Influenza porcina is a common name for the 2009 H1N1 influenza strain that the World Health Organization (WHO) called a pandemic. According to WHO, cases of H1N1 have been reported in virtually every country and linked to more than 14,000 deaths worldwide. Standard rapid flu tests may miss up to 90 percent of cases, the Centers for Disease Control and Prevention cautions. The virus can present a variety of symptoms.
Constitutional Symptoms
Constitutional symptoms reflect the immune system's response to the infection. According to the CDC, constitutional symptoms of H1N1 flu are the same as those of other flu strains and include fever or feeling feverish, chills, muscle or body aches, headaches and fatigue. In a June 18, 2009, article in the "New England Journal of Medicine," the most common symptom of swine flu was fever, which was found in 94 percent of people with laboratory-confirmed swine flu who were age 3 months up to 81 years. In 50 percent of people, constitutional symptoms subsided after three days. In some cases, symptoms lasted longer. More than 10 percent of people reported that headache and muscle pain lasted longer than a week.
Respiratory Symptoms
Flu is primarily a respiratory virus, according to the CDC, and H1N1 flu causes both upper- and lower-respiratory symptoms. These symptoms can include cough, sore throat, runny or stuffy nose and, in some cases, breathing problems. A study by C.S. Lee and J.H. Lee published November 13, 2009, in the "Journal of Clinical Microbiology and Infections" found that lower-respiratory symptoms such as cough and breathing problems were reported by 92 percent and 22 percent of patients, respectively. Cough was often one of the earliest symptoms of H1N1 flu and it was also the most persistent, lasting up to 12 days in 10 percent of people. While breathing problems were less common, 9 percent of people with H1N1 flu required hospitalization mainly due to breathing problems. Compared with lower-respiratory symptoms, upper-respiratory symptoms were reported by fewer people in the study; these symptoms included sore throat (70 percent), runny nose (64 percent) and nasal congestion (56 percent). When present, upper-respiratory symptoms tended to start a few days after constitutional and lower-respiratory symptoms were established, and they were usually rated as less severe.
Gastrointestinal Symptoms
According to the findings of the Novel Swine-Origin Influenza A (H1N1) Virus Investigation Team, gastrointestinal symptoms are more common with H1N1 when compared with seasonal flu. Almost 40 percent of outpatients reported vomiting, diarrhea or both. These figures may have been even higher among people who needed to be admitted to the hospital; however, that data was not reported. According to the article in the "Journal of Clinical Microbiology and Infections," gastrointestinal symptoms of H1N1 flu were usually mild and short-lived when compared with other kinds of symptoms. In many cases, their onset coincided with the peak of fever.
References
- WHO: Council of Europe Hearing on Pandemic (H1N1), 2009
- "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
