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Popping pills for flu fever might make things worse
THIS WEEK
A touch of flu? Hold the painkillers Debora MacKenzie
infections and increase the amount of virus we can pass on to others, says David Earn at McMaster University in Hamilton, Canada. To find out what impact this might have on a flu epidemic, Earn and his colleagues turned to a 1982 study which showed that
Tom Merton/plainpicture
NEXT time you feel the flu coming on, think twice before reaching for painkillers – they could do more harm than good. With the flu season underway across Europe and North America, millions will be taking “You shouldn’t use these flu remedies, which commonly drugs routinely for flu. include painkillers. The general Fever won’t hurt, and it medical advice in the UK and the might help” US is to take painkillers such as paracetamol (acetaminophen) or ferrets, a common animal model aspirin. But although painkillers can make you feel better they also for human flu, produced more seasonal flu virus if their fevers lower fever, which can make the were lowered either with virus worse. The first analysis of the effect of painkillers or by having their fur this on the population shows that shaved off. Earn’s team used these painkillers taken at current levels to treat fevers could cause 2000 flu findings to estimate how much more virus people with ordinary deaths each year in the US alone. Fever is thought to be an antiviral flu might produce if their fevers were suppressed, and used weapon, because many viruses epidemiological studies in people find it hard to replicate above our to estimate how many more cases normal 37 °C. But research hasn’t of flu this might cause. With the made it clear whether relieving help of a mathematical model fever slows recovery. they applied these estimates to Some studies have shown that the number of people a year in the lowering fever may prolong viral
12 | NewScientist | 25 January 2014
US who get flu, develop fever and take the drugs. They found that painkillers as used in the US could be increasing the transmission of ordinary winter flu by up to 5 per cent. Every winter 41,000 people on average, mostly elderly, die of flu in the US. So this could mean 700 to 2000 extra deaths per year, depending on the flu strain circulating (Proceedings of the Royal Society B, DOI: 10.1098/ rspb.2013.2570). Paul Andrews, a member of the McMaster team, says their estimate is conservative because it factors in only increased amounts of virus shed. Longer shedding time would also make a difference, as would people who feel better with painkillers returning to work or school while still infectious. Others are more cautious. Nick Phin, head of respiratory diseases at Public Health England, thinks the study relies too much on animal data. He says painkillers are safe and effective against flu. It is best to avoid using these drugs routinely, however, says Edward Purssell of King’s College London. He was on an official panel in England last year that recommended painkillers in children under 5 only to relieve pain. “Fever won’t hurt,” he says, “and it might help.” n
Devastating El Niños to double this century
EXTREME El Niños, which can kill tens of thousands of people, will be twice as common this century – all because of climate change. The El Niño Southern Oscillation (ENSO) has a dramatic effect on the weather. An El Niño happens when warm water spreads east across the Pacific, pushing rainfall with it to cause floods in the Americas and drought in Australia. Africa can also be hit. Despite ENSO’s influence, until recently we had no idea whether climate change would make a difference to it, since climate models disagree on whether temperatures in the Pacific will vary more in future. So Wenju Cai of the CSIRO in Melbourne, Australia, and colleagues took a different tack. They defined extreme El Niños according to their impacts on weather, rather than the changes in sea temperature. “What is really important is the rainfall,” says Dietmar Dommenget of Monash University, also in Melbourne. Defining an extreme El Niño as one where usually dry regions in South America experience a tenfold increase in rain, they found that climate models do agree after all. Models suggest that extreme El Niños should now be twice as common: about one a decade from 1990 to 2090. In the previous 100 years it was once every 20 years (Nature Climate Change, doi.org/q4c). That’s because the eastern Pacific is warming faster than the west, so peak temperatures will happen more often in the east, shifting rainfall. It is not clear if climate change has contributed to recent El Niños, but the cycle seems to be changing. Last year researchers reconstructed how ENSO had altered since 1590, and found it was more intense between 1979 and 2009 than at any earlier time (Climate of the Past, doi.org/q28). Another recent study showed that even normal El Niños will bring more severe drought and rain (Nature, doi. –Sweat it out– org/n9n). Michael Slezak n
