World Hepatitis Day 2014

5279776905_4f0477d2fc_zToday is World Hepatitis Day, which is marked by the World Health Organization (WHO) to raise awareness of a disease that continues to claim millions of lives around the world every year. Predominantly a viral disease, hepatitis is primarily characterised by an inflammation of the liver, followed in many cases by liver cirrhosis, liver failure or liver cancer.

There are five different hepatitis viruses, known as A, B, C, D and E, which all cause a different variant of the disease. All five hepatitis viruses can cause short-term (“acute”) infection; hepatitis B, C and D infections can also be long-term, or chronic, and may cause liver cancer and liver failure. An estimated 1.5 million people die of hepatitis infections every year, with Hepatitis B and C causing the large majority of these deaths.

Besides the viruses themselves, a number of other factors can also cause hepatitis or increase predisposition to it. Long-term excessive alcohol consumption and some medications and antibiotics increase the likelihood of liver cirrhosis and liver failure. Those with impaired immune systems may experience autoimmune hepatitis, where the body attacks its own liver cells. Finally, some 40% of all babies born to mothers who suffer from hepatitis B also have the disease. A vaccination is required within the first few hours after birth to prevent a continued infection in the child.

In England, hepatitis C is the most common type of viral hepatitis, affecting some 215,000 people. It is mostly spread through sharing needles for intravenous drug use, and many people are unaware that they have the virus, as the disease rarely exhibits symptoms early in the infection. In 75% of cases, the virus stays in the body and causes chronic hepatitis C, which can lead to liver cirrhosis and liver failure. There is no vaccine against hepatitis C, and while antiviral medication does exist, it can have very unpleasant side effects.

Hepatitis B, which is mainly transmitted through blood and other bodily fluids, is one of the most widespread infectious diseases worldwide. The WHO estimates that 240 million people suffer from chronic hepatitis B and 780,000 die every year, making it a major global health problem. Continue reading

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Microbe Talk: July 2014

493374987Dr Bryn Dentinger, a researcher at the Royal Botanic Gardens, Kew, bought a packet of dried porcini mushrooms in a local shop. Being an expert in fungi, Bryn wanted to know what species of porcini he had purchased, so he sequenced the dried mushrooms’ DNA (obviously) and was rather surprised at the result. Ben went to Kew to talk to Bryn about fungi and about his discovery…

Also on the podcast this month, we interviewed Artemis Louyakis, who studies Thrombolites: tough, rock-like structures, which are actually macrocolonies of bacteria. Artemis tells us about her research and the practical uses that these structures might have in space travel.

Show Notes:

  • Bryn’s paper ‘What’s for dinner?: Undescribed species of porcini in a commercial packet’ via PeerJ.
  • Bryn’s homepage.
  • Information on Thrombolites in Australia.

If you’re accessing this page on your iPhone and can’t see the podcast player, you can subscribe to Microbe Talk on iTunes.

Benjamin Thompson

Image Credit: Thinkstock
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We’ll have no bananas?

BananasReports of the imminent demise of the world’s most popular fruit have surfaced repeatedly over the course of the last decade. Bananas, particularly those grown in large monocultures for the hungry markets of the EU and the US, are vulnerable to a number of diseases, and fears are mounting that the tide is turning against our prevention and mitigation strategies. How much stock should we put in these reports – are the days of the banana truly numbered? Jon Fuhrmann investigates.

A fungal disease called Fusarium wilt, also known as Panama disease, is causing the most concern among banana producers. In the last 20 years, a new and particularly dangerous strain called Tropical Race 4 (TR4) has infected the Cavendish banana, the only widely available banana type in western supermarkets. Reports of the disease are now coming in from the Middle East and East Africa, a long way from the disease’s Southeast Asian origins.

Panama disease itself is not an unknown entity. In the first half of the 20th century, a different strain (Race 1) effectively wiped out the Gros Michel-type banana, which dominated the world markets at the time. Those who have tasted Gros Michel wax lyrical of its superior taste and texture, sweeter and more delicate than the Cavendish-type bananas we buy in supermarkets today.

Indeed, the Cavendish bananas are merely a second-best solution, adopted after Panama disease rendered Gros Michel commercially infeasible. The big banana exporting companies clung to Gros Michel because consumers preferred the taste and their hardiness meant lower transport costs compared to those needed for the Cavendish fruit. While possibly apocryphal, the song ‘Yes! We Have No Bananas’ may relate to the difficulties that American consumers faced after Panama disease destroyed the Gros Michel crops that supplied the US.

