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Infectious Disease

Global Health, Infectious Disease, Public Health, Research, Rural Health, Stanford News

Stanford bioengineer developing an “Electric Band-Aid Worm Test”

Stanford bioengineer developing an “Electric Band-Aid Worm Test”

uganda-kids“Those children are sitting on the graves of their siblings,” said a Ugandan colleague, in a tragic reminder of the impact of childhood diseases in rural Africa.

Stanford bioengineering professor Manu Prakash, PhD, took this picture two weeks ago while conducting clinical field evaluations of his lab’s various ultra-low-cost disease diagnostics inventions.

His latest project is an electromagnetic patch that non-invasively detects live parasitic worms in infected patients.

To help test this novel idea, Prakash and co-investigator Judy Sakanari, PhD, a research pathologist at the UC San Francisco School of Medicine, received a $100,000 Grand Challenges Explorations award from the Gates Foundation.

The first prototypes will be used to detect the worm that causes onchocerciasis, or “river blindness,” which afflicts approximately 37 million people in Africa, Central and South America, and Yemen. Transmitted through repeated bites of blackflies, it is a major cause of preventable blindness.

Current diagnostic methods require the use of expensive ultrasound equipment to determine whether parasitic worms are alive under the skin or inside lymph nodes. Prakash’s more frugal design consists of a Bandaid-sized patch embedded with a sensitive sensor that detects minute electrical changes when worms wiggle under the skin or form calcified cysts. He expects that the final device will cost less than $10 and will be easier to use in rural settings.

Prakash and Jim Cybulski, a Stanford mechanical engineering PhD student, were also working at several sites to clinically evaluate “Foldscope,” an inexpensive microscope made of folded paper that is being mass produced and used for diagnosing diseases like malaria, schistosomiasis, African sleeping sickness, tuberculosis and various filarial diseases in field conditions. Cybulski recently won a Global Health Equity Scholars Fellowship (NIH-funded) for field testing this device.

The magnitude of the malaria problem in Uganda, which has one of the highest rates of infected mosquitoes in the world, became crystal clear during their trip.

“There was one hut where we trapped 400 mosquitoes in one night,” said Prakash. “And some public health centers that we visited had almost 100 malaria cases per day, with mothers of large families bringing in at least one child a week for testing.”

He added, “Being in the field gives meaning to working in global health. It teaches you empathy, a driving force so strong that transforms ideas into actions.”

Prakash’s lab is also exploring how to develop “human capital” in these resource-constrained settings, a strategy that would generate more jobs and build the infrastructure to provide these services locally. “We are looking at various ways to bring appropriate tools and training to these young college graduates who don’t have much to do,” he said.

Previously: Is the worm turning? Early stages of schistosomiasis bladder infection charted, Compound clogs Plasmodium’s in-house garbage disposal, Using cell phone data to track and fight malaria and Image of the Week: Malaria developing
Photo by Manu Prakash

CDC, Global Health, Infectious Disease, Pediatrics, Research

Measles is disappearing from the Western hemisphere

Measles is disappearing from the Western hemisphere

Decades of measles and rubella vaccinations for U.S. children are paying off. A new Centers for Disease Control report published today in JAMA Pediatrics confirms that the United States has eliminated endemic transmission of three potentially devastating diseases: measles, rubella (also known as German measles) and congenital rubella syndrome, which causes serious birth defects.

The report is part of a larger effort by the World Health Organization to certify the entire Western hemisphere free of endemic measles and rubella, which are chains of transmitted cases that continue for 12 months or more. Today, the large majority of measles cases seen in the U.S. are clearly linked to international travel or contact with travelers, and genetic evidence suggests that uniquely American strains of the measles and rubella viruses no longer exist. All other countries in the Americas are also reporting elimination of endemic transmission of these diseases.

The findings confirm the value of high rates of measles and rubella vaccination. Nearly 95 percent of U.S. children have had the two vaccine doses needed to confer lasting immunity by the time they enter kindergarten. Because measles is still endemic in other parts of the world, it’s important not to let up on vaccination here, the report notes. In spite of the good news about the elimination of endemic infections, 2013 has been a relatively bad year for imported infections, as CNN reported today.

An editorial accompanying the JAMA Pediatrics report offers interesting perspective on the need to continue with vaccinations:

Prior to 1990, Mexico was the leading source of measles importations into the United States, but this year, half of all importations into the United States were from Europe. Since 2008, there has been a resurgence of measles cases in Western European countries. The majority of these outbreaks have been in unimmunized populations in countries where national immunization programs are being challenged by a combination of public and political complacency regarding the value of immunization and by the rising influence of antivaccination groups. After 500 years, we have now returned to a situation where the Americas are free from indigenous measles and rubella with Europe once again a source of importations.

The elimination of endemic measles from the Western hemisphere raises hope that global eradication of measles is on the horizon, an important public health goal since measles is most likely to kill impoverished children in developing countries. Already, the increase in vaccination in African countries has led to a 91 percent decrease in measles deaths there, with 550,000 fewer annual deaths than a decade ago.

