"Swine flu," also known as H1N1 2009, was first identified in March 2009. According to the Centers for Disease Control and Prevention (CDC), rapid flu tests miss up to 90 percent of swine flu infections. Through careful attention to symptoms, it is sometimes possible to distinguish the true effects of swine flu from those of other kinds of infections and medical problems.
Systemic Symptoms
Systemic symptoms are so-named because they are signs of system-wide infection. According to the CDC, systemic effects of swine flu include fever, headache and muscle pain. Fever above 101.3 degrees F (38 degrees C) is identified in 94 percent of cases. Some people, including very young infants, the elderly and people with multiple medical problems are unable to mount a fever, even in response to swine flu. The absence of fever in otherwise healthy adults and children suggests something other than swine flu.
Respiratory Symptoms
According to a 2009 article in the "New England Journal of Medicine," cough is the second most common symptoms of swine flu, present in 92 percent of adults. Other common respiratory symptoms of swine flu include, in descending order: sore throat (70 percent), runny nose (64 percent), nasal congestion (56 percent) and mild breathing problems (22 percent). The cough associated with "true" swine flu is dry. Cough that produces copious amounts of sputum or green or yellow sputum indicates the presence of another kind of infection, allergy or other medical problems. In addition, in "true" swine flu, lower respiratory symptoms such as sore throat, runny nose and nasal congestion usually appear a few days after the onset of cough and fever.
Gastrointestinal Symptoms
Non-H1N1 influenze strains are very rarely associated with gastrointestinal symptoms; however swine flu is somewhat different. According to the a report by the Novel Swine-Origin Influenza A (H1N1) Virus Investigation Team, nearly 40 percent of people with swine flu reported diarrhea, vomiting or both. However, in contrast to rotovirus and other more traditional gastrointestinal viral infections, gastrointestinal symptoms of swine flu tend to be short-lived and relatively mild, and onset after fever and cough.
References
- Centers for Disease Control H1N1 Flu
- "New England Journal of Medicine: Emergence of a Novel Swine-Origin Influenza A (H1N1) Virus in Humans"; Novel Swine-Origin Influenza A (H1N1) Virus Investigation Team; June 18, 2009
- "Clinical Microbiology and Infections: Dynamics of Clinical Symptoms in a Case with Pandemic Influenza A (H1N1)"; C.S. Lee and J. H. Lee; November 13, 2009
