Antibiotic Resistance

Superbugs - bacteria that resist the effects of the most powerful antibiotics - are being reported more and more frequently. Some doctors see their rise as heralding the end of the age of antibiotics. BBC News Online's health team presents an overview of the past, present and future of the 20th century's greatest medical breakthrough.

The emerging superbug
Visa is resistant to just about every antibiotic known to medicine and has been discovered in hospitals from Japan to Scotland - find out where it comes from and why it has got doctors worried.

Staphylococcus aureus - the root of the problem (picture: Pfizer)

The emergence of a superbug - a bacteria resistant to all antibiotics - could herald the end of the era of antibiotics, the biggest medical advance of the twentieth century.

That at least was the view of public health scientists in New York earlier this year when they reported a growing incidence of VISA - vancomycin intermediate-resistant Staphylococcus aureus.

These bacteria have been proving resistant to vancomycin, the most powerful antibiotic in doctors' armoury, although combinations of other antibiotics have been able to halt it.

Vancomycin is seen as the last line of defence against MRSA - Methicillin-resistant Staphylococcus aureus - which is unaffected by most antibiotics and is becoming more common.

All around the world

The emergence of VISA shows that, in doctors' race to keep antibiotics advanced enough to defeat bacteria, the bugs are taking the lead.

VISA has been found in hospitals in Japan, America, France and, more recently, in Scotland.

Although only one person is thought to have died directly from infection with the bug, the fear is that more dangerous bacteria such as those that cause tuberculosis could develop the same characteristics that allow VISA to resist even the most powerful antibiotics.

Were this to happen, doctors would be back where they started before the introduction of penicillin - confronted by a host of diseases caused by bacteria and unable to cure them.

In February, a report in the New England Journal of Medicine recorded three cases of bacteria resisting vancomycin.

In two of them, cocktails of other antibiotics cleared up the infection. In the third, a combination of antibiotics failed and the 79-year-old patient died.

Larger problem

Dr Alexander Tomasz, professor of microbiology at New York's Rockefeller University, said in the journal: "This is the tip of the iceberg. At the moment such strains are very, very rare.

"But they are not as susceptible as they used to be. They have moved up the threshold of resistance. It is a warning."

The reports suggested that it would only take one small mutation for the bacteria to develop full resistance to even the most powerful drugs.

Dr Theresa Smith, of the US Centers for Disease Control and Prevention reported two of the cases in the journal, and said the appearance of such bacteria "threatens to return us to the era before the development of antibiotics".

Optimism in Glasgow

However, when it appeared at the Royal Glasgow Infirmary Dr John Hood, consultant bacteriologist at the hospital's Infection Control Unit, was less alarmed.

He said that while the strain showed increased resistance to traditional antibiotics, it was not yet immune to them and newer drugs were also available to combat it.

But Professor Hugh Pennington, who conducted the inquiry into the 1996 Lanarkshire E. coli infection, described the development as "worrying".

"If it turns out to be the case that this strain proves resistant to Vancomycin, that really is quite bad news and would confirm our fears that these bugs are developing a full house of resistance," he said.

Links to more Antibiotics stories
Antibiotic resistance
Antibiotic Resistant "Superbug" on the Rise
New antibiotic-resistant superbug found
Super-Resistant Superbugs
Attack of the Superbug
Essential oils have been found to kill the deadly MRSA bacteria

Avian Flu

Nature’s Wake-Up Call for Humanity

The potential spread of avian influenza (also known as avian flu or bird flu) is one of the most serious public health threats humankind has ever faced. The disease is contracted by humans through the butchering or eating of infected animals such as chickens or ducks.

How meat-eating is causing a potential bird flu pandemic

Archaeologists studying animal bones have traced many diseases back to the confinement of animals, which began about 10,000 years ago. The foot bones of livestock from that period are deformed like those of confined animals, while the humans who kept them died of animal-borne diseases such as tuberculosis, smallpox and flu. Non-human illnesses such as foot-and-mouth disease appeared at the same time, wiping out livestock on which people had become dependent for food, thereby causing human malnutrition, starvation and susceptibility to sickness. Thus, directly or indirectly, humankind’s attachment to meat over the centuries has brought about catastrophes worse than any war or natural disaster could ever wreak.

