News of virus outbreaks often seems to come out of nowhere: One day, no one's heard of a virus, and the next, it's dominating headlines — like the Nipah virus outbreak in India. Or, you may have thought that a virus disappeared, only for it to re-emerge — like Ebola.
But viruses don't just pop up out of nowhere. In fact, "we really only know the tip of the iceberg of the viruses that exist in nature," said Dr. Amesh Adalja, an infectious-disease physician and a senior scholar at the Johns Hopkins Center for Health Security. Take, for example, a classic visit to the doctor's office for an upper respiratory infection, Adalja said: The doctor will most likely tell you it's a viral infection but won't know which virus it is, because diagnostic tools haven't yet gotten us there.
"There's a very, very, very select few [viruses] that can actually sustain transmission between humans, and that's where a lot of the danger lies," Adalja said.
If the viruses become capable of hurling themselves from human to human, they begin to jump countries, hitching free rides across an ever-globalized world. Then, it becomes a pandemic.
"Every time we get a little change [in a virus], we get a new outbreak," Schaffner told Live Science. Because the flu virus continuously evolves, for example, the vaccines for it are never 100 percent effective.
A more globalized world makes it easier for viruses to spread widely."Today, anyone can get on a plane anywhere in the world and be around the world in 24 hours," Schaffner said. "The world is smaller than ever — it's easier now than it was 50 years ago to introduce one of these viruses into the United States."
Nipah is on the World Health Organization’s priority list of emerging diseases that could cause a global pandemic, alongside Zika and Ebola.
“This is the first time we’ve seen the virus in south India,” says R.L. Sarita, the director of health services in the Indian state of Kerala. “And we want to make sure that it stays contained here.”
Those infected suffer a quick onset of symptoms, including fever, vomiting, disorientation, mental confusion, encephalitis and — in up to 70 percent of cases, depending on the strain — ultimately death. Here’s what we know, and don’t know, about this incurable disease:
How is the Nipah virus spread?
Several species of fruit bat that live throughout Asia carry Nipah. Several factors have increased the chance of bat-borne viruses being passed to humans, including development that has encroached on the bats’ natural habitats. “It used to be that these bats stayed far away from human populations,” Wang says.
Bats can also transmit Nipah to pigs and other livestock, which can then pass the infection onto humans. And humans can spread the virus through saliva and possibly other bodily fluids. One victim in the latest outbreak was a 31-year-old nurse who had been treating Nipah patients.
How does the virus cause infection?
Nipah and its viral cousin Hendra latch onto a proteins called ephrin-B2 and ephrin-B3 on the surface of nerve cells and the endothelial cells lining blood and lymph vessels, researchers have found. Nipah can also invade lung and kidney cells.
Virologists who have studied Nipah’s behavior in animals think that in humans, it initially targets the respiratory system before spreading to the nervous system and brain. Most patients who die succumb to an inflammation of blood vessels and a swelling of the brain that occurs in the later stages of the disease.
Why are epidemiologists worried about Nipah?
“The No. 1 reason is that it’s just so lethal,” says Linfa Wang, who heads the emerging infectious diseases program at the Duke-NUS Medical School in Singapore. In fact, the villain virus in the 2011 film Contagion was based on Nipah (SN Online: 10/19/11).
Because the symptoms of Nipah infection are similar to those for other diseases, including encephalitis and the flu, cases may be misdiagnosed. India has only two main diagnostic laboratories, both in the central city of Pune, equipped to confirm Nipah infection.
“In order for a disease to spread globally, each person has to infect at least more than one person,” Luby says. But “anytime the virus is inside a human, it has the opportunity to evolve and adapt to that human-specific environment,” Luby says. The worst-case scenario is a future strain that can transmit more quickly or easily among humans, which is why the WHO and global health experts are urging more research into vaccines and treatments.
“I hope what we learned from the Ebola outbreak, is that if we have the ability to prepare, we should do that,” says Emily Gurley, an infectious disease epidemiologist at the Johns Hopkins Bloomberg School of Public Health in Baltimore.
In fact, in response to this latest outbreak, the Coalition for Epidemic Preparedness Innovations (CEPI), a global alliance that formed last year to encourage and finance the development of vaccines, has announced that they will be granting $25 million to two American biotech companies to accelerate work on a Nipah vaccine. Researchers have tested experimental Nipah vaccines on animals, but have yet to conduct clinical trials.
Abstract
Nipah virus, a paramyxovirus whose wildlife reservoir is Pteropus bats, was first discovered in a large outbreak of acute encephalitis in Malaysia in 1998 among persons who had contact with sick pigs. Apparently, one or more pigs was infected from bats, and the virus then spread efficiently from pig to pig, then from pigs to people. Nipah virus outbreaks have been recognized nearly every year in Bangladesh since 2001 and occasionally in neighboring India. Outbreaks in Bangladesh and India have been characterized by frequent person-to-person transmission and the death of over 70% of infected people. Characteristics of Nipah virus that increase its risk of becoming a global pandemic include: humans are already susceptible; many strains are capable of limited person-to-person transmission; as an RNA virus, it has an exceptionally high rate of mutation: and that if a human-adapted strain were to infect communities in South Asia, high population densities and global interconnectedness would rapidly spread the infection. Appropriate steps to estimate and manage this risk include studies to explore the molecular and genetic basis of respiratory transmission of henipaviruses, improved surveillance for human infections, and support from high-income countries to reduce the risk of person-to-person transmission of infectious agents in low-income health care settings.
Cid_Yama wrote:News of virus outbreaks often seems to come out of nowhere: One day, no one's heard of a virus, and the next, it's dominating headlines — like the Nipah virus outbreak in India.
Another thing to put on the radar.
KaiserJeep wrote:Oddly enough, Ibon, I thought the Cloud Forest was part of your own survival plan. A particularly good plan.
KaiserJeep wrote:I mean, I could be wrong about this, but in a world of increased numbers of people and limited-by-expensive-energy-resources, those who inherited such resources have an edge - as long as they can conserve them, keep them safe, and in turn bequeath them to their own children, along with the basic strategy to preserve the family properties.
Knowing how one can live on a piece of fertile land, with a well, a woodlot, a few chickens, and a source of renewable electrical power, is a basic survival skillset and a time-honored way to weather tough times, in the Great Depression of the 1930s, or the likely Great Depression to come. Part of the scheme is to preserve your property by having little actual income, which is a tax strategy. Another tax strategy is to keep as much of the land unimproved as possible.
In this manner, land conservation is a survival strategy. Surely this resonates with a man who is part owner of a Cloud Forest and whose daughters live nearby.
Ibon wrote:......
Face it folks, the only game in town is BAU and keeping it as resilient as possible. Yes the economy will constrain, yes energy will become critical, stay out of debt and reduce your energy footprint, scale down your consumption, learn to fix things and all that stuff.
But don't kid yourselves.
GHung wrote:
It comes down to avoiding traps whenever possible. Those traps include debt, long and complex personal supply chains, and limited options.
If the exotic invaders on this list haven’t appeared yet in a town near you, they may do so soon, courtesy of increased human travel and climate change—two factors thought to play a major role in the spread of infectious agents and the animals that carry them.
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