We’re told that we can insert a gene to confer sterility and this trait would race like wildfire through Aedes aegypti. Why this species? Because it’s the vector of the Zika virus—along with the dengue and yellow fever viruses. The problem is that A. aegypti isn’t the only culprit. It’s just one of a dozen or more bloodsuckers that will also have to be wiped out. After we’ve driven these species to extinction, we’ll presumably move on to the Anopheles species that transmit malaria.

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Over two years ago I wrote that “new viruses are constantly being discovered... Then something comes out of the woodwork like SARS which causes widespread panic”. Zika virus infection bids fair to repeat the torment. On 28 January 2016 the BBC reported that the World Health Organization had set up a Zika “emergency team” as a result of the current explosive pandemic.

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This summer intrepid travelers everywhere are strapping on backpacks, dousing themselves in mosquito spray, and getting their inoculations -- ready to embark on journeys that will take them into contact with some of the most virulent viruses and nastiest bacteria on the planet. Even those of us who aren’t going off the beaten track may end up in close quarters with microbes we’d rather not befriend. Explore some of the most common infectious diseases around the globe and how to identify them in this infographic.

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Microbiology should be part of everyone’s educational experience. European students deserve to know something about the influence of microscopic forms of life on their existence, as it is at least as important as the study of the Roman Empire or the Second World War. Knowledge of viruses should be as prominent in American high school curricula as the origin of the Declaration of Independence. This limited geographic compass reflects the fact that the science of microbiology is a triumph of Western civilization, but the educational significance of the field is a global concern. We cannot understand life without an elementary comprehension of microorganisms.

Appreciation of the microbial world might begin by looking at pond water and pinches of wet soil with a microscope. Precocious children could be encouraged in this fashion at a very early age. Deeper inquiry with science teachers would build a foundation of knowledge for teenagers, before the end of their formal education or the pursuit of a university degree in the humanities.

Earth has always been dominated by microorganisms. Most genetic diversity exists in the form of microbes and if animals and plants were extinguished by cosmic bombardment, biology would reboot from reservoirs of this bounty. The numbers of microbes are staggering. Tens of millions of bacteria live in a crumb of soil. A drop of seawater contains 500,000 bacteria and tens of millions of viruses. The air is filled with microscopic fungal spores, and a hundred trillion bacteria swarm inside the human gut. Every macroscopic organism and every inanimate surface is coated with microbes. They grow around volcanoes and hydrothermal vents. They live in blocks of sea ice, in the deepest oceans, and thrive in ancient sediment on the seafloor. Microbes act as decomposers, recycling the substance of dead organisms. Others are primary producers, turning carbon dioxide into sugars using sunlight or by tapping chemical energy from hydrogen sulfide, ferrous iron, ammonia, and methane.

Bacterial infections are caused by decomposers that survive in living tissues. Airborne bacteria cause diphtheria, pertussis, tuberculosis, and meningitis. Airborne viruses cause influenza, measles, mumps, rubella, chickenpox, and the common cold. Hemorrhagic fevers caused by Ebola viruses are spread by direct contact with infected patients. Diseases transmitted by animal bites include bacterial plague, as the presumed cause of the Black Death, which killed 200 million people in the 14^th century. Typhus spread by lice decimated populations of prisoners in concentration camps and refugees during the Second World War. Malaria, carried by mosquitos, massacres half a million people every year.

Contrary to the impression left by this list of infections, relatively few microbes are harmful and we depend on a lifelong cargo of single-celled organisms and viruses. The bacteria in our guts are essential for digesting the plant part of our diet and other bacteria and yeasts are normal occupants of healthy skin. The tightness of our relationship with microbes is illustrated by the finding that human DNA contains 100,000 fragments of genes that came from viruses. We are surprisingly microbial.

