Henipavirus: take on a new virus

On August 4, The New England Journal of Medicine published a study that warned of the detection, in the Chinese provinces of Henan and Shandong, of at least 35 people infected with a new type of Henipavirus. It’s bad news.

Among the many emerging infectious viruses, the genus Henipavirus, belonging to the family Paramyxoviridae, is of particular concern due to the high mortality rates in humans exhibited by some members of the genus, such as Hendra (HeV) and Nipah (NiV) viruses.

The recent discovery of numerous henipaviruses in bats and wild rodents – including Cedar (CedV), Kumasi (KuV), and Mojiang (MojV) viruses – and evidence that they can infect human populations, have further raised concerns regarding to its diversity and its zoonotic, pathogenic and pandemic potential.

Since 2012, at least 20 divergent clades of henipaviruses have been discovered in various viral analyzes conducted by many international research groups. Such a situation reveals that the universe of this type of microorganism is still completely unknown to us. Again, this is bad news.

A wide range of symptoms

Some henipaviruses are zoonotic pathogens –transmitted by animals – which cause severe acute respiratory distress and neurological diseases in humans. The new henipavirus has been named Langya henipavirus (LayV), is phylogenetically related to Mojiang virus, and was discovered during sentinel surveillance of febrile patients with a recent history of animal exposure in eastern China.

The symptoms it causes include fever, tiredness, cough, anorexia, myalgia, nausea, vomiting, leukopenia (low white blood cells), thrombocytopenia (low platelets), and impaired liver and kidney function.

The shrew, suspicious number one

The possibility that it is a virus of zoonotic origin prompted the analysis of 25 species of small wild animals. Langya henipavirus RNA was predominantly detected in shrews (27%). This finding suggests that the shrew may be a natural reservoir of the virus. By evolutionary convergence, this animal resembles a small mouse with an elongated snout, but it is not actually a rodent.

In 2021, two new henipaviruses isolated from shrews of the genus Crocidura were discovered in South Korea. Shrews are one of the largest and most abundant groups of mammals in the world, and species of the genus Crocidura are natural reservoirs that carry pathogens harmful to humans. They are widely distributed in habitats such as rural areas, agricultural fields, and forests.

In fact, they have recently been identified in Germany several cases of patients with encephalitis caused by Borna disease virus 1, transmitted by shrews. In addition, they harbor other zoonotic pathogens, including arenaviruses, coronaviruses, hantaviruses, rotaviruses, and hepadnaviruses.

Is it transmitted between humans?

In the current analysis, contact tracing of 9 patients with 15 close family members revealed no transmission of Langya henipavirus by close contact. However, the sample size of the study is too small to determine if the virus can be transmitted from person to person.

Of course, the discovery of the Langya henipavirus, and its association with a disease with multiple symptoms in humans, warrants further investigation and surveillance of this new virus.

In addition, metagenomic studies and ongoing surveillance in small mammals for potential new human pathogenic viruses provide clues to establish preventive and mitigation strategies against new emerging and re-emerging infectious diseases.

Human-to-human transmission of the virus has not been proven so far. But the scientific community is concerned