New Zoonotic virus' Langya 'found in China: 35 known infections
Recently, the world's leading medical journal, New England Medicine (NEJM), published a joint newsletter between Chinese and Singaporean scientists,It reported that a new type of animal-derived Henipavirus that can infect humans was found to be avirus in Shandong and Henan provinces of China. The authors named it Langya henipavirus (LayV).
A newly discovered Henipa virus, probably of animal origin, has been linked to a number of febrile cases, according to the study by Professors Wei Liu and Liqun Fang of the Institute of Microbiological Epidemiology at the Academy of Military Medical Sciences, the Chinese Academy of Military Sciences, and Linfa Wang of the Duke-NUS Medical School, among others. Symptoms include fever, fatigue, cough, anorexia, myalgia and nausea. This finding warrants further investigation to better understand the associated human diseases.
"This virus is in the same genus as Nipah virus and so far these cases have not been fatal or very serious. It is therefore safe to say that this new virus should be greeted with alarm, not panic. But we need to be careful, because there are many more viruses like this in nature, and if a different virus jumps into humans, it might be a different story." Wang Linfa, a professor at the National University of Singapore Medical School and one of the researchers, told Thepaper.cn on Monday.
LayV natural host or shrew
Henipa virus is one of the important emerging causes of zoonosis in the Asia-Pacific region. Two viruses from this genus are known to infect humans: Hendra virus (HeV) and Nipah virus (NiV). The natural host of both viruses is fruit bats. Both viruses cause severe disease in animals and humans and are classified as biosafety Level 4 viruses with case fatality rates between 40% and 75%.
However, scientists have found other related Henipavirus in bats, rodents and shrews, a mammal of the family Apicidae. In that study, scientists identified a new Henipa virus, named Langya virus (LayV), in a throat swab sample from a patient using high-throughput sequencing and virus isolation during sentinel surveillance of febrile patients with recent animal exposure in eastern China.
The genome of LayV is composed of 18402 nucleotides, and its genome organization is the same as other Henipa viruses. In phylogenetic tree, this strain was found to be a new strain. In terms of evolutionary relationship, it was the most related to Henipa viruses previously discovered in Mojiang, Yunnan Province.
Further investigation revealed 35 patients with acute LayV infection in Shandong and Henan provinces of China, of whom 26 were infected only with LayV (no other pathogens were detected). The clinical symptoms of these 26 patients were fever (100%), fatigue (54%), cough (50%), anorexia (50%), myalgia (46%), nausea (38%), headache (35%), vomiting (35%), Thrombocytopenia (35%), leukopenia (54%), impaired liver function (35%) and renal function (8%) were associated.
In serological studies of domestic animals, goats (3/168 [2%]) and dogs (4/79 [5%]) were found to be positive for serum antibodies. Among the 25 wild small mammal species studied, LayV RNA was detected mainly in shrews (71/262 [27%]), a finding that suggests that shrews may be a natural host of LayV. The researchers note that although this study does not comply with the Koch hypothesis (a rule used to establish a causal relationship between disease and microorganisms), the following findings from patients with acute LayV infection suggest that LayV is the cause of febrile illness in these patients: of 35 patients with acute LayV infection, only LayV was detected in 26 (74%); The IgG titer of 86% convalescent serum was 4 times higher than that of acute convalescent serum in 14 patients. Viremia is associated with acute LayV infection. Patients with pneumonia had higher viral loads than those without pneumonia (mean [&PLusMn;SD] log10 conversion copies/mL, 7.64& PLusMn; 0.98 vs. 4.52 & plusmn; 1.13).
It has not been determined whether LayV can be transmitted from person to person
Although previous reports suggested human-to-human transmission of Henipa virus, the investigators noted that no significant spatial or temporal clustering of cases and LayV haplotypes was observed. There was no history of close contact and common exposure between different patients, suggesting that the infection may be sporadic. Follow-up of 9 patients with 15 close contact family members did not reveal close contact transmission of LayV, but the investigators also acknowledged that the sample size was too small to determine the status of human-to-human transmission of LayV and that possible cross-reactions between LayV and Henipa virus found in Mojiang should be evaluated to improve serological testing.
Finally, the researchers note that LayV, as a newly identified Henipa virus, possibly of animal origin, is associated with febrile illness in humans, and that this finding warrants further study to better understand related human diseases.
In the case of Henipa virus, the WHO noted that in the event of a suspected case, quarantine should be implemented as soon as possible, infection control measures should be taken, and public health authorities should be notified immediately.
Human infection with Hendra virus, a member of Henipa virus, can present with mild influenza-like illness or fatal respiratory or neurological illness. Human infection with Hendra virus has a mortality rate of 50 to 75 percent. Fortunately, it's not highly contagious. When humans are infected with Nipah virus, which is a member of Hennipah virus, mild cases may present with asymptomatic infection, and severe cases may develop acute respiratory syndrome and fatal encephalitis. In 1998, Nipah virus became endemic in Malaysian pig populations and caused 265 human infections, 105 of whom died. The story was later made into the film Contagion.
There is no vaccine or treatment for Henipa virus. The only treatment is supportive care to control complications. According to the World Health Organization,The two Hennipaviruses known to infect humans (Hendra and Nipaviruses) have case fatality rates of between 40% and 75%, much higher than novel coronavirus.