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Defining DNA differences to track and tackle typhoid
July 28, 2008New technology genome sequencing study reveals new genetic signatures
For the first time, next-generation DNA sequencing technologies have been turned on typhoid fever - a disease that kills 600,000 people each year. The results will help to improve diagnosis, tracking of disease spread and could help to design new strategies for vaccination.
The study sets a new standard for analysing the evolution and spread of a disease-causing bacterium: it is the first study of multiple samples of any bacterial pathogen at this level of detail. It uncovers previously hidden genetic signatures of the evolution of individual lineages of Salmonella Typhi.
The team developed methods that are being used to type outbreaks, allowing researchers to identify individual organisms that are spreading in the population: using Google Earth, the outbreaks can be easily visualized. The team hope that these mapping data can be used to target vaccination campaigns more successfully with the aim of eradicating typhoid fever.
Unlike most related Salmonella species, and in contrast to many other bacteria, Typhi is found only in humans and the genomes of all isolates are superficially extremely similar, hampering attempts to track infections or to type more prevalent variants. The detail of the new study transforms the ability of researchers to tackle Typhi.
"Modern genomic methods can be used to develop answers to diseases that have plagued humans for many years," explains Professor Gordon Dougan from the Wellcome Trust Sanger Institute and senior author on the study. "Genomes are a legacy of an organism's existence, indicating the paths it has taken and the route it is on. This analysis suggests we may have found Typhi's Achilles' heel: in adapting to an exclusively human lifestyle, it has become complacent, its genome is undergoing genetic decay and it's heading up an evolutionary dead end in humans.
"We believe that concerted vaccination programmes, combined with epidemiological studies aiming to track down and treat carriers, could be used to eradicate typhoid as a disease."
There are 17 million cases of Typhoid fever each year - although the World Health Organization cautions that this is a 'very conservative' estimate. Young people are most at risk: in Indonesia, nine out of ten cases occur in 3-19-year-olds.
"A key to survival of Salmonella Typhi is its ability to lie dormant in carriers, who show no symptoms but remain able to infect others," says Kathryn Holt, a PhD student at the Wellcome Trust Sanger Institute and first author on the study. "Our new tools will assist us in tracing the source of typhoid outbreaks, potentially even to infected carriers, allowing those individuals to be treated to prevent further spread of the disease.
"Using the genomic biology of this study, we can now type Typhi, identify the strain that is causing infection, identify carriers and direct vaccination programmes most efficiently. It is a remarkable step forward."
The study is a collaboration between researchers at the Wellcome Trust Sanger Institute, University College, Cork, Institut Pasteur in Paris and Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam. The team studied 19 isolates of Typhi from ten countries, using new sequencing methods that meant they could capture the rare signals of genetic variation in this stubborn genome. They produced more than 1.7 billion letters of genetic sequence and found evidence of fewer than 2000 mutation events, suggesting very little evolution since the emergence of Typhi at least 15,000 years ago.
Their analysis shows that the Typhi genome is decaying - as it becomes more closely allied to us, its human host, it is losing genes that are superfluous to life in the human body. More importantly, genes that contain instructions for the proteins on the surface of the bacterium - those most often attacked by our immune system defences - vary much less than do the equivalent genes in most other bacteria, suggesting that Typhi has a strategy to circumvent the selective pressures of our immune system.
"Both the genome and the proteins that make up the surface of Typhi - the targets for vaccines - show amazingly little variation," says Professor Julian Parkhill, Head of Pathogen Genomics. "We have been able to use novel technologies, developed for the analysis of human genome variation, to identify this variation: this would have been impossible a year ago. The technologies we have developed here could also be used in the battles against other disease-causing bacteria."
Wellcome Trust Sanger Institute
The team developed methods that are being used to type outbreaks, allowing researchers to identify individual organisms that are spreading in the population: using Google Earth, the outbreaks can be easily visualized. The team hope that these mapping data can be used to target vaccination campaigns more successfully with the aim of eradicating typhoid fever.
