in Liberia showed the capability of conducting rigorous research during an outbreak. By 1 month after vaccination, the vaccines had elicited immune responses that were largely maintained through 12 months. (Funded by the National Institutes of Allergy and Infectious Diseases and the Liberian Ministry of Health; PREVAIL I ClinicalTrials.gov number, NCT02344407 .).

Molecular Evidence of Sexual Transmission of Ebola Virus.

A suspected case of sexual transmission from a male survivor of Ebola virus disease (EVD) to his female partner (the patient in this report) occurred in Liberia in March 2015. Ebola virus (EBOV) genomes assembled from blood samples from the patient and a semen sample from the survivor were consistent with direct transmission. The genomes shared three substitutions that were absent from all other Western African EBOV sequences and that were distinct from the last documented transmission chain in Liberia before this case. Combined with epidemiologic data, the genomic analysis provides evidence of sexual transmission of EBOV and evidence of the persistence of infective EBOV in semen for 179 days or more after the onset of EVD. (Funded by the Defense Threat Reduction Agency and others.).

Controlling the last known cluster of Ebola virus disease - Liberia, January-February 2015.

As one of the three West African countries highly affected by the 2014-2015 Ebola virus disease (Ebola) epidemic, Liberia reported approximately 10,000 cases. The Ebola epidemic in Liberia was marked by intense urban transmission, multiple community outbreaks with source cases occurring in patients coming from the urban areas, and outbreaks in health care facilities (HCFs). This report, based on data from routine case investigations and contact tracing, describes efforts to stop the last known chain of Ebola transmission in Liberia. The index patient became ill on December 29, 2014, and the last of 21 associated cases was in a patient admitted into an Ebola treatment unit (ETU) on February 18, 2015. The chain of transmission was stopped because of early detection of new cases; identification, monitoring, and support of contacts in acceptable settings; effective triage within the health care system; and rapid isolation of symptomatic contacts. In addition, a "sector" approach, which divided Montserrado County into geographic units, facilitated the ability of response teams to rapidly respond to community needs. In the final stages of the outbreak, intensive coordination among partners and engagement of community leaders were needed to stop transmission in densely populated Montserrado County. A companion report describes the efforts to enhance infection prevention and control efforts in HCFs. After February 19, no additional clusters of Ebola cases have been detected in Liberia. On May 9, the World Health Organization declared the end of the Ebola outbreak in Liberia.

Possible sexual transmission of Ebola virus - Liberia, 2015.

On March 20, 2015, 30 days after the most recent confirmed Ebola Virus Disease (Ebola) patient in Liberia was isolated, Ebola was laboratory confirmed in a woman in Monrovia. The investigation identified only one epidemiologic link to Ebola: unprotected vaginal intercourse with a survivor. Published reports from previous outbreaks have demonstrated Ebola survivors can continue to harbor virus in immunologically privileged sites for a period of time after convalescence. Ebola virus has been isolated from semen as long as 82 days after symptom onset and viral RNA has been detected in semen up to 101 days after symptom onset. One instance of possible sexual transmission of Ebola has been reported, although the accompanying evidence was inconclusive. In addition, possible sexual transmission of Marburg virus, a filovirus related to Ebola, was documented in 1968. This report describes the investigation by the Government of Liberia and international response partners of the source of Liberia's latest Ebola case and discusses the public health implications of possible sexual transmission of Ebola virus. Based on information gathered in this investigation, CDC now recommends that contact with semen from male Ebola survivors be avoided until more information regarding the duration and infectiousness of viral shedding in body fluids is known. If male survivors have sex (oral, vaginal, or anal), a condom should be used correctly and consistently every time.

Prevalence and determinants of post-acute sequelae of COVID-19 in Liberia.

