COVID-19 PATHOGENESIS

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A novel coronavirus caused a series of acute respiratory diseases in Wuhan, China. The disease caused by this virus was termed COVID-19 later. The coronavirus disease 2019 (COVID-19) has spread at unprecedented speed all over the world. The first outbreak of COVID-19 was in Wuhan, China, where Chinese anesthesiologists had to encounter increasing numbers of infected patients since December 2019. The first case of COVID-19 was reported in early December 2019 in and it was called as pneumonia. Approximately 15 to 20% of patients with COVID-19 required some form of oxygen therapy and ventilation support.This virus transmits between humans and has led to pandemic worldwide. The phylogenetic analysis revealed that COVID-19 is a zoonotic virus.

Corona viruses are enveloped, positive-sense and single-stranded RNA viruses of ~30 kb. They infect a wide variety of host species. They are largely divided into four genera; α, β, γ, and δ based on their genomic structure. α and β corona viruses infect only mammals. Human corona viruses such as 229E and NL63 are responsible for common cold and croup and belong to α corona virus. In contrast, SARS-CoV, Middle East respiratory syndrome corona virus (MERS-CoV) and SARS-CoV-2 are classified to β corona viruses.

The symptom of patients infected with SARS-CoV-2 ranges from minimal symptoms to severe respiratory failure with multiple organ failure.

The symptoms of COVID-19 infection appear after an incubation period of approximately 5.2 days. The period from the onset of COVID-19 symptoms to death ranged from 6 to 41 days with a median of 14 days.

The most common symptoms at onset of COVID-19 illness are fever, cough, and fatigue, while other symptoms include sputum production, headache, haemoptysis, diarrhoea, dyspnoea, and lymphopenia. Clinical features revealed by a chest CT scan presented as pneumonia, however, there were abnormal features such as RNAaemia, acute respiratory distress syndrome, acute cardiac injury, and incidence of grand-glass opacities that led to death.

Patients infected with COVID-19 showed higher leukocyte numbers, abnormal respiratory findings, and increased levels of plasma pro-inflammatory cytokines. One of the COVID-19 case reports showed a patient at 5 days of fever presented with a cough, coarse breathing sounds of both lungs, and a body temperature of 39.0 °C. The patient's sputum showed positive real-time polymerase chain reaction results that confirmed COVID-19 infection. The laboratory studies showed leucopenia with leukocyte counts of 2.91 × 10^9 cells/L of which 70.0% were neutrophils. Additionally, a value of 16.16 mg/L of blood C-reactive protein was noted which is above the normal range (0–10 mg/L). High erythrocyte sedimentation rate and D-dimer were also observed.

Journal of Clinical & Molecular Pathology is a multidisciplinary peer-reviewed journal that publishes manuscripts on clinical pathology, anatomic pathology, and application of molecular biology would be happy to receive and publish article on the pathogenesis of novel corona virus.