To this day, one in three people will die from infectious diseases, most of which are derived from animals, and three fourths of all emerging human illnesses are animal-derived. By contrast, Native Americans, who traditionally did not confine animals as did other races, were virtually free of infectious diseases before the arrival of Europeans. Subsequently, a series of European animal-derived illnesses quickly wiped out ninety percent of the native population of both American continents.

Overall, among the top ten causes of death in developing countries are diseases arising from animals, the foremost of these being AIDS. The HIV virus that causes AIDS first appeared in traders of monkey and chimpanzee meat, and HIV has now infected 65 million people and killed 25 million. Scientists have determined that a monkey virus called SIV jumped species between hunters and primates a minimum of seven times before becoming HIV, demonstrating that a large amount of virus transfer occurs due to hunting.

The cycle of violence

A common method of preventing avian flu is to kill chickens carrying the disease; thus, approximately 150 million fowl have been destroyed during the recent epidemic. A survey prepared for the UN found that typical means of slaughtering the birds included beating them with sticks and iron pipes, and stuffing them in plastic bags and then burying them alive in pits. In some cases, gasoline was poured into the pits and the animals burned alive before being buried. Carbon dioxide gas, which causes piercing, stabbing pain and slow death, has also been employed.

The deadly game

Besides chicken farming, another way that bird flu can spread to humans is through duck hunting. Ducks are the main carriers of bird flu in the wild and when hunters shoot ducks, carriers spread the virus to anything that makes contact with the carcass. Throughout history, humans have spread animal-borne diseases to livestock and other humans through hunting.

While bird hunting has been banned in many countries this year due to the potential for an avian flu epidemic, hunters are largely ignoring the bans. As a Lebanese hunting official explained, “Hunters may not believe the government and so don’t take the ban seriously. They don’t realize avian influenza has made hunting national health concern, and is no longer merely a social or economic activity.”

Bird flu is also spreading through the trade in exotic birds, some of which have been seized by officials as far away from their native lands as England. Also, officials have found infected fighting cocks being smuggled out of China, and according to David Morgan, head scientist for the Convention on International Trade in Endangered Species (CITES), “You only need one specimen to get through the net to spread the disease.”

A brighter future is possible

As health administrators struggle to control outbreaks of avian flu, an effort that is costing the global economy billions of dollars and the lives of hundreds of millions of birds, one cannot help but wonder whether a more suitable solution can be found besides mass slaughter; namely, the vegetarian diet. As people buy meat in shops and supermarkets, perhaps they should ask themselves, “Is it worth risking a global epidemic for this piece of flesh?” And lest people conclude that a key law of nature is “kill or be killed,” they need only remember the dog, that model of domestication. Simply by sharing food and shelter with dogs, humans have turned a former enemy into a guide, protector and “best friend.” How much easier it would be to make friends with such placid animals as cows, pigs and chickens! Killing these animals for food is a primitive, uncivilized practice that endangers the health of all people on Earth. So let us hope that these more humane approaches to dealing with the avian influenza problem will be adopted soon.

References:
1. http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11516376&dopt=Citation
2. http://www.fas.org/irp/threat/nie99-17d.htm
3. http://content.nejm.org/cgi/content/full/353/13/1374
4. http://www.unaids.org/epi2005/index.html
5. http://bioanthropology.huji.ac.il/pdf/2.pdf

Asia on alert for bird flu

see todayonline.com reported on 18 January 2007 at:
http://www.todayonline.com/pdflive/1801WNL014.pdf


see also
- Influenza Pandemic
- Flu Fears
- WHO update of confirmed human cases as at 15 January 2007

Influenza Pandemic

A pandemic occurs when a new influenza virus emerges and starts spreading as easily as normal influenza – by coughing and sneezing. Because the virus is new, the human immune system will have no pre-existing immunity. This makes it likely that people who contract pandemic influenza will experience more serious disease than that caused by normal influenza.