Missing the opportunity to learn something about microbiology is a mistake. The uninformed are likely to be left with a distorted view of biology in which they miscast themselves as the most important organisms. For example, “Sarah” is a significant manifestation of life from Sarah’s perspective, but her body is not the individual organism that she imagines, and nor, despite her talents, is she a major player in the ecology of the planet. Her interactions with microbes will include a healthy relationship with bacteria in her gut, bouts of influenza and other viral illnesses, and death in old age from an antibiotic-resistant infection. Sarah’s microbiology will continue after death with her decomposition by fungi. In happier times she will become an expert on Milton’s poetry, and delight students by reciting Lycidas through her tears, but she will never know a thing about microbiology. This is a pity. Learning about viruses that bloom in seawater and fungi that sustain rainforests would not have stopped her from falling in love with Milton.

Even brief consideration of microorganisms can be inspiring. A simple magnifying lens transforms the surface of rotting fruit into a hedgerow of glittering stalks topped with jet-black fungal spores. Microscopes take us deeper, to the slow revolution of the bright green globe of the alga Volvox as its beats its way through a drop of pond water. A greater number of microbes are quite dull things to look at and their appreciation requires greater imagination. Considering that our bodies are huge ecosystems supported by trillions of bacteria is a good place to start, and then we might realize that we fade from view against the grander galaxy of life on Earth. The science of microbiology is a marvel for our time.

Featured image credit: BglII-DNA complex By Gwilliams10. Public domain via Wikimedia Commons

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With the Ebola virus in the news recently, you may be wondering what actions you can take to reduce the risk of contracting and spreading the deadly disease. Expert Peter C. Doherty provides valuable pointers on the best ways to stay safe and healthy in this excerpt from Pandemics: What Everyone Needs to Know answering: Is there anything that I can do personally to limit the possibility of a dangerous pandemic?

While pandemics are by their nature unpredictable, there are some things worth considering when it comes to the issue of personal safety and responsibility. The first point is to be a safe international traveler so that you don’t bring some nasty infection home with you. Protect yourself and you protect others. Though taking the available vaccines won’t prevent infection with some novel pathogen, it will contribute toward ensuring that you enjoy a successful vacation or business trip, and it should also put you in a “think bugs” mind-set. If, for instance, you are off to Africa for a wildlife safari, make an appointment at a travel clinic (or with your primary care physician) two to three months ahead of time to check your vaccine status and, if needed, receive booster shots to ensure that your antibody levels are high. Anyone who is visiting a developing country should make sure that he or she has indeed received the standard immunizations of childhood. Adolescents and young adults are much more likely to suffer severe consequences if, for instance, they contract commonplace infections like measles or mumps that have, because of herd immunity, become so unusual in Western countries that a minority of parents reject the collective responsibility of vaccinating their kids. If you’re younger and your parents are (or were) into alternative lifestyles, it may be wise to ask them very directly about your personal immunization history.

It’s also likely that, even if you were vaccinated early on, your level of immunity will have declined greatly and you will benefit from further challenge. Both possibilities will be covered if you go to a comprehensive travel clinic, as the doctors and nurses there will insist that you receive these shots (or a booster) if you don’t have a documented recent history. Any vaccination schedule should ideally be completed at least 3 to 4 weeks ahead of boarding your flight, the time needed for the full development of immunity. But this is one situation where “better late than never” applies. Should it have slipped your mind until the last minute, you should be vaccinated nevertheless. Even if you’ve never had that particular vaccine before, some level of protection could be there within 5 to 10 days, and a boosted, existing response will cut in more quickly. A travel clinic will also sell you a Gastro (gastroenteritis, not gastronomy) kit containing antibiotics to counter traveler’s diarrhea (generally a result of low-grade E. coli infection), something to decrease intestinal/gastric motility (Imodium), and sachets of salts to restore an appropriate fluid balance.

For the elderly, be aware of the decline in immunity that happens with age. You may not respond to vaccines as well as those who are younger, and you will be at greater risk from any novel infection. Depending on your proposed itinerary, it may also be essential to take anti-malarial drugs, which generally have to be started well ahead of arrival. Malaria is not the only mosquito-borne threat in tropical countries, so carry a good supply of insect repellant. In general, think about when and where you travel. Avoiding the hot, wet season in the tropics may be a good idea, both from the aspect that too much rain can limit access to interesting sites and because more standing water means more mosquitoes. Wearing long trousers, long-sleeved shirts, and shoes and socks helps to protect against being bitten (both by insects and by snakes), while also minimizing skin damage due to higher UV levels. Then, before you make your plans and again prior to embarking, check the relevant websites at the CDC, the WHO, and your own Department of Foreign Affairs (Department of State in the United States) for travel alerts. Especially if they’re off to Asia, many of my medical infectious disease colleagues travel with one or other of the antiviral drugs (Relenza and Tamiflu) that work against all known influenza strains. These require a prescription, but they’re worth having at home anyway in case there is a flu pandemic. If that happens, the word will be out that influenza is raging and stocks in the pharmacies and drugstores will disappear very quickly. But don’t rely on self-diagnosis if you took your Tamiflu with you to some exotic place; see a doctor. What you may think is flu could be malaria.

