17.8.11
Mosquitoes 'developing resistance to bed nets'
Mosquitoes can rapidly develop resistance to bed nets treated with insecticide, a new study from Senegal suggests. In recent years the nets have become a leading method of preventing malaria, especially in Africa.
The researchers also suggest the nets reduced the immunity of older children and adults to malaria infection.
But other experts say the study was too small to draw conclusions about the long term effectiveness of nets.
In the war against malaria, the cheapest and most effective weapon to date has been the long-lasting insecticide-treated bed net.
Over the last few years the nets have been widely distributed in Africa and elsewhere - the World Health Organization says that when properly deployed they can cut malaria rates by half.
In Senegal, around six million nets have been distributed over the last five years. In this study researchers looked at one small village in the country and tracked the incidence of malaria both before and after the introduction of nets in 2008.
Within three weeks of their introduction the scientists found that the number of malaria attacks started to fall - incidence of the disease was found to be 13 times lower than before the nets were used.
The researchers also collected specimens of Anopheles gambiae, the mosquito species responsible for transmitting malaria to humans in Africa. Between 2007 and 2010 the proportion of the insects with a genetic resistance to one type of pesticide rose from 8% to 48%.
By 2010 the proportion of mosquitoes resistant to Deltamethrin, the chemical recommended by the World Health Organization for bed nets, was 37%.
In the last four months of the study the researchers found that the incidence of malaria attacks returned to high levels. Among older children and adults the rate was even higher than before the introduction of the nets.
The researchers argue that the initial effectiveness of the bed nets reduced the amount of immunity that people acquire through exposure to mosquito bites. Combined with a resurgence in resistant insects, there was a rapid rebound in infection rates.
The scientists were led by Dr Jean-Francois Trape from the Institut de Recherche pour le Developpement in Dakar. The authors are worried that their study has implications beyond Senegal.
"These findings are a great concern since they support the idea that insecticide resistance might not permit a substantial decrease in malaria morbidity in many parts of Africa," they write.
But other experts in this field say that it is impossible to draw wider conclusions.
True trend?In a commentary, Dr Joseph Keating from Tulane University, New Orleans, US, acknowledges the concerns the study raises.
"If indeed this is a real trend we are seeing in this part of Senegal then it has very important implications for future malaria prevention and control strategies."
But he says there are a number of important provisos.
"I would certainly advise extending the study a couple of more years which would be helpful in determining if this is a true trend or is it something specific to that particular area.
"We need to be very careful when generalising these data to the larger continent of Africa as a whole; there is plenty of variation between communities and within communities."
Dr Keating acknowledges there is a debate within the scientific community on the issue of acquired immunity, the level of resistance to the disease that people get through being bitten.
"There is a huge discussion around acquired immunity. And how long does it take for an individual to lose this immunity once they are no longer exposed to parasite?
"So if you give someone a net he would be less exposed to parasites and it is possible that their immunity would shift to become less - but I think over all the benefits of nets certainly outweigh this potential loss of acquired immunity." (
3.8.11
Scientists Find New Superbug Strain of Salmonella
Scientists have identified an emerging "superbug" strain of salmonella that is highly resistant to the antibiotic Ciprofloxacin, or Cipro, often used for severe salmonella infections, and say they fear it may spread around the world.
The strain, known as S. Kentucky, has spread internationally with almost 500 cases found in France, Denmark, England and Wales in the period between 2002 and 2008, according a study in the Journal of Infectious Diseases.
French researchers who led the study also looked at data from North America and said reports of infection in Canada and contamination of imported foods in the United States suggest the strain has also reached there.
The study was published Wednesday as U.S. health officials reported a multi-state outbreak of another strain of antibiotic-resistant salmonella — called S. Heidelberg — which has so far made at least 76 people sick and killed one.
Salmonella infection is a major public health problem worldwide. There are an estimated 1.7 million infections in North America each year and more than 1.6 million cases were reported between 1999 and 2008 in 27 European countries.
Although most salmonella infections produce only mild gastroenteritis with stomach cramps, fever and diarrhea, older people or those with weaker immune systems are particularly at risk of life-threatening infections.
These cases are typically treated with drugs in a class of antibiotics known as fluoroquinolones, which includes the commonly-used medicine ciprofloxacin. Cipro was originally developed by Bayer and is now available as a generic.
But as with many bacteria, multi-drug-resistant, or "superbug," strains of salmonella infection have developed as the bacteria has found new ways of outfoxing the drugs, and these can spread in food and from person to person.
