COVID-19 is an infectious disease that is caused by the most recently discovered coronavirus. ‘CO’ stands for corona, ‘VI’ for virus, and ‘D’ for disease. This new disease was formally Referred to as ‘2019 novel coronavirus’ or ‘2019-n CoV.’ This new virus and disease were unknown before the outbreak that began in Wuhan a province of China in December 2019.
This coronavirus is a new virus that is linked to the same family of viruses as Severe Acute Respiratory Syndrome (SARS) and some types of common cold. In March 2020, the World Health Organization (WHO) declared the COVID-19 outbreak a pandemic. On 30 January, the WHO declared this outbreak a Public Health Emergency of International Concern (PHEIC).
WHAT IS EPIDEMIOLOGY OF VIRUSES?
Epidemiology Is basically the study of the determinants, dynamics or distribution of diseases in a population. Viral epidemiology is that branch of medical sciences that concerns with the transmission and control of virus infections in humans.
VERTICAL AND HORIZONTAL TRANSMISSION
Transmission of viruses can be vertical or horizontal, vertical means transmission from mother to child, or horizontal means transmission from person to person. Examples of vertical transmission are hepatitis B virus and ■■■ and when the baby is born, he or she has already been infected with the virus.
Epidemiology is also used to break the chain of any infection in any population during the period of outbreaks of viral diseases and when the virus has been identified, their transmission can sometimes be broken by vaccines.
In case when vaccines are not available then sanitation and disinfection can be used. Also, sometimes infected people are isolated from their community and placed in quarantine. Most viral diseases of humans and other animals have incubation periods which last from a few days to weeks.
TYPES OF VIRUSES
Viruses can be classified based on type of host, there different types, including
1. Animal viruses
These viruses infect by living with the cells of animals or humans and their genetic material is DNA or RNA. Some examples of animal viruses include influenza virus, mumps virus, rabies Virus, poliovirus, ■■■■■■ virus, etc.
2. Plant viruses
These viruses infect plants cell by invading there and genetic material is RNA. Several examples of plant virus include potato virus, tobacco mosaic virus, beet yellow virus, and Turnip yellow virus, cauliflower mosaic virus, etc.
3. Bacteriophage
Bacteriophages are those that infects bacterial cells and contain DNA. There are many types of bacteriophages like DNA virus, MV-11, RNA virus, λ phage, etc.
4. Insect virus
As the name implies these viruses infect insects and they are also called as the viral pathogen of insects. These viruses are regarded as the most powerful biocontrol agent in the landscape of modern agriculture. For example: Ascovirus virions and Entomopox virus.
WHAT IS CORONA VIRUS?
Coronaviruses are a large family of viruses that may cause illness in both animals and Humans. The name “coronavirus” is derived from Latin word “ corona” which means “crown” Or “wreath”. Coronavirus has crown like spikes on its surface, that’s why it is called as Coronavirus.
This name was discover by June Almeida and David Tyrrell who first observed and studied the human coronaviruses and this word was first used in print in 1968 by an informal group of virologists in the journal name “ Nature” to designate the new family of Viruses. In humans, several coronaviruses are known to cause respiratory infections that range from The common cold to more severe diseases such as Middle East Respiratory Syndrome (MERS) And Severe Acute Respiratory Syndrome (SARS)4.
The new corona virus that cause COVID-19 has been called severe acute respiratory syndrome coronavirus 2 (Sars-CoV-2) by the World Health Organisation.
HISTORY
Coronavirus disease was first discovered in 1931 and in 1965, the first coronavirus (HCoV-229E) was isolated from humans. Until late 2002 when there was an outbreak of severe acute Respiratory syndrome, only two human coronaviruses (HCoV) were known.
First is HCoV-229E and HCoV-OC43. Once the SARS coronavirus (SARS-CoV) had been identified, two other Human coronaviruses were also identified. So, three groups of coronaviruses exist:
Group 1 (HCoV-229E or HCoV-NL63), group 2 (HCoV-OC43 or HCoV-HKU1), group 3 (no Human CoVs yet).
STRUCTURE
Like other coronaviruses, SARS-CoV-2,6 particles are spherical and have proteins known as Spikes projecting from their surface. These spikes bind onto human cells, after that they undergo a structural change that allows the viral membrane to fuse with the cell membrane.
Then viral genes may enter the host cell to be copied thus producing more viruses. Recent Studies show that, SARS-CoV-2 spikes attach to receptors on the human cell surface called Angiotensin-converting enzyme 2 (ACE2).
They are enveloped7 with a single-stranded RNA genome and the genome size ranges from approximately 26 to 32 kilo bases which is one of the largest among RNA viruses.The average diameter of the coronavirus particles is around 125 nm. While the diameter of the envelope is 85 nm and the spikes are 20 nm long.
