Corona-virus pandemic spreads through a novel microorganism that causes respiratory illness in hosts. This is the major health problem faced by public around the world. That’s why it is indicated as global pandemic.
Corona virus is member of subfamily Orthocoronavirinae, family coronaviridae and order Nidovirales. Corona virus usually causes respiratory and gastrointestinal infections. The recent outbreak is due to unique ß-corona virus (COVID-19). The virus genome is single stranded RNA positive sense.
Various studies have been carried out to find the origin of this virus, phylogenetic analysis have also been performed and it revealed that this virus is from bat origin. Bats serve as reservoir hosts for this virus. This is virus is 82% similar to human corona virus (SARS-CoV) and 50% to MERS-CoV. Studies have revealed that there was transmission of MERS-CoV from bats to camels. There are various theories regarding current corona virus pandemic.
Corona viruses are RNA viruses and have crown like appearance when observed under electron microscope. Corona word originated from a Latin word coronum means crown like. Its crown like appearance is due to presence of surface glycoproteins.
This virus can be classified in four genera. They are α-coronavirus, ß-coronavirus, Deltacoronavirus and γ-coronavirus. The ß-coronavirus is further divided into five lineages. The phylogenetic studies have revealed that the α-coronavirus and ß-coronavirus are transmitted by bats and rodents.
Coronaviridae is a large family and the members of this family causes respiratory, GIT, hepatic and neurological disorders. There are about seven coronaviruses that can infect human beings.
There are different coronaviruses here that can infect humans includes HCoV-OC43, HCoV-HKU1, HCoV-229E, and HCoV-NL63, these all are under umbrella of α-coronaviruses. These viruses lead to upper respiratory infections and the disease is self-limiting.
Epidemiology and Clinical Picture
During the corona virus pandemic, the immuno-compromised and elder people are more prone to these infections. There are other coronaviruses that can cause illness in humans include SARS-CoV, SARS-CoV-2, and MERS-CoV. These viruses can cause respiratory or other systemic ailments. These morality rates are also variable. These are member of ß-coronaviruses.
It was thought that the recent outbreak in Wuhan was due to sea food consumption. It was the major reason for human infection. Later, there were cases that were not linked with this mechanism. It was revealed through various studies that it can be transmitted from one individual to another individual so, the people with symptoms of coronavirus are major source of infection transmission.
There are various other respiratory pathogens rhinovirus, the transmission is can occur through respiratory droplets and that can be through coughing and sneezing. Aerosol transmission has also been observed in case of exposure to elevated aerosol concentrations in closed facilities.
The transmission, in fact, is primarily to family members, healthcare professionals (doctors, nurses, other hospital staff and health workers), and people with close contact with to infected individual.
Pathophysiology and Molecular studies of Coronavirus
Pathophysiology of the agent is kind of unique, In Coronaviruses, the genomic structure is positive sense single stranded RNA of approximately 30 kilobytes in length and these are largest known RNA viruses and with a 5′-cap structure and 3′-poly-A tail. Starting from the viral RNA, the synthesis of polyprotein in the host is understood.
The transcription occurs through the replication & transcription complex that is structured in double-membrane vesicles and via the synthesis of sub-genomic RNA sequences.
The virulence of virus is due to nonstructural and structural proteins the nonstructural proteins are able to block the host immune response that’s why there is rapid damage to host system. The structural proteins are involved in assembly and release mechanisms.
The virus is still under study and scientists are working on its different structural domains for better understanding and development of treatment. It has also been observed that the virus initiates excessive immune reaction in host and that is known as cytokine storm. This results in excessive tissue damage.
The agonist for this cytokine storm is Interlukin-6 that is responsible for activation of various lymphocytes. It also helps in promotion of various other immune cells like involved in differentiation of B lymphocytes. It also helps in release of various acute phase proteins that are responsible for thermoregulation.
Histological studies and clinical observations
There are various histopathological studies that have been conducted to understand the virus pathology. The lungs were examined histologically and there were edema and excessive tissue damage. The lungs were filled proteinaceous exudate. Fibrin like material has also been observed. These implications ultimately lead to difficult breathing and pulmonary arrest.
The symptoms for COVID-19 infection are fever, coughing, soreness in throat, nasal congestion, headache, malaise, pain in muscles and generalized illness. The multiple organ failure due to sepsis has also been observed in this infection.
To date, there is no treatment for this mysterious infection. There are no specific drugs or vaccines available for its cure. Symptomatic treatment has been performed in all countries and patients are treated with oxygen supply through ventilators. The infection can be differentiated with other viral infections like Adenoviruses, Influenza, Parainfluenza, Human metapneumovirus, Respiratory syncytial virus and common cold caused by Rhino viruses.
Conclusion and Recommendations
- Avoid contact with the infected individuals
- Frequent washing of hands after contact with people or environment
- Avoid contact with domestic or wild animals
- Social distancing is really important
- Strict hygienic measures should be adopted to avoid sickness
- Avoidance of contact by already diseased people with other infected people or environment
These measures should be adopted to avoid getting infected by this notorious pathogen. The governments are doing their best to combat this pathogen. They should be supported and encouraged. The people should listen to their superiors and governments. These are difficult times and will pass. Life is precious. So, stay home and stay safe.
This article is jointly written by Hammad Ur Rehman Bajwa, Muhammad Kasib Khan, Asad Ur Rehman Bajwa, Muhammad Rashid Khalid Bajwa, Ahsan Adeel and Nauman Iftikhar