"Malaria parasites can detect when they are being threatened and change their behaviour to survive, new research has suggested." Changes in behavior may "explain how malaria" resists "drug treatment".
The study, conducted in Edinburgh, provides insight that "could lead to better control of the disease."
"Caused by a parasite called Plasmodium, malaria is spread through the bites of infected mosquitoes and kills around a million people in the world each year. Some of the parasites multiply in the bloodstream and others change into a specialised transmission form, which enables the disease to spread."
The study indicates that "when exposed to low doses of anti-malarial drugs, this delicate balance of replicating and transmitting is upset." Malaria parasites respond to the drugs by attempting to increase "their chances of survival through a safety-in-numbers strategy: they produce fewer transmission forms and concentrate more on replication."
Malaria illness produces symptoms in a cyclical pattern. This pattern corresponds with the reproduction of the parasite. "If drugs push parasites into producing more replicating stages, which cause the symptoms, then this may lead to more serious illness," says Dr. Sarah Reece, from the University of Edinburgh's school of biological sciences. "This study uncovers a new way that parasites are able to resist the effects of drugs. This is also likely to have important implications for human disease control strategies."
Source:
Reece, Sarah. Proceedings of the Royal Society. The Press Association. 19 May 2010. http://www.google.com/hostednews/ukpress/article/ALeqM5h42KsAItyKjo2vyhBDIMEBvAOdNA
Showing posts with label drug-resistant. Show all posts
Showing posts with label drug-resistant. Show all posts
Wednesday, May 19, 2010
Monday, May 10, 2010
Safer anti-malarials
In the arms race against malaria, humans wield the biggest weapons, but their cost is great. In recent years, malaria has mutated and adapted to resist the drugs used to combat it. Caused by a parasite and transmitted by mosquitoes, malaria is an infectious disease that kills nearly one million people each year. Humans struggle to prevent malaria transmission and to treat those infected with the deadly disease.
Unfortunately, some of the malaria treatments are potentially deadly as well. "Amodiaquine was introduced as an antimalarial drug, but. . . withdrawn from the market when it became clear that the drug caused serious adverse effects in the form of liver damage and impaired immune system." The drug is still used in the most severe cases of drug-resistant malaria. It saves lives, but endangers them as well.
Endeavoring to create safer drugs, scientists at the University of Gothenburg, Sweden, studied the byproducts of drugs, looking for toxins. "A pharmaceutical in the body is, in the optimal case, broken down into harmless products (metabolites) that leave the body, for example via the urine. Some pharmaceuticals, however, can be converted into toxic products, which may result in serious adverse effects." Proposed by Tove Johansson Mali'n, the scientists uncovered a process that can "simulate the metabolism of pharmaceuticals in the body". In this way they can identify and characterize several potentially toxic products that arise as the metabolites of drugs". With the aid of this methond, Mali'n "has now managed to identify. . . previously unknown metabolites that may have caused, or contributed to, the adverse effects of amodiaquine."
"We hope that the method can simplify the work of identifying potentially toxic metabolites at an early stage, and thus facilitate the development of safe drugs," says Tove Johansson Mali'n.
Tove Johansson Mali'n, Lars Weidolf, Neal Castagnoli, Ulrik Jurva. P450-catalyzed vs. electrochemical oxidation of haloperidol studied by ultra-performance liquid chromatography/electrospray ionization mass spectrometry. Rapid Communications in Mass Spectrometry, 2010; 24 (9): 1231 DOI: 10.1002/rcm.4505
University of Gothenburg (2010, May 9). New method for developing safer drugs. ScienceDaily. Retrieved May 10, 2010, from http://www.sciencedaily.com¬ /releases/2010/05/100509202645.htm
Unfortunately, some of the malaria treatments are potentially deadly as well. "Amodiaquine was introduced as an antimalarial drug, but. . . withdrawn from the market when it became clear that the drug caused serious adverse effects in the form of liver damage and impaired immune system." The drug is still used in the most severe cases of drug-resistant malaria. It saves lives, but endangers them as well.
Endeavoring to create safer drugs, scientists at the University of Gothenburg, Sweden, studied the byproducts of drugs, looking for toxins. "A pharmaceutical in the body is, in the optimal case, broken down into harmless products (metabolites) that leave the body, for example via the urine. Some pharmaceuticals, however, can be converted into toxic products, which may result in serious adverse effects." Proposed by Tove Johansson Mali'n, the scientists uncovered a process that can "simulate the metabolism of pharmaceuticals in the body". In this way they can identify and characterize several potentially toxic products that arise as the metabolites of drugs". With the aid of this methond, Mali'n "has now managed to identify. . . previously unknown metabolites that may have caused, or contributed to, the adverse effects of amodiaquine."
