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The United Nations has this week warned of a possible global resurgence of the bird flu virus, which has been widely covered in the media. News sources, such as the BBC, have also reported the circulation of a mutant strain that is able to “sidestep” current vaccines.

The UN’s Food and Agriculture Organization issued the warning after rises in the numbers of birds infected with the H5N1 strain of avian flu virus. The virus is not readily passed to humans but since it first appeared in 2003 the H5N1 strain has infected 565 people globally, 331 of whom died. However, these people were overwhelmingly individuals farming birds or raising poultry within their own homes. There is also evidence of birds in Vietnam and China becoming infected with a mutant strain that existing vaccines do not offer protection against.

It is important to remember that for people living in the UK the risk of contracting bird flu is extremely low. Although the bird flu virus is still present in other countries, the UK became officially free of bird flu in November 2008. The World Health Organization has pointed out that the evolution of the H5N1 virus poses no increased risk to public health.

 

What is avian flu?

Within birds, avian influenza, or ‘bird flu’, is a highly infectious virus that can affect species including chickens, ducks, turkeys and geese. The disease can be passed between farmed birds, wild birds and pet birds. Avian flu is spread in birds through bird droppings (which can contaminate soil), water, feed and equipment. The virus can also be carried on the feet and bodies of birds.

The bird flu virus is closely related to human flu viruses and has multiple strains or types, some of which are more dangerous than others. However, the virus does not easily transmit to humans, who generally have to be in very close contact to become infected. In cases where humans have contracted the virus it has often been in individuals farming birds or living with birds inside their homes. However, on the rare occasions that humans have contracted avian flu it has shown an ability to cause severe disease and death, often in previously healthy children and young adults.

The strain of avian flu that has caused concern in recent years is called H5N1. It is often deadly to birds, and has infected numerous species of birds in Asia, Europe and Africa. The strain has forced the culling of more than 400 million domestic poultry since it appeared in 2003.

 

Why is it in the news again today?

Bird flu is in the news because the UN’s Food and Agriculture Organization (FAO) has issued a warning over a possible major resurgence of H5N1, as well as the circulation of a new mutant strain of the virus.

The UN says that although the virus had been eliminated from most of the 63 countries infected at its peak in 2006, it remained endemic in six countries – Bangladesh, China, Egypt, India, Indonesia and Vietnam. And although the number of outbreaks in domestic poultry and wild birds shrank steadily from an annual peak of 4,000 to just 302 in mid 2008, outbreaks have risen progressively since, with almost 800 cases recorded in 2010–2011.

The UN considers the year 2008 to mark the beginning of “renewed geographic expansion” of the H5N1 virus in both poultry and wild birds, an advance that appears to be associated with migratory bird movements that may allow the virus to be carried over long distances. In the past two years, H5N1 has shown up in poultry and wild birds in countries that had been virus-free for several years. Recently-affected areas include Israel and the Palestinian Territories, Bulgaria, Romania, Nepal and Mongolia.

In Vietnam and China, a new variant of the virus known as H5N1 – 2.3.2.1 has also appeared. This strain, which is now found across most of northern and central Vietnam, can apparently sidestep the defences provided by existing vaccines. The UN says this mutant strain poses a threat to nearby countries such as Cambodia, Thailand and Malaysia, as well as the Korean peninsula and Japan further afield. Wild bird migration can also potentially spread it to birds in other continents.

The World Health Organization has pointed out that the evolution of the H5N1 virus poses no increased risk to public health. It says that human cases of H5N1 infection remain rare and occur mostly in areas where H5N1 viruses circulate regularly in poultry. However, Juan Luborth, the FAO’s chief veterinary officer has said that “preparedness and surveillance remain essential” when dealing with the threat the virus poses to farmed and wild birds, adding that “no one can let their guard down with H5N1”.

 

How is it spread to people?

