﻿ Swine Flu Symptoms, Causes, Treatment - Was swine flu (H1N1) a cause of an epidemic or pandemic in the 2009-2010 flu season? - MedicineNet

Swine Flu (cont.)

Medical Author:
Medical Editor:


Yes. An epidemic is defined as an outbreak of a contagious disease that is rapid and widespread, affecting many individuals at the same time. The swine flu outbreak in Mexico fit this definition. A pandemic is an epidemic that becomes so widespread that it affects a region, continent, or the world. As of June 11, 2009, WHO officials determined that H1N1 2009 influenza A swine flu reached WHO level 6 criteria (person-to-person transmission in two separate WHO-determined world regions) and declared the first flu pandemic in 41 years. The H1N1 flu reached over 200 different countries on every continent except Antarctica in the 2009-2010 flu season; fortunately, the severity of the disease did not increase.


In general, the majority (about 90%-95%) of people who get the disease feel terrible (see symptoms) but recover with no problems, as seen in patients in Mexico, the U.S., and many other countries.

People with suppressed immune systems historically have worse outcomes than uncompromised individuals; investigators suspect that as swine flu spreads, the mortality rates may rise and be high in this population. Current data suggest that pregnant individuals, children under 2 years of age, young adults, and individuals with any immune compromise or debilitation are likely to have a worse prognosis. Complications of swine flu may resemble severe viral pneumonia or the SARS (severe acute respiratory syndrome caused by a coronavirus strain) outbreak in 2002-2003 in which the disease spread to about 10 countries with over 7,000 cases, caused over 700 deaths, and had a 10% mortality rate. At the beginning of the pandemic, the numbers of people with flu-like illness were higher than usual and the illness initially affected a much younger population than the conventional flu. As the pandemic progressed, more young children became infected than usual, but the mortality statistics became more similar to the conventional flu mortality rate, with an older population (especially ages 50-64) having the highest death rate.

Medically Reviewed by a Doctor on 9/23/2013

Patient Comments

Viewers share their comments

Swine Flu - Concerns Question: Are you concerned about contracting swine flu? Has it affected your travel plans?

