The world has been captivated by the emergence of another new zoonotic disease in China…
The newly identified virus, the Langya henipavirus (LayV), has now infected 35 people in China according to results shared in a clinical letter to the editor published August 4th in The New England Journal of Medicine.
The phylogenetically distinct henipavirus is thought to have come from a local species of shrew and causes fever, fatigue, and a cough, though so far, there is no indication that the virus has spread from person to person.
LayV was first identified in a throat swab sample taken from one patient during sentinel surveillance of febrile patients with a recent history of animal exposure in eastern China, by means of metagenomic analysis.
Lead author, Dr Xiao-Ai Zhang from the Beijing Institute of Microbiology and Epidemiology, said that subsequent investigation identified 35 patients with acute LayV infection in the Shandong and Henan provinces of China, of whom 26 were infected specifically with LayV only (no other pathogens were present).
“These 26 patients presented with fever (100% of the patients), fatigue (54%), cough (50%), anorexia (50%), myalgia (46%), nausea (38%), headache (35%), and vomiting (35%), accompanied by abnormalities of thrombocytopenia (35%), leukopenia (54%), and impaired liver (35%) and kidney (8%) function,” Dr Zhang explained.
“There was no close contact or common exposure history among the patients, which suggests that the infection in the human population may be sporadic,” he said.
“Contact tracing of 9 patients with 15 close contact family members revealed no close-contact LayV transmission, but our sample size was too small to determine the status of human-to-human transmission for LayV.
“A serosurvey of domestic animals detected seropositivity in goats (3 of 168 [2%]) and dogs (4 of 79 [5%]), and among 25 species of wild small animals surveyed, LayV RNA was predominantly detected in shrews (71 of 262 [27%]) – a finding which suggests that this animal may be a natural reservoir of LayV.”
Dr Danielle Anderson, from the Peter Doherty Institute for Infection and Immunity in Melbourne and Singapore’s Duke NUS Medical School, was a contributor to the study, drawing on her previous work with henipaviruses here in Australia.
“Bats are the main reservoir of henipaviruses and there is molecular and serological evidence to suggest that henipavirus or henipa-related viruses are widely distributed from Australia to Asia, all the way to West Africa,” Dr Anderson explained in a study from 2020.
“Henipaviruses are classified as a biosafety level 4 (BSL4) agent and there are currently no licensed therapeutics or vaccine for human use.” [1]
Henipaviruses form a genus of RNA viruses in the family Paramyxoviridae and include the Hendra (HeV) and Nipah (NiV) viruses, both of which are known to infect humans with potentially fatal consequences.
Hendra’s first outbreak in 1994 occurred in the Brisbane suburb of Hendra (its namesake), when 13 horses and their trainer died from the previously unknown disease, along with the non-fatal infection of seven other horses and a stable hand.
To date, HeV has re-emerged on the East coast of Australia on 55 occasions, resulting in more than 97 horse deaths, two euthanized dogs, and 4 out of the 7 global human case fatalities.[2]
NiV was first linked to an outbreak in humans in 1998, associated with a respiratory illness in Malaysian pigs that resulted in a total of 256 cases, 105 of which were fatal.[3]
A further 11 cases (one fatal) were recorded in Singapore the following year amongst abattoir workers who had dealt with pigs imported from the outbreak regions in Malaysia, with measures to control the disease seeing the destruction of over one million pigs (almost half the national pig herd).
Thankfully, LayV is more phylogenetically related to the Mojiang henipavirus (MojV),a so-far non-fatal disease recently discovered in rats in southern China, and the authors point out that the potential cross-reaction with MojV should be assessed to improve serologic testing.
Associate Professor Sanjaya Senanayake, a specialist in infectious diseases and Associate Professor of Medicine at the Australian National University, said that the announcement of another new infection was not surprising.
“Over the last five decades, there have been around fifty new infections described. The vast majority, such as LayV, monkeypox and COVID-19, are viruses that have jumped from the animal to the human world,” he explained.
“The shrew may be the natural reservoir of LayV but some domestic animals were found to be infected too.
“Regarding this infection, it is still early days but there are some reassuring signs, namely that there haven’t been deaths or many serious illnesses from it, that there don’t seem to have been many cases (the earliest case seems to have been 2018), and that person-to person-transmission hasn’t been found (unlike monkeypox and COVID).”
Dr Nick Fountain-Jones, a lecturer and research associate at the University of Tasmania’s School of Natural Sciences, said the findings show how incredibly important viral surveillance is.
“This group of viruses pose a constant and real threat to humans and livestock, and viruses like LayV need to be monitored carefully,” Dr Fountain-Jones said.
“Early detection, identification of potential reservoir hosts and contact tracing, as was done in this study, are crucial steps to prevent the next pandemic.
“Unfortunately, just because we are still experiencing the SARS-CoV-2 pandemic does not mean another isn’t around the corner and more funding for research, surveillance and [initiatives] such as the global virome project are crucial for helping prevent future pandemics.”
[1] Wang, Lin-Fa & Anderson, Danielle. (2020). Henipaviruses. 10.1016/B978-0-12-814515-9.00100-4.
[2] Broder, C.C., Wong, K.T. (2016). Henipaviruses. In: Reiss, C. (eds) Neurotropic Viral Infections. Springer, Cham. https://doi.org/10.1007/978-3-319-33133-1_3
[3] David Brown, Graham Lloyd, Chapter 164 – Zoonotic viruses, Editor(s): Jonathan Cohen, Steven M. Opal, William G. Powderly, Infectious Diseases (Third Edition), Mosby, 2010, Pages 1617-1631, ISBN 9780323045797, https://doi.org/10.1016/B978-0-323-04579-7.00164-7.