The H5N1 virus does not easily infect humans, and since it emerged in 2003 it is only reported to have infected 565 people globally. It can pass directly from poultry to humans as a result of direct contact with infected birds, such as during home slaughter and plucking of infected poultry. Most cases in humans have been the result of prolonged, close contact with infected birds, among people with close associations to poultry, such as those working on chicken farms or raising chickens inside their homes.

At present the virus does not appear to be able to spread readily between humans. However, there is concern that it may undergo genetic changes that enable it to spread easily between humans, possibly by interacting with the human influenza viruses. If this happened, there would be a greater risk to people.

 

Can it be passed through food?

Avian flu is not transmitted through cooked food. In areas that have experienced outbreaks of bird flu, poultry and eggs can be safely eaten if handled and cooked properly.

 

Can I travel to affected areas?

If you are travelling in a country that has had avian flu outbreaks, do not go to live animal markets or poultry farms. Avoid bird droppings or dead birds and do not bring any live birds or poultry products back with you, including items containing feathers.

 

Do I need to take other precautions?

The risk to anyone in the UK of contracting H5N1 is extremely low, although people who work with or handle poultry are at slightly higher risk. People in this group are entitled to an annual flu vaccination. Although the current flu vaccines do not protect against avian flu, protecting against human flu reduces the risk of the viruses mixing.

You can feed wild birds and ducks but always wash your hands thoroughly afterwards and do not go near sick or dead birds. Keep away from bird droppings and wash your hands thoroughly if you accidentally touch some.

There is generally no need to change the way you look after pets, although if you have a dog that sometimes catches wild birds try to avoid areas where this is likely. In theory, H5N1 can be passed on to other animals but it is very unlikely.

It is always important to practise good hygiene, such as washing hands regularly and handling meat correctly, to prevent the spread of infection.

Links To The Headlines

Mutation of H5N1 virus could revive bird flu threat, says UN. The Guardian, August 29 2011

Mutant strain of bird flu is spreading… and it’s resistant to existing vaccines, warns UN. Daily Mail, August 29 2011

Avian flu’s back, warns UN – and new strain is resistant to vaccines. The Independent, August 30 2011

Deadly new strain of bird flu set to cause havoc in Europe this winter. Metro, August 30 2011

Bird flu fear as mutant strain hits China and Vietnam. BBC News, August 30 2011

Q&A: Bird flu. BBC News, August 30 2011

The Daily Express reported today that a “pill that stops you getting sunburn” could “prevent thousands of skin cancer deaths” and be “widely available in the UK within five years”.

This story is based on continuing research into the processes that corals use to protect themselves from damaging ultraviolet (UV) rays. Corals, and the algae that live inside them, produce compounds that protect them from the sun. The researchers examined these compounds, and believe that they can be used to develop a new type of sunscreen for humans.

This research is in its very early stages, and the compounds will still need to go through extensive laboratory and human testing before any such product might become available. The newspaper reports are based on a discovery reported in a press release, rather than on published research. As such, there is not enough detail available to judge the appropriateness of the methods that were used or the accuracy of the media reports. Further studies are needed to test the plausibility of developing a pill or lotion from this compound, the effectiveness of such a product in protecting people from UV rays and the safety of the potential product for human use.

 

Where did the story come from?

This is continuing research being carried out by researchers from King’s College London, the Australian Institute for Marine Science and the University of Maine in the US. The project is being funded by the Biotechnology and Biological Science Research Council.

The discovery of the natural compounds in the coral was described in a press release, but details have not yet been published in a peer-reviewed journal.

In general, the media did not place enough emphasis on the preliminary nature of this research, and tended to treat the study as well established and nearly complete. The different news reports were contradictory and seemingly speculative, with the Daily Express reporting that a “tablet would be available without a prescription and would be no more expensive than a sunblock”, and The Daily Telegraph and The Guardian reporting that a prescription would most likely be needed. The Daily Telegraph, however, did appropriately report that the widely quoted five-year timeline for a sunscreen pill is dependent on the research progressing as researchers hope it will.

