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COVID-19 (Reading & Sharing)

Figure is Ultrastructural morphology of SARS-Co V-2

Pathophysiology of COVID-19 Infection:

SARS-CoV-2 is a single-stranded RNA virus that belongs to the Orthocoronavirinae subfamily. It consists of 16 nonstructural proteins and 4 structural components: spike glycoprotein (S), envelope protein, membrane glycoprotein, and nucleocapsid phosphoprotein (N). However, the viral types can differ across infections at different times and at least 116 mutations have been identified. The S proteins are chritical for binding to the host cell surface receptors, whereas the N proteins are essential for viral survival and expansion.

SARS-CoV-2 is transmitted through exposure to respiratory droplets from a person with COVID-19 that are inhaled or deposited on the host’s mucous membranes. Respiratory droplets may be airbone or can land on surfaces and objects, which when exposed to a host cell with the entry receptor ACE2 (angiotensin-converting enzyme 2) in the presence of TMPRSS2 (transmembrane protease serine 2) interacting with its spike protein to gain entry. Upon binding to the ACE2 receptor, the SARS-CoV-2 spike protein is activated through proteolytic cleavage by TMPRSS2, inserted into the cell membrane, and fuses the viral and cellular membranes so that transfer of the viral RNA into the host cell cytoplasm can occur, followed by viral replication. In addition to varying entry routes into host cells, questions remain regarding how SARS-CoV-2 gains access into the central nervous system (CNS), referred to as neurotropism or the ability to infect nerve tissue. The nasal-olfactory nerve route, blood-nervous stem barrier breakdown, blood-nerve barrier or blood-cerebrospinal fluid barrier permeability, lymphatic drainage system of the brain, retrograde transmission from the enteric, lung, or kidney nerve routes, or macrophage/ monocyte cargo routes have all been suggested pathways by which the SARS-CoV-2 virus reaches the CNS.

For now, general precautions (masks, social distancing, and frequent handwashing) remain in place to control the virus, as COVID-19 vaccinations are taking place worldwide. Testing for COVID-19 infection remains a critcal component of the COVID-19 detection and surveillance efforts.

Symptoms reported during COVID 19 infection:

  • Cough
  • Fever
  • Anosmia (loss of smell)
  • Ageusia (loss of taste)
  • Anosmia or ageusia
  • Sore throat
  • Myalgia

Acute Phase of Illness (Days 0-10 from time of a positive resulte on a COVID-19 test) 5 Symptom Clusters:

  1. Dyspnea-anxiety (dyspnea, anxiety, tachycardia, headache, and abdominal pain)
  2. Cough-fatigue (cough, fatigue, muscle pain, dysgeusia, and nausea)
  3. Fever-headache (fever, headache, muscle pain, tachycardia, and abdominal pain)
  4. Chest pain-tachycardia (chest pain, tachycardia, anxiety, muscle pain, and insomnia)
  5. Diarrhea-abdominal pain (diarrhea, abdominal pain, fatigue, nausea, and headache)

The possibility that specific symptoms could correspond with more severe infection has been discussed with symptoms of chest pain, myalgia, and abdominal pain being suggested as precursors to severe illness.

Post-Acute COVID-19 Syndrome:

  • Fatigue
  • Brain fog
  • Headaches
  • Numbness/ tingling
  • Dysgeusia
  • Anosmia
  • Myalgias – one of the most common symptoms associated with COVID-19 infection, and it is thought to result from the inflammatory response due to viral invasion with release of cytokines such as interleukin-6 (IL-6) that are known to cause hyperalgesia.

A mechanism by which SARS-CoV-2 infection may lead to the development and maintenance of pain is through CNS activation of microglia, resulting in release of pain-related proinflammatory mediators and initiating inflammasomes.

Theory 1: Post-acute COVID-19 syndrome is caused when fregments of the virus are not cleared and continue to maintain an environment of low-grade inflammation.

Theory 2: Post-acute COVID-19 syndrome is caused by the autoimmune response in which immune cells damage the body’s organs and tissues.

Follow-up Management for individuals affected by COVID 19: Based on the patient’s disease course and symptoms, referrals may be made to pulmonary medicine, cardiology, neurology, and/or kidney specialists for disgnostic evaluation and follow-up care. Psychologists and counselors may be needed to address mental health issues and symptom management, including anxiety and sleep disturbances. Due to potential cardiac and pulmonary sequelae from COVID-19 infection, long-term surveillance and monitoring of symptoms are recommended to detect impaired function and provide treatment when indicated.

References:

Eze, B., & Starkweather, A. (2021) COVID-19 Pain and Commorbid Symptoms

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