In the French-led study, Francois-Xavier Weill and Simon Le Hello from the Institut Pasteur looked at surveillance data from the European countries and the United States and found 489 reported cases of the superbug S.Kentucky strain. Case numbers rose every year from 3 cases in 2002 to 174 cases in 2008.
They said the earliest infections seemed to have been picked up mainly in Egypt between 2002 and 2005, but since 2006 the infections have also been acquired in various parts of Africa and the Middle East.
"The absence of reported international travel in approximately 10 percent of the patients suggests that infections may have also occurred in Europe through consumption of contaminated imported foods or through secondary contaminations," they wrote.
As part of the study, multi drug-resistant S. Kentucky was also isolated from chickens and turkeys from Ethiopia, Morocco, and Nigeria, suggesting "poultry is an important agent for infection" the researchers said, adding the common use of fluoroquinolone antibiotics in chicken and turkey production in Nigeria and Morocco "may have contributed to this rapid spread."
They said the study highlights the importance of public health surveillance in a global food system.
"We hope that this publication might stir awareness among national and international health, food and agricultural authorities so that they take the necessary measures to control and stop the dissemination of this strain before it spreads globally," the researchers said. (Fox News)
HIV infection rates mostly stable, increasing among young, gay black men
The number of new HIV infections in the United States has remained steady, at around 50,000 cases a year over the past four years, according to the Center for Disease Control and Prevention. The new data, published online Wednesday in the scientific journal PLoS ONE, show the largest increases were among bisexual men and men who have sex with men (MSM). Of that group, young, black men had what the agency called "alarming increases."
"More than 30 years into the HIV epidemic, about 50,000 people in this country still become infected each year," said CDC Director Dr. Thomas Frieden. "Not only do men who have sex with men continue to account for most new infections, young gay and bisexual men are the only group in which infections are increasing, and this increase is particularly concerning among young African American MSM."
The data look at the period between 2006 and 2009. It's the first time HIV incidence numbers were calculated using a lab test that distinguishes recent infections from existing infections. The CDC estimates that MSM make up 2% of the U.S. population but 61% of 2009's new infections. Young men between the ages of 13 and 29 who had sex with men had the highest new infection rate/increase - more than a quarter of all new cases. The agency says while young MSM of all ethnic backgrounds have been hit hard, young blacks were the only group to see significant increases over the four-year period. Infection rates among this population jumped 48% during that time.
The reasons, according to the CDC, aren't clear. It says individual risk behaviors alone do not account for the increase. It says black MSM tend to have fewer sexual partners, are less likely to do IV drugs and are no more likely to have anal intercourse than other gay men. But the data suggests a number of possibilities for these trends - that young black MSM often don't know their HIV status, that the stigma of HIV and homosexuality in the black community can often impede the use of prevention services and that often there is limited access to health care services like testing and treatment in the black community.
"We are deeply concerned by the alarming rise in new HIV infections in young, black gay and bisexual men and the continued impact of HIV among young gay and bisexual men of all races," said Dr. Jonathan Mermin, director of CDC's Division of HIV/AIDS Prevention. "We cannot allow the health of a new generation of gay men to be lost to a preventable disease. It's time to renew the focus on HIV among gay men and confront the homophobia and stigma that all too often accompany this disease."
It's not just African Americans who are disproportionately affected. The data suggest that communities of color are shouldering a heavier burden. In 2009, blacks made up 14% of the population but accounted for 44% of all new infections. Their infection rate was almost 8 times that of whites. The rate among black men was the highest of any group - more than six times that of white men. The infection rate among black women was 15 times higher than white women. Hispanics make up about 16% of the population, and 20% of new HIV infections. Their rate of infection is about three times that of whites.
Dr. Kevin Fenton, director of CDC's National Center for HIV/AIDS, Viral Hepatitis, STD and TB Prevention, says the data are encouraging in that the number of new infections has significantly dropped from the peak seen in the mid-1980s, however there is still much work ahead. "We have plateaued at an unacceptably high level. Without intensified HIV prevention efforts, we are likely to face an era of rising infection rates and higher health care costs for a preventable condition that already affects more than 1 million people in this country."
Phill Wilson, founder & chief executive officer of the Black AIDS Institute, whose mission is to stop the pandemic in black communities says we have the tools to end the epidemic, but prevention efforts have been stalled for some time.
