Blogs / 80beats

To combat the persistent scourge of dengue fever, researchers have infected the virus-carrying mosquitoes with a bacterium that kills them before they’re old enough to transmit the virus to humans. Researchers say this “biopesticide” technique could cheaply and quickly reduce deaths due to dengue fever in the tropics, as the bacterium could rapidly spread through mosquito populations. Traditional [malaria-oriented] methods for controlling the spread of mosquito-borne disease, such as using bed nets and draining wetlands, are ineffective for the Aedes aegytpi mosquitoes that spread dengue fever virus because they bite during the day and thrive in urban areas [Nature News].

While the new process has only been tested in the lab thus far, researchers are very optimistic about the possibility of whittling away at the 20,000 deaths caused each year by the disease, and say it’s conceivable that transmission of the virus could be reduced to nearly zero. “We’re not trying to eliminate the population, but to let a bacterial symbiont in, and then shift the population,” said University of Queensland bacterial geneticist Scott O’Neill. “There will still be mosquitoes around, but only young ones. It’s a biological control” [Wired News].

(more…)

Flu season is taking a toll on chicken farms across Asia, where new bird flu outbreaks are cropping up from China to India, leading to massive poultry slaughters. Health officials say the chickens are infected with the deadly bird flu strain known as H5N1, but thus far there have been only a few cases of human infection. Two human cases have been reported in Indonesia, one in Cambodia, and in Egypt a 16-year-old girl died of the virus. Yi Guan, a Hong Kong microbiology professor, says the recent spate of cases across the region may not be completely isolated and would likely get worse as winter sets in, when the risks of influenza tend to peak [The Wall Street Journal].

In China, more than 370,000 chickens were culled after an outbreak was announced in the eastern province of Jiangsu. The usual precautions have been imposed: birds have been slaughtered in the surrounding area, farms quarantined and disinfected, and the transport of fowl banned. But no information has been released about the scale of the outbreak - how many birds were found to be carrying the H5N1 strain of the virus and how many of them died [BBC News]. Chinese authorities say migrating birds probably brought the virus to local farms.

(more…)

A new device smaller and cheaper than a postage stamp could be used to diagnose diseases in developing countries, Harvard researchers report. The sophisticated microfluidic diagnostic devices, called microPADS, are made out of little more than paper and sticky tape and cost about three cents each. “The starting point with us was asking, ‘What’s the simplest, cheapest [material] we could think of?’ … And that was paper,” [The Scientist] said co-author George Whitesides.

The microPADs, described in the Proceedings of the National Academy of Sciences [subscription required], are made with layers of paper and water-proof tape. Tiny holes and channels etched into the paper lead from a small number of single wells on top and branch out through the stack to an array of microwells on the bottom [IEEE Spectrum]. When liquids such as urine or blood is placed in the upper wells, they are absorbed through the channels into the microwells, which contain proteins, antibodies, or other chemicals. A color-change reaction indicates the absence or presence of a disease. Because the device splits one sample into dozens of separate microwells, several tests can be performed simultaneously. The prototype microPADs transported four separate liquid samples to 64 designated reservoirs within 5 minutes. In 27 out of 30 tries, the devices moved the liquids without mixing them [ScienceNOW Daily News].

(more…)

Firing new shots in the malaria war, a vaccine still in the testing stage is now a step closer to becoming a public health reality [Science News]. Two field trials in Kenya and Tanzania showed that the experimental drug reduced malaria infections by more than 50 percent in infants and young children; if a final set of trials proves that the vaccine is indeed safe and effective, the vaccine could be ready for use by 2011.

If the phase three trials are successful, it would be “an extraordinary scientific triumph,” said Dr. W. Ripley Ballou, deputy director for vaccines and infectious diseases for the Bill and Melinda Gates Foundation, which helped fund the research. But more importantly,” Ballou added, “it could save millions of children’s lives” [Los Angeles Times]. Malaria kills about 1 million people around the world each year, and most of the victims are children under the age of five.

(more…)

The nasty parasite known as Guinea worm that has plagued humans since the days of the ancient Egyptians is on the verge of being completely eradicated, former president Jimmy Carter declared on Friday. The Carter Foundation has led the effort against Guinea worm, which could soon be remembered as the second disease to ever be wiped out by human efforts, smallpox being the first. There have been fewer than 5,000 cases of the disease in six African countries this year, and on Friday Carter announced two new grants dedicated to wiping out the final hotspots: The British government has pledged $15 million, while the Bill and Melinda Gates Foundation will contribute $40 million.

Guinea Worm is one of the worst parasites you can get. The worms burrow inside of you, grow to almost three feet long, are incredibly painful, and finally pop out of the skin and have to be reeled out, inch by inch, over many days [The New York Times blog]. The parasites have been found in Egyptian mummies, and the official name for the infection, dracunculiasis, references an archaic-sounding pain: it’s Latin for “affliction with little dragons.” Doctors have no vaccines or medicine with which to combat the parasite; instead they rely on prevention to keep people from getting infected. However, humans are the only host for the parasite, so ending outbreaks in human populations would destroy the worm forever.

