According to the World Health Organization, the swine flu is a pandemic with laboratory-confirmed cases identified in more than 200 countries by the end of 2009. Swine flu, also known as H1N1 flu, produces a spectrum of disease ranging from mild upper respiratory tract illness to fatal pneumonia.
Systemic Sympoms
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.
Respiratory Symptoms
The swine flu pandemic causes both lower respiratory tract symptoms, like cough and mild breathing problems, and upper respiratory symptoms like sore throat, runny nose and nasal congestion. According to a study in the "Journal of Clinical Microbiology and Infection," cough was the single most common respiratory symptom and the second most common symptom overall, present in 92 percent of patients. In many cases, cough was the first symptom to appear, preceding the development of fever by one to two days. In other cases, they appeared at the same time. Upper respiratory symptoms were less common--sore throat (70 percent), runny nose (64 percent) and nasal congestion (56 percent)--and tended to appear later than other symptoms.
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 to 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
