The swine virus is a common name for the H1N1 flu strain which contains genes from flu viruses that infect pigs in Europe and Asia. The swine flu virus produces a spectrum of disease ranging from mild upper respiratory tract infection to life-threatening and fatal pneumonia. Although the spectrum of disease varies from person to person, some signs seem to appear earlier than others.
Systemic Symptoms
Systemic symptoms reflect the response of the immune system to infection. Common systemic symptoms of the swine virus include fever, headache and muscle or joint pain. According to a 2009 report in the "New England Journal of Medicine," fever greater than 101.3 degrees F (38 degrees C) is the most common symptom of swine virus, present in 94 percent of patients. In some cases, particularly in children, fever is also the first symptom of the swine virus. In adults, headache or muscle/joint pain may precede the onset of fever by one to two days.
Respiratory Symptoms
The swine virus produces both lower-respiratory symptoms such as cough and breathing problems and upper-respiratory symptoms such as sore throat, runny nose and nasal congestion. According to a report by the Novel Swine-Origin Influenza A (H1N1) Virus Investigation Team, cough is the second most common symptoms of the swine virus, present in 92 percent of adults. It may precede fever by one or two days or onset around the same time.
Upper-respiratory symptoms are somewhat less common than lower-respiratory symptoms. In a 2009 report in the "Journal of Clinical Microbiology and Infections," sore throat, runny nose and nasal congestion were reported in 64, 56 and 43 percent of patients, respectively. When present, these symptoms tend to appear a few days after other symptoms are established and are typically mild.
Gastrointestinal Symptoms
According to the report of the Novel Swine-Origin Influenza A (H1N1) Virus Investigation Team, vomiting, diarrhea or both were reported by nearly 40 percent of outpatients with laboratory-confirmed swine virus. These symptoms were usually mild and tended to appear a few days after fever and cough. Gastrointestinal symptoms that are severe or that present early in the course of the disease suggest an infection with something other than swine virus.
Neuropsychiatric Symptoms
In some individuals, especially young children and the elderly, a period of unusual agitation, irritability or mental confusion may precede the appearance 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 a few days before the onset of other symptoms in a variety of illnesses, including urinary tract infection, respiratory tract infection and influenza.
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; D.L. Mentes and J.H. Woods; December 2006
