Clinico-epidemiological presentations and management of Nipah virus infection during the outbreak in Kozhikode district, Kerala state, India 2023.

India experienced its sixth Nipah virus (NiV) outbreak in September 2023 in the Kozhikode district of Kerala state. The NiV is primarily transmitted by spillover events from infected bats followed by human-to-human transmission. The clinical specimens were screened using real-time RT-PCR, and positive specimens were further characterized using next-generation sequencing. We describe here an in-depth clinical presentation and management of NiV-confirmed cases and outbreak containment activities. The current outbreak reported a total of six cases with two deaths, with a case fatality ratio of 33.33%. The cases had a mixed presentation of acute respiratory distress syndrome and encephalitis syndrome. Fever was a persistent presentation in all the cases. The Nipah viral RNA was detected in clinical specimens until the post-onset day of illness (POD) 14, with viral load in the range of 1.7-3.3 × 104 viral RNA copies/mL. The genomic analysis showed that the sequences from the current outbreak clustered into the Indian clade similar to the 2018 and 2019 outbreaks. This study highlights the vigilance of the health system to detect and effectively manage the clustering of cases with clinical presentations similar to NiV, which led to early detection and containment activities.

Structural Studies of Henipavirus Glycoproteins.

Henipaviruses are a genus of emerging pathogens that includes the highly virulent Nipah and Hendra viruses that cause reoccurring outbreaks of disease. Henipaviruses rely on two surface glycoproteins, known as the attachment and fusion proteins, to facilitate entry into host cells. As new and divergent members of the genus have been discovered and structurally characterized, key differences and similarities have been noted. This review surveys the available structural information on Henipavirus glycoproteins, complementing this with information from related biophysical and structural studies of the broader Paramyxoviridae family of which Henipaviruses are members. The process of viral entry is a primary focus for vaccine and drug development, and this review aims to identify critical knowledge gaps in our understanding of the mechanisms that drive Henipavirus fusion.

Recently Emerged Novel Henipa-like Viruses: Shining a Spotlight on the Shrew.

Henipaviruses are zoonotic viruses, including some highly pathogenic and capable of serious disease and high fatality rates in both animals and humans. Hendra virus and Nipah virus are the most notable henipaviruses, resulting in significant outbreaks across South Asia, South-East Asia, and Australia. Pteropid fruit bats have been identified as key zoonotic reservoirs; however, the increased discovery of henipaviruses outside the geographic distribution of Pteropid fruit bats and the detection of novel henipa-like viruses in other species such as the shrew, rat, and opossum suggest that Pteropid bats are not the sole reservoir for henipaviruses. In this review, we provide an update on henipavirus spillover events and describe the recent detection of novel unclassified henipaviruses, with a strong focus on the shrew and its emerging role as a key host of henipaviruses.

Pathogenicity and virulence of henipaviruses.

Paramyxoviruses are a family of single-stranded negative-sense RNA viruses, many of which are responsible for a range of respiratory and neurological diseases in humans and animals. Among the most notable are the henipaviruses, which include the deadly Nipah (NiV) and Hendra (HeV) viruses, the causative agents of outbreaks of severe disease and high case fatality rates in humans and animals. NiV and HeV are maintained in fruit bat reservoirs primarily in the family Pteropus and spillover into humans directly or by an intermediate amplifying host such as swine or horses. Recently, non-chiropteran associated Langya (LayV), Gamak (GAKV), and Mojiang (MojV) viruses have been discovered with confirmed or suspected ability to cause disease in humans or animals. These viruses are less genetically related to HeV and NiV yet share many features with their better-known counterparts. Recent advances in surveillance of wild animal reservoir viruses have revealed a high number of henipaviral genome sequences distributed across most continents, and mammalian orders previously unknown to harbour henipaviruses. In this review, we summarize the current knowledge on the range of pathogenesis observed for the henipaviruses as well as their replication cycle, epidemiology, genomics, and host responses. We focus on the most pathogenic viruses, including NiV, HeV, LayV, and GAKV, as well as the experimentally non-pathogenic CedV. We also highlight the emerging threats posed by these and potentially other closely related viruses.

