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COVID-19 - An overview of the virus family and its impact

Coronaviruses are a group of viruses related by RNA. All these viruses cause diseases in mammals and birds. All of these Coronaviruses have a zoonotic origin. Most of these viruses cause respiratory infections in human beings - lethal infections such as Middle East Respiratory Syndrome (MERS), Severe Acute Respiratory Syndrome (SARS) and Corona Virus Infection Disease (COVID-19). Covid-19 is the latest version of Corona Virus that played havoc in the entire world. Any specific drug or vaccine is yet to be developed to control this new disease. Covid-19 has turned in to an epidemic in China and became a pandemic by spreading to most countries of the world. This virus was first reported from Wuhan city of Hubei province of China. This virus was not known to scientists before its detection in Wuhan city of China. Major symptoms of Covid-19 infection are fever, dry cough, muscle pain, nasal congestion, sore throat, tiredness, conjunctivitis, loss of taste and loss of smell. The symptoms looked mild at the initial stage of infection. More than 85% of patients recovered after treatment. But some patients faced difficulty in breathing and became serious. Most of the serious cases were kept in ICU with oxygen supply and even with ventilators. People with high blood pressure, high blood sugar level, heart problem, kidney problem and cancer faced more risks from Covid-19 infection. This disease spreads through human contacts, contact with infected droplets and closeness to patients without any proper protective gears. This virus can survive on the wet surface, aerosols and live animals. Social distancing, quarantine of patients, isolation of contact persons, regular sanitization, use of masks and treatment of patients in isolated hospitals can check the spread of COVID-19 infections. Lockdown and complete shutdown of cities, states and even countries are used to check the spread of this virus. Most countries found it difficult to check the spread of these viral infections. Climatic conditions are no bar to spread of this virus. Old, morbid and weak patients succumbed to this infection in most countries. But people with strong will power and high immunity recovered from Corona infections.

Coronavirus is a large spherical shaped body with surface spikes. The virus is changeable in shape and size. The viral envelop consists of a lipid bilayer. The virus has a membrane (M), envelope (E) and spikes (S). Covid-19 is an enveloped virus with a single-stranded RNA genome. The genome has a nucleocapsid of helical symmetry. The genome size ranges from 26 to 32 Kilobases. Covid-19 is the largest among all RNA viruses. Club shaped spikes are projected from the surface of Coronavirus. These spikes give a shape of the solar corona. So the name was derived as Corona Virus. The spikes are composed of proteins on the spherical surface of the virus. The RNA polymerase replicates, and the virus multiplies many times. Coronaviruses are capable of genetic recombination. It happens when at least two viral genomes are found in one infected cell.

Coronaviruses belong to family Coronaviridae with Sub family Ortho coronavirinae. These have four genera as Alpha Corona virus, Beta Corona virus, Gamma Corona virus and Delta Corona virus. Alpha Corona virus affected human beings. Many Coronaviruses have origin in bats. SARS -Cov infected human beings from bats. It was first detected in 2003 in China. MERS-Cov infection affected human beings from camels and bats. It was detected in 2012. Covid-19 was detected in December 2019 from wet market of Wuhan city in China. Some Coronaviruses were first detected in 1930s. Arthur Schalk and M.C. Hawn described about such viruses causing respiratory infections in in chickens in 1931. In 1940s two more Coronaviruses were detected as Mouse Hepatitis Virus (MHV) and Transmissible Gastro Enteritis Virus (TGEV). Human infections by Coronaviruses were detected in 1960s. Covid-19 virus is detected from Rofous Horse Shoe Bats of China. Some viruses like Rabies virus, Marbug virus, Nipah virus and Hendra virus are detected from bats. Ebola virus is believed to be transmitted to primates from some bat species of Africa. SARS and MERS are also linked to bats which cause serious infections in human beings. Testing of Corona virus infections is done through Polymerase Chain Reaction Test (PCR Test).

Many countries are trying to develop drugs and vaccine to fight Covid-19 infection. One drug named Remdesivir is developed and certified to be used for treating Covid-19 patients. It is showing a good result. Hydroxy Chloroquine Sulphate tablets are used to reduce the level of infection in a patient. Plazma therapy is also used to treat serious patients infected with Covid-19. There are many patients without any outward symptoms. Covid-19 is still a biotic puzzle for doctors and bio scientists in the world.