Langya Virus Outbreak Sounds Alarm as Monkeypox, COVID-19 Continue to Spread
A study recently described how climate change is making more than half of hundreds of known infectious diseases worse, monkeypox is spreading and on Tuesday, news broke of a Langya henipavirus outbreak in China.
Although COVID-19 is not likely to be eradicated, and the pandemic itself is not over, researchers and public health officials are turning an eye toward the future, trying to get a bead on what might cause the next pandemic
The focus is largely on zoonotic viruses, such as SARS-CoV-2, the virus that causes COVID-19. Zoonotic viruses originate in animals and make the jump, through contact or mutations, to humans. Examples include the Ebola, Zika and West Nile viruses. An April study published in Nature noted there are approximately 10,000 viruses with the potential to infect humans, and most are “circulating silently in wild mammals.” Climate change and changes in land-use patterns increase the likelihood of cross-species viral transmission.
Coronaviruses, Filoviruses and Flaviviruses
Researchers are looking closely at three broad types of viruses. The first is coronaviruses. These include SARS-CoV-2 as well as the viruses responsible for SARS and MERS. The latter two jumped from animals to humans, and it’s likely that SARS-CoV-2 did as well. Coronaviruses cause mild to moderate upper-respiratory tract diseases in humans, typically, but as we know from COVID-19, SARS and MERS, they can be deadly.
The second is Ebola, which is a member of the family filoviruses. Also a zoonotic disease, Ebola likely transferred from bats or monkeys to humans. It causes hemorrhagic fevers – leading to serious internal bleeding that can be deadly. Another member of this class is Marburg virus.
The third is mosquito-borne viruses, primarily flaviviruses. These are also transmitted by ticks. They include diseases like West Nile, dengue and yellow fever. They don’t spread from person to person, which limits the likelihood of a pandemic. They only spread as far as mosquitos travel, which, unfortunately, is expanding as the climate warms.
Langya Virus Triggers Alarm Bells
Approximately 35 people in China have been diagnosed with a newly identified virus, which is being dubbed Langya henipavirus (LayV). It comes from the same family as the Nipah and Hendra viruses, which can be deadly. LayV was identified due to an early detection system for people with fevers with a recent history of animal exposures in eastern China. The patients were primarily farmers, reporting fatigue, cough, loss of appetite and body aches. Several also developed abnormal blood cells and liver and kidney damage. All survived.
The virus does not appear to be transmitted from person to person. It seems to have been spread by shrews, a small type of rodent, which are a known vector for similar henipaviruses. The virus has also been identified in some goats and dogs. Testing of 25 wild animal species suggested the shrew was a natural reservoir for the virus, with it being identified in 27% of shrews tested (compared to 2% of goats and 5% of dogs).
FDA Expands Authorization for Monkeypox Vaccine
Experts say monkeypox is very unlikely to become pandemic, even though there is currently an outbreak. The first recorded human infection of monkeypox was in the Democratic Republic of Congo in 1970. It has only been documented outside of Africa six times. There have been about 9,000 reported cases in the U.S. to date, across 49 states, Washington, D.C. and Puerto Rico, according to the Centers for Disease Control and Prevention. No deaths have been reported in the U.S. from monkeypox.
Symptoms are similar to smallpox – which was eradicated globally in the 1970s – but are milder. Initial symptoms are similar to the flu, with fever, chills, headache, exhaustion and muscle pain. Monkeypox causes swelling of lymph nodes while smallpox does not. It is also marked by a severe rash. It generally lasts two to four weeks and can be fatal. Some reports suggest up to 10% of monkeypox patients die from the disease. It is primarily spread via skin-to-skin contact during sex. It can be spread by close physical contact, including hugging and kissing, and through contaminated bedsheets or other bedding. Currently, gay and bisexual men are considered to be at the highest risk.
There is a vaccine, which is basically the smallpox vaccine. On Tuesday, The U.S. Food and Drug Administration expanded authorization for the monkeypox vaccine in a way that will increase its availability. While it is traditionally administered via subcutaneous injection, the new authorization allows healthcare providers to give the shots to adults through intradermal injection, between the layers of the skin, which will require one-fifth of the dose. This will expand the 400,000 vials in the strategic national stockpile to about 2 million shots.
Children will still receive the shots subcutaneously as public health officials don’t have enough data on whether intradermal injections work for children. The vaccine, Jynneos, is the only FDA-approved monkeypox vaccine in the U.S. It is administered in two doses 28 days apart. It is manufactured by Danish company Bavarian Nordic.
COVID-19: Introducing BA.4.6
As of August 9, there were 1,021, 898 new cases of COVID-19. In the U.S. alone, on the same date, there were 128,676 new cases. For the most part, access to effective vaccines and booster shots, and the availability of treatments such as Gilead’s Veklury, Merck’s molnupiravir and Pfizer’s Paxlovid, as well as some of the antibody treatments, have made the disease manageable, although it can still be potentially deadly in the unvaccinated, elderly and immunosuppressed.
As we know now, SARS-CoV-2 mutates fairly easily and rapidly. Currently, the spread is by the Omicron BA.4 and BA.4 subvariants, which are extremely contagious, demonstrate some evasion from immunity caused by vaccines and previous infections but are potentially less deadly. That doesn’t mean future mutations won’t be even more deadly and even more infectious.
There is also now evidence of yet another Omicron variant, BA.4.6.
“We’ve seen a pretty rapid increase in the number of BA.4 and BA.5s and the expected increase in the number of samples we can sequence,” Bailey Glen, Ph.D., an assistant professor in the College of Medicine at the Medical University of South Carolina (MUSC) said. “And there’s definitely some subtype information that may be relevant. We see a BA.4.6 that we haven’t seen until now. There’s still lots of change going on. From a genetic perspective, it’s still rapidly adapting. It's still just kind of wild how much it’s able to change and adapt.”
It's still unknown if this subvariant will have any impact or staying power.
Julie Hirschhorn, Ph.D., director of the molecular pathology lab at MUSC, said, “I think that we’re surging again. We’re either heading into it or in it. It’s a little hard to tell because there’s not as much reporting of positive tests as before to make it as clear what’s going on. But it does appear that we’re surging again. It’ll be interesting to see how long this wave lasts.”
Bivalent vaccines that target the original Wuhan wildtype strain and Omicron are expected to roll out this fall, but it’s too early to know whether they will be effective against BA.4.6, should it continue to spread.