Nipah Virus: An Overview of the Current Status of Diagnostics and Their Role in Preparedness in Endemic Countries.

Nipah virus (NiV) is a paramyxovirus responsible for a high mortality rate zoonosis. As a result, it has been included in the list of Blueprint priority pathogens. Bats are the main reservoirs of the virus, and different clinical courses have been described in humans. The Bangladesh strain (NiV-B) is often associated with severe respiratory disease, whereas the Malaysian strain (NiV-M) is often associated with severe encephalitis. An early diagnosis of NiV infection is crucial to limit the outbreak and to provide appropriate care to the patient. Due to high specificity and sensitivity, qRT-PCR is currently considered to be the optimum method in acute NiV infection assessment. Nasal swabs, cerebrospinal fluid, urine, and blood are used for RT-PCR testing. N gene represents the main target used in molecular assays. Different sensitivities have been observed depending on the platform used: real-time PCR showed a sensitivity of about 103 equivalent copies/reaction, SYBRGREEN technology's sensitivity was about 20 equivalent copies/reaction, and in multiple pathogen card arrays, the lowest limit of detection (LOD) was estimated to be 54 equivalent copies/reaction. An international standard for NiV is yet to be established, making it difficult to compare the sensitivity of the different methods. Serological assays are for the most part used in seroprevalence studies owing to their lower sensitivity in acute infection. Due to the high epidemic and pandemic potential of this virus, the diagnosis of NiV should be included in a more global One Health approach to improve surveillance and preparedness for the benefit of public health. Some steps need to be conducted in the diagnostic field in order to become more efficient in epidemic management, such as development of point-of-care (PoC) assays for the rapid diagnosis of NiV.

Advancing the frontiers: Revolutionary control and prevention paradigms against Nipah virus.

Nipah Virus (NiV) is a highly virulent pathogen that poses a significant threat to human and animal populations. This review provides a comprehensive overview of the latest control and prevention strategies against NiV, focusing on vaccine development, antiviral drug discovery, early diagnosis, surveillance, and high-level biosecurity measures. Advancements in vaccine research, including live-attenuated vaccines, virus-like particles, and mRNA-based vaccines, hold promise for preventing NiV infections. In addition, antiviral drugs, such as remdesivir, ribavirin, and favipiravir, have the potential to inhibit NiV replication. Early diagnosis through molecular and serological assays, immunohistochemistry, and real-time reverse transcription polymerase chain reaction plays a crucial role in timely detection. Surveillance efforts encompassing cluster-based and case-based systems enhance outbreak identification and provide valuable insights into transmission dynamics. Furthermore, the implementation of high-level biosecurity measures in agriculture, livestock practices, and healthcare settings is essential to minimize transmission risks. Collaboration among researchers, public health agencies, and policymakers is pivotal in refining and implementing these strategies to effectively control and prevent NiV outbreaks and safeguard public health on a global scale.

Tackling a global epidemic threat: Nipah surveillance in Bangladesh, 2006-2021.

Human Nipah virus (NiV) infection is an epidemic-prone disease and since the first recognized outbreak in Bangladesh in 2001, human infections have been detected almost every year. Due to its high case fatality rate and public health importance, a hospital-based Nipah sentinel surveillance was established in Bangladesh to promptly detect Nipah cases and respond to outbreaks at the earliest. The surveillance has been ongoing till present. The hospital-based sentinel surveillance was conducted at ten strategically chosen tertiary care hospitals distributed throughout Bangladesh. The surveillance staff ensured that routine screening, enrollment, data, and specimen collection from suspected Nipah cases were conducted daily. The specimens were then processed and transported to the reference laboratory of Institute of Epidemiology, Disease Control and Research (IEDCR) and icddr,b for confirmation of diagnosis through serology and molecular detection. From 2006 to 2021, through this hospital-based surveillance platform, 7,150 individuals were enrolled and tested for Nipah virus. Since 2001, 322 Nipah infections were identified in Bangladesh, 75% of whom were laboratory confirmed cases. Half of the reported cases were primary cases (162/322) having an established history of consuming raw date palm sap (DPS) or tari (fermented date palm sap) and 29% were infected through person-to-person transmission. Since the initiation of surveillance, 68% (218/322) of Nipah cases from Bangladesh have been identified from various parts of the country. Fever, vomiting, headache, fatigue, and increased salivation were the most common symptoms among enrolled Nipah patients. Till 2021, the overall case fatality rate of NiV infection in Bangladesh was 71%. This article emphasizes that the overall epidemiology of Nipah virus infection in Bangladesh has remained consistent throughout the years. This is the only systematic surveillance to detect human NiV infection globally. The findings from this surveillance have contributed to early detection of NiV cases in hospital settings, understanding of Nipah disease epidemiology, and have enabled timely public health interventions for prevention and containment of NiV infection. Although we still have much to learn regarding the transmission dynamics and risk factors of human NiV infection, surveillance has played a significant role in advancing our knowledge in this regard.