In contrast to epidemics, pandemics are rare events that occur every 10 to 50 years. They have been documented since the 16th century, and in the last 400 years, at least 31 pandemics have been recorded. During the twentieth century, three influenza pandemics occurred. Their mortality impact ranged from devastating to moderate or mild. The 1918 pandemic was caused by a H1N1 virus of apparently avian origin, whereas the subsequent pandemic strains - H2N2 in 1957 and H3N2 in 1968 - were reassortant viruses containing genes from avian viruses.


THE STORY OF INFLUENZA: 1918 AND BEYOND

An influenza pandemic is a rare but recurrent event. Three pandemics occurred in the previous century: “Spanish influenza” in 1918, “Asian influenza” in 1957, and “Hong Kong influenza” in 1968. The 1918 pandemic killed an estimated 40–50 million people worldwide. That pandemic, which was exceptional, is considered one of the deadliest disease events in human history. Subsequent pandemics were much milder, with an estimated 2 million deaths in 1957 and 1 million deaths in 1968.

1918 Spanish influenza

The first influenza pandemic of the 20th century spread more or less simultaneously in 3 distinct waves during a 12-month period in 1918-1919, across Europe, Asia, and North America. It was the worst pandemic in history, killing more people than World War I, and it is generally assumed that at least 50 million people died. The first wave, which started during the spring of 1918, was highly contagious but not particularly deadly. Only the second wave, beginning in September, spread the deadly form of the pandemic.

The virus of 1918 (H1N1) was extremely virulent and caused many deaths through secondary bacterial pneumonia. The primary viral pneumonia could kill previously healthy young individuals within 2 days. The clinical course of severe cases was so unfamiliar that investigators doubted it was influenza. Symptoms in 1918 were so unusual that, initially, it was misdiagnosed as dengue fever, cholera, or typhoid.

The 1918 virus was not a reassortant virus (like those of the 1957 and 1968 pandemics), but more likely an entirely avian-like virus that adapted to humans.

1957 Asian influenza

The 1957 pandemic was caused by H2N2, a clinically milder virus than the one responsible for the 1918 pandemic. Outbreaks were frequently explosive, but the death toll was much lower. Mortality showed a more characteristic pattern, similar to that seen in seasonal epidemics, with most excess deaths confined to infants and the elderly. The global excess mortality of the 1957 pandemic has been estimated at 1-2 million deaths.

1968 Hong Kong influenza

The 1968 pandemic, caused by H3N2, was also a mild pandemic. The death toll has been estimated to have been around 1 million, and in the United States, nearly 50 percent of all influenza-related deaths occurred in the younger population under 65 years of age.

Current Situation

As unpredictable as influenza pandemics are, as unpredictable is the virus itself. We know nothing about the pathogenic potential of the next pandemic strain. The next pandemic may be relatively benign, as it was in 1968 and 1957, or truly malignant, as was the 1918 episode. We don't know if the next pandemic will be caused by the current avian influenza virus, H5N1, or by another influenza strain. We ignore how the next pandemic will evolve over time, how rapidly it will spread around the world, and in how many waves. We don't know which age groups are at the highest risk of severe outcomes. We have no idea whether the next pandemic will kill 2, 20, or 200 million people.

Not surprisingly, healthcare professionals are becoming sensitised to the risk of a new pandemic. The ongoing outbreak of H5N1 influenza among birds, with occasional transmission to human beings is of major concern because of intriguing parallels between the H5N1 virus and the 1918 influenza strain. Such H5N1 avian influenza also known as "bird flu".

Avian influenza

Health experts have been monitoring a new and extremely severe influenza virus – the H5N1 strain – for almost eight years. The H5N1 strain first infected humans in Hong Kong in 1997, causing 18 cases, including six deaths. Since mid-2003, this virus has caused the largest and most severe outbreaks in poultry on record. In December 2003, infections in people exposed to sick birds were identified.

Since then, over 260 human cases have been laboratory confirmed for ten countries worldwide, including the four seriously hit Asian countries (Indonesia, Viet Nam, Thailand, and China), and more than half of these people have died due to H5N1 avian influenza. Most cases have occurred in previously healthy children and young adults.

