Phylogenetic and epidemiologic evidence of multiyear incubation in human rabies

State of the Art: Acute Encephalitis

Encephalitis is a devastating neurologic disease often complicated by prolonged neurologic deficits. Best practices for the management of adult patients include universal testing for a core group of etiologies, including herpes simplex virus (HSV)-1, varicella zoster virus (VZV), enteroviruses, West Nile virus, and anti-N-methyl-D-aspartate receptor (anti-NMDAR) antibody encephalitis. Empiric acyclovir therapy should be started at presentation and in selected cases continued until a second HSV-1 polymerase chain reaction test is negative. Acyclovir dose can be increased for VZV encephalitis. Supportive care is necessary for other viral etiologies. Patients in whom no cause for encephalitis is identified represent a particular challenge. Management includes repeat brain magnetic resonance imaging, imaging for occult malignancy, and empiric immunomodulatory treatment for autoimmune conditions. Next-generation sequencing (NGS) or brain biopsy should be considered. The rapid pace of discovery regarding autoimmune encephalitis and the development of advanced molecular tests such as NGS have improved diagnosis and outcomes. Research priorities include development of novel therapeutics.

Case of human rabies despite post-exposure prophylaxis (PEP) and complete recovery after intrathecal rabies immunoglobulin (RIG)

Rabies, a fatal viral zoonotic disease, has become a public health concern in Sarawak, Malaysia. Despite pre-exposure and post-exposure prophylaxis being available, there has been limited progress in developing treatments for rabies, emphasising the pressing need for productive solutions. We present a laboratory-confirmed human rabies case in which the patient survived without neurological sequelae after receiving intrathecal rabies immunoglobulin.

Making genomic surveillance deliver: A lineage classification and nomenclature system to inform rabies elimination

The availability of pathogen sequence data and use of genomic surveillance is rapidly increasing. Genomic tools and classification systems need updating to reflect this. Here, rabies virus is used as an example to showcase the potential value of updated genomic tools to enhance surveillance to better understand epidemiological dynamics and improve disease control. Previous studies have described the evolutionary history of rabies virus, however the resulting taxonomy lacks the definition necessary to identify incursions, lineage turnover and transmission routes at high resolution. Here we propose a lineage classification system based on the dynamic nomenclature used for SARS-CoV-2, defining a lineage by phylogenetic methods for tracking virus spread and comparing sequences across geographic areas. We demonstrate this system through application to the globally distributed Cosmopolitan clade of rabies virus, defining 96 total lineages within the clade, beyond the 22 previously reported. We further show how integration of this tool with a new rabies virus sequence data resource (RABV-GLUE) enables rapid application, for example, highlighting lineage dynamics relevant to control and elimination programmes, such as identifying importations and their sources, as well as areas of persistence and routes of virus movement, including transboundary incursions. This system and the tools developed should be useful for coordinating and targeting control programmes and monitoring progress as countries work towards eliminating dog-mediated rabies, as well as having potential for broader application to the surveillance of other viruses.

Evaluating the Impact of Anthropogenic Factors on the Dissemination of Contemporary Cosmopolitan, Arctic, and Arctic-like Rabies Viruses

Rabies is a globally prevalent viral zoonosis that causes 59,000 deaths per year and has important economic consequences. Most virus spread is associated with the migration of its primary hosts. Anthropogenic dissemination, mainly via the transportation of rabid dogs, shaped virus ecology a few hundred years ago and is responsible for several current outbreaks. A systematic analysis of aberrant long-distance events in the steppe and Arctic-like groups of rabies virus was performed using statistical (Bayesian) phylogeography and plots of genetic vs. geographic distances. The two approaches produced similar results but had some significant differences and complemented each other. No phylogeographic analysis could be performed for the Arctic group because polar foxes transfer the virus across the whole circumpolar region at high velocity, and there was no correlation between genetic and geographic distances in this virus group. In the Arctic-like group and the steppe subgroup of the cosmopolitan group, a significant number of known sequences (15-20%) was associated with rapid long-distance transfers, which mainly occurred within Eurasia. Some of these events have been described previously, while others have not been documented. Most of the recent long-distance transfers apparently did not result in establishing the introduced virus, but a few had important implications for the phylogeographic history of rabies. Thus, human-mediated long-distance transmission of the rabies virus remains a significant threat that needs to be addressed.