 

What kind of research was this?

This was a field research project, during which the researchers collected coral samples from Australia’s Great Barrier Reef. The researchers studied the coral, and the algae that live inside it, to identify a compound they believe to be responsible for protecting the organisms from damage from the sun’s rays.

It is difficult to say, based on the press release, what methods the researchers used to isolate and examine this compound.

 

What did the research involve?

The researchers collected samples from the Great Barrier Reef and studied the processes the coral uses to protect itself, and the algae that live inside it, from the sun.

After identifying the compound they believe to be responsible for this protection, the researchers say they plan to recreate the compound in the lab and test its ability to protect human skin from UV damage. The researchers point out that they would be unable to harvest the coral as a source of the compound as it is an endangered species.

Based on the press release alone, it is not possible to say what stage the researchers have reached in the laboratory phase of the study.

 

What were the basic results?

The results of the study so far are limited, and it does not seem that intensive laboratory-based research has begun yet. The researchers say that “the algae living within the coral makes a compound that we think is transported to the coral, which then modifies it into a sunscreen for the benefit of both the coral and the algae”. They say that, as there is some evidence that this compound protects the algae, coral and the fish that feed on them, this suggests that the compound is “passed up the food chain”.

 

How did the researchers interpret the results?

Now that they have identified the compound that they believe to be responsible for protecting coral and algae from UV rays, the researchers plan to reproduce the compound in the laboratory and begin testing its ability to offer similar protection to humans.

The researchers also say that it may be possible to modify the pathway used by these corals to produce this compound, called the ‘shikimate pathway’ and generate crops that are able to withstand exposure to UV light. The researchers say this could enable crop plants that currently grow in temperate climates to survive in more tropical climates.

 

Conclusion

This is an interesting study on the ability of animals to protect themselves from damaging UV light. However, it is important to remember that this research is in very early stages, and it is not certain how far the laboratory-based phase of the research has progressed. It is not yet clear whether researchers will be able to reproduce the compound in the laboratory, whether the compound will be effective at protecting humans from UV rays or whether it will be safe for human use. Coral is an animal with a very different physiology and biology from humans, and it is not clear that the compound will be as effective in humans as it appears to be in the coral.

The transition from laboratory to human research to drug development is long and intensive. Before a sunscreen pill is developed, the researchers will need to reproduce the compound in the laboratory, and demonstrate its effectiveness and safety in this setting before moving on to preliminary studies in humans. We are still a long way away from turning this compound that seems to offer sea creatures protection from UV rays into a pill or lotion that offers similar protection to humans.

It is important that people take steps to protect themselves from damaging UV rays, which can increase the risk of skin cancer. For more information read our Live Well pages on sun health, which offer advice on the best way to protect your skin from damage.

Links To The Headlines

Sunscreen pill could be available within five years, scientists say. The Guardian, August 31 2011

Pill to prevent sunburn ‘within five years’. The Daily Telegraph, August 31 2011

Coral could hold key to sunscreen pill. BBC News, August 31 2011

Sunscreen pill that’s made from coral: One tablet could give weeks of protection. Daily Mail, August 31 2011

Sunblock tablet ‘just five years away’. Daily Mirror, August 31 2011

Pill that stops you getting sunburn. Daily Express, August 31 2011

Links To Science

Tropical coral could be used to create novel sunscreens for human use, say scientists. Press release, August 30 2011

“Eating high levels of chocolate could reduce the risk of cardiovascular disease and stroke,” reported BBC news. According to the broadcaster, a study has found that the highest levels of chocolate consumption “were associated with a 37% reduction in cardiovascular disease”.

The news is based on an analysis that combined the results of seven previous studies. These studies had looked at how chocolate consumption related to the risk of heart disease, stroke and metabolic diseases. Although this analysis did show that the risk of cardiovascular disease was lowered by about a third in the high chocolate consumers compared with the low chocolate consumers, it does not confirm that chocolate is “good for you”. This is because the studies available for inclusion were limited by the designs and methods they employed. Also, each study categorised chocolate consumption differently, making their results hard to combine accurately.