"What these numbers tell us is we are not going to be successful in driving down new infections until and unless we invest in those populations most at risk, and in America today those populations are black Americans, men who have sex with men of all races and especially young, black men who have sex with men," Wilson said. "It is outrageous that over the last three years reported in this data, since 2006-2009, we see a 48% increase in new cases among young black men who have sex with men age 13-29. We have to build the infrastructure and the capacity in these communities to respond to this epidemic in an appropriate manner."
The agency says it's working on a number of interventions for hardest hit populations. Officials hope some of the latest new prevention strategies like pre-exposure prophylaxis (PrEP) - exposing high risk populations to HIV drugs to prevent infection in both MSM, and heterosexual men and women - will have a strong impact on infection rates. In July, new data from several studies found PrEP was safe and effective in preventing infection in these populations. (Saundra Young/CNN News)
2.8.11
Tiny blood card offers easier tests for remote areas
A cheap and portable blood test could provide a breakthrough for diagnosing infections in remote areas of the world, a scientific study says.
The mChip is about the size of a credit card and can diagnose infections within minutes, according to a study in the journal Nature Medicine.
Prototype tests for diseases such as HIV and syphilis in Rwanda showed almost 100% accuracy, it said.
The US-developed device has a projected cost of $1 (60p).
This would make it much cheaper than the lab-based tests currently used.
The plastic chip contains 10 detection zones, and can test for multiple diseases with only a pinprick of blood.
Results can be seen with the naked eye or with a low-cost detector.
"The idea is to make a large class of diagnostic tests accessible to patients in any setting in the world, rather than forcing them to go to a clinic to draw blood and then wait days for their results," said Samuel Sia, a professor at New York's Columbia University who is a lead developer of the device.
Hundreds of tests using a prototype of the device were carried out in Kigali, Rwanda. They showed 95% accuracy for HIV and 76% accuracy for syphilis, the study says.
Researchers hope to use the mChip to help increase testing of sexually-transmitted diseases (STDs) in pregnant women, particularly in Africa.
A version of the device has also been designed to test for prostate cancer. (BBC News)
31.7.11
WHO: Hepatitis toll 'in millions'
Medical experts are calling for global action to tackle the viruses that cause the liver disease hepatitis.The first worldwide estimates in drug users show 10 million have hepatitis C while 1.3 million have hepatitis B.
Writing in the Lancet, experts say only a fraction of those who could benefit are receiving antiviral drugs.
Only one in five infants around the world are vaccinated against hepatitis B at birth, they say.
The figures, published in the Lancet, show about 67% of injecting drug users in the world have been exposed to hepatitis C, while around 10% have come into contact with hepatitis B.
In the UK, around half of injecting drug users have been infected with the hepatitis C virus, while the rate for exposure to hepatitis B is 9% - the highest in western Europe.
The research was led by Prof Louisa Degenhardt of the Centre for Population Health, Burnet Institute, Melbourne, Australia, and Paul Nelson from the National Drug and Alcohol Research Centre at the University of New South Wales.
They say: "The public-health response to blood-borne virus transmission in injecting drug users has mainly centred on HIV.
"Maintenance and strengthening of the response to HIV in injecting drug users remains crucial, but the significance of viral hepatitis needs to receive greater attention than it does at present."
Commenting on the study in the Lancet, Dr Joseph Amon, of Human Rights Watch, New York City, US, said: "This study provides us with a first step and powerful data to draw attention to the problem of viral hepatitis in people who use drugs.
"The next step is to challenge governments to act, and hold them accountable for implementation of rights-respecting and evidence-based programmes."
Health risks
Hepatitis is caused by five main viruses - A, B and C, and, more rarely D and E.
Hepatitis B is the most common, and can be passed from mother to baby at birth or in early childhood as well as through contaminated injections or injected drug use.
Hepatitis C is also spread through using unsterile needles and less commonly through unsafe sex or sharing razors or toothbrushes.
The E virus, caught from infected water or food, is a common cause of outbreaks of the disease in developing countries, said the World Health Organization.
Many of those carrying hepatitis are not aware they have it and can unknowingly transmit it to others. (BBC News)
'Super antibody' fights off flu
The first antibody which can fight all types of the influenza A virus has been discovered, researchers claim.
Experiments on flu-infected mice, published in Science Express, showed the antibody could be used as an "emergency treatment".
It is hoped the development will lead to a "universal vaccine" - currently a new jab has to be made for each winter as viruses change.
Virologists described the finding as a "good step forward".
Many research groups around the world are trying to develop a universal vaccine. They need to attack something common to all influenza which does not change or mutate.
