Although COVID-19 presents primarily as a lower respiratory tract infection transmitted via air droplets, increasing data suggest multiorgan involvement in patients that are infected. This systemic involvement is postulated to be mainly related to the SARS-CoV-2 virus binding on angiotensin-converting enzyme 2 (ACE2) receptors located on several different human cells. Lung involvement is the most common serious manifestation of the disease, ranging from asymptomatic disease or mild pneumonia, to severe disease associated with hypoxia, critical disease associated with shock, respiratory failure and multiorgan failure or death. Among patients with COVID-19, underlying cardiovascular comorbidities including hypertension, diabetes and especially cardiovascular disease, has been associated with adverse outcomes, whereas the emergence of cardiovascular complications, including myocardial injury, heart failure and arrhythmias, has been associated with poor survival. Gastrointestinal symptoms are also frequently encountered and may persist for several days. Haematological complications are frequent as well and have been associated with poor prognosis. Furthermore, recent studies have reported that over a third of infected patients develop a broad spectrum of neurological symptoms affecting the central nervous system, peripheral nervous system and skeletal muscles, including anosmia and ageusia. The skin, the kidneys, the liver, the endocrine organs and the eyes are also affected by the systemic COVID-19 disease. Herein, we provide a comprehensive overview of the organ-specific systemic manifestations of COVID-19.
COVID-19 probably represents the greatest pandemic event in modern human history. The disease presents with a broad spectrum of clinical signs and symptoms with involvement of vital organs such as the lungs, the heart, the gastrointestinal tract, the liver, the central nervous system, the blood and the kidneys. Commonly, multisystemic involvement is associated with severe disease and might predict worse clinical outcomes and increased mortality. The main mechanism described is the high binding affinity of the virus with the ACE2 receptors that are widely expressed in most human cells. The exact role of ACE2 receptors in COVID-19 pathophysiology is part of ongoing investigations. Furthermore, the role of the infection on dysregulation of ACE2 receptors expression, whether treatment with ARBs and ACEs modifies this expression and whether patients with comorbidities and chronic illnesses have higher expression of ACE2 receptors and are therefore more vulnerable to infection are also questions that need to be addressed in the near future. The SARS-CoV-2 virus enters the body through the respiratory tract and infects the epithelial cells of the trachea, bronchi, bronchioles and finally the lungs. It then infects the host, and infiltrating and circulating immune cells transfer the virus to other organs. Moreover, the blood-borne SARS virus infects other organs as well. Immunosuppressed patients, including the elderly and patients with chronic disease, experience more severe disease with increased mortality rates. The extent of immune cell damage, represented by the lymphocyte count, is considered a strong predictor of outcome and reflects the immune status of the patient. This multisystemic disease is associated with high mortality rates; mechanical ventilation, extracorporeal membrane oxygenation, antivirals and plasma infusion are currently being applied to reduce mortality, but none is a curative intervention. Although systematic treatments are currently at the forefront of clinical research, organ-specific treatment strategies should be also evaluated in order to optimize the management of patients with severe organ dysfunction. Several clinical trials are ongoing to evaluate the safety and effectiveness of both novel and pre-existing antiviral drugs, but the ability to vaccinate people will require unfortunately more time. The unpredictable trajectory of this unexpected pandemic requires careful surveillance, customized health strategies, control measures implementation, novel legal and bioethical framework, and specific medical guidelines to guide our decisions.
Reference & source information: https://link.springer.com/
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