Genetic diversity and evolutionary dynamics of Ebola virus in Sierra Leone.

A novel Ebola virus (EBOV) first identified in March 2014 has infected more than 25,000 people in West Africa, resulting in more than 10,000 deaths. Preliminary analyses of genome sequences of 81 EBOV collected from March to June 2014 from Guinea and Sierra Leone suggest that the 2014 EBOV originated from an independent transmission event from its natural reservoir followed by sustained human-to-human infections. It has been reported that the EBOV genome variation might have an effect on the efficacy of sequence-based virus detection and candidate therapeutics. However, only limited viral information has been available since July 2014, when the outbreak entered a rapid growth phase. Here we describe 175 full-length EBOV genome sequences from five severely stricken districts in Sierra Leone from 28 September to 11 November 2014. We found that the 2014 EBOV has become more phylogenetically and genetically diverse from July to November 2014, characterized by the emergence of multiple novel lineages. The substitution rate for the 2014 EBOV was estimated to be 1.23 × 10(-3) substitutions per site per year (95% highest posterior density interval, 1.04 × 10(-3) to 1.41 × 10(-3) substitutions per site per year), approximating to that observed between previous EBOV outbreaks. The sharp increase in genetic diversity of the 2014 EBOV warrants extensive EBOV surveillance in Sierra Leone, Guinea and Liberia to better understand the viral evolution and transmission dynamics of the ongoing outbreak. These data will facilitate the international efforts to develop vaccines and therapeutics.

Transmission dynamics of Ebola virus disease and intervention effectiveness in Sierra Leone.

Sierra Leone is the most severely affected country by an unprecedented outbreak of Ebola virus disease (EVD) in West Africa. Although successfully contained, the transmission dynamics of EVD and the impact of interventions in the country remain unclear. We established a database of confirmed and suspected EVD cases from May 2014 to September 2015 in Sierra Leone and mapped the spatiotemporal distribution of cases at the chiefdom level. A Poisson transmission model revealed that the transmissibility at the chiefdom level, estimated as the average number of secondary infections caused by a patient per week, was reduced by 43% [95% confidence interval (CI): 30%, 52%] after October 2014, when the strategic plan of the United Nations Mission for Emergency Ebola Response was initiated, and by 65% (95% CI: 57%, 71%) after the end of December 2014, when 100% case isolation and safe burials were essentially achieved, both compared with before October 2014. Population density, proximity to Ebola treatment centers, cropland coverage, and atmospheric temperature were associated with EVD transmission. The household secondary attack rate (SAR) was estimated to be 0.059 (95% CI: 0.050, 0.070) for the overall outbreak. The household SAR was reduced by 82%, from 0.093 to 0.017, after the nationwide campaign to achieve 100% case isolation and safe burials had been conducted. This study provides a complete overview of the transmission dynamics of the 2014-2015 EVD outbreak in Sierra Leone at both chiefdom and household levels. The interventions implemented in Sierra Leone seem effective in containing the epidemic, particularly in interrupting household transmission.

Features of Ebola Virus Disease at the Late Outbreak Stage in Sierra Leone: Clinical, Virological, Immunological, and Evolutionary Analyses.

We performed Ebola virus disease diagnosis and viral load estimation for Ebola cases in Sierra Leone during the late stage of the 2014-2015 outbreak (January-March 2015) and analyzed antibody and cytokine levels and the viral genome sequences. Ebola virus disease was confirmed in 86 of 1001 (9.7%) patients, with an overall case fatality rate of 46.8%. Fatal cases exhibited significantly higher levels of viral loads, cytokines, and chemokines at late stages of infection versus early stage compared with survivors. The viruses converged in a new clade within sublineage 3.2.4, which had a significantly lower case fatality rate.

Clinical and Virological Characteristics of Ebola Virus Disease Patients Treated With Favipiravir (T-705)-Sierra Leone, 2014.

BACKGROUND: During 2014-2015, an outbreak of Ebola virus disease (EVD) swept across parts of West Africa. No approved antiviral drugs are available for Ebola treatment currently. METHODS: A retrospective clinical case series was performed for EVD patients in Sierra Leone-China Friendship Hospital. Patients with confirmed EVD were sequentially enrolled and treated with either World Health Organization (WHO)-recommended supportive therapy (control group) from 10 to 30 October, or treated with WHO-recommended therapy plus favipiravir (T-705) from 1 to 10 November 2014. Survival and virological characteristics were observed for 85 patients in the control group and 39 in the T-705 treatment group. RESULTS: The overall survival rate in the T-705 treatment group was higher than that of the control group (56.4% [22/39] vs 35.3% [30/85]; P = .027). Among the 35 patients who finished all designed endpoint observations, the survival rate in the T-705 treatment group (64.8% [11/17]) was higher than that of the control group (27.8% [5/18]). Furthermore, the average survival time of the treatment group (46.9 ± 5.6 days) was longer than that of the control group (28.9 ± 4.7 days). Most symptoms of patients in the treatment group improved significantly. Additionally, 52.9% of patients who received T-705 had a >100-fold viral load reduction, compared with only 16.7% of patients in the control group. CONCLUSIONS: Treatment of EVD with T-705 was associated with prolonged survival and markedly reduced viral load, which makes a compelling case for further randomized controlled trials of T-705 for treating EVD.

Assessing Changes in Surgical Site Infections and Antibiotic Use among Caesarean Section and Herniorrhaphy Patients at a Regional Hospital in Sierra Leone Following Operational Research in 2021.

