Friday, 22 January 2016

The fight against Malaria                   

Malaria is a mosquito-borne infectious disease of humans and other animals caused by parasitic protozoans  (a group of single-celled microorganisms). This disease causes symptoms that typically include  anemia  headache, fever, shivering, joint pain, vomiting, jaundice, retinal damage, hemoglobin in the urine, fever convulsions, fatigue, vomiting, yellow skin, headaches seizures, coma  and/or death. There is no vaccine for malaria.  This deadly infectious disease has afflicted the human race since the dawn of time.

The disease is transmitted by the biting of mosquitos, and the symptoms usually begin ten to fifteen days after being bitten. If not properly treated, people may have recurrences of the disease months later.    The disease is most commonly transmitted by an infected female  mosquito. The mosquito bite introduces the  parasites  from the mosquito's saliva into a person’s blood. The parasites then travel to the liver where they mature and reproduce.    

The risk of disease can be reduced by preventing mosquito bites by using mosquito nets and insect repellents, or with mosquito-control measures such as spraying insecticides and draining standing water. Even in North America, home owners should never let water  stagnate in their bird baths. 

The disease is widespread in the tropical and subtropical regions that exist in a broad band around the equator. This includes much of Sub-Saharan Africa, Asia, and Latin America. From colonial times until the 1940s, malaria was the American disease”—annually afflicting as many as 7 million Americans 

An estimated 12,000 workers had died during the construction of the Panama Railway and over 22,000 during the French effort to build a canal. Many of these deaths were due to disease, particularly yellow fever and malaria. Yellow fever is caused by a virus and is spread by the bite of the female mosquito.  It infects only humans, other primates It can be fought with a vaccine. .

Over half a million (627,000) people still die from malaria each year, mostly children younger than five years old. There are approximately 207million cases of malaria each year. 90% of all malaria deaths occur in 45 countries in sub-Saharan Africa. It is estimated that a child in Africa dies every minute of malaria. 

In the middle part of the 20th century, the larger part of mankind finally 
succeeded in overcoming the ravages of malaria. That was because it was fought with the repellent called DDT. But within three decades, the triumph would give way to tragedy when leftist ideologues, professing concern for the integrity of the natural environment because of the dangers inherent in DDT, collaborated to ban the use of that pesticide. It was the very repellent that had made it possible to vanquish malaria from vast portions of the globe. By means of that ban, these foolish environmentalists effectively caused over the course of the ensuing 30+ years, more than 50 million people who would die needlessly of that disease that was entirely preventable.

Even in areas of stable malaria transmission such as five northernmost African countries, Algeria, Egypt and Libya, very young children and pregnant women are the population groups at highest risk for malaria morbidity and mortality. Most children experience their first malaria infections during the first year or two of life, when they have not yet acquired adequate clinical immunity. Ninety percent of all malaria deaths in Africa occur in young children.

There are three principal ways in which malaria can contribute to death in young children. First, an overwhelming acute infection, which frequently presents as seizures or coma (cerebral malaria), may kill a child directly and quickly. Second, repeated malaria infections contribute to the development of severe anemia, which substantially increases the risk of death. Third, low birth weight that frequently the consequence of malaria infection in pregnant women that is the major risk factor for death in the first month of life In addition, repeated malaria infections make young children more susceptible to other common childhood illnesses, such as diarrhea and respiratory infections, and thus contribute indirectly to their deaths.

Children who survive malaria may suffer long-term consequences of the infection. Repeated episodes of fever and illness reduce appetite and restrict play, social interaction, and educational opportunities, thereby contributing to poor development. An estimated 2% of children who recover from malaria infections affecting the brain (cerebral malaria) suffer from learning impairments and disabilities due to brain damage, including epilepsy and spasticity.

This high loss of human life may in fact be partly a result of misdiagnoses, since many facilities in Africa lack laboratory capacity and it is often difficult clinically to distinguish malaria from other infectious diseases. Nonetheless, malaria is responsible for a high proportion of public health expenditure on curative treatment, and substantial reductions in malaria incidence would free up available health resources and facilities and health workers’ time, to tackle other health problems.

Poor people are at increased risk both of becoming infected with malaria and of becoming infected more frequently. Child mortality rates from malaria are known to be higher in poorer households and malaria is responsible for a substantial proportion of these deaths.

Between 2000 and 2015, the estimated number of malaria cases declined by 88% while malaria death rates declined by 90% in the African Region. This is as a result of the scale-up of use of insecticide-treated nets, indoor residual spraying, and intermittent preventive treatment during pregnancy and artemisinin-based combination therapy. 

Sleeping under insecticide treated nets can reduce overall child mortality by 20 per cent. There is evidence that ITNs, when consistently and correctly used, can save approximately six child lives per year for every one thousand children sleeping under them. Prompt access to effective treatment can further reduce deaths. Intermittent preventive treatment of malaria during pregnancy can significantly reduce the proportion of low birth weight infants and maternal anemia.

Access to services and prevention and treatment interventions, procurement and supply of quality medicines and commodities, diagnostic capacity; routine surveillance, monitoring and evaluation concur to systems strengthening and progress towards national and international targets will stem the malaria disease. Of course, that will cost millions upon millions of dollars.

The World Health Organization in collaboration with international, continental and regional partner’s advocates, provides normative guidance and technical assistance for the scale-up of essential interventions in order to reverse the incidence of malaria. Of course all African communities must own and take part in the fight against malaria, provide human and financial resources and develop alliances to conquer the scourge of malaria. Unfortunately not all of these countries are led by governments that have the best interests of their people at heart. The money they control is denied to the welfare of sufferers of malaria because of the corruption that is rampant in these countries.