For those who may be sexually active with a previously unknown partner, carry prophylactics (condoms) and behave as responsibly as possible. Excess alcohol intake increases the likelihood that we will do something stupid. Dirty needles must be avoided, but don’t inject drugs under any circumstances. Blood-borne infections with persistently circulating viruses (HIV and hepatitis B and C) are major risks, while insect-transmitted pathogens (dengue, Chikungunya, Japanese B encephalitis) can also be in the human circulation for 5–10 days. Apart from that, being caught with illegal drugs can land you in terrible trouble, particularly in some Southeast Asian nations. No matter what passport you carry, you are subject to the laws of the country. Be aware that rabies may be endemic and that animal bites in general can be dangerous.

Can you really trust a tattooist to use sterile needles? Even if the needles are clean, what about the inks? How can they be sterilized to ensure that they are not, as has been known to occur, contaminated with Mycobacterium chelonae, the cause of a nasty skin infection? And that was in the United States, not in some exotic location where there may be much nastier bugs around.

Peter C. Doherty is Chairman of the Department of Immunology at St. Jude’s Children’s Research Hospital, and a Laureate Professor of Microbiology and Immunology at the University of Melbourne. He is the author of Pandemics: What Everyone Needs to Know, The Beginner’s Guide to Winning the Nobel Prize: Advice for Young Scientists, Their Fate is Our Fate: How Birds Foretell Threats to Our Health and Our World, and A Light History of Hot Air.

What Everyone Needs to Know (WENTK) series offers a balanced and authoritative primer on complex current event issues and countries. Written by leading authorities in their given fields, in a concise question-and-answer format, inquiring minds soon learn essential knowledge to engage with the issues that matter today. Starting July 2014, OUPblog will publish a WENTK blog post monthly.

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Image credit: Ebola virus particles by Thomas W. Geisbert, Boston University School of Medicine. Public Domain via Wikimedia Commons.

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By Peter C. Doherty

A recent New York Times editorial by author David Quammen highlighted the seriousness of the current Ebola outbreak in Guinea, but made the point that there is no great risk of any global pandemic. That’s been generally true of the viruses that, like Ebola, cause exudative diathesis, or bleeding into the tissues, and present with horrific symptoms. There’s a whole range of such infections caused by a spectrum of different virus types. These pathogens are generally maintained asymptomatically in wildlife “reservoir” species, including fruit and insectivorous bats, monkeys, field mice, and various other rodent species. Breathing dust contaminated with dried mouse feces can lead, for example, to infection with the Sin Nombre hantavirus that caused a recent outbreak in Yellowstone National Park. Others (like Ebola) may “jump” across to us from bats and are then transmitted between people following contact with contaminated human blood and other secretions.

Ebola virus virion.

From the pandemic aspect, the most dangerous we’ve seen to date is the SARS coronavirus that, in 2002, came out of nowhere to kill some 800 people in the Asia/Pacific region and also caused cases in Toronto. Spread via the respiratory route or by hand-to-face transmission following contact with contaminated surfaces this virus would, if it had emerged prior to the 19th century development of the germ theory of infectious disease, have gone on to cause a continuing human problem. As it was, once the virologists had identified the virus and worked out its mechanism of spread, instituting rigorous sanitation procedures (especially hand washing) and practicing  “barrier nursing” (latex gloves, face masks, disposable gowns) with afflicted patients led to the disease essentially “burning out” in humans. Authorities in the Middle East are, though, keeping a close watch on the closely related MERS coronavirus, which has caused a few human cases and may be maintained in nature as an asymptomatic infection of Egyptian tomb bats and camels. Could the MERS-CoV be the source of  “The Curse of the Mummy’s Tomb”?

