A team of 13 scientists reported to the NEJM journal the discovery of a new virus that infects humans in eastern China. This is the Langya virus, of the henipavirus genus and the paramyxoviridae family. It was identified in throat mucus samples from 35 patients who had a fever, 26 of whom had no other concomitant viral infections.
In addition to fever, half of the patients had fatigue, cough, anorexia , muscle pain and a lower than normal white blood cell count (defense cells) in the blood. Less than half had nausea, headache, vomiting, reduced blood platelets, and liver and kidney problems. The patient sample is too small to generalize these symptoms.
Langya is the name of a commandaria (an administrative area) established in the Chin dynasty (221-206 BC) in the current eastern coastal province of Xanthum, one of the places where the virus was found. It was also found in Honã, province on the southwest border of Xanthum.
What is the origin of Langya virus?
In preliminary investigation in the wild, the researchers point out that the main animal reservoir must be the shrews, a group of small mammals that resemble mice but are not rodents. Almost a third of the sample of 262 shrews tested positive for Langya virus, among 261 species of small wild animals. In South America, shrews are only found north of the Andes. The virus was also found at low frequencies among goats (2%) and dogs (5%), which may have been infected by interacting with shrews.
Is the virus dangerous?
As it has just been discovered, it is necessary to wait for more investigations from Langya to draw conclusions. What one can do until then is to speculate on the basis of the closest relatives. The genus of the henipaviruses has three important relatives of the Langya virus: the most similar is the Mojiang virus, and there are also the Nipah virus and the Hendra virus. The last two have bats as their animal reservoir, especially the large ones known in Southeast Asia as flying foxes. Mojiang is more present in rodents.
In a review of henipaviruses published in February in a journal of the PLOS group, the German scientists Susann Kummer and Denise-Carina Kranz, from the Center for Biological Threats and Special Pathogens at the Robert Koch Institute in Berlin report that Nipah and Hendra are highly pathogenic and can be fatal in humans and animals.
Hendra virus was identified in an outbreak in
in Australia. Its name comes from a suburb of the city of Brisbane, in the state of Queensland, where several horses and their trainer died of a hemorrhagic lung disease. Another outbreak in the same year, in the same state, led to the death of a person the following year who had suffered from persistent encephalitis since he was infected.
The Nipah virus, whose name comes from a village from Malaysia, affected 261 people in Malaysia and Singapore in outbreaks in 1998 and 1999, with 35 confirmed deaths. Neither country has had more outbreaks since then. An outbreak in Bangladesh in the year of 2001 affected 13 people, 9 of whom died — the country was less fortunate, being affected with annual outbreaks reaching 19 outbreaks until 2015. Of 261 cases, 199 resulted in deaths. Other outbreaks occurred in India in 2007, 2007 and 2018; in the Philippines in 2014, also with worrying mortality rates, but usually involving small numbers of people.
The Mojiang virus, the closest to the Langya, has a common history with the novel Covid-19 coronavirus 19: the Mojiang copper mine in southern China , where three miners contracted this henipavirus and died of pneumonia in 2012. The virus was identified by the Wuhan Institute of Virology. To date, the closest known relative of the novel coronavirus (SARS-CoV-2) is present in a sample known as RaTG, collected at the same time and in the same mine. That sample, which the institute says originates from bat feces and has since been exhausted, has undergone suspicious changes to its records that advocates of the laboratory origin of SARS-CoV-2 consider evidence favorable to this hypothesis. The virus causing the pandemic belongs to the family of coronaviridae, which differ from the henipaviruses.
Does it have the potential for a new pandemic?
As indicated by the history of two decades of Nipah virus, which has not left Southeast Asia, and the lack of more Mojiang virus outbreaks in ten years, there does not appear to be a pandemic potential in Langya.
It has high potential for transmission?
The scientists who described the Langya think not. Studying the genetic material of the virus, whose RNA is similar in size to the DNA of our mitochondria (cell organelles that produce energy), they saw a viral diversity incompatible with community transmission from person to person. The infections also lacked an obvious connection in space or time, suggesting that patients became infected while handling animals. There was also no contact history between the 35 patients. Retracing the steps of nine of them with 15 common family contacts, no close contact transmission was found. .
It is known that another henipavirus, Nipah, has the ability to pass from one person to another. It is possible that the Langya virus does the same, but further studies are needed to establish this possibility.
Hendra and Nipah may remain viable on surfaces with guano or fruit leftovers bitten by bats for hours or a few days, depending on temperature and humidity. It is important to avoid contact with domesticated animals such as dogs, horses and pigs that live in environments where there are wild animals such as bats and shrews, as domesticated animals can be the intermediate hosts that pass henipaviruses to humans. Closer contact appears to be necessary, but pigs, in particular, could mediate respiratory transmission. Infected humans can pass these viruses through their blood, feces, urine, and saliva. Nipah can remain viable in blood samples for up to a week, but the few studies have not detected it on surfaces around infected patients, except for sheets and towels (time not measured). Depending on the method of infection, the incubation period can last up to two months.
What is being done to combat it?
Malaysia and Singapore serve as examples of what to do about henipaviruses, for their success in preventing further outbreaks of the Nipah virus. Infected animals, especially pigs, were also slaughtered. Bangladesh serves as a negative lesson. Hospital precautions are crucial: in 2001, an outbreak of Nipah at Siliguri District Hospital in India began when a patient became infected 11 hospital staff members.
There is the persistent problem of the Chinese Communist Party’s lack of transparency . Taiwan, the “free China”, which did a good job at the beginning of the Covid pandemic-19, is closely monitoring the new Langya henipavirus. Chuang Jen-hsiang, from the Taiwan Center for Disease Control, told the Taipei Times that the country’s laboratories are working on a standardized molecular method to identify the virus.
Is it treatable?
There are currently no vaccines for henipaviruses. Treatment for infected patients was palliative, with mortality around 70% especially for those infected by Langya’s relatives. His own mortality is unknown.