Lyssaviruses and the Fatal Encephalitic Disease Rabies

Lyssaviruses cause the disease rabies, which is a fatal encephalitic disease resulting in approximately 59,000 human deaths annually. The prototype species, rabies lyssavirus, is the most prevalent of all lyssaviruses and poses the greatest public health threat. In Africa, six confirmed and one putative species of lyssavirus have been identified. Rabies lyssavirus remains endemic throughout mainland Africa, where the domestic dog is the primary reservoir - resulting in the highest per capita death rate from rabies globally. Rabies is typically transmitted through the injection of virus-laden saliva through a bite or scratch from an infected animal. Due to the inhibition of specific immune responses by multifunctional viral proteins, the virus usually replicates at low levels in the muscle tissue and subsequently enters the peripheral nervous system at the neuromuscular junction. Pathogenic rabies lyssavirus strains inhibit innate immune signaling and induce cellular apoptosis as the virus progresses to the central nervous system and brain using viral protein facilitated retrograde axonal transport. Rabies manifests in two different forms - the encephalitic and the paralytic form - with differing clinical manifestations and survival times. Disease symptoms are thought to be due mitochondrial dysfunction, rather than neuronal apoptosis. While much is known about rabies, there remain many gaps in knowledge about the neuropathology of the disease. It should be emphasized however, that rabies is vaccine preventable and dog-mediated human rabies has been eliminated in various countries. The global elimination of dog-mediated human rabies in the foreseeable future is therefore an entirely feasible goal.

Rabies in Costa Rica - Next Steps Towards Controlling Bat-Borne Rabies After its Elimination in Dogs

Rabies is an acute, progressive encephalitis caused by a lyssavirus, with the highest case fatality of any conventional infectious disease. More than 17 different lyssaviruses have been described, but rabies virus is the most widely distributed and important member of the genus. Globally, tens of thousands of human fatalities still occur each year. Although all mammals are susceptible, most human fatalities are caused by the bites of rabid dogs, within lesser developed countries. A global plan envisions the elimination of human rabies cases caused via dogs by the year 2030. The combination of prophylaxis of exposed humans and mass vaccination of dogs is an essential strategy for such success. Regionally, the Americas are well on the way to meet this goal. As one example of achievement, Costa Rica, a small country within Central America, reported the last autochthonous case of human rabies transmitted by a dog at the end of the 1970s. Today, rabies virus transmitted by the common vampire bat, Desmodus rotundus, as well as other wildlife, remains a major concern for humans, livestock, and other animals throughout the region. This review summarizes the historical occurrence of dog rabies and its elimination in Costa Rica, describes the current occurrence of the disease with a particular focus upon affected livestock, discusses the ecology of the vampire bat as the primary reservoir relevant to management, details the clinical characteristics of recent human rabies cases, and provides suggestions for resolution of global challenges posed by this zoonosis within a One Health context.

Modern biologics for rabies prophylaxis and the elimination of human cases mediated by dogs

Introduction: Rabies is a major viral zoonosis and neglected tropical disease, with a global distribution. Humans, domestic animals, and wild mammals are susceptible to infection. Etiological agents reside in the Order Mononegavirales, Family Rhabdoviridae, Genus Lyssavirus. This acute, progressive encephalitis causes the highest case fatality of any conventional infectious disease. Tens of millions of humans become exposed annually to the bites of infected mammals, predominantly in Asia and Africa. Despite the existence of effective vaccines and immune globulins, tens of thousands of people, typically children in the developing world, succumb. Areas covered: Concentrating upon both historical and major published references from the peer-reviewed literature over the past 5 years, we describe current biologics for rabies prevention, newly recommended principles for prophylaxis, and relevant future products in the developmental pipeline. Expert opinion: Modern human rabies biologics are pure, potent, safe, and efficacious, when used in a timely and appropriate manner. Few individuals survive after clinical signs. Anti-viral compounds are not licensed. Experimental therapy, while obviously desirable, is highly controversial. Education on bite prevention and integrated risk management are critical. Access to affordable care, dose-sparing, and shortened regimens of human rabies biologics remain key.

