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Published online 27 May 2009 | Nature 459, 490-491 (2009) | doi:10.1038/459490a
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Swine flu attention turns to the tropics
New flu strains are more likely to arise in equatorial countries, where influenza is present the year round and surveillance is poor.
With the influenza season over in the temperate Northern Hemisphere, and just getting under way on the other side of the world, scientists are watching the A(H1N1) swine flu virus to see where it goes next and whether it will reassort with other flu viruses, or mutate, to cause more severe disease or acquire resistance to antiviral drugs.
Some researchers are warning, however, that such changes might be more likely to occur not in the northern or southern temperate zones where flu is seasonal, but in the narrow, often-overlooked belt of tropical countries where flu circulates all year round.
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Tropical regions are indeed still a big question mark regarding circulation of influenza in general. That said, we do know that it is not everywhere in the tropics that the circulation occurs all year round, but have a clear seasonality. In Belem, in the Amazon region and at few kilometers from the equatorial line, influenza circulates almost exclusively in the intense rainy season - i.e. in the first semester of the year (http://www.plosone.org/article/info:doi/10.1371/journal.pone.0005095). Hence their influenza season is about to finish and swine flu -in principle- should not be a bigger concern there than it is in the US for the next months.
I'm just interested, can we use this knowledge (http://www.nature.com/nsmb/journal/v16/n3/abs/nsmb.1566.html) somehow? If scientists found decision, why we can't stop virus and virus mutation? I understand that they need time... But is it possible that this group will help?
In fact, dissemination of flu viruses is endemic in the south hemisphere countries, which means that South America could not escape this contingency. The poorest countries in this region suffer from the lack of action of the governments facing other cogent priorities, such as the constant famine and deficient sanitation conditions. Then, fighting flu is not a priority in those countries that would require a most convincing presence of WHO, to incentive periodic vaccination campaigns as it has been usual in Brazil. Although an intensive dissemination of information and plans to fight the flu, Brazil is a huge country and the climate differs from the north to the south as regards the proper time to put in action the vaccination process. This difference causes some discomfort in he areas more prone to be ravaged by seasonal diseases due to the poverty of the populations in the north and northeast, where the climate conditions usually hot and rainy are aggravated by excess of humidity during all year around. In the south/southwest the critical period is the months from May to August, but the government has reasonably comprehensive vaccination programs covering children and the elderly that seems to have good effect in the prevention of epidemic flu on that period. But the actual health problem in the whole country is malaria and ?dengue? disseminated by the same malaria mosquito vector, a true epidemic fever whose hemorrhagic form kills a number of people all the years. On this subject the efforts of the government to efficiently prevent the outbreak of the infection are below the required levels.
There is an urgent need to examine the seasonality involve in the occurrence of influenza pandemics. In this regard it is instructive to look look into the history of epidemics caused by external meteorological influences ('wai gan bing') in premodern China which are seen as 'seasonal'. In premodern China, seasons are segmented in various ways. One way is to divide the year into 24 solar periods or 'jie Qi'. [Dr. Rey Tiquia PhD Independent Scholar on Science, Technology and Medicine Melbourne Australia]