obsolete influenza virus pneumonia

Obsolete Influenza Virus Pneumonia: A Historical Perspective

Influenza virus pneumonia was once a significant cause of morbidity and mortality, particularly during the 1957-1958 pandemic. The clinical presentation of this condition has been well-documented in medical literature.

• Acute Rapidly Progressive Pneumonia: During the 1957-1958 influenza pandemic, an acute rapidly progressive pneumonia caused by the influenza virus alone or concomitant viral and bacterial pneumonia was reported (1). This condition was characterized by a rapid onset of severe progressive shortness of breath, tachypnea, and hypoxia.
• Clinical Course: The clinical course of patients with severe viral pneumonia was marked by a rapid progression to respiratory failure, often requiring mechanical ventilation (2).
• Pulmonary Syndromes: Pulmonary syndromes associated with the 1957-1958 influenza pandemic included an acute rapidly progressive pneumonia caused by the influenza virus alone or concomitant viral and bacterial pneumonia (3).

It is essential to note that these findings are specific to the 1957-1958 influenza pandemic and may not be representative of current influenza-related pneumonia.

References:

[1] The clinical course of patients with severe viral pneumonia was marked by a rapid progression to respiratory failure, often requiring mechanical ventilation. (3) [2] Pulmonary syndromes associated with the 1957-1958 influenza pandemic included an acute rapidly progressive pneumonia caused by the influenza virus alone or concomitant viral and bacterial pneumonia. (3) [3] The first documented pandemic that clearly fits the description of influenza was in 1580. At least four more pandemics occurred between 1700 and 1900, with significant mortality rates reported during these events. (4)

Early Signs and Symptoms

The early signs and symptoms of obsolete influenza virus pneumonia are similar to those of the flu, but may worsen over several days. These include:

• Fever
• Dry cough
• Headache
• Muscle pain (myalgia)
• Weakness

These symptoms typically develop over a period of several days, with the condition getting worse within a day or two.

Complications and Advanced Symptoms

As the infection progresses, more severe symptoms may appear, including:

• Increasing cough
• Shortness of breath
• Chest pain when breathing or coughing
• Congestion or chest tightness

In some cases, complications such as pneumonia can develop, especially in older people, young children, and those with chronic lung disease.

Important Notes

It's essential to seek medical attention if you experience any of the following:

• A fever of 102 degrees Fahrenheit (38.88 degrees Celsius) or higher
• Difficulty breathing
• Chest pain when breathing or coughing

Early treatment can help prevent complications and improve outcomes.

References: [6] [13] [14]

Diagnostic Tests for Obsolete Influenza Virus Pneumonia

The diagnostic tests for influenza virus pneumonia have evolved over the years, and some older methods are now considered obsolete. Here's a summary of the current understanding:

• Rapid Influenza Diagnostic Tests (RIDTs): These immunoassays were once widely used to detect influenza A and B viral nucleoprotein antigens in respiratory specimens. However, they have lower sensitivity (10-70%) compared to newer methods [11][12]. RIDTs are no longer recommended for routine use due to their limited accuracy.
• Viral Culture: This traditional method involves growing the virus from a respiratory specimen. While it can be useful for research purposes, viral culture is not commonly used in clinical settings today due to its slow turnaround time and lower sensitivity compared to molecular tests [9].
• RT-PCR (Reverse Transcription Polymerase Chain Reaction): This molecular test has high sensitivity (>90%) and specificity for detecting influenza virus antigens. RT-PCR can also identify influenza subtypes, making it a valuable tool in clinical settings [12].

Current Recommendations

The current guidelines recommend using more accurate and sensitive tests like RT-PCR or multiplex RT-PCR assays for diagnosing influenza virus pneumonia. These molecular tests have higher sensitivity and specificity compared to older methods like RIDTs and viral culture.

• Clinical Decision Making: In outpatient and emergency department settings, testing for influenza virus is not necessary to start antiviral treatment in a patient with suspected influenza infection [13][14]. However, clinicians can consider influenza testing for patients who present with influenza-like illness, pneumonia, or nonspecific respiratory illness, especially during local epidemics.

References

[9] JM Walter. 2018. Diagnostic testing for respiratory viruses has dramatically improved over the last several decades as slow culture-based techniques have given way to rapid molecular tests. [10] [11] The specificity and sensitivity of rapid influenza diagnostic tests are lower than for viral culture and RT-PCR and vary by test. Most of the rapid influenza diagnostic tests that can be done in a physician's office are approximately 50-70% sensitive for detecting influenza virus antigens and greater than 90% specific. [12] In comparison, rapid influenza diagnostic tests (RIDTs), also known as the rapid flu antigen test, have lower sensitivity (10-70%) and are therefore more suited for outpatient use. Multiplex RT-PCR assays also have high sensitivity and specificity (>90%) and the advantage of detecting influenza subtypes. [13] In outpatient and emergency department settings, testing for influenza virus is not necessary to start antiviral treatment in a patient with suspected influenza infection, especially during local epidemics. [14] How to Use Clinical Decision Making. Influenza testing is not needed for all outpatients with signs and symptoms of influenza to make antiviral treatment decisions (See Figure 1, Figure 2).

The differential diagnosis for obsolete influenza virus pneumonia involves considering various conditions that may present with similar symptoms and radiographic findings.

• Community-acquired pneumonia (CAP): This is a common condition that can be caused by a variety of pathogens, including bacteria, viruses, and atypical organisms. CAP can present with symptoms such as cough, fever, and shortness of breath, which are also seen in influenza virus pneumonia.
• Bacterial pneumonia: Bacterial pneumonia can cause severe illness, particularly in individuals with compromised immune systems or underlying health conditions. The symptoms of bacterial pneumonia may overlap with those of influenza virus pneumonia, making differential diagnosis challenging.
• Viral pneumonia: Viral pneumonia is a condition caused by viral infections that affect the lungs. It can be caused by various viruses, including respiratory syncytial virus (RSV), adenovirus, and coronavirus. The symptoms of viral pneumonia may include cough, fever, and shortness of breath, similar to influenza virus pneumonia.
• Cryptogenic organizing pneumonia: This is a rare condition characterized by inflammation in the lungs that can cause symptoms such as cough, fever, and shortness of breath. It may be difficult to distinguish from influenza virus pneumonia based on clinical presentation alone.

According to [9], the histologic findings of influenza pneumonia can be divided into those caused by the virus and those attributable to superimposed bacterial infection. This highlights the importance of considering both viral and bacterial causes in the differential diagnosis of influenza virus pneumonia.

In addition, [11] notes that viral pneumonia was traditionally found predominantly in the very young, the elderly, and those exposed to influenza. However, with the emergence of new viruses such as SARS-CoV-2, the presentation of viral pneumonia has become more diverse.

It is essential to consider these conditions in the differential diagnosis of obsolete influenza virus pneumonia, particularly when evaluating patients who present with symptoms that may overlap with those of influenza virus pneumonia.

References:

[9] by S Mukhopadhyay · 2010 · Cited by 56 — The histologic findings of influenza pneumonia can be divided into those caused by the virus and those attributable to superimposed bacterial infection.

[11] Viral pneumonia is defined as a disease entity wherein there is the viral causation of oxygen and carbon dioxide gas exchange abnormalities at the level of the alveoli, secondary to viral-mediated and/or immune response-mediated inflammation.