Sunday, 14 December 2014

Malaria Is Down - But Not Yet Out

Scale-up in effective malaria control dramatically reduces deaths | WHO 9 December 2014:

Brilliant news that the infection and death rate from malaria has fallen worldwide and especially sharply in Africa where 90% of malaria deaths occur - and it's all down to science again.

The number of people dying from malaria has fallen dramatically since 2000 and malaria cases are also steadily declining, according to the World malaria report 2014. Between 2000 and 2013, the malaria mortality rate decreased by 47% worldwide and by 54% in the WHO African Region - where about 90% of malaria deaths occur.

New analysis across sub-Saharan Africa reveals that despite a 43% population increase, fewer people are infected or carry asymptomatic malaria infections every year: the number of people infected fell from 173 million in 2000 to 128 million in 2013.

[...]

In 2013, 2 countries reported zero indigenous cases for the first time (Azerbaijan and Sri Lanka), and 11 countries succeeded in maintaining zero cases (Argentina, Armenia, Egypt, Georgia, Iraq, Kyrgyzstan, Morocco, Oman, Paraguay, Uzbekistan and Turkmenistan). Another 4 countries reported fewer than 10 local cases annually (Algeria, Cabo Verde, Costa Rica and El Salvador).


This success has been largely due to a three-pronged attack by the WHO:
  1. Insecticide-impregnated anti-mosquito nets, use of which has risen from just 3% in sub-Saharan Africa in 2000 to almost 50%.
  2. Increased use of powerful artemisinin-based combination therapies (ACTs), up from 11 million courses in 2005 to 392 million course in 2013.
  3. Increased use of rapid diagnostic kits to identify and target infections and asymptomatic carriers, up from 46 million in 2008 to 319 million in 2013.

We have the right tools and our defences are working. But we still need to get those tools to a lot more people if we are to make these gains sustainable.”

Dr Margaret Chan, WHO Director-General
The cheapest, and in the longer term, most effective of these is the use of anti-mosquito nets. If use of these nets could be increased to 100% in all malaria areas of the world, malaria would become history with no need to diagnostic kits or anti-malarial therapies and no worries about the emerging signs of artemisinin resistance because malaria relies entirely on transmission in the bite of female mosquitoes.

Biologically speaking we can render the malarial parasites extinct by a simple change in their environment, erecting an effective barrier to its transmission and so interrupting its highly specialised life cycle. And, for the creationists here, all this happens with not a single change in any genome but a radical change in the meaning of the genomic information. Moreover, this change occurs not in the meaning of the information contained in the malaria parasite's genome but in the genome of one of its vectors - the mosquito.

To understand this you need to understand the evolution of, first the mosquitoes and secondly the malaria parasites of the Plasmodium genus.

Mosquitos are members of the vast Diptera (two-winged) order of insects which includes the true flies, midges, gnats and crane flies. They almost certainly evolved as plant-sap feeders and the males still live on plant sap, not blood as the females do. A primitive pre-modern mosquito-like fossil has been found from 90-100 millions years ago in amber from Burma. More typically modern fossils have been found from 79 million years ago in Canadian amber. Although it is possible that female mosquitoes or their ancestors may have fed on reptilian blood they were almost certainly feeding on mammalian and avian blood fairly soon after these classes evolved.

Mosquitoes detect their victims at least partly by scent. Carolyn S. McBride, et al. recently found that a 'domestic' for of the species Aedes aegypti has recently evolved to detect humans by evolving a refined odour receptor. The 'wild' form still exists and predates on forest animals rather than humans.

So, mosquitoes detect their victims by scent, possibly by using a system originally evolved as a method for detecting a mate.

The Plasmodium parasites, which actually causes malaria, evolved once this blood-sucking parasitic life-style had evolved and created a niche for it to occupy. Their remote ancestors were almost certainly photosynthetic protozoans:

The Apicomplexa—the phylum to which Plasmodium belongs—are thought to have originated within the Dinoflagellates, a large group of photosynthetic protozoa. It is thought that the ancestors of the Apicomplexa were originally prey organisms that evolved the ability to invade the intestinal cells and subsequently lost their photosynthetic ability. Some extant Dinoflagellates, however, can invade the bodies of jellyfish and continue to photosynthesize, which is possible because jellyfish bodies are almost transparent. In other organisms with opaque bodies this ability would most likely rapidly be lost.

