COVID-19 has put a deadly stop to the normal life of all the citizens in more than 160countries around the world. It’s about time we understand how a virus works. In order to satiate our curiosity about how a tiny infectious agent can spread like a wildfire, we ought to know what’s the story behind the global pandemics that have affected humans to date and both changes that followed temporarily and permanently in their daily lives. Complete coverage: Coronavirus
Crux of the Matter
The ‘Viral’ Trend: How do Viruses Spread? A virus particle or a virion consists of nucleic acid, coat of protein and lipid membrane. Unlike human cells or bacteria, viruses don’t contain the enzymes needed to carry out the chemical reactions for life. Instead, they carry only one or two enzymes that decode their genetic instructions. So, a virus must have a hostcell (bacteria, plant or animal) in order to live and make more viruses.
Once they enter the desired host cell available in its nearest vicinity, they follow the lytic cycle to invade its chemical machinery. As they start attacking cells in a human body, the immune system responds to the infection, and in the process of fighting, it produces chemicals called pyrogens that cause your body temperature to increase. This fever helps you to fight the infection by slowing down the rate of viral reproduction. Generally, the body’s chemical reactions have an optimal temperature of 98.6 degrees Fahrenheit (37 degrees Celsius).
About Outbreaks, Epidemics and Pandemics
As an epidemiologist listening to the steady stream of conversation around the coronavirus, I’m hearing newscasters and neighbours alike mixing up three important words my colleagues and I use in our work every day.
– Rebecca S.B. Fischer, The Conversation
Outbreaks are medical events that happen at a smaller scale. If we take up an analogy, imagine an unusual spike in the number of children with a fever at a daycare. One or two sick kids might be normal in a typical week, but if 15 children in daycare come down with fever all at once, that is an outbreak. When a new disease emerges, outbreaks are more noticeable since the anticipated number of illnesses caused by that disease was zero. So the group of pneumonia cases that sprung up unexpectedly among market-goers in Wuhan, China, were considered a part of an outbreak initially before the real culprit emerged as the novel coronavirus or COVID-19.
An epidemic is an outbreak of a disease that spreads quickly and affects many individuals at the same time. It occurs when there is a sudden increase in the number of cases of a disease, in a community or a particular geographical area. Many people aren’t familiar with these epidemics unless they’re directly affecting their home region. A few of them include: The Zika Virus of continental US, Ebola virus of Africa and SARS Epidemic in Asia.
Pandemic is international and out of control. So once an epidemic spreads to multiple countries anda large number of peoplein different regions of the world altogether, it is considered a pandemic. However, epidemiologists classify a situation as a pandemic only once the disease is sustained in some of the newly affected regions through local transmission. Say, a sick traveler with COVID-19 who returns to the U.S. from China doesn’t make a pandemic until they start infecting family members and friends visiting him/her. Neither the CDC nor the WHO specify how many countries or how many people need to be affected in order for something to be declared a pandemic, like in the case of 1918 and 2009 Pandemics. (H1N1 Virus)
History of Past Pandemic Preparedness, Century by Century Human society has always been subject to major pandemics and has dealt with them over the millennia in various ways including denial, misinformation carriers, quarantine measures and ultimately vaccine usage.
Take the Black Death of 1346-53. Killing over 50 million people and finishing off 60% of Europe’s entire population, it was a pandemic of bubonic plague. The disease was caused by the bacterium Yersinia pestis that circulated among wild rodents which lived in a plague reservoir or focus area in insane numbers. Transmitted from these rats to humans via bites of infected fleas, it is thought to have ended because of quarantine and personal hygiene adopted by all the survivors along with the practice of cremations rather than burials.
Finally came the Spanish Flu of 1918-1919. The cause of 50 million deaths globally, the spread of the malady is linked to the trans-Atlantic deployments of American forces in the final days of World War I, and to the victorious return home of Allied forces after November 1918. If enough awareness had surfaced regarding the preparedness measures to be taken, more people wouldn’t have died due to the flu rather than the World War I’s battlefield itself. A strict maritime quarantine was imposed after the authorities could not give a uniform response.
The 1817–1824Cholera pandemic started in India’s Ganges delta and was caused by a bacterium called Vibrio Cholerae that survived in warm and salty water. It wasn’t known outside northeast India, but the British Empire, conquering North India, opened up trade routes and the railways spread it rapidly when it got to Europe, killing millions of people with the exact number of figures remain unknown till date. Scientists believe the transmission stopped all of a sudden due to cold weather conditions.
So while cholera has largely been eradicated in developed countries now, it’s still a persistent killer in third-world countries lacking adequate sewage treatment and access to clean drinking water.
How Bad is COVID-19? With total Novel Coronavirus death count reaching 14,927 on March 22, it still pales in comparison to other pandemics throughout recorded human history. With the world-wide lockdowns, the course of an entire generation can either be changed or this time could go down as yet another battle won in the human survival timeline.
On the fact forefront, fatality rates give a fair enough idea of how many people have actually been infected and how many have died. However people likely to have mild infections haven’t been counted by researchers, so there is a possibility of a fudged data being represented as of now. Preliminary datasuggest roughly 2% of people who tested positive for the virus have died. Yet times have changed in terms of availability of modern sanitation techniques, advanced research methodologies in medicine and social media tools for instant awareness. After all, 3 and a half months after it started creating havoc, the talks of vaccine trials for COVID-19 gives a rather promising outlook to us global patriots.
If the virologists work ethically, government issues public measures of containment proactively in time and the citizens believe in taking each and every action of theirs seriously, it would help in controlling the ongoing pandemic and normalising things in our day to day life once again.
A virus is a biological agent that reproduces inside the cells of living hosts. When infected by a virus, a host cell is forced to quickly produce thousands of identical copies of the original virus. Unlike most living things, viruses do not have cells that divide; new viruses are assembled in the infected host cell. But unlike still simpler infectious agents like prions, viruses contain genes, which gives them the ability to mutate and evolve. Over 4,800 species of viruses have been discovered. The origins of viruses are unclear: some may have evolved from plasmids i.e pieces of DNA that can move between cells while others may have evolved from bacteria. A virus consists of two or three parts: genes, made from either DNA or RNA, long molecules that carry genetic information and a protein coat that protects the genes. More Info
RNA v/s DNA – Ribonucleic acid (RNA) is a polymeric molecule essential in various biological roles in coding, decoding, regulation and expression of genes. DNA or deoxyribonucleic acid is a long molecule that contains our unique genetic code. Both RNA and DNA are nucleic acids, and, along with lipids, proteins and carbohydrates, constitute the four major macromolecules essential for all known forms of life. Like DNA, RNA is assembled as a chain of nucleotides, but unlike DNA, RNA is found in nature as a single strand folded onto itself, rather than a paired double strand. Cellular organisms use messenger RNA (mRNA) to convey genetic information (using the nitrogenous bases of guanine, uracil, adenine, and cytosine, denoted by the letters G, U, A, and C) that directs synthesis of specific proteins. Many viruses encode their genetic information using an RNA genome. More Info
A vaccine is a biological preparation that provides active acquired immunity to a particular infectious disease. It typically contains an agent that resembles a disease-causing microorganism and is often made from weakened or killed forms of the microbe, its toxins, or one of its surface proteins. The agent stimulates the body’s immune system to recognize the agent as a threat, destroy it, and to further recognize and destroy any of the microorganisms associated with that agent that it may encounter in the future. Vaccines can be prophylactic, to prevent or ameliorate the effects of a future infection by a natural or wild pathogen, or therapeutic like the vaccines against cancer, which are being investigated. More Info