Everything You Need to Know about the Wuhan Coronavirus (2019 Novel Coronavirus (2019-nCoV))
What is a virus?
A virus is a small (you cannot see a virus with the naked eye) infectious agent that cannot replicate itself without infecting a host cell. But, once a virus infects a suitable host cell, its genetic material can replicate and dramatically increase the amount of virus in that host (the viral load) as it spreads through many other cells of that host. How severe the viral infection will be in humans often depends upon the age of the person who is infected, the general health of the person infected and how strong the immune system of the person is. There are viruses that are relatively harmless to adults with normal immune systems, but that can cause severe disease or death in children with certain forms of immune deficiency.
There are many types of viruses. Some cause infection in humans; others do not. Of those that do infect humans, they all vary in terms of how contagious they are (how easily transmitted from one person to another), how they are transmitted (through the air, through an animal bite, through close contact, through exposure to bodily fluids, or through sexual contact), how easily they are transmitted (e.g., the measles virus is unusual in that it can remain contagious in a room long after an infected child has left the room, while most other viruses will require closer contact), and what parts of the body they primarily attack and how they are manifest (e.g., skin (rash), upper respiratory tract (coughing, sneezing, runny nose), or central nervous system (meningitis, encephalitis)). Viruses that infect humans have varying incubation periods, i.e., the period between the time of exposure to the time of illness. Generally, these incubation periods are a number of days, but can be weeks, and in the case of some viruses, e.g., the AIDS virus, the incubation period can be months to years.
There is not a cure for most viral infections. Generally, we provide supportive treatment – ensuring that the person maintains sufficient fluid intake, managing symptoms and often providing some sort of isolation of the patient or protective measures for caregivers and visitors to try to minimize the spread of the virus. In most cases, if the infected person has a normal immune system, it will ramp up to attack and kill the virus and rid the body of the infection.
However, we do have immunizations for many viruses that provide varying degrees of protection from getting infected with the virus in the first place and that help create a sufficiently large population of people who are immune and not particularly susceptible to the virus (herd immunity) that even if someone does get infected, human-to-human spread will be minimized and not cause an epidemic.
We do have treatments for some viral infections. These anti-virals are typically drugs that impair the ability of the virus to replicate, allowing the body’s own immune system to rid itself of the virus.
What is a coronavirus?
Coronaviruses are a type of virus that are grouped together because of common features. They were first identified in the 1960s and up until 2002, there were four known strains that caused infection in humans, and all of the illnesses associated with coronavirus up until that time were relatively mild, causing cold-like symptoms. These viruses got their name from the spikes on their surface, which when viewed under special microscopes resemble a crown (the Latin word for crown is coronam).
When and why did the new, much more severe strains of coronavirus emerge?
The four, relatively mild strains of coronavirus involved human-to-human transmission. The three severe strains of coronavirus that emerged since 2002 all appear to have been transmitted from animals to humans. Two of these strains emerged in China and one in Saudi Arabia. There is speculation, and mounting evidence, that these new threats may be due to markets that sell exotic animals for human consumption that keep the exotic animals in close confinement and in some cases, poor sanitary conditions. Epidemiological evidence and DNA sequencing of these new viruses can help us trace the origins of these infections.
In November 2002, a new strain of coronavirus (SARS-CoV) was first recognized in China, and it subsequently caused a world-wide outbreak in 2002-2003 with 8,098 identified infections, resulting in 774 deaths. The illness was named severe acute respiratory syndrome (SARS).
In 2012, a new coronavirus strain causing infection was identified in Saudi Arabia. That illness was called Middle East Respiratory Syndrome (MERS) and the virus was named (MERS-CoV).
The current seventh strain of coronavirus was identified by Chinese officials on January 9, 2020 while investigating an outbreak of pneumonia in Wuhan City, Hubei Province, China that began in December 2019. This new virus is named 2019 Novel Coronavirus (2019-nCoV). Epidemiologic studies have connected many of the initial cases to a particular market in Wuhan City that sells exotic animals for human consumption. Many viruses that can be transmitted from animals to humans are not easily then transmitted from human to human. However, because many of the early cases had no connection to this exotic animal market, it is believed that human-to-human transmission is now accounting for the majority of cases, especially since the market has been closed and cases continue to emerge.
