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The East African : June 16th 2014
The EastAfrican OUTLOOK JUNE 14-20,2014 S CI E N C E Hope for an accurate children’s TB test Resea≥che≥s we≥e able to develop a TB ≥isk sco≥e in a seven-yea≥ study By A SPECIAL CORRESPONDENT IRIN A ccurate diagnosis of tuberculosis among children is difficult because the bacteria causing the disease tend to be detectable in the sputum only of adults, and because the clinical symptoms used to diagnose TB in children are also present in other conditions. This leads to false positives and consequent inappropriate treatment and increased drug resistance; and to false negatives, which means a correct diagnosis is only possible when it’s too late, after the disease has spread from the lungs to the brain or other organs. In many poor countries, health staff using a standard test fail to detect TB in children up to 93 per cent of the time, according to medical charity Médecins Sans Frontières. According to new research — published in the New England Journal of Medicine — involving 2,800 children hospitalised in South Africa, Malawi and Kenya, the key to better TB diagnosis could lie in 51 genes found in the blood of infected children. During the seven-year study, re- searchers determined which of these genes were activated and suppressed among infected children. Using this information to develop a “TB risk score”, the method was found to be accurate in more than 80 per cent of cases. The hope is that the discovery of such a “signature” will lead to a FACTS ABOUT TUBERCULOSIS TUBERCULOSIS: Infectious disease caused by bacteria, commonly affects lungs In 2012 8.6 million people fell ill with TB 1.3 million people died from TB in 2012 (including 320 000 people with HIV) A total of TB occurs in every part of the world. Nearly 60pc of new TB cases occurred in Asia in 2012. The greatest rate of new cases per capita was in sub-Saharan Africa. About 56 million TB patients have been successfully treated since 1995 worldwide Upto 22 million lives have been saved since 1995 through DOTS and the Stop TB Strategy cheap and effective test for childhood TB. “Childhood TB is a major prob- lem in African hospitals. An accurate test for childhood TB would be an enormous breakthrough, enabling earlier diagnosis, reducing long hospital admissions for investigation of TB suspects, and limiting the number of children treated The world is on track to achieve two global TB targets set for 2015: Europe and Africa are not on track Source: WHO inappropriately,” Brian Eley from the University of Cape Town, who led the clinical study in South Africa, said. Joseph Sitienei, head of Ken- ya’s national TB programme, said that while more effective diagnosis would be welcome, the challenge lay in ensuring “that the testsare quickly available in poor countries where they are most needed.” “Being able to accurately di- agnose TB in children means reducing TB related deaths among them,” Mr Sitienei said. Laura Guay, head of research at Elizabeth Glaser Paediatric Aids Foundation, EGPAF, and a professor at the George Washington University, said, that “Additional efforts must be made to ensure that governments, organisations that focus on eradication of TB and those that fund research in these areas devote sufficient attention and resources to addressing the unique challenges facing the diagnosis and treatment of children with TB.” Apart from hampering treat- ment, analysts also fear poor diagnosis has led to an underestimation of the burden of the disease among children even in countries where it is endemic. In 2011, for instance, up to 1.3 million deaths in children from TB-endemic countries were attributed to pneumonia though the causes of the deaths were never verified. Children who live with TB often live in poor conditions with limited access to healthcare. Across the world, there are some 16 current or scheduled clinical trials for new drugs to treat TB among children, and expectant mothers. There are also “several research groups that have devoted considerable time and effort to the search for better TB diagnostics for children, including in many research centres throughout Africa,” Ms Guay said. Better diagnosis is one of the key elements of a roadmap aimed at reaching zero tuberculosis deaths among children, drawn up in 2011 by a group of major international health organisations. Mala≥ia-hit count≥ies unable to test quality of d≥ugs By A SPECIAL CORRESPONDENT IRIN SOME 60 PER CENT of countries where malaria is endemic lack solid information about the quality of available drugs to treat the disease, according to a new study. The study, published in the Malaria Journal in April, looked at 251 reports from 104 malaria-endemic countries since 1946. It found that of the 43 countries