Subsequent mortality in survivors of Ebola virus disease in Guinea: a nationwide retrospective cohort study

Expansion of myeloid suppressor cells and suppression of Lassa virus-specific T cells during fatal Lassa fever

Lassa fever is a highly lethal hemorrhagic fever endemic to West Africa. In the absence of efficient prophylactic or therapeutic countermeasures, it poses a substantial threat to public health in this region. The pathophysiological mechanisms underlying the severity of the disease are poorly known because Lassa virus (LASV), its causative agent, has to be handled in BSL-4 laboratories and access to clinical samples is difficult. The control of Lassa fever is associated with a rapid and well-balanced immune response and viral clearance. However, severe disease is characterized by uncontrolled innate immune activation and symptoms reminiscent of sepsis and a cytokine storm. In a model of cynomolgus monkeys infected with two different strains of the virus, one causing moderate disease and the other a lethal outcome, we show that the control of LASV infection is characterized by the induction of a LASV-specific T-cell response, whereas severity is associated with the expansion of suppressive myeloid cells, alterations of the stromal network of secondary lymphoid organs, and the anergy of specific T cells. These results suggest that T cells are crucial for the control of LASV and that immunomodulatory therapeutics, such as checkpoint inhibitors, could contribute to new therapeutic strategies to treat Lassa fever. They also highlight how immunosuppressive mechanisms described in sepsis and cancer patients may play a role in the pathogenicity of Lassa fever, as well as in other similar hemorrhagic fevers.

Using autopsies to dissect COVID-19 pathogenesis

The emergence of SARS-CoV-2 has resulted in millions of deaths as a result of COVID-19. Suitable models were missing at the beginning of the pandemic, and studies investigating disease pathogenesis relied on patients who had succumbed to COVID-19. Since then, autopsies of patients have substantially contributed to our understanding of the pathogenesis of COVID-19 and associated major organ complications. Here we summarize how autopsies have complemented experimental studies, mainly in animal models, and how they have facilitated critical knowledge of COVID-19 to improve daily clinical practice and develop therapeutic interventions. Employing advanced histopathologic and molecular genetic methods in post-mortem tissues, the COVID-19 pandemic has highlighted the importance of autopsies for virology research and clinical practice in current and emerging infectious diseases.

Ebola virus disease: A review for the emergency medicine clinician

INTRODUCTION

Ebolavirus, the causative agent of Ebola virus disease (EVD) has been responsible for sporadic outbreaks mainly in sub-Saharan Africa since 1976. EVD is associated with high risk of transmission, especially to healthcare workers during patient care.

OBJECTIVE

The purpose of this review is to provide a concise review of EVD presentation, diagnosis, and management for emergency clinicians.

DISCUSSION

EVD is spread through direct contact, including blood, bodily fluids or contact with a contaminated object. Patients may present with non-specific symptoms such as fevers, myalgias, vomiting, or diarrhea that overlap with other viral illnesses, but rash, bruising, and bleeding may also occur. Laboratory analysis may reveal transaminitis, coagulopathy, and disseminated intravascular coagulation. The average clinical course is approximately 8-10 days with an average case fatality rate of 50%. The mainstay of treatment is supportive care, with two U.S. Food and Drug Administration-approved monoclonal antibody treatments (Ebanga and Inmazeb). Survivors of the disease may have a complicated recovery, marked by long-term symptoms.

CONCLUSION

EVD is a potentially deadly condition that can present with a wide range of signs and symptoms. Emergency clinicians must be aware of the presentation, evaluation, and management to optimize the care of these patients.