"We hope that the method can simplify the work of identifying potentially toxic metabolites at an early stage, and thus facilitate the development of safe drugs," says Tove Johansson Mali'n.
Tove Johansson Mali'n, Lars Weidolf, Neal Castagnoli, Ulrik Jurva. P450-catalyzed vs. electrochemical oxidation of haloperidol studied by ultra-performance liquid chromatography/electrospray ionization mass spectrometry. Rapid Communications in Mass Spectrometry, 2010; 24 (9): 1231 DOI: 10.1002/rcm.4505
University of Gothenburg (2010, May 9). New method for developing safer drugs. ScienceDaily. Retrieved May 10, 2010, from http://www.sciencedaily.com¬ /releases/2010/05/100509202645.htm
Sunday, March 7, 2010
Drug-resistant malaria
"In a dusty village near the Thai-Cambodia border, 24-year-old Oeur Samoeun sits on a dark green hammock recovering from a strain of malaria that has resisted the most powerful drugs available. . . Ravaged by days of fever and chills, he is considered lucky: the parasite has left his body. But for many others, the potentially deadly disease never quite disappears."
Pailin province, where Samoeun lives, is the unwitting nursery of drug-resistant malaria. It "is the epicenter of strains of malaria that have baffled healthcare experts worldwide, raising fears a dangerous new form of malaria could already be spreading across the globe."
Last year, a study published by the New England Journal of Medicine "showed that conventional malaria-fighting treatments derived from artemisinin took almost twice as long to clear the parasites that cause the disease in patients in Pailin and others in northwestern Thailand, suggesting the drugs were losing potency in the area." USAID, a U.S. development agency, agrees that traditional arteminsinin-based therapies are "now taking two to three times longer to kill malaria parasites along the Thai-Cambodian border than elsewhere."
Three drug-resistant malaria parasites have emerged from this province over the past five decades. "Thanks to prolonged civil conflict, dense jungles and movement of mass migrants in the gem mines in the 1980s and 90s, the strains multiplied and dispersed through Myanmar, India and two eventually reached Africa."
"Few can say why it is a hotbed for drug-resistant malaria", but experts point to "a combination of sociological factors and a complicated history spanning the Khmer Rouge era when 1.7 million people, nearly a quarter of Cambodia's population, perished from execution, overwork or torture during their 1975-79 rule."
Insurgents clung to Pailin, and it was "one of their last holdouts" before their defeat in the late 1990s. During the era of the Khmer Rouge, people resided in Pailin illegally. When they contracted malaria, they bought medication through black markets and self-medicated.
Self-medication was the only way to curb the rising number of malaria cases, so Cambodia made the decision to make anti-malarial drugs available over the counter. "The strategy carried risks. Easy access reduced the number of cases but also led to incorrect dosages and substandard or counterfeit medicine". Instead of eradicating the malaria parasites, over-the-counter treatments made the parasitic population stronger against widely used medications.
Without adequate drugs to combat the disease, drug-resistant malaria parasites threaten the world. Preventative measures, such as the use of bed-nets to avoid mosquito bites, may be our best defense against malaria. Donate a bed net through Nothing But Nets.
Source:
Win, Thin Lei. Reuters. "Cambodia drug-resistant malaria stirs health fears." 6 March 2010.
Pailin province, where Samoeun lives, is the unwitting nursery of drug-resistant malaria. It "is the epicenter of strains of malaria that have baffled healthcare experts worldwide, raising fears a dangerous new form of malaria could already be spreading across the globe."
Last year, a study published by the New England Journal of Medicine "showed that conventional malaria-fighting treatments derived from artemisinin took almost twice as long to clear the parasites that cause the disease in patients in Pailin and others in northwestern Thailand, suggesting the drugs were losing potency in the area." USAID, a U.S. development agency, agrees that traditional arteminsinin-based therapies are "now taking two to three times longer to kill malaria parasites along the Thai-Cambodian border than elsewhere."
Three drug-resistant malaria parasites have emerged from this province over the past five decades. "Thanks to prolonged civil conflict, dense jungles and movement of mass migrants in the gem mines in the 1980s and 90s, the strains multiplied and dispersed through Myanmar, India and two eventually reached Africa."
