Sierra Leone in West Africa is in a Lassa fever-hyperendemic region that also includes Guinea and Liberia. Each year, suspected Lassa fever cases result in submission of ≈500-700 samples to the ...Kenema Government Hospital Lassa Diagnostic Laboratory in eastern Sierra Leone. Generally only 30%-40% of samples tested are positive for Lassa virus (LASV) antigen and/or LASV-specific IgM; thus, 60%-70% of these patients have acute diseases of unknown origin. To investigate what other arthropod-borne and hemorrhagic fever viral diseases might cause serious illness in this region and mimic Lassa fever, we tested patient serum samples that were negative for malaria parasites and LASV. Using IgM-capture ELISAs, we evaluated samples for antibodies to arthropod-borne and other hemorrhagic fever viruses. Approximately 25% of LASV-negative patients had IgM to dengue, West Nile, yellow fever, Rift Valley fever, chikungunya, Ebola, and Marburg viruses but not to Crimean-Congo hemorrhagic fever virus.
Summary Background The limited data available for long-term Ebola virus disease health outcomes suggest that sequelae persist for longer than 1 year after infection. The magnitude of the present ...outbreak in west Africa necessitates a more complete understanding of the health effects and future medical needs of these patients. Methods We invited adult survivors of the 2007 Bundibugyo Ebola virus outbreak in Uganda and their contacts to take part in an observational study roughly 29 months after the outbreak. We collected information about health status, functional limitations, and demographics. We collected blood samples for clinical chemistry, haematology, and filovirus antibodies using ELISA. Analyses were restricted to probable and confirmed survivors and their seronegative contacts. Findings We recruited 70 survivors of the 2007 Bundibugyo Ebola virus and 223 contacts. We did analyses for 49 probable and confirmed survivors and 157 seronegative contacts. Survivors of the Bundibugyo Ebola virus were at significantly increased risk of ocular deficits (retro-orbital pain RR 4·3, 95% CI 1·9–9·6; p<0·0001, blurred vision 1·9, 1·1–3·2; p=0·018), hearing loss (2·3, 1·2–4·5; p=0·010), difficulty swallowing (2·1, 1·1–3·9; p=0·017), difficulty sleeping (1·9, 1·3–2·8; p=0·001), arthralgias (2·0, 1·1–3·6; p=0·020), and various constitutional symptoms controlling for age and sex. Chronic health problems (prevalence ratio PR 2·1, 95% CI 1·2–3·6; p=0·008) and limitations due to memory loss or confusion (PR 5·8, 1·5–22·4; p=0·010) were also reported more frequently by survivors of Bundibugyo Ebola virus. Interpretation Long-term sequelae persist for more than 2 years after Ebola virus disease. Definition of health consequences related to Ebola virus disease could improve patient care for survivors and contribute to understanding of disease pathogenesis. Funding Chemical Biological Technologies Directorate, Defense Threat Reduction Agency.
Crimean-Congo hemorrhagic fever (CCHF) is the most medically important tick-borne viral disease of humans and tuberculosis is the leading cause of death worldwide by a bacterial pathogen. These two ...diseases overlap geographically, however, concurrent infection of CCHF virus (CCHFV) with mycobacterial infection has not been assessed nor has the ability of virus to persist and cause long-term sequela in a primate model. In this study, we compared the disease progression of two diverse strains of CCHFV in the recently described cynomolgus macaque model. All animals demonstrated signs of clinical illness, viremia, significant changes in clinical chemistry and hematology values, and serum cytokine profiles consistent with CCHF in humans. The European and Asian CCHFV strains caused very similar disease profiles in monkeys, which demonstrates that medical countermeasures can be evaluated in this animal model against multiple CCHFV strains. We identified evidence of CCHFV persistence in the testes of three male monkeys that survived infection. Furthermore, the histopathology unexpectedly revealed that six additional animals had evidence of a latent mycobacterial infection with granulomatous lesions. Interestingly, CCHFV persisted within the granulomas of two animals. This study is the first to demonstrate the persistence of CCHFV in the testes and within the granulomas of non-human primates with concurrent latent tuberculosis. Our results have important public health implications in overlapping endemic regions for these emerging pathogens.