It is thought that Plasmodium evolved from a parasite spread by the fecal-oral route which infected the intestinal wall. At some point this parasite evolved the ability to infect the liver. This pattern is seen in the genus Cryptosporidium, to which Plasmodium is distantly related. At some later point this ancestor developed the ability to infect blood cells and to survive and infect mosquitoes. Plasmodium subsequently evolved a mechanism to invade the salivary glands of mosquitoes, allowing for transmission from mosquito to host. Once mosquito transmission was firmly established, the previous fecal-oral route was lost within the Plasmodium genus.

The survivorship and relative fitness of mosquitoes are not adversely affected by Plasmodium infection which indicates the importance of vector fitness in shaping the evolution of Plasmodium. Plasmodium has evolved the capability to manipulate mosquito feeding behavior. Mosquitoes harboring Plasmodium have a higher propensity to bite than uninfected mosquitoes. This tendency has facilitated the spread of Plasmodium to the various hosts.

[...]

Plasmodium evolved about 130 million years ago. This period coincided with the rapid spread of the angiosperms (flowering plants). This expansion in the angiosperms is thought to be due to at least one genomic duplication event. It seems probable that the increase in the number of flowers led to an increase in the number of mosquitoes and their contact with vertebrates.

Environmental factors play a considerable role in the evolution of Plasmodium and the transmission of malaria. The genetic information of Plasmodium falciparum has signaled a recent expansion that coincides with the agricultural revolution It is likely that the development of extensive agriculture increased mosquito population densities by giving rise to more breeding sites, which may have triggered the evolution and expansion of Plasmodium falciparum.


Like all parasites, and contrary to what creationists pseudoscientist frauds tell their dupes, the evolution of Plasmodium involved a loss of complexity and an increasing dependency not on their own genome for essential functions, but on the genomes of their hosts. In particular, the Plasmodium species that cause malaria are now entirely dependent on their mosquito hosts to find the next victim in which to complete their lifecycle.

Until we invented mosquito nets, and especially now insecticide-impregnated mosquito nets, the meaning of the information in the mosquito genes which allows them to detect and bite humans meant, for the mosquito, "There's a source of your next blood meal. Go for it!"; for any Plasmodium parasites it was carrying it meant, "There's your next host! Wait for it!". Now that same genome and that same information means, "There's a barrier to go and kill yourself on! Go for it!"; for the Plasmodium parasite, it means, "Game over, loser!"

And so, with a simple environmental change, the genome which has been successfully evolving for hundreds of millions of years is heading blindly and stupidly for the cliff edge and extinction with not a single mutation being involved.

But it's not all over yet. As the WHO warned:

While funding to combat malaria has increased threefold since 2005, it is still only around half of the US$ 5.1 billion that is needed if global targets are to be achieved.

"Against a backdrop of continued insufficient funding the fight against malaria needs a renewed focus to ensure maximum value for money,” says Fatoumata Nafo-Traoré, Executive Director of the Roll Back Malaria Partnership. “We must work together to strengthen country ownership, empower communities, increase efficiencies, and engage multiple sectors outside health. We need to explore ways to do things better at all levels."

Globally, 3.2 billion people in 97 countries and territories are at risk of being infected with malaria. In 2013, there were an estimated 198 million malaria cases worldwide (range 124-283 million), 82% of which were in the WHO African region. Malaria was responsible for an estimated 584 000 deaths worldwide in 2013 (range: 367 000 – 755 000), killing an estimated 453 000 children under five years of age.

Source: WHO
There is nothing good about malaria parasites or the mosquitoes that spread them. No great ecological disaster would befall the planet if we expunged them from history. If any creationist ID proponent can make a case for them being the intelligent design of their benevolent designer who designed everything just for humans, feel free to make that case below. If you can't, ask yourself what malign intent designed them and why your magic friend is not only powerless to counter them but, according to Michael J Behe, is actively helping them to overcome our chemical defences.

The answer is because ID is nonsensical and disconnected from the real world as we can observe it. Evolution by Darwinian natural selection is the only explanation required because it fully and completely explains the observable reality.

We have the science and it's not rocket science. By contrast, prayer had never killed a single mosquito unless it happened to be between the hands clasped in useless gesture.

Malaria is beatable. All we need now is the willpower and political resolve to apply the coup de grâce.

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