Survival in human rabies but left against medical advice and death followed – Community education is the need of the hour

Human survival after developing rabies is very scary to humanity. We report a case of a 58-year-old woman from Uttar Pradesh (north India), who presented with 5-days of fever and 1-day of altered sensorium associated with agitation, hydrophobia, and bedwetting after 20 days of WHO category 3 bite in the face by a rabid dog. She had taken three doses of anti-rabies vaccinations but not immunoglobulin of postexposure prophylaxis. Laboratory investigation showed a rising titer of virus-neutralizing antibodies in both serum and cerebrospinal fluid (CSF). We treated the patient according to the modified Milwaukee protocol. The patient remained to survive and had a recovery trend during hospital stays of 15 days before relatives took her left against medical advice (LAMA). As we know rabies has approximately 100% mortality rate but by using the aggressive treatment approach (like Milwaukee protocol), the patient may survive. Rabies can be effectively prevented by using adequate postexposure vaccine prophylaxis and rabies immunoglobulin (in category-3) after bite of a rabid animal. Our report along with other published reports should give more motivation to clinicians and education to the public to have an intensive treatment approach and patience, respectively to make rabies survival.

New human rabies vaccines in the pipeline

Rabies remains endemic in more than 150 countries. In 99% of human cases, rabies virus is transmitted by dogs. The disease, which is nearly always fatal, is preventable by vaccines given either before and/or after exposure to a rabid animal. Numerous factors including the high cost of vaccines, the relative complexity of post-exposure vaccination protocols requiring multiple doses of vaccine, which in cases of severe exposure have to be combined with a rabies immune globulin, lack of access to health care, and insufficient surveillance contribute to the estimated 59,000 human deaths caused by rabies each year. New, less expensive and more immunogenic rabies vaccines are needed together with improved surveillance and dog rabies control to reduce the death toll of human rabies. Here, we discuss new rabies vaccines that are in clinical and pre-clinical testing and evaluate their potential to replace current vaccines.

Viral Meningitis and Encephalitis

PURPOSE OF REVIEW

This article discusses meningitis and encephalitis infections caused by viruses, excluding herpes family and human immunodeficiency virus (HIV).

RECENT FINDINGS

The viral infections of the nervous system detailed in this article have no specific treatment other than supportive care. However, many of the viruses discussed are highly preventable by vaccination, proper skin protection against transmitting vectors, and postexposure prophylaxis.

SUMMARY

While meningitis and encephalitis caused by viruses may have some clinical overlap, the management and outcomes can be highly disparate, making distinction between the two imperative. Furthermore, despite their relative rarity in terms of clinical disease, many of the viral infections discussed herein are highly preventable. Given the morbidity and mortality attached to such infections, provider and patient education are the best approach available to prevent these potentially devastating illnesses.

High-throughput sequencing for the aetiologic identification of viral encephalitis, meningoencephalitis, and meningitis. A narrative review and clinical appraisal

Background

Viral aetiologies are the most common cause of central nervous system (CNS) infections. Approximately one-half of CNS infections remain of undetermined origin. High-throughput sequencing (HTS) brought new perspectives to CNS infection investigations, allowing investigation of viral aetiologies with an unbiased approach. HTS use is still limited to specific clinical situations.

Objectives

The aim of this review was to evaluate the contribution and pitfalls of HTS for the aetiologic identification of viral encephalitis, meningoencephalitis, and meningitis in CNS patient samples.

Sources

PubMed was searched from 1 January 2008 to 2 August 2018 to retrieve available studies on the topic. Additional publications were included from a review of full-text sources.

Content

Among 366 studies retrieved, 29 used HTS as a diagnostic technique. HTS was performed in cerebrospinal fluid and brain biopsy samples of 307 patients, including immunocompromised, immunocompetent paediatric, and adult cases. HTS was performed retrospectively in 18 studies and prospectively in 11. HTS led to the identification of a potential causal virus in 41 patients, with 11 viruses known and ten not expected to cause CNS infections. Various HTS protocols were used.

Implications

The additional value of HTS is difficult to quantify because of various biases. Nevertheless, HTS led to the identification of a viral cause in 13% of encephalitis, meningoencephalitis, and meningitis cases in which various assays failed to identify the cause. HTS should be considered early in clinical management as a complement to routine assays. Standardized strategies and systematic studies are needed for the integration of HTS in clinical management.