A touch of flu? Hold the painkillers Debora MacKenzie
infections and increase the amount of virus we can pass on to others, says David Earn at McMaster University in Hamilton, Canada. To find out what impact this might have on a flu epidemic, Earn and his colleagues turned to a 1982 study which showed that
Tom Merton/plainpicture
NEXT time you feel the flu coming on, think twice before reaching for painkillers – they could do more harm than good. With the flu season underway across Europe and North America, millions will be taking “You shouldn’t use these flu remedies, which commonly drugs routinely for flu. include painkillers. The general Fever won’t hurt, and it medical advice in the UK and the might help” US is to take painkillers such as paracetamol (acetaminophen) or ferrets, a common animal model aspirin. But although painkillers can make you feel better they also for human flu, produced more seasonal flu virus if their fevers lower fever, which can make the were lowered either with virus worse. The first analysis of the effect of painkillers or by having their fur this on the population shows that shaved off. Earn’s team used these painkillers taken at current levels to treat fevers could cause 2000 flu findings to estimate how much more virus people with ordinary deaths each year in the US alone. Fever is thought to be an antiviral flu might produce if their fevers were suppressed, and used weapon, because many viruses epidemiological studies in people find it hard to replicate above our to estimate how many more cases normal 37 °C. But research hasn’t of flu this might cause. With the made it clear whether relieving help of a mathematical model fever slows recovery. they applied these estimates to Some studies have shown that the number of people a year in the lowering fever may prolong viral
12 | NewScientist | 25 January 2014
US who get flu, develop fever and take the drugs. They found that painkillers as used in the US could be increasing the transmission of ordinary winter flu by up to 5 per cent. Every winter 41,000 people on average, mostly elderly, die of flu in the US. So this could mean 700 to 2000 extra deaths per year, depending on the flu strain circulating (Proceedings of the Royal Society B, DOI: 10.1098/ rspb.2013.2570). Paul Andrews, a member of the McMaster team, says their estimate is conservative because it factors in only increased amounts of virus shed. Longer shedding time would also make a difference, as would people who feel better with painkillers returning to work or school while still infectious. Others are more cautious. Nick Phin, head of respiratory diseases at Public Health England, thinks the study relies too much on animal data. He says painkillers are safe and effective against flu. It is best to avoid using these drugs routinely, however, says Edward Purssell of King’s College London. He was on an official panel in England last year that recommended painkillers in children under 5 only to relieve pain. “Fever won’t hurt,” he says, “and it might help.” n
Devastating El Niños to double this century
EXTREME El Niños, which can kill tens of thousands of people, will be twice as common this century – all because of climate change. The El Niño Southern Oscillation (ENSO) has a dramatic effect on the weather. An El Niño happens when warm water spreads east across the Pacific, pushing rainfall with it to cause floods in the Americas and drought in Australia. Africa can also be hit. Despite ENSO’s influence, until recently we had no idea whether climate change would make a difference to it, since climate models disagree on whether temperatures in the Pacific will vary more in future. So Wenju Cai of the CSIRO in Melbourne, Australia, and colleagues took a different tack. They defined extreme El Niños according to their impacts on weather, rather than the changes in sea temperature. “What is really important is the rainfall,” says Dietmar Dommenget of Monash University, also in Melbourne. Defining an extreme El Niño as one where usually dry regions in South America experience a tenfold increase in rain, they found that climate models do agree after all. Models suggest that extreme El Niños should now be twice as common: about one a decade from 1990 to 2090. In the previous 100 years it was once every 20 years (Nature Climate Change, doi.org/q4c). That’s because the eastern Pacific is warming faster than the west, so peak temperatures will happen more often in the east, shifting rainfall. It is not clear if climate change has contributed to recent El Niños, but the cycle seems to be changing. Last year researchers reconstructed how ENSO had altered since 1590, and found it was more intense between 1979 and 2009 than at any earlier time (Climate of the Past, doi.org/q28). Another recent study showed that even normal El Niños will bring more severe drought and rain (Nature, doi. –Sweat it out– org/n9n). Michael Slezak n