Pengayaan Malaria

7/29/2019 Pengayaan Malaria

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Malaria and the Night- Feeding Mosquitoes

Each year, about 1 million people malaria, a long-lasting disease that sporozoan

species (plasmodium) cause. More than 100 million people, especially in tropical and

subtropical regions, are now infected.

Malaria got its name in the seventeenth century. Italians made a connection between

the disease and swamps near Rome, where noxious gases filled the air and mosquitoes

flourished (mal, bad; aria, air). So many people became severely ill that the diseaseindirectly contributed to the decline of the ancient Greek and Roman empires.

Only the bite of a female Anopheles mosquito can transmit a motile infective stage to

human hosts. That stage, called the sporozoite, travels in blood vessels to liver cells, in

which it reproduces asexually by repeated fissions. Some of the offspring--merozoites--

reproduce asexually in red blood cells, which they rupture and kill. Still other merozoites

develop into male and female gametocytes. These gametocytes do not mature into

gametes until they enter the gut of another mosquito.

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ke-2 & 3



Malaria symptoms start as soon as infected liver cells rupture and release merozoites,

metabolic wastes, and cellular debris into blood. Shaking, chills, a burning fever, and

drenching sweats follow. After one episode, symptoms usually subside for a few weeks

or months. Infected people may feel healthy, but they should expect relapses, Jaundice,

kidney failure, convulsions, and coma are later outcomes.

Amazingly, Plasmodium is sensitive to temperature and oxygen levels of its hosts. Why

can’t gametocytes mature in humans? Humans are warm-bodied, and there is little free

oxygen in human blood; most is bound to hemoglobin. A female Anopheles mosquitohas a lower body temperature and takes in oxygen from the air along with blood. In this

insect’s gut, gametes mature. Zygotes form, divide, and give rise to sporozoites. This

infective stage then migrates to the mosquito’s salivary glands, there to await a new

bite.

Historically, malaria has been most prevalent in tropical and subtropical parts of Africa.

Today the cases reported in North America and elsewhere are rising dramatically. The

increase is attributed to globe-hopping travelers, unprecedented waves of human

immigration, and long-term climate change that is causing some formerly cool

temperate zones to warm up.

Many strains of Plasmodium are now resistant to order antimalarial drugs. Artemisinin, a

compound isolated from sweet wormwood (Artemisia), has promise as a treatment, not

a cure. It reduces the fever and number of parasites in blood, so it can slow the course

of infection.



Efforts to design a vaccine are ongoing. Vaccines are preparations that are introduces

into the body to induce the immune system to recognize a specific pathogen. The

vaccines developed for malaria are not equally effective against all stages that develop

during sporozoan life cycles. Generally, this is a problem for researchers who are

working to develop a vaccine against most parasites that have a complex life cycle.

At this writing, a vaccine that is based on a merozoite surface protein is being tested in

human adults I Africa. If it proves to be safe and effective, widespread clinical trials may

start in 2006 or 2007. In the meantime, every thirty seconds, one African child dies of

malaria.

PENYAKIT MALARIA DI INDONESIA

Peta malaria di Indonesia dapat dilihat pada situs:

http://www.malariamaps.hps.scot.nhs.uk/images/malariamaps/indonesia



BERITA TERKAIT KLB MALARIA



JURNAL ILMIAH

DNA barcoding on track to revolutionise malaria control© 2009 The Natural History Museum. All Rights Reserved

Scientists wishing to tackle the deadly disease malaria are using DNA barcoding to help.Malaria, along with several other devastating diseases, is transmitted by mosquitoes. Each year, upto 500 million people across the world are infected with malaria, and more than a million people dieas a result of contracting the disease.

There are 3490 species of mosquito currently recognised and until now, a major obstacle ineradicating malaria has been correctly identifying them. DNA barcoding, however, is proving to bethe most accurate way to identify mosquito species and therefore which particular strain of disease itcarries.

'Managing malaria doesn't mean getting rid of all mosquitoes, it means controlling the keyspecies that transmit the disease,' says Yvonne-Marie Linton, biomedical researcher at the NaturalHistory Museum and leader of the Mosquito Barcoding Initiative (MBI) .'But different mosquito species can look so similar that it's hard to identify them, which underminesany attempts at control. DNA barcoding offers a cheap and accurate way of telling the difference

between species, based on snippets of DNA code.'

First global effort

The MBI, which includes 11 institutions worldwide, is led by the Natural History Museum in the UKand the Smithsonian in Washington DC. This is the first time mosquito researchers from around theworld have collaborated in a global effort to tackle mosquito-borne diseases.

Worldwide access

The DNA information is held in a database that can be accessed by researchers globally. Thismeans scientists out in the field or in developing countries will immediately know what species they

are working with, without having to depend on high-tech laboratories or outdated visual guides.

More efficient and effective control

By accurately identifying the carrier species, it is possible to target the larval habitats or adult restingsites of the mosquito in question, minimising cost and making disease control more efficient andmore effective.

As Yvonne-Marie Linton explains this week at the second International Barcode of Life Conferencein Taipei, 'The MBI has already made more than 3000 DNA records for more than 250 speciesavailable since we started six months ago, but there is still lots of work to be done.'