BACKGROUND: Evidence from resource-rich settings indicates that many people continue to have persistent symptoms following acute SARS-CoV-2 infection, called post-acute sequelae of COVID-19 (PASC). Only a few studies have described PASC in sub-Saharan Africa (SSA). We aimed to describe PASC in Liberia. METHODS: We randomly sampled all people who were reported from the most populous county to the Liberian Ministry of Health (MOH) as having a laboratory-confirmed SARS-CoV-2 infection from June to August 2021. We interviewed individuals by phone 3 to 6 months later. Those with persistence of at least one symptom were considered to have PASC. RESULTS: From among 2848 people reported to the MOH from Montserrado County during the period of interest, we randomly selected 650; of these, 548 (84.3%) were reached and 505 (92.2%) of those who were contacted were interviewed. The median age was 38 years (interquartile range (IQR), 30-49), and 43.6% were female. During acute infection, 40.2% were asymptomatic, 53.9% had mild/moderate disease and 6.9% had severe/critical disease. Among the 59.8% (n = 302) who were initially symptomatic, 50.2% (n = 152) reported at least one persistent symptom; the most common persistent symptoms were fatigue (21.2%), headache (16.2%) and cough (12.6%); 40.1% reported that PASC significantly affected their daily activities. Being hospitalized with moderate disease [adjusted prevalence ratio (aPR), 2.00 (95% CI, 1.59 to 2.80] or severe/critical disease [aPR, 2.11 (95% CI, 1.59 to 2.80)] was associated with PASC, compared with those not hospitalized. Females were more likely than males to report persistent fatigue [aPR, 1.67 (95% CI, 1.08 to 2.57)]. CONCLUSIONS: Our findings suggest that persistent symptoms may have affected a large proportion of people with initially symptomatic COVID-19 in west Africa and highlight the need to create awareness among infected people and health care professionals.

Pregnancy, pregnancy outcomes, and infant growth and development after recovery from Ebola virus disease in Liberia: an observational cohort study.

BACKGROUND: Minimal data exist on pregnancy following recovery from Ebola in people of child-bearing potential (females aged roughly 18-45 years). The aim of this study was to assess viral persistence or reactivation in pregnancy, the frequency of placental transfer of anti-Ebola IgG antibodies, and pregnancy outcomes in this population. METHODS: In this observational cohort study, we studied self-reported pregnancies in two groups: seropositive people who had recovered from Ebola virus disease (seropositive group) and seronegative people who had close contact with people with Ebola (seronegative group). Participants had enrolled in the PREVAIL III longitudinal study and were exposed during the 2014-2016 Liberian Ebola outbreak. The primary outcome was pregnancy result. We assessed rates of livebirths and other pregnancy results in both study groups, and presence of Ebola RNA by PCR in samples of placenta, maternal and cord blood, breastmilk, and vaginal secretions from people who had recovered from Ebola who conceived a median of 14 months after acute Ebola virus disease. Mixed-model logistic regression evaluated associations between first-reported pregnancy outcome, age, and study group. Growth and neurodevelopment in the infants born to people in the seropositive group were assessed at 6-month intervals for 2 years. Data were accrued by PREVAIL III study staff. FINDINGS: 1566 participants were enrolled between June 17, 2015, and Dec 14, 2017, of whom 639 became pregnant (215 seropositive, 424 seronegative) and 589 reported pregnancy outcomes (206 seropositive, 383 seronegative). 105 infants born to 98 mothers in the seropositive group were enrolled in the birth cohort. Ebola RNA was not detected in 205 samples of placenta, cord blood, or maternal blood taken at birth from 54 mothers in the seropositive group, nor in 367 vaginal swabs. Viral RNA was found in two of 354 longitudinal breastmilk samples. All but one of 57 infants born during these 54 births were seropositive for anti-Ebola antibodies. Neonates showed high concentrations of anti-Ebola IgG, which declined after 6 months. Odds of adverse pregnancy outcome among the two groups were indistinguishable (OR 1·13, 95% CI 0·71-1·79). Compared with WHO standards, infants born to those in the seropositive group had lower median weight and length, and larger median head circumference over 2 years. Compared with a cohort from the USA accrual of gross motor developmental milestones was similar, whereas attainment of pincer grasp and early vocalisation were mildly delayed. INTERPRETATION: The risks of Ebola virus reactivation in the peripartum and postpartum period and of adverse birth outcomes are low in those who have recovered from Ebola virus disease and become pregnant approximately 1 year after acute Ebola virus disease. The implication for clinical practice is that care of people who are pregnant and who have recovered from Ebola can be offered without risks to health-care providers or stigmatisation of the mothers and their offspring. The implication for prospective mothers is that safe pregnancies are entirely possible after recovery from Ebola. FUNDING: National Institute of Allergy and Infectious Diseases and Liberia Ministry of Health.

Clinical sequelae among individuals with pauci-symptomatic or asymptomatic Ebola virus infection and unrecognised Ebola virus disease in Liberia: a longitudinal cohort study.

