Severe Acute Respiratory Syndrome Coronavirus 2019

Key Features

Essentials of Diagnosis

• Asymptomatic in approximately 20–35% of adults and most children

• When symptomatic, adults often have upper respiratory tract illness with fever and cough

• Advanced pulmonary complications (pneumonia, acute respiratory distress syndrome [ARDS]) occur with fulminant disease

• Mortality of 1–21% (varied by geographic area and strain)

• High predilection for the elderly, the immunocompromised, those with chronic diseases, those living in crowded conditions

General Considerations

• A case tally and other current information are available through

  • The WHO website (https://www.who.int/emergencies/diseases/novel-coronavirus-2019)

  • The Johns Hopkins University Coronavirus Resource Center website (https://coronavirus.jhu.edu/map.html)

• Incubation period: ranges from 2 to 24 days with an average of about 5 days

• Transmission

  • Principal mode: respiratory droplets

  • R₀ is the basic reproductive number signifying the number of contacts infected by one infectious individual

    • Calculations of R₀ for SARS-CoV-2 have varied

    • However, the true R₀ likely lies somewhere between 2 and 3

  • Reported rates of transmission are 5% for close contacts and 10–40% for household contacts

  • Presymptomatic spread accounts for many cases, and the viral load for SARS-CoV-2 is highest the day before symptoms develop

  • In utero transmission is reported but appears to be rare

  • In general, the virus does not appear to be transmitted in breastmilk

• Risk factors

  • Age

  • Chronic conditions (diabetes; obesity; hypertension; chronic heart, lung, or kidney disease; and prior stroke)

  • Cigarette smoking

  • Symptomatic disease appears to develop in men more often than in women

Clinical Findings

Symptoms and Signs

• Most infected individuals are asymptomatic

• Adults can manifest a wide range of symptoms from mild to severe illness that typically begin 2–14 days after exposure

• Symptomatic patients may have cough, fever, chills/rigors, or myalgias

• The presence of dyspnea is variable, but it is common in severe infection

• No one symptom should be used as a discriminant for disease

• Less frequent symptoms include rhinitis, pharyngitis, abdominal symptoms such as nausea and diarrhea, headaches, anosmia and cacosmia, and ageusia and cacogeusia

• It appears that 15–20% of adults require hospitalization and 3–5% require critical care

Differential Diagnosis

• Upper respiratory infection

• Seasonal influenza infection

• Secondary hemophagocytic lymphohistiocytosis

Diagnosis

Laboratory Findings

• Neutrophilia, absolute lymphopenia, and an increased neutrophil to lymphocyte ratio

• Elevated liver biochemical tests and total bilirubin

• Serum markers of systemic inflammation are increased

  • Lactate dehydrogenase

  • Ferritin

  • C-reactive protein

  • Procalcitonin

  • Interleukin 6 (IL-6)

• A coagulopathy often is seen

• Elevated von Willebrand factor (VWF) antigen

• Elevated D-dimer

• Fibrinogen levels are higher than in disseminated intravascular coagulation

Imaging

• Early in the disease course,

  • Neither chest radiographs nor chest CT scans provide diagnostic utility

  • Both may be normal

    ...