"Few can say why it is a hotbed for drug-resistant malaria", but experts point to "a combination of sociological factors and a complicated history spanning the Khmer Rouge era when 1.7 million people, nearly a quarter of Cambodia's population, perished from execution, overwork or torture during their 1975-79 rule."
Insurgents clung to Pailin, and it was "one of their last holdouts" before their defeat in the late 1990s. During the era of the Khmer Rouge, people resided in Pailin illegally. When they contracted malaria, they bought medication through black markets and self-medicated.
Self-medication was the only way to curb the rising number of malaria cases, so Cambodia made the decision to make anti-malarial drugs available over the counter. "The strategy carried risks. Easy access reduced the number of cases but also led to incorrect dosages and substandard or counterfeit medicine". Instead of eradicating the malaria parasites, over-the-counter treatments made the parasitic population stronger against widely used medications.
Without adequate drugs to combat the disease, drug-resistant malaria parasites threaten the world. Preventative measures, such as the use of bed-nets to avoid mosquito bites, may be our best defense against malaria. Donate a bed net through Nothing But Nets.
Source:
Win, Thin Lei. Reuters. "Cambodia drug-resistant malaria stirs health fears." 6 March 2010.
Friday, September 4, 2009
Malaria and antibiotics
Malaria is a parasite that is transmitted by mosquitoes and infects a million people a year. Since this disease is not caused by a bacterium, how is it that antibiotics affect malaria and improve the health of sickened individuals?
From 1920 to 1950, antibiotics were a widely used treatment for malaria, although medical practitioners were not entirely sure why this treatment was so effective (Butcher). In the early 1980s, it was "discovered that antibiotics ... are active as antimalarial agents" (Oronsky). More recently, azithromycin [also called Zithromax] has been used to treat malaria in Ethiopia after it was shown "to have efficacy in the prevention and treatment of malaria due to both Plasmodium falciparum and Plasmodium vivax," (Travis).
After research, scientists have hypothesized that antibiotics treat malaria because they attack the plasmodia (a protozoa) within the parasites; therefore the antibiotics diminish the malaria" (Flam). Furthermore, antibiotics alleviate the immune system of other infections that may coexist with malaria.
"The treatment may also have unintended consequences...including the inducement of antibiotic resistance" (Travis). However, the situation is further complicated by the development of drug-resistant bacteria in malaria-infested areas that have had no exposure to antibiotics.
As mysterious as the seemingly unfounded effectiveness of antibiotics on malaria in the 20th century, the unexplained drug-resistant bacteria in "remote rainforest communities in Guyana" confounded scientists (Juncosa). New studies revealed "that overuse of a drug used to prevent and treat malaria may be contributing to growing antibiotic resistance...Drug-resistant bacteria are known to arise from the overuse of antibiotics, which is why researchers were surprised to discover that they can develop in areas that do not have access to" that particular antibiotic [ciprofloxacin]. Michael Silverman, "an infectious disease specialist at Lakeridge Health Network in Ontario" says that antibiotic-resistant E. coli were more widespread in these remote Guyanese villages than in U.S. hospitals "where every second person is on antibiotics." Silverman's study showed that the patients infected with drug-resistant E.coli had been "given the drug chloroquine to prevent and treat malaria" (Juncosa).
According to Silverman, "It is very possible that the antimalarial drugs may be inducing a large amount of the antibiotic resistance that occurs in the tropics." Unfortunately, "plasmodia, the causative organisms of malaria, have developed resistance to antibiotics" as well and "at the same time, the mosquitoes that carry plasmodia have become resistant to the insecticides that were once used to control them. Consequently, although malaria had been almost entirely eliminated, it is now again rampant in Africa, the Middle East, Southeast Asia, and parts of Latin America" (MSN).
The increasing number of drug-resistant strains of malaria parasite, plasmodia, and other bacteria is another reason why an effective malaria vaccine is so important. We cannot continue treating malaria in the ways that we have in the past, for very soon, these old methods will be rendered ineffective.
Sources:
Butcher, Geoff. “Million Murdering Death.” History Today April 1998: 24-28.
Flam, Fray. “Scientists Find Weak Spot in Defense of Tenacious Malaria Parasite.” Tribune News Service November 1997: 26-28.
Juncosa, Barbara. "Antibiotic Resistance: Blame it on Lifesaving Malaria Drug?" Scientific American 21 July 2008.
