Coronavirus: Transmission, symptoms and treatment

Coronavirus is a type of virus that causes respiratory infections which are typically mild but, in rare cases, can be lethal. Coronavirus can in some cases lead to organ failure, thus making it very deadly. There are no vaccines or antiviral drugs that are approved for prevention or treatment. Coronaviruses are enveloped viruses with a positive-sense single-stranded RNA genome and with a nucleocapsid of helical symmetry. 

Coronaviruses were discovered in the 1960s; the earliest ones discovered were infectious bronchitis virus in chickens and two viruses from the nasal cavities of human patients with the common cold that were subsequently named human coronavirus 229E and human coronavirus OC43. It is believed that there exist many coronaviruses that infect animals, only a few have so far been transmitted to human beings through food. 

Types of coronaviruses

There are seven strains of human coronaviruses:

1. Human coronavirus 229E (HCoV-229E): is a single-stranded, positive-sense, RNA virus species in the genus Alphacoronavirus of the subfamily Coronavirinae, in the family Coronaviridae, of the order Nidovirales. Along with Human coronavirus OC43, it is among the viruses responsible for the common cold.
2. Human coronavirus OC43 (HCoV-OC43): is a subspecies of enveloped, positive-stranded RNA virus in the species Betacoronavirus 1 (genus Betacoronavirus, subfamily Coronavirinae, family Coronaviridae, order Nidovirales).
3. Severe acute respiratory syndrome-related coronavirus (SARS-CoV, SARSr-CoV): is the virus that causes severe acute respiratory syndrome (SARS).
4. Human coronavirus NL63 or HCoV-NL63: is a species of Alphacoronavirus found primarily in young children, the elderly, and immunocompromised patients with acute respiratory illness.
5. Human coronavirus HKU1 (HCoV-HKU1): is a positive-sense, single-stranded RNA virus with the HE gene, which distinguishes it as a group 2, or Betacoronavirus.
6. Middle East respiratory syndrome-related coronavirus (MERS-CoV), or EMC/2012 (HCoV-EMC/2012): is a novel positive-sense, single-stranded RNA virus of the genus Betacoronavirus.
7. COVID-19, or Wuhan coronavirus, or 2019 novel coronavirus (2019-nCoV): is a contagious virus that causes respiratory infection and has shown evidence of human-to-human transmission, first identified by authorities in Wuhan, Hubei, China.

COVID-19 (Wuhan coronavirus)

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), formerly known as the 2019 novel coronavirus (2019-nCoV), is a positive-sense single-stranded RNA virus. It is contagious among humans and is the cause of coronavirus disease 2019 (COVID-19). There is no vaccine. On 31 December 2019, a novel strain of coronavirus, officially designated as 2019-nCoV by the World Health Organization, was reported in Wuhan, China, as responsible for the 2019–20 Wuhan coronavirus outbreak. 

The Wuhan strain was identified as a new strain of Betacoronavirus from group 2B with an ~70% genetic similarity to the SARS-CoV. SARS-CoV-2 has strong genetic similarity to known bat coronaviruses, making a zoonotic origin in bats likely, although an intermediate reservoir such as a pangolin is thought to be involved. 

From a taxonomic perspective SARS-CoV-2 is classified as a strain of the species severe acute respiratory syndrome-related coronavirus. SARS-CoV-2 is the cause of the ongoing 2019-20 coronavirus outbreak, a Public Health Emergency of International Concern that originated in Wuhan, China. Because of this connection, the virus is sometimes referred to informally, among other nicknames, as the “Wuhan coronavirus”.

Transmission of coronavirus

The virus is generally thought to be hosted by bats or snakes. The viruses are transmitted between animals and people and then evolve into strains not previously known to human beings. Coronavirus is spread from one person to another through droplets when a sick person coughs or sneezes, close personal contact such as touching or shaking hands, touching contaminated objects/surfaces like door handles or railings, and in some rare cases through fecal contamination. The virus enters the body through the eyes, nose or mouth, it then finds a host cell in the respiratory system, the ‘host cell’ then bursts and infects others nearby cells.