Unlike most related Salmonella species, and in contrast to many other bacteria, Typhi is found only in humans and the genomes of all isolates are superficially extremely similar, hampering attempts to track infections or to type more prevalent variants. The detail of the new study transforms the ability of researchers to tackle Typhi.
"Modern genomic methods can be used to develop answers to diseases that have plagued humans for many years," explains Professor Gordon Dougan from the Wellcome Trust Sanger Institute and senior author on the study. "Genomes are a legacy of an organism's existence, indicating the paths it has taken and the route it is on. This analysis suggests we may have found Typhi's Achilles' heel: in adapting to an exclusively human lifestyle, it has become complacent, its genome is undergoing genetic decay and it's heading up an evolutionary dead end in humans.
"We believe that concerted vaccination programmes, combined with epidemiological studies aiming to track down and treat carriers, could be used to eradicate typhoid as a disease."
There are 17 million cases of Typhoid fever each year - although the World Health Organization cautions that this is a 'very conservative' estimate. Young people are most at risk: in Indonesia, nine out of ten cases occur in 3-19-year-olds.
"A key to survival of Salmonella Typhi is its ability to lie dormant in carriers, who show no symptoms but remain able to infect others," says Kathryn Holt, a PhD student at the Wellcome Trust Sanger Institute and first author on the study. "Our new tools will assist us in tracing the source of typhoid outbreaks, potentially even to infected carriers, allowing those individuals to be treated to prevent further spread of the disease.
"Using the genomic biology of this study, we can now type Typhi, identify the strain that is causing infection, identify carriers and direct vaccination programmes most efficiently. It is a remarkable step forward."
The study is a collaboration between researchers at the Wellcome Trust Sanger Institute, University College, Cork, Institut Pasteur in Paris and Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam. The team studied 19 isolates of Typhi from ten countries, using new sequencing methods that meant they could capture the rare signals of genetic variation in this stubborn genome. They produced more than 1.7 billion letters of genetic sequence and found evidence of fewer than 2000 mutation events, suggesting very little evolution since the emergence of Typhi at least 15,000 years ago.
Their analysis shows that the Typhi genome is decaying - as it becomes more closely allied to us, its human host, it is losing genes that are superfluous to life in the human body. More importantly, genes that contain instructions for the proteins on the surface of the bacterium - those most often attacked by our immune system defences - vary much less than do the equivalent genes in most other bacteria, suggesting that Typhi has a strategy to circumvent the selective pressures of our immune system.
"Both the genome and the proteins that make up the surface of Typhi - the targets for vaccines - show amazingly little variation," says Professor Julian Parkhill, Head of Pathogen Genomics. "We have been able to use novel technologies, developed for the analysis of human genome variation, to identify this variation: this would have been impossible a year ago. The technologies we have developed here could also be used in the battles against other disease-causing bacteria."
Wellcome Trust Sanger Institute
Typhoid Current Events and Typhoid News RSSTraDIS technique tackles typhoid
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New biosensor can detect bacteria instantaneously
A research group from the Rovira i Virgili University (URV) in Tarragona has developed a biosensor that can immediately detect very low levels of Salmonella typhi, the bacteria that causes typhoid fever.
Typhoid fever cases in US linked to foreign travel
Infection with an antimicrobial-resistant strain of typhoid fever among patients in the United States is associated with international travel, especially to the Indian subcontinent (India, Pakistan, and Bangladesh).
Vi typhoid vaccine proves highly effective in young children
A new study has found that a currently available yet underused vaccine against typhoid fever is highly effective in young children and protects unvaccinated neighbors of vaccinees.
Details of bacterial 'injection' system revealed
New details of the composition and structure of a needlelike protein complex on the surface of certain bacteria may help scientists develop new strategies to thwart infection.
Superbug risk to war wounded
Soldiers who survive severe injuries on battlefields such as those in Iraq and Afghanistan can be at risk from developing infections of their wounds with multidrug resistant bacteria.
How much is the world spending on neglected disease research and development?
The first comprehensive survey of global spending on neglected disease R&D, published in this week's PLoS Medicine, finds that just over $US 2.5 billion was invested into R&D of new products in 2007, with three diseases-HIV/AIDS, TB, and malaria-receiving nearly 80% of the total.
