A lot has been written about the symptoms, prevention and public health policy of the novel coronavirus (COVID-19), which has now become a pandemic. Yet, little information can be found about the virus itself.
The present outbreak virus has an official name: Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2). It might be easier to remember if this virus was called the Wuhan virus, like Ebola, which denotes the place where it was isolated for the first time, but no one should be remembered solely by a tragedy, so the virologists from the International Committee on Taxonomy of Viruses prefer to use SARS-CoV-2.
The “2” is to show that this virus is very similar to a virus that was responsible for a SARS outbreak that lasted for nine month in 2002–2003, which infected 8,000 people worldwide and killed 10 percent of them. It was also the reason why this virus was initially called 2019-nCoV, in which “n” stands for “novel” or “new”.
COVID-19 and other coronaviruses give an appearance of a spiked crown when they are visualized using electron microscopy, hence their name. Corona means crown in Latin.
As of Wednesday the new coronavirus has infected 227 people in Indonesia, killing 19 of them, while globally the number of confirmed cases has topped 200,000.
Viruses do not have their own machineries to replicate, so they need to hijack human or animal cells and use the cells’ machineries for this purpose. Coronaviruses favor lung and intestinal cells. Studies on the organs of patients who died in the previous SARS outbreak show this.
We don’t have a lot of information about the SARS-CoV-2 yet because organs are difficult to get and tests may need some times to perform, unlike clinical information.
Dr. Tian from Wuhan, China, where the outbreak began last December, and her coworkers had a chance to analyze the lung tissue of two patients that were removed because of lung cancer.
They describe the damage caused by this virus in a future edition of the Journal of Thoracic Oncology. This information will give us more understanding on the course of COVID-19 in the future.
From the first SARS outbreak, we learned that SARS attacks the lungs in three phases: viral replication followed by immune hyperreactive and pulmonary destruction. As the name implies, further damage is mainly caused by the immune system’s overreaction to the damage already done by the virus.
When the damage continues, it lead to the last phase, the destruction of the lungs. In SARS, only a minority of patients went through all of these phases.
SARS viruses were also found in the tissue of the intestine. According to data published in the New England Journal of Medicine on the first 1,099 patients with COVID-19 in China, around 5 percent of the patients had diarrhea. In animals such as cows, it is already known that coronaviruses cause diarrhea. At this moment, it is not clear whether the transmission of COVID-19 can also occur through stool.
From this clinical data, it seems that elderly people who have other medical conditions, such as diabetes, chronic lung or heart diseases, are more susceptible to COVID-19. At this moment, we can only hypothesize that these people might be more prone to infection and experience more severe initial damages, as well as a greater hyperreaction of the immune system in comparison to people without these medical conditions. It will take time to prove these theories.
Using a technique called viral genome sequencing, the China Novel Coronavirus Investigating and Research Team showed that the SARS-CoV-2 is 96 percent similar to the bat coronavirus. This finding raised the speculation that the origin from this present outbreak is the bat, like the previous SARS outbreak.
COVID-19 is indeed a zoonosis: a disease that can jump from animal to human. But bats are not sold in the Wuhan wholesale market where the virus was first detected.
Another suspected source of this virus is the Pangolin. These are endangered mammals, a relative of anteaters, whose scale are of interest for Chinese medicine and are traded illegally in some markets in China.
How can we know that someone has COVID-19? The doctors needs to collect samples from suspected patients, meaning that they will swab the throat and the area behind the nose. Sputum can also be collected. For more severe patients in the hospital, samples are also collected by passing the fluid through the small part of the lung, the bronchoalveolar lavage, in a procedure that is normally performed by a lung specialist (pulmonologist). These samples are then sent to a qualified lab where tests are performed.
To be qualified, the labs need to show that they are able to detect the coronavirus. The labs use a polymerase chain reaction (PCR) test, which amplifies several genetic sequences that are specific to this SARS-CoV-2. Each test takes three to four hours.
Although this test is very reliable, there is still a chance that it can fail to show the presence of the virus (a false negative result).
This may occur due to sampling errors, for example, if the swab does not cover the area where the virus is expected to be found.
Taking samples is thus very important. False negative results can also occur when a patient sheds the virus later on in the infection and not at the moment of sampling. The virus is not routinely cultured on the sample from a patient because culturing viruses takes time.
Indonesian medical specialist in clinical microbiology at Erasmus University Medical Center, Rotterdam, the Netherlands
Disclaimer: The opinions expressed in this article are those of the author and do not reflect the official stance of The Jakarta Post.