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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Researchers have revealed that seasonal flu and swine flu cause different symptoms because they have different destinations in the body: the seasonal flu lodges itself mainly in the nasal passages, while the swine flu virus travels into the trachea and lung, and even makes its way to the intestines. It also replicates more quickly and causes more damage than the seasonal flu, according to a pair of studies published in Science.
Flu viruses wreak their havoc by binding to molecules on the surface of cells in mammals’ respiratory tracts, including humans. But the researchers found that the swine flu binds to surfaces that are unusually deep in the respiratory tract, such as the branches within the lungs known as bronchioles. The scientists used ferrets for the experiments because the animals respond to the flu much the way humans do. Research teams in the United States and the Netherlands found that the new H1N1 flu virus replicated more extensively in the respiratory tract, going to the lungs, whereas the seasonal flu virus stayed in the animals’ nasal cavity. The U.S. team also found that the new virus, unlike the seasonal one, went into the ferrets’ intestinal tract [Forbes], which explains the unusual symptoms of nausea and vomiting that some swine flu patients experienced.
Such information could prove crucial to the public health response to the swine flu, which so far has sickened more than 77,000 people worldwide, killing at least 332, according to the World Health Organization.
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In the first confirmed case of drug-resistant swine flu worldwide, a Danish patient developed resistance to Tamiflu, the antiviral treatment used for flu prevention and treatment. The patient recovered and did not appear to have passed the resistant strain to others. While a drug-resistant virus could make it harder to treat and prevent the spread of the flu, experts maintain that the isolated case is not a cause for alarm, and say Tamiflu is still effective against the swine flu.
A spokesman for Tamiflu manufacturer Roche says the Danish patient developed drug-resistant swine flu while taking the drug as a preventative to avoid the contraction of swine flu…. He was probably already infected with the virus, and resistance to the drug emerged because he was given the lower preventative dose [The Wall Street Journal]. This type of resistance is known as drug-induced resistance, as opposed to naturally occurring resistance, in which a strain itself mutates to become unresponsive to a medication.
The U.S. Centers for Disease Control and Prevention continues to recommend Tamiflu to treat the flu, along with another flu drug, Relenza. The World Health Organization also is expected to keep supporting the use of Tamiflu. Tamiflu-resistant strains of the seasonal flu have been found in Japan, which has used more than half the world’s supply of the drug each year. But those strains were weak and did not spread. A Tamiflu-resistant strain of the H5N1 bird flu was also isolated from a Vietnamese patient being treated with low-dose Tamiflu in 2005, but it also died out [The New York Times].
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Seasonal flu outbreaks typically taper off in the warm and humid summer months, as the influenza virus can’t survive as long in those conditions as it does in the cold, dry air of winter. But the current outbreak of the H1N1 swine flu virus is quite different than a typical flu season, and may produce a very different pattern of infection: It may produce an extended year-round flu season that disproportionately hits young people, health officials said on Thursday…. “The fact that we are seeing ongoing transmission now indicates that we are seeing something different” [Reuters], said Daniel Jernigan of the Centers for Disease Control and Prevention.
The swine flu outbreak, which the World Health Organization officially declared a pandemic last week, has continued to spread around the world, although its fatality rate remains fairly low. Health officials estimate that at least 100,000 people in the United States have been infected, 1,600 people have been hospitalized, and 44 have died. In another difference from typical seasonal flu outbreaks, the swine flu has disproportionately infected young, healthy people. Jernigan says its likely that older people have been exposed to a similar virus to the H1N1 virus at some point, which gives them some immune response to the current virus, while children are believed to have a “complete lack of immunity to this particular virus” [Reuters], he said.
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The World Health Organization is expected to officially classify the ongoing H1N1 swine flu outbreak as a pandemic in the next couple of days, but health officials are taking pains to stress that the “pandemic” label only indicates that the virus is spreading through communities in more than one region of the globe–it does not mean that the virus is killing everyone in its path.
WHO official Keiji Fukuda explains: “It does not mean that the severity of the situation has increased or that people are getting seriously sick at higher numbers or higher rates than they are right now…. One of the critical issues is that we do not want people to ‘over-panic’ if they hear that we are in a pandemic situation” [Reuters].
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Pest control has never looked so sweet. Scientists have found that a simple derivative of sugar can shut down the immune defenses of ravaging termites, thus leaving the insects open to attacks from bacteria and fungus. Says lead researcher Ram Sasisekharan: “When you have an immune system that is compromised, you have a variety of opportunistic infections that take over…. You give these microbes sort of a leg up to attacking more seriously” [The Scientist].
As termites cause an estimated $30 billion in crop and building damages each year, and most current methods used to combat them rely on toxins that disrupt the termites’ nervous systems. These new findings could give rise to a whole new class of safer pest-control treatments, the authors say. “We wanted something environmentally friendly, biodegradable, and [that] does not play a toxic role” [National Geographic News], says Sasisekharan.
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