Even in the absence of specific antiviral drugs and vaccines, modern science protects us by defining the problem so that public health and medical professionals can take appropriate counter-measures. Still, though such viruses do not generally change their mode of transmission to spread readily by the dangerous respiratory route (we can’t choose when and where to breathe!), the basic message is that the price of freedom (from such infections) is constant vigilance. That’s why government agencies like the CDC and the US Public Health Service are so important for our defense. So far, the “worst-case” pandemic scenario for any hemorrhagic fever virus is that portrayed in the movie Contagion. Hopefully, a catastrophe of such magnitude will remain in the realm of fiction, but we do need to keep our guard up.  The much more immediate and likely pandemic danger is always, so far as we are aware, from the influenza A viruses.

Peter C. Doherty is Chairman of the Department of Immunology at St. Jude’s Children’s Research Hospital, and a Laureate Professor of Microbiology and Immunology at the University of Melbourne. He is the author of The Beginner’s Guide to Winning the Nobel Prize: Advice for Young Scientists, Their Fate is Our Fate: How Birds Foretell Threats to Our Health and Our World, published in Australia as Sentinel Chickens: What Birds Tell us About Our health and the World, A Light History of Hot Air and Pandemics: What Everyone Needs to Know.

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Image: Ebola virus virion. Public domain via Wikimedia Commons.

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By Alfred Rolington

Cyber attacks on Iran have been well publicised in the press and on Western television. General William Shelton, a top American cyber general, has now turned these attacks around saying that these events are giving Iran a strategic and tactical cyber advantage creating a very serious “force to be reckoned with.”

Since 2010, Iran’s infrastructure has been attacked hundreds of times by cyber viruses. To date the most documented and best known cyber attacks have been aimed at Iran and are known as cyber worms called Stuxnet. These electronic worms were used to attack Iranian nuclear power plants and connected systems. General Shelton, who heads up Air Force Space Command and Air Force cyber operations, gave a briefing to reporters in January 2013, where he said that the 2010 Stuxnet virus attack on Iran’s Natanz uranium processing plant had generated considered responses from Iran that have led to improved offensive and defensive cyber-capabilities.

In December 2012, the Stuxnet virus returned and hit computer and energy operations and companies in the southern Hormozgan region. Shelton claimed that Iran’s improved cyber defense capability had helped Iran protect it against subsequent attacks on oil terminals and other manufacturing plants. This new capability, he believed, will subsequently be used by Iran against its enemies in the near future. “They are going to be a force to be reckoned with,” said General Shelton, “with the potential capabilities that they will develop over the years.” At present he stated that America had over six thousand cyber specialists employed to monitor, analyse and counter cyber attacks, and he was intending to employ another thousand specialists over the next twelve months to improve America’s effectiveness in this vital area.

Moreover, assassinations and assassination attempts in conjunction with cyber attacks are thought to be part of an integrated plan of attacks on Iran’s nuclear research and manufacturing capabilities. A year ago on 11 January 2012, Ahmadi Roshan, a 32-year-old Iranian scientist, and his driver were both killed when a motorcyclist attached a bomb to their car as they were driving. So far these attacks, which seem to form part of the broader cyber-related strategy aimed at Iran’s nuclear program, have successfully killed five Iranian nuclear scientists in the last two years according to FARS, a Tehran news agency. However, in January 2013, the Iranian Intelligence Minister Heydar Moslehi claimed that his organisation had stopped a number of attempts to kill nuclear scientists so it is uncertain which reports are accurate.

These attacks on Iran’s electronic systems represent only a very small amount of the current cyber attack and threat capability. Increasingly, all governments and corporations must respond to the cyber reality. With an interconnected world, cyber attacks on infrastructure have become frequent and damaging. Cyber crime is costing businesses billions of pounds although they tend to keep quiet about the attacks. (The BBC reported that UK cyber crime costs £27bn a year.) Efforts to get a grip on the problem had been hampered by firms who don’t want to admit they had been the victims of attacks for fear of “reputational damage”. Baroness Neville-Jones, Prime Minister David Cameron, and Foreign Secretary William Hague met the bosses of some of Britain’s biggest businesses, including Barclays, HSBC, Tesco and BA, to urge them to take the problem more seriously.