SYMPTOMS OF COVID-19
COVID-19 symptoms may range from mild to severe. It takes 2-14 days after exposure for Symptoms to develop in humans. Most common symptoms of COVID-198 are fever, dry cough, and tiredness while other Symptoms that are less common include aches and pains, headache, sore throat, diarrhoea, loss of taste or smell or a rash on skin or discoloration of fingers or toes etc.
According to the study of nearly 56,0009 Laboratory confirmed cases cited in the WHO report. The most common symptom that are experienced by 88% of confirmed patients is a fever . While other most common symptoms according to that study are follows.
i. Dry cough (68%)
ii. Fatigue (38%)
iii. Coughing up /mucus production (33%)
iv. Shortness of breath (19%)
v. Joint or muscle pain (15%)
vi. Sore throat (14%)
vii. Headache (14%)
viii. Chills (11%)
ix. Nausea or vomiting (5%)
x. Nasal congestion (5%)
xi. Diarrhoea (3%)
xii. Coughing up blood (1%)
CORONAVIRUS RISK FACTORS
It seems that the people of all ages are susceptible to this virus10 but those who are at most
Risk of this are, the elder people and those with health issues (like high blood pressure, heart disease, lung Disease, cancer and diabetes) according to the World Health Organization (WHO).The U.S. Centres for Disease Control and Prevention (CDC) further clarifies by stating this:
i. Adults 65 and above or people with serious lung or heart disease.
ii. Those who are immunocompromised (especially those with ■■■)
iii. People with Obesity and liver disease.
iv. People with chronic kidney disease and undergoing dialysis.
According to most recent global numbers11 (27 March 2020) about 14.8% of people over 80 years old are infected with this and died from it as compared to 0.4% in none in children under 9 years and this situation across countries is rapidly changing and will continue to change as this disease shifts.
CORONAVIRUS TRANSMISSION
It can directly from person to person or indirectly through surfaces and sneezing, coughing.
How Does Covid-19 Spread?
Coronaviruses are zoonotic12 which means that they first develop in animals than humans and pass from animals to humans when a person come into close contact with an animal that carries the virus and in human, COVID-1913 mainly spread from others who have this virus.
The disease transmits primarily from person to person through small droplets from the nose or mouth or expelled when a person with this virus coughs, sneezes, or speaks. These droplets are relatively heavy so do not travel far and rapidly sink to the ground. So, people can catch this when they breathe in these infected droplets.
So, it is important to stay at least 1 meter away from others. These droplets are also present on objects and surfaces around the infected person such as tables, doorknobs and handrails. People can also infect when they touch these objects or surfaces, then touching their eyes, nose or mouth.
SPREAD OF COVID-19 IN WORLD
On 31 December 2019 14 the health authorities in China reported to the World Health Organisation (WHO) many viral pneumonia cases of unknown cause in its city Wuhan. So, an investigation was launched in early January 2020.
Health officials are still tracing the exact origin of this new coronavirus but early hypotheses thought that it may be linked to a seafood market in Wuhan, China. Some people who went to the market developed viral illness caused by this new coronavirus.
A study that came out on 25 January 2020 noted that the individual with the first reported case who had no link with seafood market became ill on 1 December 2019. Further Investigations are ongoing as to show how this virus originated and spread.
In January 31, 2020, 16there were 11,374 confirmed cases of COVID-19 and 252 deaths and 98.7% of confirmed cases were in mainland China. In April 22, 2020 there were 2,603,147 confirmed global cases of COVID-19. And United States continues to have the highest number of confirmed cases with 834,858.
While the total confirmed deaths from COVID-19 worldwide is 45,894. In February 5, 2020 there were 27,669 confirmed cases of this outbreak with 563 deaths. In March 6, 2020, there were 100,685 confirmed cases and 3,411 Deaths. 55,753 cases were recovered.
Outside china, there were 96 countries and special Administrative regions that have at least one confirmed case of COVID-19.
In April 22, 2020, there were 2,603,147 global cases of COVID-19 and United States continues to have the highest cases.
Total deaths from this worldwide was 45,894 and total of 185 countries’ or regions were now reporting at least one confirmed case of COVID-19. On May 9, 2020, 17 this virus has infected more than 3,947,799 people and 275,130 deaths From this virus. There is no vaccine available yet for COVID-19 so the only effective way to protect yourself as:
i. Clean your hands properly for 2 minutes.
ii. Try to avoid touching your eyes, mouth and nose.
iii. Make sure that you cover your cough with the bend of elbow or tissue.
iv. Try to maintain a distance of at least 1 metre from others.
CONCLUSION
The coronavirus disease is a pandemic and spread all over the world and people of all ages may susceptible to this. The only way to stop the spread of COVID-19 is to take precautionary measures like wash your hands, use sanitizer, maintain social distance etc. And if anyone have symptoms of COVID-19 he or she may have to consult the doctor and isolate himself to protect their love ones from this contagious disease.