Progress so far

Male Anopheles oswaldoi B mosquito from Putumayo in southernColombia. Scientists have discovered it is naturally infected with thehuman malarial parasite Plasmodium vivax .'The good news is we are already starting to see significant progress insome malarial-stricken areas.For example, one species in Latin America, Anopheles oswaldoi , was notthought to be a carrier of malaria in southern Brazil and yet they werecarriers in north Brazil, Venezuela and Colombia. DNA barcoding revealed

An. oswaldoi to be a group of four species, rather than one .



By separating out the group it is now possible to accurately track where it is a malaria carrier andwhere it is not - information that can be used by authorities in those countries to devise effectivecontrol measures.'

Aims of the initiative

The MBI aims to sequence the DNA of 80 per cent of all known mosquitoes within two years, and

will also include information on species that transmit other mosquito-borne diseases, for exampleWest Nile virus and dengue fever.From October 2007, the MBI will be teaming up with the Scholar Ship , a floating research instituteheaded by Dr Ravinder Bhatia, and will be sailing around the world, offering high-tech DNAbarcoding facilities onboard, which will allow other mosquito workers to participate in this excitingventure.The Mosquito Barcoding Initiative is a Demonstrator Project of the Consortium for the Barcode of Life (CBOL) which represents a group of major natural history museums, universities, zoos,herbaria and others interested in biodiversity. Working together, they will enable the rapididentification of the Earth's fauna and flora, an estimated 10 million species by 2010.



Malaria, Sickle-Cell Anemia, and Natural Selection (May 31, 2007 by G. Stolyarov II)

http://www.associatedcontent.com/article/261814/malaria_sicklecell_anemia_and_natural_pg2.ht

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The Genetics Behind the Survival of Sickle-Cell Disease

This paper explores the genetics behind malaria and sickle-cell anemia, a fascinatingcase where the presence of an allele for sickle-cell anemia prevents individuals from gettingmalaria. This effect explains the presence of some natural selection in favor of the sickle-cellanemia allele. Alternative versions of a gene are alleles. Each gene resides at a specificchromosome locus. The DNA at that locus, however, can vary somewhat in sequence of nucleotides and information content. Alleles are these possible DNA variations.

Individuals who are homozygous for an allele have both alleles of the same sort, one oneach pertinent locus of two homologous chromosomes. Individuals who are heterozygous for anallele have two different alleles, one on each of the homologous chromosomes.

Natural selection through differential reproductive success can cause allele frequencies ina population to change. Disasters or dramatic changes in the environment can also bring about abottleneck effect whereby the small quantity of individuals remaining does not statisticallyrepresent the former population. Thus, the available gene pool has been altered dramatically.

Malaria is a tropical disease transmitted through the bite of a mosquito. The malarialprotozoa infect the liver and reproduce, subsequently infecting the victim's red blood cells andbecoming available for transfer to other individuals via another mosquito.

People in Africa or of African descent often carry the sickle-cell anemia allele becauseheterozygotes for the allele can be protected from malaria while not exhibiting considerablesymptoms of sickle-cell anemia. They can survive to reproductive age and transfer the allele tooffspring, thus perpetuating the allele's occurrence in the gene pool.

Natural selection can serve as a mechanism for the survival in heterozygotes of certainrecessive alleles which pose great harm to recessive homozygotes. If the allele confers an

advantage to a heterozygote that is lacked by the dominant homozygote (which in this case isvulnerable to malaria), this allele can be spread to future generations, since its carriers reachreproductive age with greater likelihood. In a different environment, however, where malaria doesnot occur frequently or at all, there will be little or no survival advantage from being a carrier of thesickle-cell allele. Although these individuals can still reproduce without great obstacles, they areno longer favored over the homozygous dominant genotype. Thus, in places such as the UnitedStates, the sickle-cell allele is not nearly as frequent as in the tropical regions of Africa.Nevertheless, it does occur in a very small percentage of the population of African descent,seeing as insufficient time has passed in order for the allele frequency to decline to negligibleamounts.

One of the reasons why sickle-cell disease can still potentially exist in malaria-freeenvironments is the fact that heterozygotes' normal phenotypes "mask" the existence of the allele

within their genotypes. Thus, they can mate with healthy heterozygote partners and producediseased offspring. Perhaps technological advancement in the near future will enable individualsto learn of their own genotypes and the possibility of transferring such diseases to their children,thus enabling them to make more prudent decisions concerning reproduction. Heterozygotes maychoose to marry dominant homozygotes in the United States, or clone themselves in Africa so asto ensure that malaria resistance will be passed to their children without the risk of them acquiringsickle-cell disease.

Yet natural selection does not always function in a perfect or desirable manner. In manyexperimental cases, introducing just one heterozygote into an area with high rates of malariadeath failed to establish the sickle-cell allele. Many factors can account for this, including thepossibility that the heterozygote did not transfer the recessive allele to his offspring, or that hedied of a cause absolutel unrelated to malaria or sickle-cell anemia rior to transferrin the allele

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