There may be a time in the future when this disease is completely eradicated. Alas, I don’t think that any of us alive today will see that happening in our lifetimes. It will take a great deal of effort on the part of countries that are ravaged by this disease to make the effort to stamp out this disease. Help from the World Health Organization, isn’t enough. We need the scientists to complete the task or eradicating mosquitos.

The fear of genetically-modified (GMO) organisms escaping from the lab is the basis for a thousand sci-fi stories, but it’s also a legitimate concern. That’s why genetic engineers are inventing kill switches, or genetically-encoded suicide triggers, for GMOs  they want to keep contained. Here’s how they work.

Why we need kill switches. When we talk about GMOs now, we usually mean genetically modified food (GMF) corn, soybeans, canola, extra-crisp apples. While GM crops have occasionally spread into the wild, plants are, relatively speaking, easy to contain.

But what about a genetically modified mosquito(GMM) that can fly away? Or microscopic GM bacteria (GMB) oozing through the ground? Once such organisms escape, there’s really no going back. And these aren’t far-fetched scenarios. Scientists are already investigating ways to mobilize GMB  to clean up toxic spills. And the mosquito scenario is already happening because sterile GM mosquitos are already being used to stop the spread of dengue fever. What we don’t want is an unintended ecological disaster, as GM organisms and their genes spread through the environment.

What’s to stop it? A kill switch, or a piece of genetic code that kills the GM organism when its job is done. Kill switches have already been developed to confine lab-made GMOs to the lab. But if we’re going to purposely release GMOs into the wild, we’ll need more sophisticated kill switches. And they are coming.

A kill switch is basically a lethal piece of genetic code that be easily switched on or off. The trigger could be a change in the environment, such as heat or cell density. The most common strategy, though, is basically chemical dependence: Feed the GMO a lab chemical that it can’t get in the wild. Then make the GMO’s life dependent on it. If the GMO escapes into the outside world, it dies without its chemical.

Scientists are already using this kind of kill switch right now. Genetically modified Aedes aegypti mosquitoes are used to fight dengue fever. The company Oxitec has experimented with releasing these mosquitos, which need tetracycline to survive. Tetracycline is better known as an antibiotic, but it plays very different role for these modified mosquitos.

Oxitec has inserted in its mosquitos a genetic sequence that includes a protein called tTa, or tetracycline transactivator. The genetic sequence is engineered in such a way that once tTa is activated, it causes the cell to keep making more and more of the protein—leading to the runway production of tTA. tTa then clogs up the cellular machinery, eventually killing the mosquito.

Tetracycline acts like an antidote to tTA. Oxitec raises male mosquitos with the tTA and feeds them tetracycline. Once released into the wild, they die without the antibiotic—but not before mating and passing the tTa genes off to offspring that can’t live without tetracycline either. It’s pretty ingenious.

What’s still missing?  The tTa system might work with mosquitos, but it’s not a one-size-fits-all solution to GMOs. That’s especially true for GM bacteria, which might be the wiliest of them all.

For one, bacteria evolve very quickly, in part because they have the special ability to suck up DNA they encounter in the environment. A kill switch that relies on, say, a GM bacteria’s inability to metabolize a single vital nutrient might be easily foiled if it picks up that relevant gene. This also means that killing GM bacteria might not be enough to prevent its genes from spreading. If its modified DNA sticks around, other bacteria in the environment might pick it up.

That’s why this year, scientists have suggested two new strategies. They both still involve a chemical trigger, but they add another piece to the puzzle.

One strategy takes synthetic nutrients one step further to synthetic amino acids, the very molecules that are the building blocks of proteins. Earlier this year, scientists announced they were able to create E. coli that take up synthetic amino acids by actually modifying translation, the process by which our cells read the genetic code of RNA to make proteins.

It usually works like this. Every three letters of RNA makes up a codon, which corresponds to one of the 20 amino acids that make up proteins. Codons are redundant, so that more than one codon can code for the same amino acid. There are also three stop codons (UAG, UAA, UGA) that all signal the end of a protein. Scientists took one of these stop codons (UAG) and assigned it to a 21st amino acid—a synthetic one. Then they redesigned essential proteins in the cell to include this synthetic amino acid. Take away this synthetic amino acid, and the cell can no longer survive. It also can’t as readily pass on its genes to other bacteria, since this interferes with the very process of making proteins.

Recently scientists announced a new type of kill switch that kills the genetically modified organism (GMO) and erases its modified genes. It uses CRISPR, a hot new tool in molecular biology right now. The CRISPR system has an enzyme that cuts target DNA very precisely. It literally self-destructs the mosquito’s DNA
In a new study, scientists specially engineered E. coli with genes for CRISPR that only become active in the presence of a sugar called arabinose. Once the bacteria sense arabinose, the CRISPR machinery comes alive, chewing up DNA to kill the cell. Its CRISPR system can also be tweaked to erase manmade DNA sequences, keeping them out of the environment and also keep them secret as trade secrets.

In the cases of both synthetic amino acids and self-destructing DNA, the recent studies are proofs of concept, and it will probably be years before the technology is ready for full use. But scientists are definitely thinking about how to contain genetically modified organisms. More sophisticated GMOs are coming, and scientists will need more sophisticated ways to contain them. Once they do, they will be used to eradicate mosquitos. 

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