The 2013–present Western African Ebola virus disease (EVD) outbreak is the largest ever recorded with >28,000 reported cases. Ebola virus (EBOV) genome sequencing has played an important role ...throughout this outbreak; however, relatively few sequences have been determined from patients in Liberia, the second worst-affected country. Here, we report 140 EBOV genome sequences from the second wave of the Liberian outbreak and analyze them in combination with 782 previously published sequences from throughout the Western African outbreak. While multiple early introductions of EBOV to Liberia are evident, the majority of Liberian EVD cases are consistent with a single introduction, followed by spread and diversification within the country. Movement of the virus within Liberia was widespread, and reintroductions from Liberia served as an important source for the continuation of the already ongoing EVD outbreak in Guinea. Overall, little evidence was found for incremental adaptation of EBOV to the human host.
Display omitted
•140 EBOV genomes from Liberian patients sequenced and analyzed with 782 other sequences•Multiple EBOV introductions into Liberia, but one led to most cases and spread•Re-introductions from Liberia helped sustain the Guinea and Mali outbreaks•Limited evidence of incremental Ebola virus adaptation to the human host
Ladner et al. sequenced 140 Ebola virus genomes sampled throughout 11 months across 13 Liberian counties. Analysis of these and 782 other sequences reveals that, despite multiple introductions, the Liberian outbreak was driven by within-country spread and diversification. Multiple re-introductions of Ebola virus from Liberia contributed to transmission within Guinea.
Arthorpod-borne viruses (arboviruses) cause wide-spread morbidity in sub-Saharan Africa, but little research has documented the burden and distribution of these pathogens.
Using a population-based, ...cross-sectional study design, we administered a detailed questionnaire and used ELISA to test the blood of 1,141 healthy Kenyan adults from three districts for the presence of anti-viral Immunoglobulin G (IgG) antibodies to the following viruses: dengue (DENV), West Nile (WNV), yellow fever (YFV), Chikungunya (CHIKV), and Rift Valley fever (RVFV).
Of these, 14.4% were positive for DENV, 9.5% were WNV positive, 9.2% were YFV positive, 34.0% were positive for CHIKV and 0.7% were RVFV positive. In total, 46.6% had antibodies to at least one of these arboviruses.
For all arboviruses, district of residence was strongly associated with seropositivity. Seroprevalence to YFV, DENV and WNV increased with age, while there was no correlation between age and seropositivity for CHIKV, suggesting that much of the seropositivity to CHIKV is due to sporadic epidemics. Paradoxically, literacy was associated with increased seropositivity of CHIKV and DENV.
•An orthogonal diagnostic system with multiple assays provides the greatest confidence in a diagnostic result.•Lateral flow immunoassays (LFIs) can significantly reduce infections in ongoing ...outbreaks.•Multiplex, magnetic bead-based assays are a significant improvement over traditional ELISAs.•Next-generation sequencing (NGS) will revolutionize the understanding of Lassa virus and its epizootiology.•Future LASV diagnostics will consist of fast, simple assays that consider the genetic and geographical diversity across LASV lineages.
Lassa fever is a unique viral hemorrhagic fever that is endemic in parts of West Africa, primarily Sierra Leone, Guinea, Liberia, and Nigeria. The disease is caused by the Lassa virus, an Old World arenavirus that has as primary reservoir host the multimammate rodent Mastomys nataliensis, which lives in association with humans. Recent estimates suggest LF causes two million cases and 5000–10000 deaths annually, mainly in West Africa.
Clinical diagnosis and laboratory confirmation have always been major challenges for effective management and control of the disease in afflicted areas of West Africa. Recent advancements in molecular biology, recombinant DNA technology, and genomics sequencing has facilitated major advancement in development of better diagnostic and surveillance tools for Lassa fever virus. These include, the multiplex, magnetic bead-based immunodiagnostics for both Lassa virus antigens and antibodies; molecular probe-based quantitative real-time PCR for genomic signatures; rapid diagnostics tests that detects the most prevalent West African lineages; and the successful utilization of next-generation sequencing technology to diagnose and characterize Lassa virus in West Africa. These advances will continue to improve disease treatment, control, and prevention.
