Another day, another swine flu story: Amidst all the chatter, it can be hard to find the most reliable sources and relevant info. To keep you informed of the latest intelligence, 80beats will round up the news each week.
On Monday, the President’s Council of Advisors on Science and Technology issued an alarming report spelling out a “plausible scenario” for how the swine flu pandemic will play out during the coming flu season. The report estimated that the H1N1 virus could hospitalize 1.8 million Americans, potentially clogging emergency rooms and intensive care wards, and could kill up to 90,000 people in the United States. In a typical year, the seasonal flu virus kills about 35,000 Americans.
But on Tuesday, some public health officials walked back the report’s conclusions. One expert who helped prepare the report said that the numbers were probably on the high side, given that some weeks had passed since the calculations were finished in early August. “As more data has come out of the Southern Hemisphere, where it seems to be fading, it looks as if it’s going to be somewhat milder,” said the expert, Marc Lipsitch…. “If we were betting on the most likely number, I’d say it’s not 90,000 deaths; it’s lower” [The New York Times].
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Amidst concerns over the safety of DEET, scientists are on the lookout for a new mosquito repellent. Now they may have found a way to keep biting insects at bay–by blocking their olfactory sense, according to a paper published in Nature.
Mosquitoes sense the presence of humans and animals by detecting the carbon dioxide we exhale with each breath. Researchers have found two compounds, 2,3-butanedione and 1-hexanol, that could keep the biters at bay by blocking the insects’ ability to detect this gas. Using these compounds could be advantageous because the amount of chemical required is relatively small…. Further, the chemicals themselves are not complicated to manufacture and are available through conventional sources. “From both perspectives, this adds up to a viable tool in tackling the problems like that of malaria in Africa” [Scientific American], says study coauthor Anandasankar Ray. Considering the number of diseases spread by insects such as mosquitoes–for example, 250 million people contract malaria each year–there’s a lot more at stake here than a few itchy bug bites.
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Up to half of the U.S. population could contract swine flu this upcoming flu season, killing up to 90,000 people and hospitalizing 1.8 million, according to a report released by the President’s Council of Advisors on Science and Technology.
Americans lack immunity to the swine flu, which gives the virus the potential to infect more people than the seasonal flu generally does. And although many people who contract the disease might not show symptoms, and most would not be hospitalized, the pandemic would put a strain on the U.S. health-care system … because those patients could occupy between 50% and 100% of available intensive-care beds at the peak of the epidemic in affected regions, while ICU units normally operate close to capacity. Seasonal flu normally causes about 200,000 hospitalizations a year [The Wall Street Journal].
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Saving Tasmanian devils from the infectious cancer that has quickly rendered the small marsupials an endangered species will be an even harder than we realized, according to a new study. The latest bad news from Tasmania: Researchers have found that devils are not solitary creatures with small social networks, but instead frequently interact with other devils, allowing for faster spread of the disease. The devastating cancer, known as devil facial tumor disease, is spread by biting, something the aggressive animals apparently do a lot of.
Investigating the social behaviour of devils, which are nocturnal, forest-dwelling and mate underground is tricky [ABC Science], notes lead researcher Rodrigo Hamede. To get around this difficulty, Hamede outfitted 46 wild devils in a disease-free area with radio collars that recorded every time one devil approached within 12 inches of another–close enough to bite. The scientists found that all 27 of the devils from which intact collars were recovered belong to a single large social group. Each animal is connected to all the others, either directly or through connections with other animals. The finding suggests that if any one of the animals becomes infected with the facial tumor disease, the cancer would spread to the entire network [Science News].
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One of the greatest musical geniuses the world has ever seen might have been struck down at the height of his powers by a bacterial infection that school nurses yawn at. A new analysis suggests that Wolfgang Amadeus Mozart may have died of complications relating to strep throat.
Mozart died on December 5, 1791 in Vienna after abruptly taking ill about two weeks before. The cause of death for the 35-year-old man was recorded as “fever and rash,” which even in the 18th century were considered symptoms, not a disease. Many causes have been suggested over the centuries: syphilis, the effects of treatment with salts of mercury, rheumatic fever, vasculitis leading to renal failure, infection from a bloodletting procedure, trichinosis from eating undercooked pork chops [The New York Times]. As no autopsy was conducted at the time of death and the common grave that held Mozart’s remains was later dug up to make room for new graves, modern medical sleuths have little direct evidence to go on.
