3.2. Epidemics and pandemics

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3.2.1. Influenza

Influenza is a viral infection that affects mainly the nose, throat, bronchi and, occasionally, lungs. Infection usually lasts for about a week, and is characterized by sudden onset of high fever, aching muscles, headache and severe malaise, non-productive cough, sore throat and rhinitis. The virus is transmitted easily from person to person via droplets and small particles produced when infected people cough or sneeze. Influenza tends to spread rapidly in seasonal epidemics. Most infected people recover within one to two weeks without requiring medical treatment. However, in the very young, the elderly, and those with other serious medical conditions, infection can lead to severe complications of the underlying condition, pneumonia and death (World Health Organization). Click here for more information on influenza.


3.2.2. Avian influenza

In 1997, after causing outbreaks in domestic fowl in the region of Hong Kong, China, the avian influenza virus A (H5N1) for the first time showed a capacity to infect humans. In 2003 and 2004, it caused millions of infections in domestic fowl and over 400 cases in human beings.

This virus is considered very infectious, and when it infects humans it has a high rate of severe morbidity as well as high mortality. To date, person-to-person transmission has only affected family members or other individuals caring for patients. The principal risk factor for human contraction of a zoonotic infection by virus H5N1 is direct contact with or exposure at close range to infected domestic fowl. Since 2003, WHO has encouraged countries to prepare for a possible avian flu pandemic and provided cooperation for the purpose. For more information, see the WHO page on Avian influenza.


3.2.3. Influenza A (H1N1) 2009

Influenza H1N1, known as 'swine flu,' emerged in Mexico in mid-March of 2009. The virus proved to be a new subtype of the H1N1 strain that had not previously circulated in human beings, and as a result there was no natural immunity.

This flu primarily affecs the very young or old, pregnant women, obese individuals, and people with preexisting diseases. Most clinical presentations feature high fever, sore throat, cough, and general malaise, with deaths occurring as a result of severe pulmonary complications.

Influenza H1N1 has spread rapidly to the countries of all continents, providing several lessons for disaster managers. All of the countries in the Region of the Americas were affected within half a year of the virus’s emergence in Mexico. For more information on this disease, see the information from WHO on Pandemic (H1N1) 2009 and the associated Frequently Asked Questions

Pandemic H1N1 is one of the best examples of how a health disaster can harm a country’s economy. According to a preliminary assessment by ECLAC on the impact of the disease in Mexico, losses totaled US$ 9 billion.