In September 2012, a hacker called vorVzakone posted a message on a Russian online forum saying that a malevolent Trojan, called Project Blitzkrieg, was capable of attacking the American financial industry, that it had already critically affected up to five hundred American targets, and that it had stolen over five million dollars. “This attack combines both a technical, innovative backend with the tactics of a successful, organized cybercrime movement,” a McAfee report explained, adding that the next target would probably be investment banks.

Hackers, apparently working independently as criminal gangs, have grown in their specialization faster than most police and government intelligence organisations would have believed possible. Yet cyber hackers working for governments have targeted everything from computer systems to power plants from the US to Iran, Europe to China, Australia and beyond. These civil servant hackers are often employed by governments to help fulfill a strategy, to change information and publicity, or to gain information and bring systems down.

One example comes from Ray Boisvert, who recently retired from the post of Assistant Director of Intelligence for the Canadian Security Intelligence Service. He believes the current capabilities of most governments is not enough to counter the current cyber threats. He said that cyber threats were fundamentally undermining Canada’s “future prosperity as a nation.” He stated there is a lack of response on three levels. First from government and corporate policy-makers who do not, in his opinion, understand the technical complexities of digital telecommunications security. Second the government has not invested enough to protect Canada’s communications and electricity systems from cyber attacks. Third, he thought there was an inherent corporate shortsightedness regarding protecting Canada’s communications infrastructure.

The cyber issue is growing and will become a rising threat to governments and corporations. It may require a serious attack such as a massive electricity system shut down before a full government response is played out.

Alfred Rolington is the author of Strategic Intelligence for the 21st Century: The Mosaic Method, an industry insider’s assessment of current intelligence methods and offers a new strategic model, directed toward the police, military, and intelligence agencies. He was formerly CEO of Jane’s Information Group, responsible for such publications as Jane’s Defense Review and Jane’s Police Review, as well as CEO for Oxford Analytica. He has over thirty years’ experience of analytical publishing and media companies, producing information and intelligence for commerce, law enforcement, the, military and government. He has written about and given lectures on intelligence and strategic planning to Cambridge, Oxford, and Harvard Universities, and to organisations such as Thomson Reuters, the CIA, SIS (MI6), NATO Headquarters, and GCHQ.

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Image credits: Information Systems Technician 2nd Class Ryan Allshouse uses the intrusion detection system to monitor unclassified network activity from the automated data processing workspace. As a work of the U.S. federal government, the image is in the public domain via Wikimedia Commons;  Maps and charts are scanned from “Atlas of the Middle East”, published in January 1993 by the U.S. Central Intelligence Agency. [Public domain], via Wikimedia Commons

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Contagion,” the extraordinary film portraying the outbreak of lethal virus that spreads rapidly around the world, may seem eerily familiar: from the medieval plague to the Spanish flu of 1918-19 to more recent fears of avian influenza, SARS, and H1N1 “swine flu”, contagions have long characterized the human condition. The film captures almost perfectly what a contemporary worst-case scenario might look like, and is eerily familiar because it trades on realistic fears. Contagion, the transmission of communicable infectious disease from one person to another (either by direct contact, as in this film — sneezing or coughing or touching one’s nose or mouth, then a surface like a tabletop or doorknob that someone else then touches

By Dorothy Crawford Chance is a fine thing, especially when it leads to a major new discovery. Remarkably, this often seems to be the case with scientific discoveries, at least in my field - tumour virology. We now know that around 20% of cancers are caused by microbes but without chance this figure might be substantially lower. The first human tumour virus was discovered in 1964 by Anthony Epstein and Yvonne Barr at the Middlesex Hospital in London with the virus being named Epstein-Barr virus (EBV) after its discoverers.

by Cassie, Associate Publicist

Michael B. A. Oldstone is a Member (Professor) at the Scripps Research Institute, where he directs a laboratory of viral immunobiology. He is also the author of Viruses, Plagues, and History: Past, Present, and Future, a look at viruses from smallpox to ebola to West Nile to the flu. In this excerpt, Oldstone explains how pigs, dogs, and ferrets help scientists discover that the flu was a virus, not bacteria.

