According to the World Health Organization, the swine flu is a pandemic with laboratory-confirmed cases identified in more than 200 countries. Swine flu, also known as H1N1 flu, produces a spectrum of disease ranging from mild upper respiratory tract illness to fatal pneumonia. Although the spectrum of disease varies from person to person, some symptoms seem to appear earlier than others.
Fever
According to the findings of the Novel Swine-Origin Influenza A (H1N1) Virus Investigation Team, fever greater than 101.3 degrees F (38 degrees C) is the most common symptom of swine flu, appearing in 94 percent of patients. In many cases, particularly children, fever is also the first symptom of swine flu. Fever usually peaks two to three days after onset. In 50 percent of people treated with oseltamivir, fever peaked at two days and resolved within three.
Cough
According to a 2009 study in the New England Journal of Medicine, cough is the second most common symptom of swine flu, reported by 92 percent of people. In some cases, cough may precede the development of fever by one or two days. In other cases, they appear at the same time. Unlike the cough associated with the common cold and many bacterial infections, the cough associated with swine flu is a "dry" hacking cough. The presence of green or yellow sputum or large amounts of sputum suggests a cause other than swine flu.
Muscle Pain
In a 2009 report in the Journal of Clinical Microbiology and Infections, muscle pain was reported by 43 percent of patients. In adults, muscle pain--particularly in the lower extremities--may begin one to two days before fever, or they may present at the same time. Muscle pain is often one of the most persistent symptoms of swine flu, lasting longer than eight days in up to 10 percent of patients, even those treated with oseltamivir.
Altered Mental Status
In some individuals, especially elderly people, 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 several days before the onset of other symptoms in a variety of illnesses, including urinary tract infection, respiratory tract infection and flu.
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); CS Lee and JH Lee; November 13 2009
- Journal of the American Geriatric Society; Agitated Behavior as a Prodromal Symptom of Influenza; DL Mentes and JH Woods; December 2006