BACKGROUND: Whether or not individuals with pauci-symptomatic or asymptomatic Ebola virus infection and unrecognised Ebola virus disease develop clinical sequelae is unknown. We assessed current symptoms and physical examination findings among individuals with pauci-symptomatic or asymptomatic infection and unrecognised Ebola virus disease compared with Ebola virus disease survivors and uninfected contacts. METHODS: Between June 17, 2015, and June 30, 2017, we studied a cohort of Ebola virus disease survivors and their contacts in Liberia. Surveys, current symptoms and physical examination findings, and serology were used to characterise disease status of reported Ebola virus disease, unrecognised Ebola virus disease, pauci-symptomatic or asymptomatic Ebola virus infection, or no infection. We pre-specified findings known to be differentially prevalent among Ebola virus disease survivors versus their contacts (urinary frequency, headache, fatigue, muscle pain, memory loss, joint pain, neurological findings, chest findings, muscle findings, joint findings, abdominal findings, and uveitis). We estimated the prevalence and incidence of selected clinical findings by disease status. FINDINGS: Our analytical cohort included 991 reported Ebola virus disease survivors and 2688 close contacts. The median time from acute Ebola virus disease onset to baseline was 317 days (IQR 271-366). Of 222 seropositive contacts, 115 had pauci-symptomatic or asymptomatic Ebola virus infection and 107 had unrecognised Ebola virus disease. At baseline, prevalent findings of joint pain, memory loss, muscle pain, and fatigue were lowest among those with pauci-symptomatic or asymptomatic infection or no infection, higher among contacts with unrecognised Ebola virus disease, and highest in reported survivors of Ebola virus disease. Joint pain was the most prevalent finding, and was reported in 434 (18%) of 2466 individuals with no infection, 14 (12%) of 115 with pauci-symptomatic or asymptomatic infection, 31 (29%) of 107 with unrecognised Ebola virus disease, and 476 (48%) of 991 with reported Ebola virus disease. In adjusted analyses, this pattern remained for joint pain and memory loss. Survivors had an increased odds of joint pain compared with unrecognised Ebola virus disease contacts (adjusted odds ratio [OR] 2·13, 95% CI 1·34-3·39); unrecognised Ebola virus disease contacts had an increased odds of joint pain compared with those with pauci-symptomatic or asymptomatic infection and uninfected contacts (adjusted OR 1·89, 95% CI 1·21-2·97). The adjusted odds of memory loss was more than four-times higher among survivors than among unrecognised Ebola virus disease contacts (adjusted OR 4·47, 95% CI 2·41-8·30) and two-times higher among unrecognised Ebola virus disease contacts than in those with pauci-symptomatic or asymptomatic infection and uninfected contacts (adjusted OR 2·05, 95% CI 1·10-3·84). By 12 months, prevalent findings had decreased in the three infected groups. INTERPRETATION: Our findings provide evidence of post-Ebola virus disease clinical sequelae among contacts with unrecognised Ebola virus disease but not in people with pauci-symptomatic or asymptomatic Ebola virus infection. FUNDING: National Cancer Institute and National Institute of Allergy and Infectious Diseases of the National Institutes of Health.

The impact of the 2014 Ebola epidemic on HIV disease burden and outcomes in Liberia West Africa.

BACKGROUND: Detailed longitudinal studies of HIV-positive individuals in West Africa are lacking. Here the HIV prevalence, incidence, all-cause mortality, and the proportion of individuals receiving treatment with cART in two cohorts of participants in Ebola-related studies are described. SETTING: Individuals of all ages were enrolled and followed at four sites in the area of Monrovia, Liberia. METHODS: Two cohorts identified in response to the Ebola epidemic are described to provide insights into the current state of the HIV epidemic. HIV testing was performed at baseline for participants in both cohorts and during follow-up in one cohort. RESULTS: Prevalence and incidence of HIV (prevalence of 3.1% for women and 1.4% for men and incidence of 3.3 per 1,000) were higher in these cohorts compared to 2018 national estimates (prevalence of 1.3% and incidence of 0.39 per 1,000). Most participants testing positive did not know their status prior to testing. Of those who knew they were HIV positive, 7.9% reported being on antiretroviral treatment. The death rate among those with HIV was 12.3% compared to 1.9% in HIV-negative individuals (adjusted odds ratio of 6.87). While higher levels of d-dimer were associated with increased mortality, this was not specific to those with HIV, however lower hemoglobin levels were associated with increased mortality among those with HIV. CONCLUSION: These findings point to a need to perform further research studies aimed at fulfilling these knowledge gaps and address current shortcomings in the provision of care for those living with HIV in Liberia.

