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UEA Add Dengue Fever To The List

August 28, 2014
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By Paul Homewood

 

h/t Dave Ward

 

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https://www.uea.ac.uk/mac/comm/media/press/2014/August/climate-change-dengue

 

“Experts” from the UEA warn us that global warming will bring Dengue fever to Europe.

 

The UEA report:

The study used current data from Mexico, where dengue fever is present, and information about EU countries to model the likelihood of the disease spreading in Europe. They found that coastal regions around the Mediterranean and Adriatic seas, the Po Valley and North East Italy were most at risk.
Dengue fever is a tropical disease caused by a virus that is spread by mosquitoes, with symptoms including fever, headache, muscle and joint pain. Each year, dengue infects 50 million people worldwide and causes approximately 12,000 deaths – mostly in South-east Asia and the Western Pacific.
Because the mosquitoes that carry and transmit the virus thrive in warm and humid conditions, it is more commonly found in areas with these weather conditions. Dense populations and global travel are also associated with increasing the spread of the disease, which was observed in the last few decades.

 

 Prof Duane Gubler is one of the world’s leading experts on tropical diseases. In 1998, he authored one of the definitive studies on dengue fever, “Dengue and Dengue Hemorrhagic Fever

 

ABSTRACT

Dengue fever, a very old disease, has reemerged in the past 20 years with an expanded geographic distribution of both the viruses and the mosquito vectors, increased epidemic activity, the development of hyperendemicity (the cocirculation of multiple serotypes), and the emergence of dengue hemorrhagic fever in new geographic regions. In 1998 this mosquito-borne disease is the most important tropical infectious disease after malaria, with an estimated 100 million cases of dengue fever, 500,000 cases of dengue hemorrhagic fever, and 25,000 deaths annually. The reasons for this resurgence and emergence of dengue hemorrhagic fever in the waning years of the 20th century are complex and not fully understood, but demographic, societal, and public health infrastructure changes in the past 30 years have contributed greatly. This paper reviews the changing epidemiology of dengue and dengue hemorrhagic fever by geographic region, the natural history and transmission cycles, clinical diagnosis of both dengue fever and dengue hemorrhagic fever, serologic and virologic laboratory diagnoses, pathogenesis, surveillance, prevention, and control. A major challenge for public health officials in all tropical areas of the world is to develop and implement sustainable prevention and control programs that will reverse the trend of emergent dengue hemorrhagic fever.

 

 The maps below show just how far the aegypti mosquitoes have spread in the Americas, but what is apparent is that they were equally well spread in the 1930’s. ( Also note the spread around the tip of S America – hardly a hot spot! Also Argentina).

 

F1.medium

A. aegypti distribution in the Americas during the 1930s and in 1970 and 1998.

Figure 1

 

 

Gubler even points out that dengue fever was discovered in Philadelphia back in 1780! As he says, the causes of this explosion of dengue are numerous and complicated, but he outlines them:

 

 

Factors Responsible for the Increased Incidence

The factors responsible for the dramatic resurgence and emergence of epidemic dengue and DHF, respectively, as a global public health problem in the past 17 years are complex and not fully understood. However, the resurgence appears to be closely associated with demographic and societal changes over the past 50 years. Two major factors have been the unprecedented global population growth and the associated unplanned and uncontrolled urbanization, especially in tropical developing countries. The substandard housing, crowding, and deterioration in water, sewer, and waste management systems associated with unplanned urbanization have created ideal conditions for increased transmission of mosquito-borne diseases in tropical urban centers.

A third major factor has been the lack of effective mosquito control in areas where dengue is endemic. The emphasis during the past 25 years has been on space spraying with insecticides to kill adult mosquitoes; this has not been effective  and, in fact, has been detrimental to prevention and control efforts by giving citizens of the community and government officials a “false sense of security”. Additionally, the geographic distribution and population densities of A. aegypti have increased, especially in urban areas of the tropics, because of increased numbers of mosquito larval habitats in the domestic environment. The latter include nonbiodegradable plastics and used automobile tires, both of which have increased dramatically in prevalence during this period.