Based on these studies it is not possible to say whether chocolate reduces the risk of cardiovascular disease and stroke. They also do not explain how chocolate might reduce risk, for example, whether chocolate contains chemicals that are protective, or whether eating chocolate causes people to be less stressed. Chocolate is high in calories, fat and sugar, and can lead to weight gain, which is a known risk factor for heart disease and diabetes. This study does not give enough evidence to suggest that chocolate is protective of the heart.

 

Where did the story come from?

The study was carried out by researchers from the University of Cambridge. It received no specific funding. The study was published in the peer-reviewed British Medical Journal.

The newspapers advised that it is not appropriate to eat large amounts of chocolate in an attempt to reduce the risk of heart disease. This is appropriate advice.

 

What kind of research was this?

This was a systematic review and meta-analysis that aimed to identify randomised controlled trials and observational studies that had looked at whether there was an association between chocolate consumption and the risk of developing heart and metabolic disorders (including diabetes).

The researchers said some previous laboratory and observational studies have suggested that a chemical found in chocolate, called flavonol, may have the potential to be good for the heart and prevent metabolic disorders. However, the researchers wanted to look at all of the available evidence from studies in humans to see whether there is any association between chocolate intake and the risk of developing ‘cardiometabolic disorders’. These include the following conditions:

• cardiovascular disease – stroke, heart failure and heart attack
• diabetes
• metabolic syndrome – a group of risk factors that occur together and increase the risk for coronary artery disease, stroke and type 2 diabetes

 

What did the research involve?

The researchers looked for all randomised controlled trials, cohort studies, case-control studies or cross-sectional studies that had looked at chocolate and cardiovascular disease or metabolic disorders in adults. To gather studies they searched various medical and scientific publication databases, which contained publications from 1950 to October 2010.

Two reviewers independently looked at the abstracts of the papers to decide whether they were suitable to be included in the study (based on the study type and the topic of the paper). Included papers were assessed for quality. For example, the researchers assessed whether the participants’ usual chocolate consumption was measured using a validated method, whether a diagnosis of cardiometabolic disease was made through objective examinations (rather than self-reporting by participants) and whether adjustments were made for factors such as age, gender, body mass index, smoking, physical activity and other dietary factors.

Where feasible they pooled all of the data together and looked at the relative differences between high and low chocolate consumption and outcomes such as diabetes, heart disease, cardiovascular disease, death following heart disease, and incidence of stroke and deaths from stroke.

They also performed statistical tests to see how variable the studies were (their heterogeneity) and they also assessed whether there had been ‘publication bias’. This is where studies with particular results (often positive ones) are more likely to be published than those without significant findings.

 

What were the basic results?

Out of 4,576 studies that were initially identified the researchers found that seven met their criteria and were included in the review. In total these seven studies provided data on 114, 900 participants. One was a cross-sectional study carried out in the US, and the other six studies were cohort studies that had been carried out in Germany, the Netherlands, Sweden, Japan and North America. Most of the participants in the study were white, but one study also included Hispanic and African American people, and one study looked at an Asian population. The age of the participants across the studies varied between 25 and 93 years.

In three of the studies the participants were taking medication, including hormone replacement therapy drugs and drugs for cardiovascular disease.

All of the studies reported overall chocolate consumption, but did not report whether people had eaten white or dark chocolate. All of the studies reported chocolate consumption in a different manner, either by including ranges reflecting how often people ate chocolate or the grams of chocolate eaten a day. For example, one study grouped participants into three categories according to consumption levels, with the highest consumption category including people eating chocolate once a week or more. Another study categorised people into four groups, with people in the top quarter eating up to 7.5 grams a day. Given the differences in the ways each study reported and measured chocolate consumption, the researchers decided to use the highest and lowest categories in each study to measure the association of chocolate consumption and metabolic disorders.

