Pneumonia is an infection of the air-exchanging tissues of the lungs. Fluid accumulates in these tissues due to the infection, impeding air exchange. Many viruses can cause community or hospital-acquired pneumonia. Influenza and parainfluenza virus, adenovirus and respiratory syncytial virus are among the causative agents. Symptoms of viral pneumonia are similar to bacterial pneumonia. Overall, viral pneumonia tends to be a milder illness than bacterial pneumonia. However, among people with preexisting illnesses, viral pneumonia may be life-threatening.
Fever, Chills and Sweats
The University of Maryland Medical Center reports that fever is a common symptom of viral pneumonia, especially in children. Chills and sweats may accompany fever. Certain types of viral pneumonia are more likely to cause fever than are others. According to the medical reference text, "Principles and Practice of Infectious Diseases," pneumonia caused by influenza virus is more often associated with fever than is pneumonia caused by parainfluenza or respiratory syncytial virus. Notably, young infants and the elderly may not develop fever with viral pneumonia. Further, the presence or absence of fever does not correlate with the severity of lung involvement.
Wheezing
Wheezing may be a presenting symptom of viral pneumonia, according to the University of Virginia Health System. This symptom can be a clue to viral pneumonia because wheezing is not typically present with bacterial pneumonia. The Centers for Disease Control and Prevention reports that wheezing commonly develops in infants with respiratory syncytial virus pneumonia. Infants and young children, the elderly, and people with a weakened immune system are at greatest risk of developing pneumonia with respiratory syncytial virus infection.
Cough
Cough is a prominent feature of viral pneumonia. Phlegm is commonly produced, although this is not uniformly the case. In a review article on respiratory syncytial infections among elderly adults published in "Clinical Microbiology Reviews," Drs. A. Falsey and E. Walsh reported that cough was present with this infection in 90 to 97 percent of cases. However, phlegm production occurred in only 22 to 67 percent of those affected.
Shortness of Breath
Shortness of breath is a frequent symptom of viral pneumonia, as noted by Dr. Benjamin Medoff on Medline Plus. The occurrence of shortness of breath depends on the degree of involvement of the lungs, and an individual's lung and heart reserve capacity. For example, an otherwise healthy 20-year-old with viral pneumonia may have no shortness of breath; the uninvolved lung tissue can easily compensate for the infected area. In contrast, a 65-year-old with emphysema may experience pronounced respiratory distress with viral pneumonia; the uninfected areas of his lungs are not healthy enough to compensate.