As a result, Cavendish bananas, which are resistant to the fungus, became the bulk of worldwide trade and have remained so for the past sixty years. During this time, a variety of bacterial and fungal diseases have plagued banana plantations and prompted ever more extreme levels of fungicide spraying, which affects both plants and plantation workers – but Cavendish continues to dominate.

Tilting at windmills

In the early 1990s, a new strain of Fusarium wilt was discovered in Southeast Asia and christened tropical race 4 (TR4) due to its prevalence in tropical regions. Cavendish bananas are highly susceptible to TR4, which is resistant to fungicides and spreads rapidly through a plantation after initial infection. The fruit are unable to evolve resistance to the fungus because all Cavendish bananas are genetically identical and grown from a homogenous seed stock.

Confined to Southeast Asia and the Pacific region for the best part of a decade after its discovery, TR4 did little harm to the West African and Latin American plantations supplying western markets. In the last decade, however, reports of the disease have appeared from Oman, Jordan and Mozambique. The disease is clearly on the move – but how did it spread over such large distances so suddenly? Unsurprisingly, human action is the probably to blame. Workers, machinery and plant material all move between banana-producing regions, and contaminated soil on tools or boots can introduce TR4 to new regions.

The end of Cavendish?

It is unlikely that TR4 will cause Cavendish-type bananas to become extinct – although it may cause significant problems to the huge monocultures in which the plants are grown, as was seen with Gros Michel. Fusarium wilt spreads rapidly through adjacent plants but is not easily spread over large distances like some other air- or waterborne pathogens such as Phytophthora ramorum, which causes sudden oak death. This means that smallholders are much more likely to be able to grow Cavendish bananas even if the larger export market is in decline. Again, this is true of the Gros Michel variant, which can still be found in marketplaces in Southeast Asia.

Of course, there is a chance that Cavendish bananas will become commercially infeasible if TR4 continues to spread through Africa or reaches the Americas. To prevent this, stringent controls are needed to halt the spread of the fungus. Examples of this exist in Australia, where the state of Queensland has implemented strict biosecurity measures and has so far managed to keep Fusarium wilt at bay despite its prevalence in the adjacent Northern Territory. It may prove more difficult to enforce such measures across the multiple borders present in Latin America.

Are there alternatives?

While Cavendish is by far the most common banana used in export, there are a large number of other banana varieties cultivated around the world. These bananas feed millions of people around Asia and Africa, and scientists are testing them to find which ones are resistant to TR4. This means that while Cavendish is, of course, an important food crop in many parts of the world, its disappearance from mass production is unlikely to cause a food security crisis in low- or middle-income countries, as alternatives are available.

As for western countries importing bananas, the situation is less straightforward. While the precedent of Gros Michel’s fate in the 20th century gives us some idea of a potential outcome, the difference is that when Gros Michel became infeasible, the Cavendish variety was already known as a potential replacement. Currently, there is no such replacement for Cavendish.

Mitigating the Musa menace

While many researchers think it likely that TR4 will eventually spread to the Americas, delaying this event allows more time for effective countermeasures to be put in place and for research to continue on resistant banana varieties.

For Western consumers and exporting companies, the task at hand is twofold. Scientists are working to develop resistant varieties that display as many of Cavendish’s positive attributes as possible. While a few such Cavendish-based varieties have been made, they either require prohibitively expensive modifications to the transportation process or are unlikely to be accepted by consumers because their shape or taste are too different.

Additionally, consumer tastes will have to change if a new kind of banana is to find widespread acceptance and commercial success. It may be that the banana of the future will be a different average size or shape, or that it ripens differently so that greener or browner bananas become more common on supermarket shelves.

Fortunately, it seems unlikely that bananas will be lost forever. As the downfall of Gros Michel shows, even a crash in the world’s most grown banana will not lead to a complete demise of the fruit. Research, information dissemination and appropriate management can combine to produce a brighter future for bananas.

Jon Fuhrmann

The Society has recently produced a briefing document on banana disease, which further outlines the problems facing banana growers. You can find it here.

Image credit: Ian Ransley on Flickr
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New to Science: July 2014

BambooEach month, the Society for General Microbiology publishes the International Journal of Systematic and Evolutionary Microbiology, which details newly discovered species of bacteria, fungi and protists. Here are a few of the new species that have been discovered, and the places they’ve been found. The full papers are available to journal subscribers, but the abstracts are free to read.

While summer is well and truly upon us in England, many of us are staying in to watch the plethora of fantastic sporting events that are keeping us glued to our television sets. While Wimbledon and the Tour de France brought numerous world-class athletes onto British soil, the football World Cup in Brazil will nevertheless remain the focal point of global attention until its conclusion on Sunday 13 July.