Genomic characterization, transcriptome analysis, and pathogenicity of the Nipah virus (Indian isolate).

Nipah virus (NiV) is a high-risk pathogen which can cause fatal infections in humans. The Indian isolate from the 2018 outbreak in the Kerala state of India showed ~ 4% nucleotide and amino acid difference in comparison to the Bangladesh strains of NiV and the substitutions observed were mostly not present in the region of any functional significance except for the phosphoprotein gene. The differential expression of viral genes was observed following infection in Vero (ATCC® CCL-81™) and BHK-21 cells. Intraperitoneal infection in the 10-12-week-old, Syrian hamster model induced dose dependant multisystemic disease characterized by prominent vascular lesions in lungs, brain, kidney and extra vascular lesions in brain and lungs. Congestion, haemorrhages, inflammatory cell infiltration, thrombosis and rarely endothelial syncitial cell formation were seen in the blood vessels. Intranasal infection resulted in respiratory tract infection characterised by pneumonia. The model showed disease characteristics resembling the human NiV infection except that of myocarditis similar to that reported by NiV-Malaysia and NiV-Bangladesh isolates in hamster model. The variation observed in the genome of the Indian isolate at the amino acid levels should be explored further for any functional significance.

Human Exposure to Bats, Rodents and Monkeys in Bangladesh.

Bats, rodents and monkeys are reservoirs for emerging zoonotic infections. We sought to describe the frequency of human exposure to these animals and the seasonal and geographic variation of these exposures in Bangladesh. During 2013-2016, we conducted a cross-sectional survey in a nationally representative sample of 10,002 households from 1001 randomly selected communities. We interviewed household members about exposures to bats, rodents and monkeys, including a key human-bat interface-raw date palm sap consumption. Respondents reported observing rodents (90%), bats (52%) and monkeys (2%) in or around their households, although fewer reported direct contact. The presence of monkeys around the household was reported more often in Sylhet division (7%) compared to other divisions. Households in Khulna (17%) and Rajshahi (13%) were more likely to report drinking date palm sap than in other divisions (1.5-5.6%). Date palm sap was mostly consumed during winter with higher frequencies in January (16%) and February (12%) than in other months (0-5.6%). There was a decreasing trend in drinking sap over the three years. Overall, we observed substantial geographic and seasonal patterns in human exposure to animals that could be sources of zoonotic disease. These findings could facilitate targeting emerging zoonoses surveillance, research and prevention efforts to areas and seasons with the highest levels of exposure.

A Novel DNAzyme-Based Fluorescent Biosensor for Detection of RNA-Containing Nipah Henipavirus.