Early DNA sequencing studies are ongoing, but it appears that the 2019-nCoV came from a bat. Because the time of year was not one that would be associated with much bat activity, it is suspected that a bat transmitted the virus to an intermediate host (another animal) that in turn infected humans. The SARS-COV was determined to have been transmitted to humans through civet cats and the MERS-CoV through camels. The early evidence also suggests that the 2019-nCoV may have emerged from a virus related to SARS.
How does human-to-human transmission of the 2019 novel coronavirus occur?
Transmission appears to occur when an infected person coughs or sneezes and spreads the virus in droplets through the air to other people who are in close (within about 6 feet) proximity. We believe that these droplets then land in the nose or mouths of a healthy person, and these droplets can then be inhaled into their lungs, setting up infection in a new person. It is not known yet whether this virus, like some others, can survive for any period of time on surfaces following an infected person’s cough or sneeze and then be passed on to a healthy person by them touching the surface where the droplet has landed and then placing their hand to their mouth or nose, and recently, there has been some cause for concern that the droplets might be able to transmit the virus through contact with a healthy person’s eyes.
How contagious is this new virus?
We simply do not know yet. There is some reason to believe that the risk of human-to-human transmission is still low and may require sustained, prolonged, close contact with the infected person. This is in large part, due to the fact that we have not seen a lot of cases within families. However, we just recently observed the first two instances of transmission from a patient to a family member in the U.S. and it was after such prolonged, close contact.
What is the incubation period for this virus?
The period of time from exposure to the onset of symptoms appears to as short as several days and as long as 14 days. The concerning news is that it appears that people can be contagious prior to the onset of symptoms. Unfortunately, before that was known, passengers arriving from Wuhan, China were screened for fever and other signs of illness, but then admitted into the United States if negative. Unfortunately, we now realize that it is possible some of these travelers might still be infected and contagious, even if they did not have fever or report symptoms.
What are the symptoms of 2019-nCoV?
Infected people have ranged between mild cold-like symptoms to severe respiratory illnesses, including fever, cough, shortness of breath and pneumonia.
How serious is the infection?
While the statistics are likely to change (for the better) as we get better at identifying these cases, it appears that 20 percent of those who become ill will develop severe illness and perhaps about two percent of those who become infected and symptomatic will die. However, these numbers are very unreliable at this stage of investigation. It could be that we are missing many mild cases, which will make both of these statistics over-exaggerated. As of the time of this writing, only one death has occurred outside of China (Philippines).
How many cases of 2019-nCoV are there in the United States?
This is a constantly evolving number, as we are early on in the transmission of this disease. Some people are suspected to have this illness and have been tested, but test results are not back yet.
The United States has declared a public health emergency. This means that non-U.S. citizens who have been to China within the past 14 days are banned from entry into the U.S. and federal funds have been released to assist the Centers for Disease Control (CDC) and other public health agencies monitor, assess and control this public health threat.
World-wide, there are more than 17,000 confirmed cases of this infection. Most of these are in China. There are now eleven confirmed cases in the U.S. and another 82 patients undergoing testing. The test is not available other than through the CDC, and therefore there is a considerable time lag between testing and obtaining results.
So far, the states that have one or more cases of identified 2019-nCoV cases are Arizona, California, Illinois, Massachusetts and Washington. At the time of this writing, there are no cases in Idaho.
Should I get tested for 2019-nCoV?
Keep in mind that we are in the middle of cold and flu season. If you have cold-like symptoms, the overwhelming likelihood is that you have a cold or perhaps the flu.
The only reasons for us to be concerned and test you for 2019-nCoV would be that you have traveled to China in the past two weeks or someone with whom you have close contact has traveled to China in the past two weeks.