Despite the proceedings in the country’s stadia, Brazilian scientists remain hard at work cataloguing our planet’s microbes. In the Amazon rainforest, researchers from Rio de Janeiro teamed up with colleagues from Belgium and Australia to identify Bradyrhizobium manausense in cowpea, an important food crop in the area. The new species is named after Manaus, the biggest city in the Amazon rainforest (and the site of England’s defeat to Italy in the World Cup). Continue reading

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Opinion: The Longitude Prize and antibiotic research funding

methicillin-resistant Staphylococcus aureus and a dead human neutrophilCash prizes have long been the drivers of scientific innovation, be it in the development of synthetic blue pigment in 19th century France, or the XPrize’s continuing efforts to award those developing “radical breakthroughs for the benefit of humanity”.

This year, Nesta relaunched the Longitude Prize, first offered by the British Government in 1714 as a reward for solving a major problem of the day – determining a ship’s longitude. The original prize was won by the clockmaker John Harrison, who received around £15,000 for his efforts, which equates to over £1.8 million in today’s currency.

300 years later, the reborn 2014 Longitude Prize is even bigger – offering a fund of £10 million to those interested in solving the major problems that affect mankind today. The prize opened with a vote that allowed the public to decide which challenge they thought was most deserving. As Chief Executive of the Society for General Microbiology, I’m delighted to say that the winning challenge of the Longitude Prize 2014 is ‘Antibiotics’.

The prize’s website says the fund aims “to create a cost-effective, accurate, rapid, and easy-to-use test for bacterial infections that will allow health professionals worldwide to administer the right antibiotics at the right time.”

This mirrors a call made in the Society for General Microbiology’s recent report Microbiology and the challenge of sexually transmitted infections, in which we state that the development of rapid point-of-care diagnostic devices will have a major impact in slowing the spread of antimicrobial-resistant bacterial infections, some of which – for example, gonorrhoea – threaten to become resistant to all available drugs and, ultimately, untreatable. Continue reading

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From Poo to Papillomavirus: Peculiar Penguin Pathogens

Adélie penguinsResearchBlogging.orgPenguin poo has seen a surprising range of scientific applications, from a comprehensive census of emperor penguins from satellite data to a calculation of the rectal pressures required to avoid defecating into their own nests; the latter research, unsurprisingly, even won the 2005 Ig Nobel Prize in fluid dynamics. More recently, the droppings of Adélie penguins were studied from a different angle in research published in the Journal of General Virology. Dr Arvind Varsani, a virologist at the University of Canterbury in Christchurch, New Zealand, isolated a previously unknown species of virus from these droppings and produced the first fully identified genome of any penguin-associated virus.

So far, we have only scratched the surface of the world of viruses. While we are aware of a significant proportion of mammal and reptile species, we only know an estimated 1% of all virus species – and within this 1%, most research focuses on viruses that cause disease in humans, certain animals and plants. The new virus Dr Varsani and his team discovered in the Adélie droppings is a species of papillomavirus. This is a large family of more than 270 virus types, over 160 of which infect humans; some of them are benign, while others can cause warts on various parts of the body or even cause cancer. The remaining 100-odd strains are found in a wide variety of animals – mostly mammals and a handful of reptiles. However, the Adélie papillomavirus is only the fourth species known associated with birds. Continue reading

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Microbe Talk: June 2014

Keble_College_ChapelThis month on the Podcast, we sent Ben to Keble College at the University of Oxford, to attend a conference that celebrated the 50th anniversary of the first paper to detail the Epstein–Barr virus. The virus, also known as EBV, was the first virus shown to cause cancer in humans.

On the podcast this month:

Sir Anthony Epstein, who was one of the co-discoverers of EBV and published the first paper on the virus, in the Lancet in 1964.

Professor Paul Farrell (Imperial College London), who was an author on the first paper that detailed the genetic sequence of EBV.

Professor Jeffrey Cohen (US National Institute of Allergy and Infectious Diseases), who is working to develop a vaccine against the virus.

Show notes:

  • Information on the Epstein-Barr Virus via Wikipedia.
  • A great write up about EBV’s history on the CRUK blog.
  • Professor Farrell’s research page.
  • The Nature paper that first published the EBV genetic sequence.
  • Dr Jeffrey Cohen’s research page.

If you’re accessing this page on your iPhone and can’t see the podcast player, you can subscribe to Microbe Talk on iTunes.

Benjamin Thompson

Image Credit: David Iliff under CC-BY-SA
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