Human communication

A new zoonotic Langya virus identified in China

In a recent report published in The New England Journal of Medicine, scientists discuss their discovery of the novel Langya henipavirus (LayV) in eastern China. To date, a total of 36 patients have been diagnosed with acute LayV infection in Shandong and Henan provinces.

Study: A zoonotic henipavirus in febrile patients in China. Image Credit: CI Photos / Shutterstock.com

The current epidemic

While monitoring febrile patients who reported recent animal contact in eastern China, LayV infection was first identified through metagenomic analysis of a swab sample from a patient’s throat. This analysis revealed that the LayV genome consists of 18,402 nucleotides and is phylogenetically related to the Mojiang henipavirus which was previously discovered in southern China in 2014.

After their initial discovery of this infected patient, the researchers identified 35 other patients with acute LayV infection. Notably, 26 of these people were infected with LayV alone.

Among these 26 patients, 100% presented with fever, 54% with fatigue, 50% with anorexia and cough, 46% with myalgia, 38% with headache and 35% with vomiting. Thrombocytopenia and leukopenia were reported in 35% of patients, while hepatic and renal function were reported in 35% and 8% of these patients, respectively.

The researchers who first identified the LayV virus also studied 25 species of small wild animals as potential hosts for this virus. To this end, the ribonucleic acid (RNA) LayV was identified in 27% of the shrews surveyed, thus suggesting that this animal is the most probable reservoir of this virus. Other LayV-seropositive domestic animals comprised 2% and 5% of goats and dogs surveyed, respectively.

A review of other henipaviruses

Other notable viruses in the henipavirus genus include Nipah virus (NiV) and Hendra virus (HeV). NiV and HeV are naturally present in Pteropus bats spp; however, their spillover to mammals eventually led to their ability to infect humans.

During an outbreak of HeV in 1994, the infection initially presented with flu-like symptoms after an incubation period of seven to 16 days. Of the seven people infected, two recovered and one developed pneumonitis and died of organ failure. The other three patients presented with encephalitic manifestations, including confusion and ataxia, with fatal seizures reported in two patients.

NiV was first discovered in 1999 following a reported outbreak in pigs and humans in Malaysia and Singapore. Since then, several outbreaks of NiV have been identified in Bangladesh, India and Malaysia.

While the Malaysian strain of NiV (NiV-M) is associated with a case fatality rate (CFR) of 40% and primarily causes neurological symptoms, the Bangladesh strain (NiV-B) typically causes severe respiratory distress and has a 90% CFR.

NiV and HeV infections occur following exposure to infected human or animal secretions and respiratory droplets. Notably, previous outbreaks of NiV in Bangladesh revealed that human-to-human transmission occurred in patients with respiratory symptoms of the infection. Comparatively, NiV-M and HeV outbreaks were not associated with human-to-human transmission.

Approaches to Mitigate the LayV Outbreak

In previous NiV outbreaks, public health officials have urged the widespread use of sensitive rapid diagnostic tests (RDTs) to quickly identify and isolate potentially infected people. Several preventive and non-pharmaceutical measures can also be put in place to effectively reduce the R0 until medical countermeasures are available.

NiV and other henipaviruses are associated with high pathogenicity and therefore are considered pathogens with significant epidemic potential. Although there are currently no therapies available to treat henipavirus encephalitis, several broadly active antiviral therapeutics that target different RNA and DNA viruses could potentially be used against henipavirus infection. However, many of these drugs require additional preclinical and clinical studies to determine their effectiveness against henipaviruses.

Several monoclonal antibodies (mAbs) are also being developed against henipaviruses. Thus, these agents could be used as both pre- and post-exposure prophylactic measures until a vaccine becomes available.

conclusion

Since LayV was the only pathogen identified in the majority of patients with acute LayV infection, the researchers are confident that LayV was the primary cause of their febrile illness. Notably, contact tracing of 15 people who interacted with nine LayV-infected patients did not reveal that human-to-human transmission had occurred; however, the small study sample size does not eliminate the possibility that human-to-human transmission of this virus is possible.

Sentinel surveillance of similar febrile illnesses reported in individuals who have recently interacted with shrews or other potential LayV reservoirs is essential to better understand this human disease. Due to the sporadic and often unpredictable nature of henipavirus outbreaks, it is critical to isolate suspected cases of LayV infection and maintain open communication with public health agencies about new data as it becomes available. .

Sources:

Journal reference:

  • Zhang, X., Li, H., Jiang, F., et al. (2022). A zoonotic henipavirus in febrile patients in China. The New England Journal of Medicine 387(3). doi:10.1056/NEJMc2202705.