(more…)

Happiness is catching and spreads like the flu, according to a study that followed a whole community of people for 20 years. The effect of one happy person could ripple through three degrees of separation, researchers report. “It is sometimes said that you can’t be happier than your least happy child. It is truly amazing to discover that when you replace the word ‘child’ with ‘best friend’s neighbor’s uncle,’ the sentence is still true,” [Boston Globe] said psychologist Daniel Gilbert, who was not involved in the study. The researchers liken the pattern of happiness transmission to the spread of a virus: those with the most number of happy contacts are the mostly likely to catch the happy bug.

The study, published in the British Medical Journal, followed more than 4,700 people living in Framingham, Massachusetts from 1983 to 2003. The participants answered periodic questionnaires about their emotional well-being and listed the names of relatives, friends, and co-workers, many of whom were also participating in the study. Researchers found that happiness wasn’t scattered evenly throughout the population but instead seemed to spread through social networks. “Happiness is like a stampede,” said [co-author] Nicholas Christakis… “Whether you’re happy depends not just on your own actions and behaviors and thoughts, but on those of people you don’t even know” [AP].

(more…)

The official death toll from the cholera outbreak in Zimbabwe has climbed to nearly 500, according to the World Health Organization. But doctors on the ground say the actual fatalities may be closer to 1,000, with more than 12,000 infected since the start of the outbreak in August. Severe shortages of clean water, food, and medicine have allowed the normally treatable illness to ravage the country. Poorer areas have been without running water for months and just this week, the government cut off water to the nation’s capital, Harare. “The country is reaching a catastrophic level, in terms of food, health delivery, education,” said Morgan Tsvangirai, the MDC [opposition party] leader. “Everything seems to be collapsing around us” [Times Online].

Authorities say they have run out of water-purifying chemicals and have therefore shut down the water system in an attempt to contain the waterborne disease. But without running water, sanitation systems are nonexistent and sewage lies in the open air. “Proper hygiene is the best protection against cholera and you can’t do that without clean water,” [BBC News] said Marcus Bachmann of Doctors Without Borders. Residents have resorted to digging shallow wells and using contaminated water despite the government’s warning to use only boiled water. “We are afraid but there is no solution, most of the time the electricity is not available so we just use the water,” resident Naison Chakwicha said [USA Today]. The Health Minister has even asked residents to stop shaking hands. “Although it’s part of our tradition to shake hands, it’s high time people stopped,” he said [CNN].

(more…)

Somewhere in the world within the next five years, terrorists are likely to use a biological agent like anthrax or Ebola in a major attack, a new congressional report predicts. The report acknowledges that terrorist groups still lack the needed scientific and technical ability to make weapons out of pathogens…. But it warns that gap can be easily overcome, if terrorists find scientists willing to share or sell their know-how. “The United States should be less concerned that terrorists will become biologists and far more concerned that biologists will become terrorists,” the report states [AP].

The report, which will be officially released on Wednesday by the Commission on the Prevention of Weapons of Mass Destruction and Terrorism, covers the threat of both biological and nuclear attacks. It argues that bioterrorism is a greater threat: Nuclear facilities are closely guarded, the report says, while many civilian labs contain dangerous pathogens and could more easily be breached. The number of such “high-containment” labs in the United States has tripled since 2001, yet U.S. officials have not implemented adequate safeguards to prevent deadly germs from being stolen or accidentally released, it says. “The rapid growth in the number of such labs in recent years has created new safety and security risks which must be managed,” the draft report states [Washington Post].

(more…)

To mark World AIDS Day yesterday, researchers engaged in a “thought experiment” meant both to demonstrate the challenges and the possibilities confronting a world beset by the HIV virus. What would happen, they asked, if everyone was tested annually for HIV, and all people with positive results were immediately put on antiretroviral drugs? In a new study published in the journal The Lancet [subscription required], researchers predicted what the effects of such a policy would be in South Africa. They worked out that treating everyone with the virus with antiretroviral drugs would reduce incidence from 20 per 1000 people to just 1 per 1000 within 10 years…. That’s because the drugs keep levels of the virus in the blood down, making people less infectious - even if they have unsafe sex [New Scientist].

Currently, people have to seek out HIV tests, and those who don’t engage in high-risk behavior (like unsafe sex or intravenous drug use) often never get tested. In addition, the expensive antiretroviral drugs currently aren’t prescribed to HIV-positive patients until their immune systems are compromised and they begin to show symptoms of AIDS. The researchers argue in their article that present policies aren’t working, as 33 million people around the world are currently infected with HIV. The American College of Physicians also released new recommendations this week, advising doctors to routinely screen all patients if possible.

(more…)

Indonesia’s Papua province may be the first region in the world to force some HIV/AIDS patients to be implanted with microchip trackers. A controversial bill requiring the extreme measures already has full backing from the provincial parliament and will become law with a majority vote from the provincial legislative body. The microchips are meant to monitor “aggressive” sexual behavior in an effort to control the spread of the disease. Lawmaker John Manangsang said, “It’s a simple technology. A signal from the microchip will track their movements and this will be received by monitoring authorities” [Reuters].