Human source
It has already been suggested that some people who had swine flu may develop 'super immunity' to other infections.
Scientists from the Medical Research Council's National Institute for Medical Research at Mill Hill and colleagues in Switzerland looked at more than 100,000 samples of immune cells from patients who had flu or a flu vaccine.
They isolated an antibody - called FI6 - which targeted a protein found on the surface of all influenza A viruses called haemagglutinin.
Sir John Skehel, MRC scientist at Mill Hill, said: "We've tried every subtype of influenza A and it interacts with them all.
"We eventually hope it can be used as a therapy by injecting the antibody to stop the infection."
Professor Antonio Lanzavecchia, director of the Institute for Research in Biomedicine, Switzerland, said: "As the first and only antibody which targets all known subtypes of the influenza A virus, FI6 represents an important new treatment option."
When mice were given FI6, the antibody was "fully protective" against a later lethal doses of H1N1 virus.
Mice injected with the antibody up to two days after being given a lethal dose of the virus recovered and survived.
This is only the antibody, however, not the vaccine.
A vaccine would need to trigger the human body's immune system to produce the antibody itself.
Sir John said the structure of the antibody and how it interacted with haemagglutinin had been worked out, which would help in the search for a vaccine, but that was "definitely years away".
Professor John Oxford, a virologist at Queen Mary, University of London, said: "It's pretty good if you've got one against the whole shebang, that's a good step forward." (James Gallagher/BBC News)
24.7.11
Life-giving plants battle death at Mount Pulag
Mount Pulag, whose fertile environment nurtures life-prolonging plant species, is in danger of dying.
Environmentalists are concerned that Mount Pulag's mossy forest, where a specie of the cancer-curing Yew tree is found , is being killed by illegal vegetable gardeners, loggers, and squatters.
One significant plant specie in Mount Pulag is the Philippine or Sumatran yew (Taxus sumatrana). A study conducted by the Kao-shiung-based Sun Yat Sen University has revealed Sumatran yew contains elements that could cure cancer.
Taxol, the revolutionary drug for ovarian and breast cancer, was developed from the bark of the Pacific Yew (Taxus brevifolia) found in the Pacific Northwest (Oregon and Washington states in the United States) forests more than 50 years ago.
The Kalanguya tribe of Pulag also believe in the life-prolonging elements of the Sumatran yew and use it as tea.
Mount Pulag is the second highest peak in the country standing 2,954 meters above sea level, connecting the provinces of Benguet, Ifugao, and Nueva Vizcaya. Its summit is covered with grass and dwarf bamboo plants. At lower elevations, the mountainside has a mossy forest veiled with fog, and full of ferns, lichens and moss. Below this is the pine forest growing on barren, rocky slopes. Falls, rivers and small lakes mark the area. This makes it a favorite of mountaineers, nature lovers and hikers.
The Park contains a unique diversity of flora and fauna, many of which are endemic to the mountain. Its wildlife includes threatened mammals such as the Philippine Brown Deer, Northern Luzon Giant Cloud Rat and the Luzon Pygmy Fruit Bat. One can also find several orchid species some of which are possibly endemic to Mt. Pulag, and other rare flora such as the pitcher plant.
One of the nation's most critical watersheds, Mount Pulag provides the water necessities of many stakeholders for domestic and industrial use, irrigation, hydroelectric power production and aquaculture. It is a major headwater for Ambuclao, Binga and San Roque dams. Destruction of the national park means the siltation of the dams.
A few dedicated workers of the Department of Environment and Natural resources (DENR) are determined to protect the 11,550 hectares wilderness created by then Pres. Corazon C. Aquino as a National Park in February 20, 1987 from illegal mountain intruders.
One day recently, Emerita B. Albas, DENR Mount Pulag parks superintendent, came to the office of Cordillera Ecological Center (PINE TREE), in tears having lost all the cases they filed in court against forest destroyers. She also said she and her staff have been receiving death threats.
As early as 2004, Albas said many intruders started bulldozing many parts of the park. Recently, they apprehended a backhoe operator ravaging Tabeyeo Lake but the case was also dismissed. The backhoe was not even confiscated by the authorities. Tabeyeo lake went dry last summer.
Roy Lupos, who once worked as a park ranger in Pulag said those who have intruded into the park are not merely gardeners. The forest destroyers are rich, he claimed. To bring in chainsaws, bulldozers and backhoes as well and trucks for the logs in clearing a forest needs millions of pesos, he stressed.
