According to the World Health Organization (WHO), as of December 2009, cases of laboratory-confirmed swine flu (H1N1) were reported in more than 208 countries and were associated with at least 12,000 deaths. The spectrum of disease produced by swine flu varies tremendously, ranging from mild upper respiratory tract infection in some people to severe and fatal pneumonia in others. Although the spectrum of disease varies from person to person, some symptoms seem to appear earlier than others.
Systemic Symptoms
Systemic symptoms of swine flu reflect the presence of infection throughout the body, and include fever, headache and muscle pain. Fever is the single most common symptom of swine flu. According to a 2009 report in the "New England Journal of Medicine," 94 percent of swine flu patients exhibited a fever of at least 101.3 degrees F (38 degrees C). Fever may also be the earliest symptom of swine flu in some people, although others report that muscle pain, particularly in the lower extremities, precedes the onset of fever.
Respiratory Symptoms
Respiratory symptoms of swine flu include upper respiratory symptoms such as sore throat, runny nose and nasal congestion, and lower respiratory symptoms such as cough and mild breathing problems, although not every patient develops all of these symptoms. According to a 2009 report in the "New England Journal of Medicine," cough is the second most common symptoms of swine flu, reported by 92 percent of patients. In adults, cough may appear one to two days before a fever, or they may appear at the same time. Upper respiratory symptoms are rarely among the initial symptoms of swine flu, and usually appear after the onset of fever.
Altered Mental Status
In some people, especially the elderly, a period of unusual agitation or mental confusion precedes the development of other symptoms of swine flu. However, this is not a specific sign of infection with swine flu. According to a 2006 study published in the "Journal of the American Geriatric Society," mental status changes typically began five to seven days before the onset of other symptoms for a variety of illnesses, including urinary tract infection, respiratory tract infection and flu.
References
- World Health Organization: H1N1
- "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 2009
- "Journal of the American Geriatric Society"; Agitated behavior as a prodromal symptom of influenza; Mentes and Woods; December 2006
