Bed nets and vaccines together may
worsen malaria
Combining insecticide-treated bed nets with
vaccines may not provide the best chance at eliminating malaria, finds a
study.
Currently, over 20 malaria vaccine candidates are in different stages of development but none are licensed for use. No one knows for sure what will happen when vaccines and bed nets are used together.
A University of Michigan-led research team used a mathematical model of malaria transmission to find this out.
The researchers examined potential interactions between the two control measures and found that - in some cases - the combination of bed nets and a vaccine actually makes the problem worse.
"The joint use of bed nets and vaccines will not always lead to consistent increases in the efficacy of malaria control. In some cases, the use of vaccines and bed nets may actually make the situation worse," said Mercedes Pascual, professor in the department of ecology and evolutionary biology.
The study suggests that the combined use of some malaria vaccines with bed nets can lead to increased morbidity and mortality in older age classes.
"Ironically, the vaccines that work best with bed nets are the ones that do not protect the vaccinated host but, instead, block transmission of malaria in mosquitoes that have found an opportunity to bite vaccinated hosts," Artzy-Randrup said.
The malaria vaccines under development fall into three categories, each focusing on a different stage of the malaria life cycle. That cycle involves human hosts and Anopheles mosquitoes infected with Plasmodium parasites. In 2013, there were an estimated 198 million malaria cases worldwide, including 584,000 deaths, according to the World Health Organisation (WHO).
Most deaths occur among children living in Africa, where a child dies every minute from malaria, according to the WHO.
The study appeared in the journal Proceedings of the National Academy of Sciences.
22.01.2015
Deadly TB strains emerged in Asia
over 6,000 years ago
In a path-breaking find, an evolutionary geneticist
from the National Museum of Natural History in Paris has decoded the
tuberculosis (TB) genome, suggesting that a pernicious family of the strain emerged
in Asia over 6,000 years ago.
The study of nearly 5,000 samples of Mycobacterium tuberculosis from around the world showed how a lineage of the bacterium that emerged thousands of years ago in China has since become a global killer, widely resistant to antibiotic drugs, the Nature Genetics reported.
The evolutionary geneticist Thierry Wirth and his team analysed 4,987 samples of the "Beijing lineage" from 99 countries, fully sequencing the genomes of 110 of them and more limited stretches of DNA in the rest. The researchers then used the information to date the expansion of the lineage and show how the strains are related.
Consistent with its name, the "Beijing lineage" did emerge near north-eastern China."And it did so around 6,600 years ago which coincides with archaeological evidence for the beginnings of rice farming in China's upper Yangtze river valley," Wirth noted.
Although M. tuberculosis, probably, first emerged some 40,000 years ago in Africa, the disease did not take hold until humans took to farming with the consequent settling down. "The grouping of people in settlements made it easier for the respiratory pathogen to spread from person to person," Wirth pointed out.
Of all the M. bacterium strains circulating today, few strike more fear in public-health officials than the Beijing lineage.
First identified in greater Beijing in the mid-1990s, this lineage now circulates throughout the world and many strains are resistant to drugs that vanquish other types of TB.
The increasing availability of antibiotics in the 1960s, meanwhile, coincides with a fall in the numbers of the bacterium. The lineage rebounded, however, in the late 1980s and early 1990s.
Since it emerged, the "Beijing lineage" has become much more infectious, Wirth says, so it out-competes other strains of the bacterium.
His team identified mutations related to antibiotic resistance, metabolism and evasion of immune responses that may have contributed to the success of the "Beijing lineage".
22.01.2015
Happiness is
the absence of
the striving for happiness
Zhuangzi
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