The highest levels of chocolate consumption were associated with a 37% reduction in cardiovascular disease compared with the lowest levels (relative risk 0.63, 95% confidence interval 0.44 to 0. 90) and a 29% reduction in stroke compared with the lowest levels (relative risk 0.71, 95% confidence interval 0.52 to 0.98).

Only one of the studies evaluated the association between chocolate consumption and diabetes, and it reported a beneficial risk reduction associated with the highest level of consumption in Japanese men and women: compared with the lowest consumption they experienced risk reductions of 35% and 27%, respectively (hazard ratios 0.65, 95% CI 0.43 to 0.97, and 0.73, 95% CI 0.48 to 1.13, respectively).

 

How did the researchers interpret the results?

The researchers said that their findings confirmed that “existing studies generally agree on a potential beneficial association of chocolate consumption and a lower risk of cardiometabolic disorders”. However, they did warn that eating too much chocolate can have harmful effects. They said that corroboration is now needed from further studies to assess whether chocolate caused the effects or was just associated with a lowered risk of cardiometabolic disorders.

 

Conclusion

This research reviewed the available evidence on whether there is an association between chocolate consumption and risk of cardiovascular disease, diabetes and metabolic syndrome. It found that people who consumed more chocolate had approximately a third lowered risk of cardiovascular disease.

However, the review is limited by the quality of the available studies. It only examined studies with cross-sectional and cohort designs rather than randomised controlled trials, which would provide the best method for assessing whether a defined level of chocolate consumption had an effect on later health outcomes. Observational studies are not able to establish a cause and effect relationship, The cross-sectional study in particular was not able to establish cause and effect as it simply questioned participants on chocolate consumption at the same time as assessing coronary heart disease.

Another key problem with combining the results of these seven studies was that they had each categorised chocolate consumption differently. For this reason it is not possible to say how much chocolate is “good” for you or assess the risk of eating “high levels” of chocolate relative to “low levels” in any context. It is not possible, for example, to judge whether people eating high levels of chocolate would be eating sufficient to gain weight over time, which may in turn lead to an increased risk of cardiometabolic disorders. Also, in some studies the amount of chocolate needed to be classed in the highest consumption groups could be considered to be relatively low, as in some cases it was the equivalent of just one standard bar per week. This would mean that whether a participant had one bar or ten bars per week they would be classified in the same group, potentially distorting the results.

The researchers themselves highlight that the available data on the topic were limited and each of the studies was very different. Therefore, it is not possible to establish a clear relationship between the amount of chocolate eaten and the risk of cardiometabolic disorders.

The researchers also said that their research would need to be followed up by other studies, not only to confirm whether there is an association but also to see whether chocolate was actually responsible for the decreased risk. For example, two theories that would require testing are whether chemicals such as flavonol cause a decreased risk, or whether not denying yourself chocolate is associated with decreased stress that leads to positive cardiometabolic effects. Neither of these theories was addressed directly by this research.

Other limitations to this study were that the population was predominantly white and did not contain British participants. It, therefore, may not be relevant for the British population as a whole.

Overall, the analyses presented by these researchers are worthy of follow-up but the limitations of the studies included in this pooled analysis make it too limited to draw firm conclusions on whether chocolate lowered the risk of cardiometabolic diseases.

Analysis by Bazian

Links To The Headlines

Chocolate may protect the brain and heart. BBC News, August 30 2011

Chocolate is good for you, declares study (well, sort of). The Guardian, August 30 2011

Chocolate ‘cuts heart risk by a third’. The Daily Telegraph, August 30 2011

Links To Science

Buitrago-Lopez A, Sanderson J, Johnson L et al. Chocolate consumption and cardiometabolic disorders: systematic review and meta-analysis. BMJ 2011; 343:d4488