In a recently published report The New England Journal of Medicine, Scientists discuss their discovery of a 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.
Studies: Zoonotic henipaviruses in febrile patients in China. Image credit: CI Photo / Shutterstock.com
The current outbreak
LayV infection was first identified through metagenomic analysis of a patient’s throat swab sample while monitoring febrile patients with recent contact with animals in eastern China. This analysis revealed that the LayV genome contains 18,402 nucleotides and is phylogenetically related to the Mojiang henipavirus that was previously discovered in southern China in 2014.
After the initial discovery of this infected patient, the researchers identified an additional 35 patients with acute LayV infection. Notably, 26 of these individuals were infected only with LayV.
Of 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 dysfunction were reported in 35% and 8% of patients, respectively.
The researchers who first identified the LayV virus surveyed 25 species of wild small animals as potential hosts for the virus. To this end, LayV ribonucleic acid (RNA) was identified in 27% of surveyed shrews, thus indicating that this animal is the most likely reservoir for the virus. Other domestic animals that were seropositive for LayV included 2% and 5% of surveyed goats and dogs, respectively.
A review of other henipaviruses
Other notable viruses in the Henipavirus genus include Nipah virus (NiV) and Hendra virus (HeV). Both NiV and HeV occur naturally Pteropus SPP bats; However, their spread to mammals ultimately led to their ability to infect humans.
During the 1994 HeV outbreak, infection initially showed influenza-like symptoms after an incubation period of seven to 16 days. Of the seven infected individuals, two recovered and one developed pneumonitis and died of organ failure. The remaining three patients experienced encephalitic manifestations, including confusion and ataxia, with fatal seizures reported in two patients.
NIV was first discovered in 1999 following outbreaks in both pigs and people in Malaysia and Singapore. Since then, several NIV outbreaks have been identified in Bangladesh, India and Malaysia.
While the Malaysian NiV (NiV-M) strain is associated with a case fatality rate (CFR) of 40% and causes mainly neurological symptoms, the Bangladesh strain (NiV-B) typically causes severe respiratory distress and has a CFR of 90%. .
NIV and HEV infections occur after exposure to secretions and respiratory droplets of infected humans or animals. Notably, a previous NIV outbreak in Bangladesh found that human-to-human transmission occurred in patients experiencing respiratory symptoms of infection. By comparison, both NiV-M and HeV outbreaks have not been associated with human-to-human transmission.
Approaches to reduce LayV outbreaks
In previous NIV outbreaks, public health officials have called for widespread use of sensitive rapid diagnostic tests (RDTs) to quickly identify and isolate potentially infected individuals. A number of preventive and non-pharmacological measures can also be applied to effectively reduce R0 Until medical solutions are available.
NiV and other henipaviruses are associated with high pathogenicity and, consequently, are considered potential pathogens of significant epidemics. Although no treatment is currently available to treat henipavirus encephalitis, several broadly active antiviral therapeutics targeting various RNA and DNA viruses can be used against henipavirus infection. However, many of these drugs require additional pre-clinical and clinical investigations to determine their efficacy against henipaviruses.
Several monoclonal antibodies (mAbs) are also being developed against Henipavirus. Thus, these agents can be used as both pre- and post-exposure prophylaxis until a vaccine is available.
Because LayV was the only pathogen identified in most patients with acute LayV infection, the researchers were confident that LayV was the primary cause of their febrile illness. Interestingly, contact tracing of 15 people who interacted with nine LayV-infected patients did not reveal that human-to-human transmission occurred; However, the small sample size of the study does not eliminate the possibility of human-to-human transmission of the virus.
A better understanding of this human disease requires sentinel surveillance of similar febrile illnesses in people who have recently interacted with shrews or other potential reservoirs. Because of the sporadic and often unpredictable nature of henipavirus outbreaks, it is important to isolate suspected cases of LayV infection and maintain open communication with public health agencies as new data become available.
- Zhang, X., Li, H., Jiang, F., And so on and so forth. (2022). Zoonotic henipaviruses in febrile patients in China. The New England Journal of Medicine 387(3). doi:10.1056/NEJMc2202705.