Influenza - World Weekly Summary


The Provinces of Quebec and British Columbia reported increases in flu activity, while other regions across the country reported decreased activity. Since the beginning of the flu season, most of the identified viruses have been the regular seasonal flu virus. The number of 2009 pandemic H1N1 strains (swine flu) have decreased to about 7% of the positive flu viruses detected through laboratory testing.

United States:

As reported by the CDC, flu activity is widespread in 44 states. Five states have reported regional flu virus circulation while the District of Columbia and one state reported local activity. Puerto Rico and the U.S. Virgin Islands have detected only sporadic flu activity. Nevertheless, the proportion of deaths attributed to pneumonia and influenza was at the epidemic threshold. The 2009 pandemic H1N1 strain (swine flu) is still responsible for 23.2% of all influenza type A viruses and so far has caused 4 deaths in children.


Flu activity remains high in most of Europe, although flu virus circulation may have peaked in many western and northern European countries. Eight of the 41 reporting countries (Albania, Belarus, the Czech Republic, Iceland, Kazakhstan, the Republic of Moldova, Serbia and Slovakia) reported increased activity while 6 (Ireland, Israel, Malta, Norway, Spain and the United Kingdom) reported decreased activity. Georgia, Luxembourg and the Siberian region of the Russian Federation reported very high levels of flu. The continued circulation of the 2009 pandemic H1N1 strain (swine flu) is contributing to higher than normal death rates in the age group from 15-64 years. Most of the people who died (60-70%) had a pre-existing medical condition associated with an increased risk of severe influenza. In contrast with North America, more of the identified flu strains (44%) were the 2009 pandemic H1N1 strain (swine flu).

North Africa and the Middle East:

In North Africa and the Middle East, flu activity has been declining for several weeks. Nevertheless, the 2009 pandemic H1N1 strain (swine flu) is still circulating.

Northern Asia:

Flu activity is generally decreasing. In contrast to North America and Europe, the 2009 pandemic H1N1 strain (swine flu) is more commonly found in northern Asia (57% of the identified flu strains). In most countries of northern Asia, there has been a recent shift from the regular seasonal flu strains to the 2009 pandemic H1N1 strain (swine flu).

Tropical Countries:

Flu activity is generally low throughout the tropical zone. Countries of Central America and the Caribbean islands have reported only sporadic activity. Madagascar is reporting continuing active flu transmission while Kenya has reported decreasing detection of flu viruses. Most of these are the 2009 pandemic H1N1 strain (swine flu).

In southern China, flu activity has remained low; however, 88% of the identified influenza A viruses were the 2009 pandemic H1N1 strain (swine flu). Hong Kong reports that most of the flu strains are the pandemic swine flu strain. Singapore has detected increasing levels of respiratory infections and the majority appear to be infected with the 2009 pandemic H1N1 strain (swine flu).

Some of the Pacific Islands (Federated States of Micronesia, Kiribati, Tuvalu, Marshall Islands and French Polynesia) have noted increases in respiratory infections.

Southern Hemisphere Temperate Countries:

During the summer season, there is very little flu transmission. Australia continues to detect sporadic seasonal and pandemic strains.

Advice to Travellers:

Travellers in the northern hemisphere should be aware that circulation of flu viruses is variable, ranging from high levels to low levels depending on the country or region visited. In some countries, the continued circulation of the 2009 pandemic H1N1 strain (swine flu) poses a significant risk, especially for persons with pre-existing medical conditions that might be a risk for severe flu. Travellers should consider vaccination with the recommended flu vaccine which will provide protection against currently circulating flu viruses.

Visit our Health Library for more information on exposure to and the prevention of Flu.

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