A fourth factor responsible for the global emergence of dengue and DHF is increased air travel, which provides the ideal mechanism for the transport of dengue and other urban pathogens between population centers of the world. For instance, in 1994, an estimated 40 million persons departed the United States by air, over 50% of whom traveled for business or holiday to tropical countries where dengue is endemic. Many travelers become infected while visiting tropical areas but become ill only after returning home, resulting in a constant movement of dengue viruses in infected humans to all areas of the world and ensuring repeated introductions of new dengue virus strains and serotypes into areas where the mosquito vectors occur.

A fifth factor that has contributed to the resurgence of epidemic dengue has been the decay in public health infrastructures in most countries in the past 30 years. Lack of resources has led to a critical shortage of trained specialists who understand and can develop effective prevention and control programs for vector-borne diseases. Coincident with this has been a change in public health policy that placed emphasis on emergency response to epidemics by using high-technology mosquito control methods rather than on preventing those epidemics by using larval source reduction through environmental hygiene, the only method that has been shown to be effective.

A sixth factor was the ecologic disruption in the Southeast Asia and Pacific theaters during and following World War II created ideal conditions for increased transmission of mosquito-borne diseases, and it was in this setting that a global pandemic of dengue began.

Another factor was the discontinuation of the eradication programme in the Americas in the early 1970’s. In the 1950s, 1960s, and most of the 1970s, epidemic dengue was rare in the American region because the principal mosquito vector, Aedes aegypti, had been eradicated from most of Central and South America. The eradication program was discontinued in the early 1970s, and this species then began to reinvade the countries from which it had been eradicated. By the 1990s, A. aegypti had nearly regained the geographic distribution it held before eradication was initiated (Fig. 1). Epidemic dengue invariably followed reinfestation of a country by A. aegypti. By the 1980s, the American region was experiencing major epidemics of dengue in countries that had been free of the disease for 35 to 130 years. New dengue virus strains and serotypes were introduced (DEN-1 in 1977, a new strain of DEN-2 in 1981, DEN-4 in 1981, and a new strain of DEN-3 in 1994). Moreover, many countries of the region evolved from nonendemicity (no endemic disease) or hypoendemicity (one serotype present) to hyperendemicity (multiple serotypes present), and epidemic DHF emerged, much as it had in Southeast Asia 25 years earlier. From 1981 to 1997, 24 American countries reported laboratory-confirmed DHF.

In summary, demographic and societal changes, decreasing resources for vector-borne infectious disease prevention and control, and changes in public health policy have all contributed to increased epidemic dengue activity, the development of hyperendemicity, and the emergence of epidemic DHF.

http://cmr.asm.org/content/11/3/480.full

 

 

 

Nowhere in his analysis does Prof Gubler mention climate change, but don’t expect the UEA to tell you any of this.

But, hey, they’ve got models, so they must be right!

11 Comments
  1. Heber Rizzo permalink
    August 29, 2014 7:49 am

    The real question is, why the spread diminished from 1930 to 1970? DDT perhaps?

  2. DaveW permalink
    August 29, 2014 8:31 am

    I checked the University of East Anglia press page to make sure there wasn’t some kind of mistake, but your screen grab is the same as what is up there now. Not only are they ignorant of the history and epidemiology of the dengue viruses, but they don’t even know what a mosquito looks like.

    The fly on offer opposed to the mysterious trifurcate structure is not a mosquito and is a male (notice the claspers on the end and very large eyes) to boot. Even if it were a mosquito, male mosquitoes do not bite and are not vectors. Apparently the University of East Anglia simply plucked Mr Portellano’s mislabelled image off of Flickr of “Mosquito posado en una ramita” and used it.

    And just to keep up the farce, the non-mosquito doesn’t look ‘perched on a twig’ either. Most of the legs and tarsi are in an unnatural position for perching. I’d guess the poor fly is dead and posed. Looks like a dance fly to me (Empididae) and the long beak my be for feeding at flowers (many species are predatory on other insects).