Ebola virus persistence and disease recrudescence in the brains of antibody-treated nonhuman primate survivors

Effective therapeutics have been developed against acute Ebola virus disease (EVD) in both humans and experimentally infected nonhuman primates. However, the risk of viral persistence and associated disease recrudescence in survivors receiving these therapeutics remains unclear. In contrast to rhesus macaques that survived Ebola virus (EBOV) exposure in the absence of treatment, we discovered that EBOV, despite being cleared from all other organs, persisted in the brain ventricular system of rhesus macaque survivors that had received monoclonal antibody (mAb) treatment. In mAb-treated macaque survivors, EBOV persisted in macrophages infiltrating the brain ventricular system, including the choroid plexuses. This macrophage infiltration was accompanied by severe tissue damage, including ventriculitis, choroid plexitis, and meningoencephalitis. Specifically, choroid plexus endothelium-derived EBOV infection led to viral persistence in the macaque brain ventricular system. This resulted in apoptosis of ependymal cells, which constitute the blood-cerebrospinal fluid barrier of the choroid plexuses. Fatal brain-confined recrudescence of EBOV infection manifested as severe inflammation, local pathology, and widespread infection of the ventricular system and adjacent neuropil in some of the mAb-treated macaque survivors. This study highlights organ-specific EBOV persistence and fatal recrudescent disease in rhesus macaque survivors after therapeutic treatment and has implications for the long-term follow-up of human survivors of EVD.

Recognition of Long-COVID-19 Patients in a Canadian Tertiary Hospital Setting: A Retrospective Analysis of Their Clinical and Laboratory Characteristics

A proportion of patients with COVID-19 have symptoms past the acute disease phase, which may affect quality of life. It is important for clinicians to be aware of this "long-COVID-19" syndrome to better diagnose, treat, and prevent it. We reviewed clinical and laboratory characteristics of a COVID-19 cohort in a Toronto, Ontario tertiary care center. Demographic, clinical, and laboratory data were collected, and patients were classified as "long-COVID-19" or "non-long-COVID-19" using consensus criteria. Of 397 patients who tested positive for COVID-19, 223 met inclusion criteria, and 62 (27%) had long-COVID-19. These patients had a similar age distribution compared to non-long-COVID-19 patients overall but were younger in the admitted long COVID-19 group. The long-COVID-19 group had more inpatients compared to the non-long-COVID-19 group (39% vs. 25%) and more frequent supplemental oxygen or mechanical ventilation use. However, long-COVID-19 patients did not differ by duration of mechanical ventilation, length of stay, comorbidities, or values of common laboratory tests ordered. The most frequent symptoms associated with long-COVID-19 were fatigue and weakness, as reported most commonly by the infectious disease, respirology and cardiology disciplines. In conclusion, by retrospective chart review, 27% of COVID-19 patients presenting to a tertiary care center in Toronto, Canada, were found to meet criteria for long-COVID-19. Past medical history and routine laboratory testing at presentation did not predict for long-COVID-19 development.

Implications of Innate Immunity in Post-Acute Sequelae of Non-Persistent Viral Infections

Non-persistent viruses classically cause transient, acute infections triggering immune responses aimed at the elimination of the pathogen. Successful viruses evolved strategies to manipulate and evade these anti-viral defenses. Symptoms during the acute phase are often linked to dysregulated immune responses that disappear once the patient recovers. In some patients, however, symptoms persist or new symptoms emerge beyond the acute phase. Conditions resulting from previous transient infection are termed post-acute sequelae (PAS) and were reported for a wide range of non-persistent viruses such as rota-, influenza- or polioviruses. Here we provide an overview of non-persistent viral pathogens reported to be associated with diverse PAS, among them chronic fatigue, auto-immune disorders, or neurological complications and highlight known mechanistic details. Recently, the emergence of post-acute sequelae of COVID-19 (PASC) or long COVID highlighted the impact of PAS. Notably, PAS of non-persistent infections often resemble symptoms of persistent viral infections, defined by chronic inflammation. Inflammation maintained after the acute phase may be a key driver of PAS of non-persistent viruses. Therefore, we explore current insights into aberrant activation of innate immune signaling pathways in the post-acute phase of non-persistent viruses. Finally, conclusions are drawn and future perspectives for treatment and prevention of PAS are discussed.

Review of Ebola virus disease in children - how far have we come?