The bill does not specify who would qualify as “sexually aggressive” patients, but if the bill is passed, a committee will be formed to decide who will be implanted; the executive director of the committee will be a physician with a knowledge of epidemiology. Supporters say authorities would be in a better position to identify, track and ultimately punish those who deliberately infect others with up to six months in jail or a $5,000 fine [AP]. Meanwhile, health care workers and AIDS activists called the proposal “abhorrent” and a clear violation of human rights. “No one should be subject to unlawful or unnecessary interference of privacy,” [said Nancy Fee, the UNAIDS country coordinator], adding that while other countries have been known to be oppressive in trying to tackle AIDS, such policies don’t work. They make people afraid and push the problem further underground, she said [AP].

(more…)

In a remarkable announcement, German researchers have declared that they “functionally cured” a patient of AIDS, eradicating all traces of the virus from his body. The feat was accomplished with a bone marrow transplant from a donor who had a genetic resistance to the virus, and researchers say that 20 months later they can find no trace of the virus in the patient’s blood, bone marrow, or organ tissue.

But the accomplishment shouldn’t be taken as a sign that a cure for the 33 million people living with AIDS is around the corner, researchers are hasty to add. Professor Rodolf Tauber from the [German] clinic said: “This is an interesting case for research. But to promise to millions of people infected with HIV that there is hope of a cure would not be right” [BBC News]. Reasons for this caution include the small number of potential donors with the HIV-resistant mutation, and the difficulty and expense of bone marrow transplants.

(more…)

How do you get a snot sample from a shy behemoth of the deep? That question stumped researchers studying whale health, who wanted to give the animals check-ups without corralling and traumatizing them. Now, researchers have come up with an ingenious answer, flying a remote-control helicopter through the jets ejected by the whales’ blowholes. The helicopter has petri dishes strapped to it, which collect any bacteria, fungi, and viruses that were in the whales’ lungs.

The collected samples could make a big contribution to scientists’ understanding of infectious diseases in whale populations. Researcher Karina Acevedo-Whitehouse explains: “We don’t know much about them because they are so big and they are in the water all the time, and that makes it really difficult to obtain biological samples that are relevant to determining health in these populations; unless they’ve already stranded or unless they are in captivity, which are hardly representative of a normal population” [BBC News].

(more…)

Scientists say they have bred super immune cells that are able to recognize and destroy many variants of HIV-infected cells. The news comes after a bleak year for AIDS research that saw the failure of the Merck HIV vaccine trial and the cancellation of another. “I think the field as a whole has been taking a step back and thinking we need some different ideas all together,” [New Scientist] said immunologist Philip Goulder.

The researchers’ novel idea was to create a mutant type of immune cells, called T-cells, that would target SL9, a protein that is part of HIV and also appears on the surface of HIV-infected cells. They started with particularly strong T-cells taken from a patient who had resisted HIV infection. “When we tested the T cells from this patient, it looked as if he was responding to a number of those variants that normally escape the immune system,” [The Guardian] said researcher Brent Jakobsen. Through a process of directed evolution, the researchers selected for T-cell mutants that had receptors enhanced to recognize and latch onto SL9. In Nature Medicine [subscription required], the researchers report that in lab cultures of human cells, the souped-up T-cells easily destroyed HIV-infected cells and even recognized tricky variants of the SLP9 protein.

(more…)

The chicken industry has been remarkably effective in breeding efficient egg-layers and plump-breasted broilers, but a new study says that focus has created a chicken population that lacks genetic diversity, leaving the birds more vulnerable to diseases. The study found that industrial chickens have lost about half of the genetic variations once found in the wild chicken populations, and some have lost 90 percent of those genes.

This means most of the world’s chickens lack characteristics that evolved when they lived in the wild, and may be useful again to help them face stress and disease as livestock. Scientists want to breed DNA for traits such as disease resistance, or “animal well-being”, back into commercial birds without introducing undesirable traits at the same time [New Scientist]. Researchers say the biggest concern is that if commerical chickens are nearly identical genetically they’ll all be susceptible to the same infectious diseases, and an outbreak of of a ailment like avian flu could devastate the entire industry.

(more…)

Eating red meat could make your body more vulnerable to a dangerous bacterial toxin, according to a new study. A sugar molecule, Neu5Gc, found in beef, lamb, pork, and unpasteurized milk can attach itself to the cells lining the human intestines and act as a magnet for toxins produced by certain strains of E. coli, often carried in the same meats. The result is bloody diarrhea and sometimes death. “This uncovered the first example of bacterium causing disease in humans by targeting a molecule which is incorporated into our bodies through what we eat,” [ABC Science] says researcher Travis Beddoe.

The study, published in Nature [subscription required], was conducted in petri dishes using mouse tissues and human cells. The scientists tested human gut and kidney cells steeped in these sugar molecules and discovered that the toxin was about seven times more likely to bind to these cells if the sugar was present. It is still “not clear how to extrapolate this precisely to the human body,” [Science News] says co-author Ajit Varki. That is, researchers don’t know exactly what it means for human health yet. (more…)