Nepalese researchers identify cost-effective treatment for drug-resistant typhoid
New research carried out by researchers in Nepal has shown that a new and affordable drug, Gatifloxacin, may be more effective at treating typhoid fever than the drug currently recommended by the World Health Organisation.
Nepalese researchers identify cost-effective treatment for drug-resistant typhoid
New research carried out by researchers in Nepal has shown that a new and affordable drug, Gatifloxacin, may be more effective at treating typhoid fever than the drug currently recommended by the World Health Organisation.
New bacterium discovered -- related to cause of trench fever
A close cousin of the bacterium that debilitated thousands of World War I soldiers has been isolated at UCSF from a patient who had been on an international vacation. The woman, who has since recovered, suffered from symptoms similar to malaria or typhoid fever, two infections that can occur in returning travelers.
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Typhoid Mary by Judith Walzer Leavitt (Author) She was an Irish immigrant cook. Between 1900 and 1907, she infected twenty-two New Yorkers with typhoid fever through her puddings and cakes; one of them died. Tracked down through epidemiological detective work, she was finally apprehended as she hid behind a barricade of trashcans. To protect the public's health, authorities isolated her on Manhattan's North Brother Island, where she died some thirty years later. This book tells the remarkable story of Mary Mallon--the real Typhoid Mary. Combining social history with biography, historian Judith Leavitt re-creates early-twentieth-century New York City, a world of strict class divisions and prejudice against immigrants and women. Leavitt engages the reader with the excitement of the early days of microbiology and brings to life... |
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NOVA - Typhoid Mary: The Most Dangerous Woman in America Interweaving biography and social history, The Most Dangerous Woman in America tells the extraordinary story of Mary Mallon, better known as Typhoid Mary. She gained this notoriety by being the first person in North America to be identified as a healthy carrier of typhoid fever. Despite her indignant protests of innocence, she was incarcerated for years on an island in New York's East River. Mary Mallon's saga throws into vivid relief the emerging science of public health and the social, ethical, and legal dilemmas it posed to its pioneers at the turn of the twentieth century. Special DVD features include: materials and activities for educators; a link to the NOVA Web site; scene selections; closed captions; and described video for the visually impaired. On one DVD5 disc. Region... |
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Het Loo Wilhelmina Typhoid Apeldoorn 1902 by old-print Old Antique Historical Victorian Prints Maps and Historic Fine Art ----------. Het Loo Wilhelmina Typhoid Apeldoorn 1902 Page From An Issue 1878 . The Illustrated London News . These Wood Engravings From Sketches, Or Early Photographs Would Make An Ideal Gift For Christmas Or Birthday . The Actual Date Is Printed On Each Page . This Engraving Is Over 120 Years Old. And Is Not A Modern Copy. These Images Are Scanned At Low Resolution For Quick Uploading And Are Much Better Than The Scanned Image.. Size Of Print Is Approx 14" X 9.1/2" If It Is Shown As Whole Page, Or Prorata.. Approx. Page Size = 16" High X 11" Wide. Ready To Matt And Frame. These Old Prints Really Look Great With Matt And Framed. . Note This Print Is From A Periodical And Has Printing On Reverse. |
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Take Shelter by Typhoid Mary | |
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Filthy Habit Typhoid Mary (Primary Contributor) |
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Typhoid Mary by Anthony Bourdain (Author) In 1906, at a prosperous Long Island summer home, a family falls ill and typhoid is diagnosed. When Dr George Soper is called in to find the source of the contagion, he notices that the household cook has gone missing. She is Mary Mallon, the woman who would become known as Typhoid Mary. Soper, sanitary engineer turned sleuth, sees Mary as his Moriarty. He finds there has been an outbreak of typhoid fever in every household she has worked in over the past decade. Mary is a 'carrier', a seemingly healthy individual who passes on her dangerous germs, sometimes with fatal consequences. Now Soper must hunt the cook down before she can infect more unsuspecting victims. A poor Irish immigrant, Mary refuses to believe that she can harbour typhoid in her strong and healthy body, and she doesn't... |
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