Ebola virus (EBOV) causes an extremely contagious viral haemorrhagic fever associated with high mortality. While, historically, children have represented a small number of total cases of Ebolavirus disease (EVD), in recent outbreaks up to a quarter of cases have been in children. They pose unique challenges in clinical management and infection prevention and control. In this review of paediatric EVD, the epidemiology of past EVD outbreaks with specific focus on children is discussed, the clinical manifestations and laboratory findings are described and key developments in clinical management including specific topics such as viral persistence and breastfeeding while considering unique psychosocial and anthropological considerations for paediatric care including of survivors and orphans and the stigma they face are discussed. In addition to summarising the literature, perspectives based on the authors' experience of EVD outbreaks in the Democratic Republic of the Congo (DRC) are described.Abbreviations: ARDS: acute respiratory distress syndrome; aOR: adjusted odds ratio; ALT: alanine transferase; ALIMA: Alliance for International Medical Action; AST: aspartate transaminase; BUN: blood urea nitrogen; CNS: central nervous system; CUBE: chambre d'urgence biosécurisée pour épidémie; COVID-19: coronavirus disease 2019; C_t: cycle threshold; DRC: Democratic Republic of Congo; ETC: ebola treatment centre; ETU: ebola treatment unit; EBOV: ebola virus; EVD: ebolavirus disease; FEAST: fluid expansion as supportive therapy; GP: glycoprotein; IV: intravenous; MEURI: monitored emergency use of unregistered interventions; NETEC: National Ebola Training and Education Centre; NP: nucleoprotein; ORS: oral rehydration solution; PALM: Pamoja Tulinde Maisha; PREVAIL: Partnership for Research on Ebola Virus in Liberia; PPE: personal protective equipment; PCR: polymerase chain reaction; PEP: post-exposure prophylaxis; RDTs: rapid diagnostic tests; RT: reverse transcriptase; RNA: ribonucleic acid; UNICEF: United Nations International Children's Emergency Fund; USA: United States of America; WHO: World Health Organization.

Use of Ebola Vaccine: Recommendations of the Advisory Committee on Immunization Practices, United States, 2020

This report summarizes the recommendations of the Advisory Committee on Immunization Practices (ACIP) for use of the rVSVΔG-ZEBOV-GP Ebola vaccine (Ervebo) in the United States. The vaccine contains rice-derived recombinant human serum albumin and live attenuated recombinant vesicular stomatitis virus (VSV) in which the gene encoding the glycoprotein of VSV was replaced with the gene encoding the glycoprotein of Ebola virus species Zaire ebolavirus. Persons with a history of severe allergic reaction (e.g., anaphylaxis) to rice protein should not receive Ervebo. This is the first and only vaccine currently licensed by the Food and Drug Administration for the prevention of Ebola virus disease (EVD). These guidelines will be updated based on availability of new data or as new vaccines are licensed to protect against EVD.ACIP recommends preexposure vaccination with Ervebo for adults aged ≥18 years in the U.S. population who are at highest risk for potential occupational exposure to Ebola virus species Zaire ebolavirus because they are responding to an outbreak of EVD, work as health care personnel at federally designated Ebola treatment centers in the United States, or work as laboratorians or other staff at biosafety level 4 facilities in the United States. Recommendations for use of Ervebo in additional populations at risk for exposure and other settings will be considered and discussed by ACIP in the future.

Public Health Program for Decreasing Risk for Ebola Virus Disease Resurgence from Survivors of the 2013-2016 Outbreak, Guinea

At the end of the 2013–2016 Ebola virus disease outbreak in Guinea, we implemented an alert system for early detection of Ebola resurgence among survivors. Survivors were asked to report health alerts in their household and provide body fluid specimens for laboratory testing. During April–September 2016, a total of 1,075 (88%) of 1,215 survivors participated in the system; follow up occurred at a median of 16 months after discharge (interquartile range 14–18 months). Of these, 784 acted as focal points and reported 1,136 alerts (including 4 deaths among survivors). A total of 372 (91%) of 408 eligible survivors had >1 semen specimen tested; of 817 semen specimens, 5 samples from 4 survivors were positive up to 512 days after discharge. No lochia (0/7) or breast milk (0/69) specimens tested positive. Our findings underscore the importance of long-term monitoring of survivors’ semen samples in an Ebola-affected country.