Already in the tentative list of the World Heritage Convention under natural category, the widespread destruction may derail Mount Pulag's chances of making it to the final list.
Albas said the problem in Mount Pulag is that many of the intruders claim to own parts of Mount Pulag. They make use of the Indigenous Peoples' Rights Act (IPRAS) in invoking their claim.
But by biological reality, the vast majority of the land has never been occupied. The intense growth of trees, plants, ferns and other botanical biodiversity tells of thousands of years of growth. Meaning, Albas explained, no one has really been dwelling in the forest. "So most of the intruders are outsiders," she said.
Inocencio Nerio, an agriculturist of PINE TREE said the gardeners have invaded into Mount Pulag because the cold climate favors the production of potatoes, carrots and cabbages. The same phenomenal fate that befell Mount Data National Park from 1960 to 1990 is happening to Mount Pulag, he warned.
Mount Data National Park used to be a 5,512 mossy forest. However, the mossy forest is now a mere 89 hectares, the rest are vegetable gardens. Mossy forests with pine trees, giant ferns oak trees, petroleum trees and other species exactly as those in Mount Pulag, have all been destroyed.
Even fauna like Philippine deer, cloud rat, civet cat and wild pigs used to abound in Mount Data National Park. Now, they are none left, he said. The same is happening to Mount Pulag, he disclosed.
A source within the regional office of DENR said there are persons with great influence who are behind the destruction of the forest. A few are local government officials of the municipality of Kabayan where Mount Pulag is located, others are lawyers and even one or two DENR staff themselves.
PINE TREE, in response to the plea of Albas and her park rangers, has launched a public information and education campaign to save Mount Pulag. It is using the social network Facebook to condemn the rape of the land through its group called A TRREE A DAY which has some 1,500 members in 37 countries.
It has called for legal assistance from Tanggol Kalikasana and the Legal Rights and Resources Center and will be convening a public legal forum to dramatize the plight of Mount Pulag and gain public support for the government to do its best at the soonest before things turn worse to worst.
It has made known to DENR Secretary Ramon Paje Jr. the state of Pulag as well as the death threats being received by the undermanned national park workers. (Michael A. Bengwayan,Yahoo News)
21.7.11
World Health Organization calls for TB blood test ban
More than two million such tests are carried out annually, but the WHO says they are unethical and lead to misdiagnosis and the mistreatment of patients.
The organisation's review of these tuberculosis test kits says they give wrong results in around 50% of cases.
The kits are mainly sold in the developing world.
However, most of the 18 kits on the market are produced in Europe and North America.
According to Dr Mario Raviglone, the director of the WHO Stop TB Department, the tests must be banned.
He said: "A blood test for diagnosing active TB disease is bad practice. Tests are inconsistent, imprecise and put patients' lives in danger."
The tests work by detecting antibodies or antigens in the blood that are produced in response to the bacterium.
But some of these commercial tests have what's called "low sensitivity" which leads to large numbers of patients being told they do not have TB when they do.
'Unethical'
Dr Karen Weyer, who is also from the WHO Stop TB department, added: "The evidence we reviewed over the past couple of months shows that one in two patients will be wrongly diagnosed, either [as] false negative or false positive.
"If it's a false negative patients get the all clear when they in fact have TB, the disease continues to spread, and the patients may die.
"If, on the other hand, it's false positive, patients are put on treatments unnecessarily while the true cause of their disease remains undiagnosed."
"We would describe this as unethical - and we are making a very strong urge to governments to consider that TB is a threat and the use of these ineffective tests is also a threat."
The WHO says that the tests which are manufactured in Europe and North America are prevented from going on sale where they are made due to regulations that call for extensive evidence of accuracy.
But this is not the case in the developing world - including in India and China.
Dr Weyer added: "One of the major problems is that these developing countries often have little or very weak regulatory mechanisms to make sure that tests are registered before they are used at country level.
"Another problem is that these tests are often used in the private sector, which is a difficult sector to regulate and as a result there is a wide misuse, I would say, of these inaccurate tests in the private sector in at least 17 countries that we are aware of."
She said there was a need for a TB test that could be used "at the bedside". But she added: "We don't have a blood test for TB that can be used at the point of care level."
The WHO says this call for a ban is a highly unusual move - It's the first time the organisation has issued an explicitly negative policy recommendation against a practice that is widely used in tuberculosis care.
TB kills 1.7m people every year, and is the biggest cause of death of people living with HIV. (Matt McGrath/BBC News)
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