Characteristics and Causes of COVID-19

COVID-19 is a highly transmittable viral disease.
It causes respiratory infections in humans.
It can be fatal.
COVID-19 is classified as an ecological hazard.
An ecological hazard is defined as a biological or chemical hazard that has the potential to impact adversely on the wellbeing of people or the environment.

Coronaviruses are a large family of viruses common in humans and animals, including bats, cows, cats, and camels.
These viruses cause upper-respiratory infections ranging from a common cold to more serious illness.

Officially named by the World Health Organisation in February 2020.
'CO' stands for 'corona,' 'VI' for 'virus,' 'D' for 'disease,' and '19' for 2019, the year it was discovered.

A virus is an infectious agent that can only multiply in the living cells of an organism.
COVID-19 is classified as an ecological hazard because it is a virus.

Common symptoms include:
- A fever
- Cough
- Fatigue
- Shortness of breath
Other symptoms include:
- A sore throat
- Headache
- Muscle or body aches
- Diarrhoea
- Loss of taste and smell
Serious symptoms include:
- Difficulty breathing (e.g., pneumonia)
- Chest pain
- Loss of speech or movement
Severe symptoms include:
- Severe pneumonia
- Organ failure, leading to possible death

Asymptomatic means not developing or displaying any symptoms.
Most people infected with SARS-CoV-2 are symptomatic, but some are asymptomatic.
Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is the virus that causes COVID-19 disease.
Once the viral load is high enough, it causes the disease.

It is believed that the initial host animal of SARS-CoV-2 is bats due to the genetic similarities of SARS-CoV-2 to the previous SARS-CoV that originated from bat populations of the genus Rhinolophus.
The World Health Organisation suggested the transmission of SARS-CoV-2 through another animal species.

Zoonotic ecological hazard happens when a virus 'spills over' from a host species to infect humans, either directly or through an intermediate host (different species likely to be handled by humans).

Due to human activities that disrupt natural ecosystems such as deforestation, which destroys wildlife habitats and forces animals closer to human settlements.
Wildlife trade and consumption increases direct contact with potentially infected animals.
Intensive agriculture, where dense livestock populations can act as intermediate hosts.

Primarily spread through airborne droplets of the virus within saliva or discharge from the nose when an infected person coughs or sneezes.
The virus can also be spread from a person touching objects or surfaces contaminated with droplets of the virus and then touching their face, eyes, nose, or mouth.

Once the SARS-CoV-2 virus enters the body, it invades the cells along the respiratory tract and hijacks the call, instructing it to make copies of the virus.
These virus copies leave the 'host' call, spreading and invading new calls to repeat this process.
This period is known as the incubation period, the time between initial infection, the establishment of the virus, and the first symptoms of the disease showing.
On average, the incubation period takes 5.6 days or even as long as 14 days.

Infected Person -> Coughs, sneezes, or talks -> Releases respiratory droplets -> Droplets land on surfaces OR Droplets are inhaled
Droplets land:
- Another person touches contaminated surface -> Touches face: eyes, nose, or mouth -> Virus enters body and a new person becomes infected
Droplets Inhaled:
- Another person inhales droplets -> Virus enters body and a new person becomes infected