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Antiviral treatments such as Tamiflu should not be administered to children under the age of 12 because the risks of the drugs outweigh the possible benefits in lessening symptoms of swine flu, according to a study published in the British Medical Journal.
Although antiviral drugs can shorten the duration of the flu in children by an average of 1.5 days, they fail to fight certain effects of the infection, having little effect on the risk of asthma flare-ups, for instance. In fact, the drugs can bring dangerous side effects like vomiting, which can be dangerous because it puts children at risk of dehydration. In the research review, scientists looked at four trials of 1,766 children treated with antivirals, including 1,243 with confirmed flu, and three trials of 863 who were exposed to flu but didn’t exhibit symptoms and were treated with antivirals preventively. Only one trial looked at children with asthma [CBC]. Overuse of antivirals can also increase the risk of viral strains that become resistant to such treatments.
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The genome of an HIV virus is a truly twisted thing, but now for the first time researchers have traced its every fold and contour. By mapping its entire structure, they hope to gain a greater understanding of how the virus operates, and potentially accelerate the development of drug treatments [BBC News]. Usually geneticists focus on the sequence of genes that comprise an organism’s genome, but recent evidence suggests that the structure can also play a role in how it functions.
Like many other viruses, the HIV genome consists of single-strand RNA, rather than the double-stranded DNA found in most animals. Though scientists have identified HIV’s genes and their order, just one-fifth of its genome has been described in precise spatial detail. That’s important because genomes don’t look anything like the neatly linear, bar code-like pictures returned by basic sequencing techniques. In reality, genomes are arranged in intricate, three-dimensional loops and whorls. And just as a list of machines isn’t very useful without a description of their arrangement on a factory floor, structure matters [Wired.com].
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Researchers have determined how malaria first came to afflict humanity, and have laid the blame on our closest relative, the chimpanzee. Researchers have long known that chimps get infected with a malaria parasite of their own, called Plasmodium reichenowi, which is closely related to the human malaria parasite, Plasmodium falciparum, but they believed that the two parasites evolved from a common ancestor many millions of years ago and then developed on parallel tracks. Now a new genetic comparison indicates that the human version more likely developed from the chimpanzee type [AP].
“Current wisdom that P. falciparum has been in humans for millions and millions of years is wrong,” said study co-author Nathan Wolfe, director of the Global Viral Forecasting Initiative…. “We now know that there was a point in time when this was primarily a disease in chimpanzees that jumped and took hold in humans” [National Geographic News]. Malaria probably came to our species when mosquitoes that had previously fed on infected chimpanzees bit humans, Wolfe says, and the transmission may have happened as recently as 10,000 years ago.
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In the first known case of its kind, scientists have identified a strain of HIV that can be traced to gorillas, not chimpanzees, according to a report in Nature Medicine. The new strain was detected in a Cameroonian woman living in France.
Previous strains of HIV virus type 1, the main type of the disease, have been shown to have arisen from chimpanzees, and researchers found that the new virus is dissimilar enough from previously known strains that it cannot be detected by standard HIV tests. After genetic analysis, scientists also found that the infection is closely related to gorilla simian immunodeficincy virus, or SIVgor, the gorilla version of HIV. Genetic analysis of the woman’s virus shows that it is so closely related to SIVgor that “the most likely explanation for its emergence is gorilla-to-human transmission” [Bloomberg], says co-author Jean-Christopher Plantier.
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Malaria in Cambodia is becoming increasingly resistant to one of strongest anti-malarial treatment available, according to a study published in the New England Journal of Medicine. That could cause literally millions of deaths as malaria, already the world’s third-deadliest infectious disease, becomes unresponsive to remedies that once proved effective against the disease.
The drugs examined were derived from artemisinin, the basis of the most effective treatment for the bloodborne parasite that causes malaria. To study the treatment’s effectiveness, researchers compared the effects of artemisinin drugs in 40 malaria patients in western Cambodia and 40 patients in northwestern Thailand. On average, the patients in Thailand were clear of malaria parasites within 48 hours, compared to 84 hours for the Cambodian patients [HealthDay News]. That means the remedies were significantly less effective against the mosquito-transmitted parasite in Cambodia. Furthermore, in the time since the study concluded, healthcare workers have observed lengthened clearance times among malaria patients in southern Cambodia, indicating the resistant strain has already begun to spread.