Epidemiological and Genetic Characteristics of Rabies Virus Transmitted Through Organ Transplantation

In January 2016, two patients died of rabies after receiving kidney transplants from a common organ donor at a hospital in Changsha, Hunan, China. The medical records, epidemiological data of the organ donor, two kidney and a liver recipients were reviewed. Intravitam saliva samples of the two kidney recipients were tested for rabies virus (RABV) using real-time RT-PCR, and the nucleoprotein (N) gene was amplified and sequenced by Sanger sequencing. Whole genome sequences were analyzed using next-generation sequencing. The N genes of the two kidney recipients showed 100% nucleic acid identity. Phylogenetic analysis of the complete genome, N and glycoprotein (G) genes indicated that the RABV was homologous with dog isolates from the Hunan province and belong to the China I lineage, which is widespread in China. The organ donor was a 22-month-old boy who died from unknown acute progressive encephalitis. After undergoing sub-hypothermia hibernation therapy, rabies-associated symptoms were atypical, and rabies was neglected because serum RABV-specific antibodies were negative. An unknown wound on the forehead of the donor was found 2 months before the onset of symptoms. Based on the clinical, epidemiological, and molecular findings, we speculated that the RABV initially originated in the donor from a dog bite, and was then transmitted to the recipients by organ transplantation. An uncertain exposure history and misdiagnosis played important roles in the spread of the RABV. Rabies should be considered in patients with acute progressive encephalitis of unexplained etiology, especially in potential organ donors.

Lyssaviruses and rabies: current conundrums, concerns, contradictions and controversies

Lyssaviruses are bullet-shaped, single-stranded, negative-sense RNA viruses and the causative agents of the ancient zoonosis rabies. Africa is the likely home to the ancestors of taxa residing within the Genus Lyssavirus, Family Rhabdoviridae. Diverse lyssaviruses are envisioned as co-evolving with bats, as the ultimate reservoirs, over seemingly millions of years. In terms of relative distribution, overt abundance, and resulting progeny, rabies virus is the most successful lyssavirus species today, but for unknown reasons. All mammals are believed to be susceptible to rabies virus infection. Besides reservoirs among the Chiroptera, meso-carnivores also serve as major historical hosts and are represented among the canids, raccoons, skunks, mongooses, and ferret badgers.  Perpetuating as a disease of nature with the mammalian central nervous system as niche, host breadth alone precludes any candidacy for true eradication. Despite having the highest case fatality of any infectious disease and a burden in excess of or comparative to other major zoonoses, rabies remains neglected. Once illness appears, no treatment is proven to prevent death. Paradoxically, vaccines were developed more than a century ago, but the clear majority of human cases are unvaccinated. Tens of millions of people are exposed to suspect rabid animals and tens of thousands succumb annually, primarily children in developing countries, where canine rabies is enzootic. Rather than culling animal populations, one of the most cost-effective strategies to curbing human fatalities is the mass vaccination of dogs. Building on considerable progress to date, several complementary actions are needed in the near future, including a more harmonized approach to viral taxonomy, enhanced de-centralized laboratory-based surveillance, focal pathogen discovery and characterization, applied pathobiological research for therapeutics, improved estimates of canine populations at risk, actual production of required vaccines and related biologics, strategies to maximize prevention but minimize unnecessary human prophylaxis, and a long-term, realistic plan for sustained global program support to achieve success in disease control, prevention, and elimination.

Microbiological laboratory diagnostics of neglected zoonotic diseases (NZDs)

This review reports on laboratory diagnostic approaches for selected, highly pathogenic neglected zoonotic diseases, i.e. anthrax, bovine tuberculosis, brucellosis, echinococcosis, leishmaniasis, rabies, Taenia solium-associated diseases (neuro-/cysticercosis & taeniasis) and trypanosomiasis. Diagnostic options, including microscopy, culture, matrix-assisted laser-desorption-ionisation time-of-flight mass spectrometry, molecular approaches and serology are introduced. These procedures are critically discussed regarding their diagnostic reliability and state of evaluation. For rare diseases reliable evaluation data are scarce due to the rarity of samples. If bio-safety level 3 is required for cultural growth, but such high standards of laboratory infrastructure are not available, serological and molecular approaches from inactivated sample material might be alternatives. Multiple subsequent testing using various test platforms in a stepwise approach may improve sensitivity and specificity. Cheap and easy to use tests, usually called "rapid diagnostic tests" (RDTs) may impact disease control measures, but should not preclude developing countries from state of the art diagnostics.

The case for case reports

Case reports have seemingly fallen upon hard times. Once esteemed by William Osler and C. Miller Fisher, these reports are now considered anachronistic. Nonetheless, case reports remain valuable and formed the largest proportion of publications written last year by residents in our training program (the Partners Neurology Residency). Although they are easy to produce, it is reasonable to ask if these modern exercises are of equal significance to the narratives of migraine by John Graham in the 1950s or descriptions of Parkinson disease by James Parkinson in 1817. Even a brief reading of currently published case reports raises doubts about the value of many of them but also emphasizes their utility. We argue here that the case report format remains of considerable merit, especially to the aspiring academic clinician.