    Sad to say this is about what one expects from university press releases today: a brief bit of handwaving and hype before moving on to the next bit of propaganda. There is no interest accuracy, no attempt at truth, just grubbing for headlines and grant money.

    Gubler’s analysis is exactly right. The ongoing dengue pandemic is the direct result of the breakdown in vector control and public heath services and increased world travel. Chikungunya virus has the same vectors and, like dengue, infected humans are the source of the virus. It has recently colonized the New World. Expect similar BS about climate change and Chikungunya.

  3. Bloke down the pub permalink
    August 29, 2014 8:45 am

    In the UK, many diseases that were common and spread by mosquitos have disappeared. The most likely reason is that fewer people today live in proximity to marshland. The EU and the Environment Agency would like to see large areas of productive farmland returned to marshland, yet they want people to think that the return of these diseases is due to climate change.

  4. August 29, 2014 9:18 am

    Even now, the risk of Malaria to the UK, as a result of “climate change”, is being hyped.

    http://www.independent.co.uk/environment/climate-change/britain-faces-malaria-risk-as-climate-change-sees-mosquitoes-thriving-in-garden-water-butts-9413402.html

    Even in this article the real reasons are given as the UHI effect and the increasing number of water butts, and infected people returning to the UK, contradicting the headline. Nothing to do with “climate change” unless you count UHI as “climate change”.

    This of course ignores the fact that Malaria existed in England from the 16th to 19th century.

    http://www.ncbi.nlm.nih.gov/pubmed/7898959

  5. mitigatedsceptic permalink
    August 29, 2014 1:53 pm

    Just another example of post-normal science (PNS) hawked around in UEA.

  6. mike fowle permalink
    August 29, 2014 5:30 pm

    What was so depressing about this story is that the East Anglian Daily Times, as normal, ran it without question. What happened to journalism?

  7. manicbeancounter permalink
    August 29, 2014 5:58 pm

    It is another example of those that believe in “climate science” believing that they have expertise in everything else. It includes (but is not limited to) economics, public policy making, policy implementation, philosophy of science, ethics and statistics. They ignore the accumulated wisdom of the ages along with modern science.

  8. August 29, 2014 10:07 pm

    By blaming everything on the climate, officials are off the hook for fixing this. I am thinking this is the goal—to make life so miserable that people will think that a cut in energy is the least of their problems. The gamble is whether or not people will wake up first, as with the case of energy in Europe where lignite is now the fuel of choice in places. Wind and solar failed and fear shut down nuclear. However, the people apparently noticed before complete depression set in.

  9. Derek permalink
    August 30, 2014 11:09 am

    There is no doubt that all this drip, drip of information is having an effect on the public. It is rife in the world of councils where I have some experience. Almost every report on anything where climate could possibly have an influence mentions and enhances the effect of “global warming”, quoting from some other report like the one in this post. My own council recently produced a “tree management policy” running to around a hundred pages. There was a section devoted to the effect of climate change on the viability of traditional British trees. I have pointed out to our tree expert that the real threat to our trees is not from climate change, but from disease – see here.

    • August 30, 2014 2:20 pm

      But they will doubtless find some way of blaming the disease on “climate change”!

  10. David A permalink
    September 1, 2014 7:38 am

    I found this very post normal, “..Dengue fever ( was this not in a Sherlock Holmes story?) could make headway in popular European destinations if climate change continues on the projected trajectory” .
    ==================================================
    “Continues on the projected trajectory” ??

    No warming for 15 plus years, polar ice projections wrong, global temp projections wrong, ocean “acidification” wrong, tropospheric hot spot wrong, water vapor projections wrong, severe weather projections wrong, sea level rise projections wrong, world crop projections wrong, ocean temp projections wrong, global precipitation projections wrong, decrease in ability of CO2 to grow more food on less water, wrong, increase in droughts wrong, decrease in snowfall wrong.

    When has CAGW theory ever been observed to follow its projected trajectory? (Or is it simply models all the way down?)

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