In this review we will discuss progression of Lassa virus diagnostics from the past and into the future.
Rodents serve as reservoirs and/or vectors for several human infections of high morbidity and mortality in the tropics. Population growth and demographic shifts over the years have increased contact ...with these mammals, thereby increasing opportunities for disease transmission. In Africa, the burden of rodent-borne diseases is not well described. To investigate human seroprevalence of selected rodent-borne pathogens, sera from 657 healthy adults in ten rural communities in Ghana were analyzed. An in-house enzyme-linked immunosorbent assay (ELISA), for immunoglobulin G (IgG) antibodies to Lassa virus was positive in 34 (5%) of the human samples. Using commercial kits, antibodies to hantavirus serotypes, Puumala and Dobrava, and Leptospira bacteria were detected in 11%, 12% and 21% of the human samples, respectively. Forty percent of residents in rural farming communities in Ghana have measurable antibodies to at least one of the rodent-borne pathogens tested, including antibodies to viral hemorrhagic fever viruses. The high seroprevalence found in rural Ghana to rodent-borne pathogens associated with both sporadic cases and larger disease outbreaks will help define disease threats and inform public health policy to reduce disease burden in underserved populations and deter larger outbreaks.
To support Liberia's response to the ongoing Ebola virus (EBOV) disease epidemic in Western Africa, we established in-country advanced genomic capabilities to monitor EBOV evolution. Twenty-five EBOV ...genomes were sequenced at the Liberian Institute for Biomedical Research, which provided an in-depth view of EBOV diversity in Liberia during September 2014-February 2015. These sequences were consistent with a single virus introduction to Liberia; however, shared ancestry with isolates from Mali indicated at least 1 additional instance of movement into or out of Liberia. The pace of change is generally consistent with previous estimates of mutation rate. We observed 23 nonsynonymous mutations and 1 nonsense mutation. Six of these changes are within known binding sites for sequence-based EBOV medical countermeasures; however, the diagnostic and therapeutic impact of EBOV evolution within Liberia appears to be low.
Abstract
Rapid pathogen identification is a critical first step in patient isolation, treatment, and controlling an outbreak. Real-time PCR is a highly sensitive and specific approach commonly used ...for infectious disease diagnostics. However, mismatches in the primer or probe sequence and the target organism can cause decreased sensitivity, assay failure, and false negative results. Limited genomic sequences for rare pathogens such as Ebola virus (EBOV) can negatively impact assay performance due to undiscovered genetic diversity. We previously developed and validated several EBOV assays prior to the 2013–2016 EBOV outbreak in West Africa, and sequencing EBOV Makona identified sequence variants that could impact assay performance. Here, we assessed the impact sequence mismatches have on EBOV assay performance, finding one or two primer or probe mismatches resulted in a range of impact from minimal to almost two log sensitivity reduction. Redesigning this assay improved detection of all EBOV variants tested. Comparing the performance of the new assay with the previous assays across a panel of human EBOV samples confirmed increased assay sensitivity as reflected in decreased Cq values with detection of three positive that tested negative with the original assay.
During 2013-2014, we collected 1,926 serum samples from humans and 4,583 ticks (Hyalomma asiaticum or Dermacentor nuttalli) in select regions of Mongolia to determine the risk for Crimean-Congo ...hemorrhagic fever virus (CCHFV) infection among humans in this country. Testing of human serum samples by ELISA demonstrated an overall CCHFV antibody prevalence of 1.4%; Bayankhongor Province had the highest prevalence, 2.63%. We pooled and analyzed tick specimens by real-time reverse transcription PCR; 1 CCHFV-positive H. asiaticum tick pool from Ömnögovi was identified. In phylogenetic analyses, the virus's partial small segment clustered with CCHFV isolates from Central Asia, and the complete medium segment grouped with CCHFV isolates from Africa, Asia, and the Middle East. This study confirms CCHFV endemicity in Mongolia and provides information on risk for CCHFV infection. Further research is needed to better define the risk for CCHFV disease to improve risk mitigation, diagnostics, and surveillance.
PDF