Nipah virus (NiV) is a zoonotic RNA virus which infects humans and animals in Asian countries. Infection in humans occurs in different forms, from asymptomatic infection to fatal encephalitis, and death occurred in 40-70% of those infected in outbreaks that occurred between 1998 and 2018. Modern diagnostics is carried out by real-time PCR to identify pathogens or by ELISA to detect antibodies. Both technologies are labor-intensive and require the use of expensive stationary equipment. Thus, there is a need to develop alternative simple, fast and accurate test systems for virus detection. The aim of this study was to develop a highly specific and easily standardized system for the detection of Nipah virus RNA. In our work, we have developed a design for a Dz_NiV biosensor based on a split catalytic core of deoxyribozyme 10-23. It was shown that the assembly of active 10-23 DNAzymes occurred only in the presence of synthetic target Nipah virus RNA and that this was accompanied by stable fluorescence signals from the cleaved fluorescent substrates. This process was realized at 37 °C, pH 7.5, and in the presence of magnesium ions, with a 10 nM limit of detection achieved for the synthetic target RNA. Constructed via a simple and easily modifiable process, our biosensor may be used for the detection of other RNA viruses.

Hendra Virus: An Update on Diagnosis, Vaccination, and Biosecurity Protocols for Horses.

Hendra virus (HeV) emerged as a zoonotic pathogen in the 1990s, causing low morbidity but high mortality in humans and horses. Pteropid bats are the natural reservoir of HeV and other important zoonotic viruses such as Nipah and Ebola viruses. Equivac HeV, manufactured by Zoetis (Parkville, Victoria, Australia), is the only commercially available vaccine for horses. There is no commercial vaccine for humans. The epidemiology, clinical features, pathology, diagnosis, management, and prevention of HeV will be reviewed.

Nipah Virus Exposure in Domestic and Peridomestic Animals Living in Human Outbreak Sites, Bangladesh, 2013-2015.

Spillovers of Nipah virus (NiV) from Pteropus bats to humans occurs frequently in Bangladesh, but the risk for spillover into other animals is poorly understood. We detected NiV antibodies in cattle, dogs, and cats from 6 sites where spillover human NiV infection cases occurred during 2013-2015.

Langya henipavirus: Is it a potential cause for public health concern?

A new virus, named Langya henipavirus (LayV), has recently been identified in Shandong and Henan provinces in China and has so far infected 35 individuals between April 2018 and August 2021. It is closely related to other known henipaviruses (Nipah and Hendra viruses) that can cause up to 70% human case fatality. Even though LayV has not been shown to be fatal in humans and does not appear to be transmitted from human-to-human, it is an RNA virus with the capacity to evolve genetically in the infected hosts (e.g. shrews) and can infect humans (e.g. farmers who have been in close contacts with shrews). It is therefore important to be vigilant about this new viral outbreak.

Molecular Pathogenesis of Nipah Virus.

Viral diseases are causing mayhem throughout the world. One of the zoonotic viruses that have emerged as a potent threat to community health in the past few decades is Nipah virus. Nipah viral sickness is a zoonotic disease whose main carrier is bat. This disease is caused by Nipah virus (NiV). It belongs to the henipavirous group and of the family paramyxoviridae. Predominantly Pteropus spp. is the carrier of this virus. It was first reported from the Kampung Sungai Nipah town of Malaysia in 1998. Human-to-human transmission can also occur. Several repeated outbreaks were reported from South and Southeast Asia in the recent past. In humans, the disease is responsible for rapid development of acute illness, which can result in severe respiratory illness and serious encephalitis. Therefore, this calls for an urgent need for health authorities to conduct clinical trials to establish possible treatment regimens to prevent any further outbreaks.

Detection of Serum Antibody Responses in Nipah Virus-Infected Pigs.

Nipah virus (NiV) is an emerging, zoonotic paramyxovirus that is among the most pathogenic of viruses in humans. During the first reported outbreak of NiV in Malaysia and Singapore in the late 1990s, pigs served as an intermediate host, which enabled the transmission to humans. Although subsequent outbreaks in Asia only reported direct bat-to-human and human-to-human transmission, pigs are still considered a potential source for viral dissemination in the epidemiology of the disease. Thus, serological assays such as Enzyme-linked immunosorbent assay (ELISA) or virus neutralization test (VNT) represent powerful tools to characterize the serum antibody responses in NiV-infected pigs as well as to perform seroepidemiological surveillance studies on the potential circulation of NiV or NiV-related viruses among pig populations worldwide. This chapter describes both methods in detail. Furthermore, we discuss some of the major pitfalls and indicate how to avoid them.