MSN Encarta."Antibiotics"
Oronsky, Arnold L. Treatment of malaria with antibiotics. "United States Patent 4496549" 29 Jan 1985.
Science News. "Distribution Of Antibiotic For Eye Disease Linked To Low Death Risk Among Ethiopian Children." 1 Sept 2009.
Travis C. Porco; Teshome Gebre; Berhan Ayele; Jenafir House; Jeremy Keenan; Zhaoxia Zhou; Kevin Cyrus Hong; Nicole Stoller; Kathryn J. Ray; Paul Emerson; Bruce D. Gaynor; Thomas M. Lietman. Effect of Mass Distribution of Azithromycin for Trachoma Control on Overall Mortality in Ethiopian Children: A Randomized Trial. JAMA, 2009; 302 (9): 962-968
From 1920 to 1950, antibiotics were a widely used treatment for malaria, although medical practitioners were not entirely sure why this treatment was so effective (Butcher). In the early 1980s, it was "discovered that antibiotics ... are active as antimalarial agents" (Oronsky). More recently, azithromycin [also called Zithromax] has been used to treat malaria in Ethiopia after it was shown "to have efficacy in the prevention and treatment of malaria due to both Plasmodium falciparum and Plasmodium vivax," (Travis).
After research, scientists have hypothesized that antibiotics treat malaria because they attack the plasmodia (a protozoa) within the parasites; therefore the antibiotics diminish the malaria" (Flam). Furthermore, antibiotics alleviate the immune system of other infections that may coexist with malaria.
"The treatment may also have unintended consequences...including the inducement of antibiotic resistance" (Travis). However, the situation is further complicated by the development of drug-resistant bacteria in malaria-infested areas that have had no exposure to antibiotics.
As mysterious as the seemingly unfounded effectiveness of antibiotics on malaria in the 20th century, the unexplained drug-resistant bacteria in "remote rainforest communities in Guyana" confounded scientists (Juncosa). New studies revealed "that overuse of a drug used to prevent and treat malaria may be contributing to growing antibiotic resistance...Drug-resistant bacteria are known to arise from the overuse of antibiotics, which is why researchers were surprised to discover that they can develop in areas that do not have access to" that particular antibiotic [ciprofloxacin]. Michael Silverman, "an infectious disease specialist at Lakeridge Health Network in Ontario" says that antibiotic-resistant E. coli were more widespread in these remote Guyanese villages than in U.S. hospitals "where every second person is on antibiotics." Silverman's study showed that the patients infected with drug-resistant E.coli had been "given the drug chloroquine to prevent and treat malaria" (Juncosa).
According to Silverman, "It is very possible that the antimalarial drugs may be inducing a large amount of the antibiotic resistance that occurs in the tropics." Unfortunately, "plasmodia, the causative organisms of malaria, have developed resistance to antibiotics" as well and "at the same time, the mosquitoes that carry plasmodia have become resistant to the insecticides that were once used to control them. Consequently, although malaria had been almost entirely eliminated, it is now again rampant in Africa, the Middle East, Southeast Asia, and parts of Latin America" (MSN).
The increasing number of drug-resistant strains of malaria parasite, plasmodia, and other bacteria is another reason why an effective malaria vaccine is so important. We cannot continue treating malaria in the ways that we have in the past, for very soon, these old methods will be rendered ineffective.
Sources:
Butcher, Geoff. “Million Murdering Death.” History Today April 1998: 24-28.
Flam, Fray. “Scientists Find Weak Spot in Defense of Tenacious Malaria Parasite.” Tribune News Service November 1997: 26-28.
Juncosa, Barbara. "Antibiotic Resistance: Blame it on Lifesaving Malaria Drug?" Scientific American 21 July 2008.
MSN Encarta."Antibiotics"
Oronsky, Arnold L. Treatment of malaria with antibiotics. "United States Patent 4496549" 29 Jan 1985.
Science News. "Distribution Of Antibiotic For Eye Disease Linked To Low Death Risk Among Ethiopian Children." 1 Sept 2009.
Travis C. Porco; Teshome Gebre; Berhan Ayele; Jenafir House; Jeremy Keenan; Zhaoxia Zhou; Kevin Cyrus Hong; Nicole Stoller; Kathryn J. Ray; Paul Emerson; Bruce D. Gaynor; Thomas M. Lietman. Effect of Mass Distribution of Azithromycin for Trachoma Control on Overall Mortality in Ethiopian Children: A Randomized Trial. JAMA, 2009; 302 (9): 962-968
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