Swine flu is the common name for the novel strain of influenza now known as H1N1/09. Although the name suggests otherwise, according to the Centers for Disease Control and Prevention (CDC), swine flu does not affect animals. Symptoms of swine flu in humans can be divided into three categories: systemic symptoms, respiratory symptoms and gastrointestinal symptoms.
Systemic Symptoms
Systemic symptoms reflect the response of the immune system to infection. Systemic symptoms of swine flu include fever, headache, muscle pain and joint pain. According to the Novel Swine-Origin Influenza A (H1N1) Virus Investigation Team, fever over 101.3 degrees F (38 degrees C) is the most common symptoms of swine flu, present in 94 percent of people. Fever may be the first symptom of swine flu, or it may follow one or two days after the onset of headache and pain in the muscles and joints.
Respiratory Symptoms
Swine flu is primarily a respiratory virus. The spectrum of disease it produces ranges from mild, self-limited cold-like symptoms to fatal pneumonia. According to a 2008 article in the Journal of Clinical Microbiology and Infection, the single most common respiratory symptoms of swine flu was dry, hacking cough, present in 92 percent of people. Other common symptoms, in descending order by prevalence, include: sore throat, runny nose, nasal congestion and mild breathing problems. Painful breathing, difficult breathing, shaking chills and blood in sputum can be signs of pneumonia, either due to swine flu or secondary bacterial infections.
Gastrointestinal Symptoms
Influenza is almost always associated with a lack of appetite. This is attributable to the effects of chemical messengers released by the immune system on the appetite centers of the brain. In addition, respiratory symptoms such as sore throat and runny nose may make swallowing painful and cause nausea due to post-nasal drip. According to the CDC, many people with swine flu also experience vomiting, diarrhea or both. These symptoms are typically mild and short-lived compared with other kinds of symptoms.
References
- 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
- Centers for Disease Control and Prevention H1N1 Flu
