Swine flu is the common name for the novel strain of influenza virus now known as H1N1. According to the World Health Organization, swine flu is a pandemic with laboratory-confirmed cases in more than 200 countries and linked to more than 12,000 deaths in 2009. People between 10 and 49 years old are among the hardest hit by swine flu infection.
Systemic Symptoms
Systemic symptoms include fever, headache and muscle pain and reflect the burden of infection throughout the entire body. According to researchers in the New England Journal of Medicine, fever over 101.3 degrees F (38 degrees C) is the single most common symptom of the swine flu pandemic, present in 94 percent of people. Headache was reported in 61 percent of patients, and muscle pain was reported in 43 percent of patients. All symptoms peaked approximately two days after onset. Muscle pain was often the last systemic symptom to resolve, with 5 percent of patients reporting persistent pain after 10 days.
Lower Respiratory Symptoms
Lower respiratory symptoms of swine flu include cough and breathing problems. According to a 2009 report in the Journal of Clinical Microbiology and Infection, cough was the second most common symptoms of swine flu, present in 92 percent of culture-proved cases. Cough was also the most persistent symptoms of swine flu, still present in more than 10 percent of patients 10 days later.
Breathing problems associated with swine flu range from dyspnea, or difficult and labored respiration, to life-threatening pneumonia. Dyspnea is reported by up to 22 percent of swine flu patients. Ten percent of swine flu patients are admitted to the hospital for breathing problems. Approximately one-third of these patients develop respiratory failure.
Upper Respiratory Symptoms
Upper respiratory symptoms commonly associated with swine flu include sore throat (70 percent), runny nose (64 percent) and nasal congestion (56 percent.) According to authors in the Journal of Clinical Microbiology and Infections, these symptoms were typically mild and began after the onset of fever and cough. In almost all cases, upper respiratory symptoms of swine flu resolved completely within seven days.
Gastrointestinal Symptoms
A distinguishing feature of the swine flu pandemic is the presence of gastrointestinal symptoms, which are rarely seen with seasonal flu. In the initial investigation of the Novel Swine-Origin Influenza A (H1N1) Virus Investigation Team, nearly 40 percent of patients reported vomiting, diarrhea or both. If they are present at all, these symptoms are usually rated as mild compared with the other symptoms of swine flu and they are among the first to resolve.
References
- World Health Organization
- 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