Although suspected influenza epidemics occurred during several decades of the 1700s, Robert Johnson, a physician from Philadelphia, is generally credited with the first description of influenza during the 1793 epidemic. With his description available and improved public health statistics, epidemics were documented in 1833, 1837, 1847, 1889–90, and 1918.

However, the identity of the infectious agent that caused influenza remained debatable. In Germany, Richard Pfeiffer discovered “bacteria” present in great numbers in the throats and lungs of patients with influenza. Because of this agent’s large size, it could not pass through a Pasteur-Chamberland-type filter, causing many observers to speculate that influenza originated from a bacterium and not a virus.

Only by serendipity was the true nature of influenza as a virus discovered. This is a tale of pigs, hounds, foxes, and ferrets—all of which played decisive roles in the determination that influenza was a virus…

The story begins with J. S. Koen of Fort Dodge, Iowa, an inspector for the U.S. Bureau of Animal Husbandry. In 1918, he observed in pigs a disease that resembled the raging human influenza plague of 1918–19:

Last fall and winter we were confronted with a new condition, if not a new disease. I believe I have as much to support this diagnosis in pigs as the physicians have to support a similar diagnosis in man. The similarity of the epidemic among people and the epidemic among pigs was so close, the reports so frequent, that an outbreak in the family would be followed immediately by an outbreak among the hogs, and vice versa, as to present a most striking coincidence if not suggesting a close relation between the two conditions. It looked like “flu,” and until proved it was not “flu,” I shall stand by that diagnosis.

Koen’s views were decidedly unpopular, especially among farmers raising pigs, who feared that customers would be put off from eating pork if such an association were made. Ten years later, in 1928, a group of research veterinarians in the U.S. Bureau of Animal Husbandry, led by C. N. McBryde, reported the successful transmission of influenza infection from pig to pig by taking mucus and tissue from the respiratory tracts of sick pigs and placing it into the noses of healthy pigs. However, these investigators were unable to transmit the disease after passing the material through a Pasteur-Chamberland-type filter. Therefore, no evidence was yet available that a virus caused influenza. That situation changed when Richard Shope, working at the Rockefeller Institute of Comparative Pathology at Princeton, New Jersey, repeated McBryde’s experiments within a year of the negative report. By reproducing influenza disease in healthy pigs after inoculating them with material taken from sick pigs and passed through the Pasteur-Chamberland filter, Shope provided the first evidence that viruses transmitted influenza of swine.

…Initially, dogs were used for research on the [canine distemper] virus and for studies to develop the vaccine, but problems soon surfaced. Among the difficulties was the issue that some dogs had become immune because of a previous encounter with canine distemper virus so did not contract the disease when exposed; additionally, antivivisectionists and some pet owners objected to using “man’s best friend” as a research tool. These problems vanished when ferrets were substituted for dogs. Hound keepers on the English country estates had noticed that ferrets also developed distemper, presumably transmitted from dogs. Soon ferrets replaced dogs in canine distemper studies at both the Wellcome and the MRC laboratories.

In 1933, the first epidemic of influenza since 1919 struck London and, as before, spread quickly. Among the many humans infected were several members of the research staff at Wellcome and MRC laboratories. However, unexpectedly, ferrets kept at the Wellcome laboratory also became ill, with symptoms of wheezing, sneezing, and coughing reminiscent of human influenza infection. When Wilson Smith, a senior researcher at the MRC unit, recognized the situation, he infected ferrets with nasal washings from influenza-infected patients. As the ferrets came down with the influenza-like syndrome, both Smith and Christopher Andrewes examined them. A story soon told was that a sick ferret sneezed in Christopher Andrewes’ face. A few days later, Andrewes came down with influenza. Smith obtained washings from Andrewes’s throat, passed the material through a Pasteur-Chamberland-like filter, then injected the filtrate into healthy ferrets. Soon they too began sneezing and coughing, discharging phlegm from the nose and eyes and spiking a temperature. Here was the first evidence that a virus caused human influenza, at the same time fulfilling Koch’s postulates.