Triangulating Evidence to Infer Pathways that Influence Ebola Virus Disease-Related Stigma and Clinical Findings among Survivors: An Observational Cohort Study.

Visible signs of disease can evoke stigma while stigma contributes to depression and mental illness, sometimes manifesting as somatic symptoms. We assessed these hypotheses among Ebola virus disease (EVD) survivors, some of whom experienced clinical sequelae. Ebola virus disease survivors in Liberia were enrolled in an observational cohort study starting in June 2015 with visits every 6 months. At baseline and 18 months later, a seven-item index of EVD-related stigma was administered. Clinical findings (self-reported symptoms and abnormal findings) were obtained at each visit. We applied the generalized estimating equation method to assess the bidirectional concurrent and lagged associations between clinical findings and stigma, adjusting for age, gender, educational level, referral to medical care, and HIV serostatus as confounders. When assessing the contribution of stigma to later clinical findings, we restricted clinical findings to five that were also considered somatic symptoms. Data were obtained from 859 EVD survivors. In concurrent longitudinal analyses, each additional clinical finding increased the adjusted odds of stigma by 18% (95% CI: 1.11, 1.25), particularly palpitations, muscle pain, joint pain, urinary frequency, and memory loss. In lagged associations, memory loss (adjusted odds ratio [AOR]: 4.6; 95% CI: 1.73, 12.36) and anorexia (AOR: 4.17; 95% CI: 1.82, 9.53) were associated with later stigma, but stigma was not significantly associated with later clinical findings. Stigma was associated with select symptoms, not abnormal objective findings. Lagged associations between symptoms and later stigma substantiate the possibility of a pathway related to visible symptoms identified by community members and leading to fear of contagion.

Partnership for Research on Ebola VACcination (PREVAC): protocol of a randomized, double-blind, placebo-controlled phase 2 clinical trial evaluating three vaccine strategies against Ebola in healthy volunteers in four West African countries.

INTRODUCTION: The Ebola virus disease (EVD) outbreak in 2014-2016 in West Africa was the largest on record and provided an opportunity for large clinical trials and accelerated efforts to develop an effective and safe preventative vaccine. Multiple questions regarding the safety, immunogenicity, and efficacy of EVD vaccines remain unanswered. To address these gaps in the evidence base, the Partnership for Research on Ebola Vaccines (PREVAC) trial was designed. This paper describes the design, methods, and baseline results of the PREVAC trial and discusses challenges that led to different protocol amendments. METHODS: This is a randomized, double-blind, placebo-controlled phase 2 clinical trial of three vaccine strategies against the Ebola virus in healthy volunteers 1 year of age and above. The three vaccine strategies being studied are the rVSVΔG-ZEBOV-GP vaccine, with and without a booster dose at 56 days, and the Ad26.ZEBOV,MVA-FN-Filo vaccine regimen with Ad26.ZEBOV given as the first dose and the MVA-FN-Filo vaccination given 56 days later. There have been 4 versions of the protocol with those enrolled in Version 4.0 comprising the primary analysis cohort. The primary endpoint is based on the antibody titer against the Ebola virus surface glycoprotein measured 12 months following the final injection. RESULTS: From April 2017 to December 2018, a total of 5002 volunteers were screened and 4789 enrolled. Participants were enrolled at 6 sites in four countries (Guinea, Liberia, Sierra Leone, and Mali). Of the 4789 participants, 2560 (53%) were adults and 2229 (47%) were children. Those < 18 years of age included 549 (12%) aged 1 to 4 years, 750 (16%) 5 to 11 years, and 930 (19%) aged 12-17 years. At baseline, the median (25th, 75th percentile) antibody titer to Ebola virus glycoprotein for 1090 participants was 72 (50, 116) EU/mL. DISCUSSION: The PREVAC trial is evaluating-placebo-controlled-two promising Ebola candidate vaccines in advanced stages of development. The results will address unanswered questions related to short- and long-term safety and immunogenicity for three vaccine strategies in adults and children. TRIAL REGISTRATION: ClinicalTrials.gov NCT02876328 . Registered on 23 August 2016.