Surgical site infections (SSIs) are a major public health threat to the success of surgery. This study assessed changes in SSIs and use of antibiotics among caesarean section (CS) and herniorrhaphy patients at a regional hospital in Sierra Leone following operational research. This was a comparative before and after study using routine hospital data. The study included all the CS and herniorrhaphy patients who underwent surgery between two time periods. Of the seven recommendations made in the first study, only one concerning improving the hospital's records and information system was fully implemented. Three were partially implemented and three were not implemented. The study population in both studies showed similar socio-demographic characteristics. The use of postoperative antibiotics for herniorrhaphy in both studies remained the same, although a significant increase was found for both pre- and postoperative antibiotic use in the CS patients, 589/596 (98.8%) in 2023 and 417/599 (69.6%) in 2021 (p < 0.001). However, a significant decrease was observed in the overall incidence of SSIs, 22/777 (2.8%) in 2023 and 46/681 (6.7%) in 2021 (p < 0.001), and the incidence of SSIs among the CS patients, 15/596 (2.5%) in 2023 and 45/599 (7.5%) in 2021 (p < 0.001). The second study highlights the potential value of timely assessment of the implementation of recommendations following operational research.

Rapid deployment of a mobile biosafety level-3 laboratory in Sierra Leone during the 2014 Ebola virus epidemic.

BACKGROUND: Ebola virus emerged in West Africa in December 2013. The high population mobility and poor public health infrastructure in this region led to the development of the largest Ebola virus disease (EVD) outbreak to date. METHODOLOGY/PRINCIPAL FINDINGS: On September 26, 2014, China dispatched a Mobile Biosafety Level-3 Laboratory (MBSL-3 Lab) and a well-trained diagnostic team to Sierra Leone to assist in EVD diagnosis using quantitative real-time PCR, which allowed the diagnosis of suspected EVD cases in less than 4 hours from the time of sample receiving. This laboratory was composed of three container vehicles equipped with advanced ventilation system, communication system, electricity and gas supply system. We strictly applied multiple safety precautions to reduce exposure risks. Personnel, materials, water and air flow management were the key elements of the biosafety measures in the MBSL-3 Lab. Air samples were regularly collected from the MBSL-3 Lab, but no evidence of Ebola virus infectious aerosols was detected. Potentially contaminated objects were also tested by collecting swabs. On one occasion, a pipette tested positive for EVD. A total of 1,635 suspected EVD cases (824 positive [50.4%]) were tested from September 28 to November 11, 2014, and no member of the diagnostic team was infected with Ebola virus or other pathogens, including Lassa fever. The specimens tested included blood (69.2%) and oral swabs (30.8%) with positivity rates of 54.2% and 41.9%, respectively. The China mobile laboratory was thus instrumental in the EVD outbreak response by providing timely and reliable diagnostics. CONCLUSIONS/SIGNIFICANCE: The MBSL-3 Lab significantly contributed to establishing a suitable laboratory response capacity during the emergence of EVD in Sierra Leone.

Age and Ebola viral load correlate with mortality and survival time in 288 Ebola virus disease patients.

BACKGROUND: A Chinese medical team managed Ebola virus disease (EVD) patients in Sierra Leone from October 2014 to March 2015 and attended to 693 suspected patients, of whom 288 had confirmed disease. METHODS: A retrospective study was conducted of the 288 patients with confirmed disease. Clinical symptoms, manifestations, and serum viral load were analyzed and compared among the different groups for mortality and survival time. RESULTS: Among the 288 confirmed EVD patients (149 male and 139 female, median age 28 years, and median log viral load 6.68), 98 died, 36 recovered, and 154 were lost to follow-up. Common symptoms were fever (77.78%), fatigue (64.93%), abdominal pain (64.58%), headache (62.85%), and diarrhea (61.81%). Compared to patients aged<18 years, those who were older than 40 years had a higher probability of death (odds ratio 2.855, p=0.044). Patients with a viral load of >10(6) copies/ml had a higher case fatality rate than those with <10(6) copies/ml (odds ratio 3.095, p=0.004). Cox regression showed that age, viral load, and the presence of diarrhea correlated with mortality. CONCLUSION: Patients with a high viral load, of older age, and with diarrhea had a higher mortality and shorter survival time.

Prognostic Analysis of Patients with Ebola Virus Disease.

BACKGROUND: The Ebola virus causes an acute, serious illness which is often fatal if untreated. However, factors affecting the survival of the disease remain unclear. Here, we investigated the prognostic factors of Ebola virus disease (EVD) through various statistical models. METHODOLOGY/PRINCIPAL FINDINGS: Sixty three laboratory-confirmed EVD patients with relatively complete clinical profiles were included in the study. All the patients were recruited at Jui Government Hospital, Sierra Leone between October 1st, 2014 and January 18th, 2015. We first investigated whether a single clinical presentation would be correlated with the survival of EVD. Log-rank test demonstrated that patients with viral load higher than 10(6) copies/ml presented significantly shorter survival time than those whose viral load were lower than 10(6) copies/ml (P = 0.005). Also, using Pearson chi-square test, we identified that chest pain, coma, and viral load (>10(6) copies/ml) were significantly associated with poor survival of EVD patients. Furthermore, we evaluated the effect of multiple variables on the survival of EVD by Cox proportional hazards model. Interestingly, results revealed that patient's age, symptom of confusion, and viral load were the significantly associated with the survival of EVD cases (P = 0.017, P = 0.002, and P = 0.027, respectively). CONCLUSIONS/SIGNIFICANCE: These results suggest that age, chest pain, coma, confusion and viral load are associated with the prognosis of EVD, in which viral load could be one of the most important factors for the survival of the disease.