that had some information about anti-malarial quality, 25 had only one or two published reports. “Estimates of anti-malarial quality vary widely depending on the sampling methodology used, with most reports not employing rigorous scientific techniques, potentially biasing results,” said the authors of the report. “Although there are clear foci of poor quality anti-malarials, the current global situation remains unclear, poorly documented; and their impact on public health uncertain.” This means that when attempting to reduce the number of poor quality and illicit medicines in the market, individual states are often unable to quantify the extent of the problem in their Antimalaria drugs. Poor quality drugs sold globally are responsible for drug resistance. Picture: File country. The report found that globally, of the nearly 10,000 anti-malarial drugs sampled, 30 per cent failed quality tests. According to the International Medical Prod- ucts Anti-Counterfeiting Taskforce (Impact), preparations sold as effective antimalarials often contain substances such as rat poison, mercury, lead, boric acid, paint, brick dust and floor wax. Such poisons can cause kidney failure, can- cer, developmental defects, stroke, high blood pressure and other health complications. Worldwide Antimalarial Resistance Network (WWARN) said poor quality anti-malarials containing lower quantities of the required active ingredient increase the risk of malaria drug resistance, compounding the problem. While it has been known for some time that there are a large number of fake and poor quality drugs on the market, “the efforts put into addressing the quality have had little tangible impact in comparison to the size of the problem” say the authors of the study, “because the programmes have mostly been slow, under-funded and fragmented.” Challenges related to terminology and patent- ing have also hampered progress in reducing poor quality antimalarial medications. “The controversy over definitions has disa- bled much that could be done and the use of the unwieldy term ‘substandard/spurious/falsely labelled/falsified/counterfeit medical products (SSFFCs)’ has not helped,” noted the authors of the study, because medicine quality reports don’t standardise their terminology or use the same metrics for calculating poor quality drugs. 33 Af≥icans lose natu≥al ≥esistance to mala≥ia By CHRISTABEL LIGAMI Special Correspondent THE MALARIA causing parasite, Plasmodium vivax, responsible for nearly 20 million cases of malaria in the world, may be “rapidly evolving” to overcome the natural resistance conferred by a blood type found in millions of Africans, according to a report in a new study published in the journal of PLOS Neglected Tropical Diseases. The study indicates that vivax malaria appears to be “rapidly evolving” and also find that previous genome sequence analyses may have missed “important genes” that allow the parasite to make people sick. The scientists say that while there is not yet enough evidence to conclude that the P. vivax parasite is gaining virulence, the genetic mechanisms uncovered could dramatically change the understanding of the important form of malaria that doesn’t get as much attention as falciparum malaria, even though it causes severe disease and may be more deadly than many think. Vivax malaria is in one respect more dangerous than falciparum malaria. The Plasmodium vivax parasite has the ability to “hide” in the liver and re-emerge multiple times in the bloodstream to cause relapse infections. The Duffy protein The scientists say some 95 per cent or more of the population in sub-Saharan Africa have been considered protected from vivax malaria because of something they lack in their red blood cells— the Duffy blood group protein. The absence of this protein has been well known to hinder the ability of vivax malaria parasites to gain entry into red blood cells. But over the past five years, ma- laria researchers have been surprised to see a growing number of reports from Africa and South America of infections in people who are Duffy-negative and should be resistant to vivax malaria. While not regarded as deadly as malaria caused by the falciparum parasite, vivax malaria threatens almost as many people worldwide — some 2.49 billion are at risk. But that number could be significantly higher if the blood type is not as fully protective as previously believed. “We discovered previously un- known genetic mechanisms in the P. vivax parasite that could give it other ways to invade red blood cells and help explain why we are seeing these vivax malaria infections in people who are Duffynegative,” said Peter Zimmerman, a professor at the Case-Western Reserve University and a co-author of the new study.
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