Symptoms of coronavirus

Coronavirus is believed to cause a significant percentage of all common colds in human adults and children. Older people, and those with underlying medical problems like high blood pressure, heart problems or diabetes, are more likely to develop serious illness. People may be sick with the virus for 1 to 14 days before developing symptoms. Some people become infected but don’t develop any symptoms and don’t feel unwell. Some of the symptoms of coronavirus include:

1. Fever.
2. Runny nose.
3. Severe coughs/dry cough.
4. Breathing difficulties/breath shortness.
5. Sore throat/throat swollen adenoids.
6. Severe acute respiratory syndrome.
7. Kidney failure.
8. Tiredness.
9. Aches and pains.
10. Nasal congestion.
11. Diarrhea.
12. Bronchitis, either direct viral bronchitis or a secondary bacterial bronchitis.
13. Pneumonia, either direct viral pneumonia or a secondary bacterial pneumonia.

Diagnosis of coronavirus

Wuhan coronavirus is tested using what is referred to as real-time polymerase chain reaction (RT-PCR). The technique is used to identify the viral RNA in a sample collected from a patient. The sample can be from a throat swab, cough sample or even a blood sample if the patient is very sick.

Prevention of coronavirus

Standard recommendations for the prevention of further infections include:

• Regularly and thoroughly clean your hands with an alcohol-based hand rub or wash them with soap and water. Washing your hands with soap and water or using alcohol-based hand rub kills viruses that may be on your hands.
• Maintain at least 1 meter (3 feet) distance between yourself and anyone who is coughing or sneezing. When someone coughs or sneezes they spray small liquid droplets from their nose or mouth which may contain virus. If you are too close, you can breathe in the droplets, including the COVID-19 virus if the person coughing has the disease.
• Avoid touching eyes, nose and mouth. Hands touch many surfaces and can pick up viruses. Once contaminated, hands can transfer the virus to your eyes, nose or mouth. From there, the virus can enter your body and can make you sick.
• Make sure you, and the people around you, follow good respiratory hygiene. This means covering your mouth and nose with your bent elbow or tissue when you cough or sneeze. Then dispose of the used tissue immediately. Droplets spread virus. By following good respiratory hygiene, you protect the people around you from viruses such as cold, flu and COVID-19.
• Stay home if you feel unwell. If you have a fever, cough and difficulty breathing, seek medical attention and call-in advance. Follow the directions of your local health authority. National and local authorities will have the most up to date information on the situation in your area. Calling in advance will allow your health care provider to quickly direct you to the right health facility. This will also protect you and help prevent spread of viruses and other infections.
• Keep up to date on the latest COVID-19 hotspots (cities or local areas where COVID-19 is spreading widely). If possible, avoid traveling to places, especially if you are an older person or have diabetes, heart or lung disease. You have a higher chance of catching COVID-19 in one of these areas.

How coronavirus kills

Most victims of the coronavirus die from complications including pneumonia and swelling in the lungs. Severe pneumonia can kill people by causing them to ‘drown’ in the fluid flooding their lungs. The virus also causes swelling in the respiratory system, which can make it hard for the lungs to pass oxygen into the bloodstream leading to organ failure and eventually death.

Treatment of coronavirus

There is no specific medicine or vaccines or antiviral drugs to prevent or treat coronavirus disease (COVID-19). People may need supportive care to help them breathe. Most people (about 80%) recover from the disease without needing special treatment. If you have mild symptoms, stay at home until you’ve recovered. You can relieve your symptoms if you:

• Rest and sleep.
• Keep warm.
• Drink plenty of liquids.
• Use a room humidifier or take a hot shower to help ease a sore throat and cough.

Controlling or getting rid of coronaviruses is not an easy thing because of their genetic material. It means that instead of DNA, the viruses have RNA as their genetic material. As a result, the viruses can blend with the DNA of their hosts and then mutate rapidly. The mutation is what makes it difficult for scientists to develop medicine because the viruses continue changing their genetic structure. Antibiotics cannot be of any help since it is viral pneumonia. 

Those who get infected should, therefore, be admitted to hospitals where they can get support for their lungs and other organs as well as fluids. Here, an individual’s immune system comes into play, and recovery favours those with a strong immune system. A significant number of those who have succumbed to the coronavirus are people who were already in poor health.