As there have been increasing update of avian influenza (bird flu) cases reported in more countries such as Japan and Hong Kong (see report here), cumulative number of confirmed human cases of avian influenza A/(H5N1) reported to WHO as at 15 January 2007 since 2003 showing a total of 267 cases (only laboratory-confirmed cases are reported) with 161 deaths including Vietnam, China, Indonesia, Azerbaijan, Cambodia, Djibouti, Egypt, Iraq, Thailand and Turkey. (see WHO report here)

See the following reports for further details and updates:
- Influenza pandemic
- Ten things you need to know about pandemic influenza
- Influenza Report 2006
- Flu Fears
- WHO's Avian Influenza Outbreak
- CDC's Avian Influenza (Bird Flu)
- Flu.gov.sg

Flu Fears

[excerpted from www.todayonline.com published on Monday, January 15, 2007]

A recent spate of new poultry outbreaks in Asia are signs the bird flu virus could make a resurgence this winter, health experts warn.

While most Asian countries are better prepared than they were a year ago to prevent or contain the spread of avian influenza, epidemiologists say there is no room for complacency about the virus that remains widespread in the region.

Experts warn that the risk will increase when China, Vietnam and other countries celebrate the Lunar New Year in the middle of next month, when the movement of both poultry and people traditionally increases sharply. Migratory birds also pose a risk.

Infections in birds and people are increasing, particularly in Asia, where the virus was first identified a decade ago. Hong Kong, Japan, Vietnam, South Korea and Nigeria have reported diseased birds in the past month, while China and Egypt also found new human cases.

Almost all human H5N1 cases have been linked to close contact with sick or dead birds, such as children playing with them or adults butchering them or plucking feathers.

Bird flu has killed 161 people worldwide since late 2003. Scientists fear it could mutate and trigger a deadly, global pandemic. — AFP

Vietnam

Bird flu has spread to a sixth province in southern Vietnam, officials said yesterday, after the virus killed over 800 ducks on a farm in Tra Vinh province in the Mekong Delta. Last month (December), after a one-year hiatus, bird flu struck scores of poultry farms in the southern provinces.

Japan

Japan has confirmed a fresh bird flu outbreak but officials said it was not clear if it involved the H5N1 strain.

The confirmation came after about 2,400 chickens died at a farm in the south of the country. Officials will cull the remaining 9,600 chickens at the affected farm.

Japan confirmed an outbreak of the H5N1 strain of bird flu in January 2004.

China

China last week reported its first human case of bird flu in six months, but the farmer who fell ill made a full recovery.

Hong Kong

A dead wild bird found in Hong Kong has tested positive for a milder strain of the bird flu virus. Further tests are now being carried out on the carcass of the Crested Hoshawk.

Another dead wild bird, a scaly breasted munia, was found in Causeway Bay on Dec 31 and tested positive for the H5N1 strain last week.

Hong Kong was the scene of the world's first reported major bird flu outbreak among humans in 1997, when six people died of a then-unknown mutation of the avian flu virus.

Indonesia

Bird flu has killed two young women in Indonesia, taking fatalities in the past week to four in the country worst-hit by the disease. The women bought live chickens – which later died suddenly – from a market, and were admitted a few days later to hospital, where they died of acute pneumonia.

Also infected was an 18-year-old man in Indonesia whose mother, 37, died of the disease last week, creating a new cluster of infections that doctors are monitoring for signs the virus is becoming more adept at infecting humans.

Another four suspected cases are being treated in a hospital in West Java province.

Indonesia attracted international attention in May last year when seven members of a family from the island of Sumatra contracted the H5N1 virus, six of them fatally.

The cases represented the largest reported cluster of infections and the first laboratory-proven instance of human-to-human transmission.


see also:
- Influenza Pandemic
- WHO update of confirmed human cases as at 15 January 2007
- Ten things you need to know about pandemic influenza
- WHO's Avian Influenza Outbreak
- CDC's Avian Influenza (Bird Flu)
- Flu.gov.sg
- WHO's SARS Outbreak
- CDC's Severe Acute Respiratory Syndrome (SARS) Site
- SARS.gov.sg