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Clinical trials began in the Australia this week on a vaccine to thwart a possible flu epidemic of the virus that has so far killed more than 700 people worldwide. Similar trials will soon begin in the United States in the hopes of producing a vaccine in time for flu season.
Two separate seven-month trials to test a possible swine flu vaccine in Australia began on Monday and Wednesday; the studies have 300 and 240 subjects, respectively. Because it’s winter in the Southern Hemisphere, and therefore flu season, Australian authorities said it was important to test vaccines there as soon as possible. “[The Southern Hemisphere] is where the problem is right now,” Nikolai Petrovsky [director of one of the manufacturers of the vaccines in the trial] told the Associated Press. “The demand was here yesterday. We’re right in the middle of a surge of swine flu cases where perhaps the United States won’t have to worry about it as much until their flu season hits in six months” [AP].
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Developing nations may be where infectious diseases like malaria and tuberculosis flourish, but ironically, these regions often have the fewest resources for equipment to diagnose the maladies.
A new fluorescence microscope, however, could offer an affordable solution: One that attaches to an ordinary mobile phone. Once snapped on to any mobile phone that has a basic camera function, the microscope can illuminate pathogens, allowing the viewer to identify them and even send the image to a health care facility, according to an article published in the journal PLoS ONE.
To use the device, called the CellScope, fluorescent molecular “tags” are added to a blood sample, which attach themselves to a certain pathogen, such as tuberclosis-causing bacteria. The pathogens are then illuminated by microscope, which uses cheap commercial light-emitting diodes as the light source – in place of the high-power, gas-filled lamps used in laboratory versions of the device, and cheap optical filters to isolate the light coming from the fluorescent tags [BBC News]. The apparatus allows the viewer to “see” things as small as one-millionth of a meter.
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In September 2007, HIV research faced a serious setback: Scientists found that a promising HIV vaccine was actually increasing the rate of HIV infection, and the so-called STEP vaccine trial was immediately halted. The failure had a ripple effect, and caused researchers to call off another vaccine trial that operated on a similar principle. Since then, researchers have developed multiple explanations for why the vaccine upped the risk of infection. Now two new studies presented in Nature Medicine refutes the latest of these hypotheses, which gives researchers valuable information but ultimately leaves the mystery unsolved.
The recent theory held that some people responded more strongly than others to a component of the vaccine tested in the STEP trial, making them more vulnerable to HIV, which attacks immune cells that are actively responding to a pathogenic threat [Nature News]. Because the vaccine was constructed on the modified backbone of the virus that causes the common cold, the theory posited that white blood cells called helper T-cells jumped into action to combat this infectious particle. Unfortunately, HIV targets these T-cells, scientists reasoned, so vaccination actually gave HIV a larger target. This would explain why vaccination increased the risk of HIV infection.
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Genetic “pieces” of the 1918 flu virus, which killed between 50 and 100 million people worldwide, were likely circulating between pigs and people two to 15 years before the pandemic struck, according to a new study published in Proceedings of the National Academy of Sciences.
Catch two different flu viruses at once and a new one can emerge, something scientists call reassortment. Birds are the ultimate origin of influenza viruses, but because pigs can catch both bird and human flu strains, they’ve long been recognized as a species mixing vessel [AP]. The research shows that lethal flu strains may be the result of such reassortment of pre-existing strains, not a sudden genetic “jump.” It’s a cautionary tale for those studying the current swine flu outbreak, say researchers, as the findings suggest that the swine flu virus could evolve slowly over many years into a more dangerous form.
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It’s unknown whether the swine flu virus will mutate to a more deadly strain in the coming year, but the federal government is preparing for the worst in case the pandemic continues to spread. At yesterday’s flu summit at the National Institutes of Health, Health and Human Services Secretary Kathleen Sebelius revealed the government’s provisions for a possible swine flu emergency.
The campaign to combat the swine flu is different from the strategy usually employed against the seasonal flu. One reason is that the swine flu appears to be most deadly to children and young adults, while the seasonal flu traditionally is most fatal to the elderly. Therefore, if mass vaccination becomes necessary, school-aged children will be among the first to be immunized; this likely will occur at school, in a manner reminiscent of the 1950s polio vaccination campaign. “We are likely to have a different target population,” Sebelius said. “We will be seeking partnerships with schools potentially and other vaccination sites.” Time will have to be spent writing consent forms so parents are not blindsided when schools ask to vaccinate their children, Sebelius said [Reuters]. States should also prepare a plan for closing schools if needed.
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