Following his studies with tuberculosis, Robert Koch formalized the criteria eventually called Koch’s postulates to distinguish a microbe causing disease from one that is a happenstance passenger. According to the postulates, a link between agent and disease is valid when the organism is regularly found in the lesions of the disease; the organism can be isolated in pure culture on artificial media; inoculation of this culture produces a similar disease in experimental animals, and the organism can be recovered from the lesions in these animals. These postulates require modification for viruses, however, because they cannot be grown on artificial media (viruses require living cells for their replication), and some are pathogenic only for humans. Nevertheless, these experiments with ferrets, humans, and influenza virus filled the bill for a modified Koch’s postulate. Considering the role serendipity played in the use of ferrets and the initial isolation of human influenza virus, one agrees with Pasteur: “Chance favors the prepared mind.”

Dorothy H. Crawford is a Professor of Medical Microbiology and Assistant Principle for the Public Understanding of Medicine at the University of Edinburgh. Her most recent book, Deadly Companions: How Microbes Shaped Our History, takes us back in time to follow the interlinked history of microbes and man, impressing upon us how a world free of dangerous microbes is an illusion.  In an excerpt this morning we looked at SARS.  The excerpt below looks at the effect of poverty on disease.

It is glaringly obvious from a glance at the figures that poverty is the major cause of microbe-related deaths. On a worldwide scale microbes are still major killers, accounting for one in three of all deaths. But the huge discrepancy in the death rates between rich and poor nations reveals the stark reality. Whereas only 1–2 per cent of all deaths in the West are caused by microbes, this figure rises to over 50 per cent in the poorest nations of the world, and it is in these highly microbe-infected areas where over 95 per cent of the global deaths from infections occur. Most of the 17 million killed by microbes each year are children in developing countries where the link with poverty is clear. It is the poor who are malnourished, live in filthy, overcrowded urban slums and go without clean drinking water or sewage disposal, and therefore they are the ones who fall prey to the killer microbes: HIV, malaria, TB, respiratory infections and diarrhea diseases like cholera, typhoid and rotavirus; all eminently preventable and treatable given the resources.

The spread of HIV is an excellent example of how microbes exploit the poor, striking at the most disadvantaged in the community. The virus emerged in Central Africa and spread silently throughout the continent in the 1970s, given a head start by its long silent incubation period, and aided by despotic leaders, corrupt governments, civil wars, tribal conflicts, droughts and famines. Carried by undisciplined armies and terrorists, the virus infiltrated city slums, infected commercial sex workers, was picked up by migrant workers and passed on to their wives and families. While malnutrition accelerated the onset of AIDs, breakdown of health-care services in the political turmoil of Africa excluded any possibility of medical support for the millions in need.

Now we are living through the worst pandemic the world has ever known, with 40 million living with HIV, 25 million already dead and around 10,000 dying daily—the equivalent of over three 9/11disasters every twenty-four hours. A third of people living in sub-Saharan African cities are HIV-infected, and while highly active antiretroviral therapy (HAART) has converted this lethal disease into a manageable chronic infection in the West, presently only a tiny proportion of Africans living with HIV receive this treatment; for most there is no hope of obtaining the drugs vital for keeping them alive.

The dynamics of HIV in Africa reflects its mode of spread. As the virus is sexually transmitted gender inequalities mean that women are particularly vulnerable. In general they are poorer and less well educated than their male counterparts, and are often powerless to choose or restrict their sexual partners, or to insist on condom use. Indeed many are forced to exchange sex for essentials like food, shelter and schooling. Now one in four African women are HIV-infected by the age of twenty-two years (compared to one in fourteen men of the same age), and women account for 60 per cent of all those living with HIV.

Over 90 per cent of HIV-positive women in Africa are mothers, and the virus has created 15 million orphans worldwide, 12 million of them in sub-Saharan Africa. These children are bearing the burden of the HIV pandemic; they miss school to care for their sick mothers or to earn the family income; the virus has not only deprived them of their parents but their childhood and their education as well.

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