Previously: Measles are on the rise; now’s the time to vaccinate, says infectious-disease expert, Tips for parents on back-to-school vaccinationsA look at the causes and potential cost of the U.S. measles outbreaks and Unvaccinated children may pose a public health risk

CDC, Infectious Disease, Medical Education, Patient Care, Public Health, Science, Stanford News

Free online course aims to educate about “pressing public health threat” of antibiotic resistance

Free online course aims to educate about "pressing public health threat" of antibiotic resistance

antibioticsAre you smart about antibiotics? That’s the question the CDC is asking as part of its week-long effort to educate people about antibiotic resistance – something the organization calls “one of today’s most pressing public health threats.” Its Get Smart About Antibiotics website offers valuable tips and information on antibiotic use, and CDC Director Thomas Frieden, MD, MPH, will be answering questions on the topic during a live Twitter chat Friday morning. (Follow the hashtag #CDCchat at 10 AM Pacific time tomorrow to join the conversation.)

Stanford, meanwhile, is aiming to educate medical professionals by launching a free online course called “Antimicrobial Stewardship: Optimization of Antibiotic Practice.” The course, directed by Stan Deresinski, MD, head of Stanford’s Antimicrobial Stewardship Program, will “offer a practical approach to prescribing antibiotic therapy and development of antimicrobial stewardship across all specialties and settings.” As for the need for such a course, the website explains:

Antibiotics are among the most frequently prescribed classes of drugs and it is estimated that approximately 50% of antibiotic use, in both the outpatient and inpatient settings, is inappropriate.  At the same time, in contrast to any other class of drugs, every antibiotic use has a potential public health consequence – inappropriate use may not harm only the individual patient, but contributes to societal harm by exerting an unnecessary selective pressure that may lead to antibiotic resistance among bacteria.

The course is sponsored by the Division of Infectious Diseases and Geographic Medicine in the Department of Medicine. Participants have the option of taking the course for CME credit.

Previously: Side effects of long-term antibiotic use linked to oxidative stress, New method may speed identification of antibiotic targets, Harnessing evolutionary forces to develop more effective methods for treating superbugs and Norway’s strategy for fighting drug-resistant bacteria
Photo by Iqbal Osman1

Chronic Disease, Dermatology, Global Health, In the News, Infectious Disease, Public Health

Eradicating leprosy?

In this age of medical advancements it’s sometimes hard to believe that any disease we can treat could still persist. Here on Scope, we’ve discussed several such diseases that we can treat but can’t quite eradicate, such as malaria and leprosy. Leprosy, as my colleague explains, is an ancient disease that continues to thrive in the modern world even though an effective and free treatment is widely available to patients suffering from the disease.

If you’re slack-jawed in disbelief, you have good company. Yet, as incredible as this sounds, access to an effective and affordable treatment isn’t the only barrier to eradicating a disease. Yesterday, this article in The Economist Explains discusses some of the nuances to eradicating treatable diseases.

From The Economist:

A big obstacle to eradicating leprosy is the long delay between its onset and detection. It usually takes three to five years before the symptoms show up. In some cases the incubation period from infection to disease can be as long as 20 years. Leprosy attacks the skin and nerves, leaving behind scaly patches on the body. It looks like a skin disorder and can be easily misdiagnosed. Since many medical colleges do not stock infected skin smears, most doctors are not qualified to recognise it early on.

Eradication of leprosy would be a formidable task. Getting rid of other diseases (such as tuberculosis and malaria) would be a higher priority for most countries, since they kill huge numbers of people. Leprosy does not.

On a brighter note, the article points out that efforts to reduce the cases of leprosy and detect the disease earlier are still underway.

Previously: Leprosy in the modern worldAll in the family: Uncovering the genetic history of the world’s most lethal pathogensImage of the Week: Leprosy bacteria and interferon-beta and Tropical disease treatments need more randomized, controlled trials, say Stanford researchers

Infectious Disease, Pediatrics, Public Health, Stanford News

Measles are on the rise; now’s the time to vaccinate, says infectious-disease expert

Measles are on the rise; now's the time to vaccinate, says infectious-disease expert

According to data from the Centers for Disease Control, cases of measles in the U.S. are on the rise, with this year looking to be the worst in more than 15 years. And if that news doesn’t disturb you, take a look at some statistics from the CDC on what the impact of measles was in the U.S. prior to the start of the measles vaccination program in 1963:

  • About 3 to 4 million people got the disease each year
  • Roughly 48,000 of those people were hospitalized
  • 1,000 suffered brain damage or became deaf
  • 450 died

If you want to learn more about measles and the importance of parents getting their children vaccinated, check out this Q&A with Hayley Gans, MD, an infectious-disease specialist at Lucile Packard Children’s Hospital.

Previously: Tips for parents on back-to-school vaccinationsA look at the causes and potential cost of the U.S. measles outbreaks and Unvaccinated children may pose a public health risk

Global Health, Infectious Disease, Public Health, Public Safety, Research, Stanford News

Global community must do a better job of managing risk of Nipah virus, expert says

Global community must do a better job of managing risk of Nipah virus, expert says

fruit batIf a South Asian disease that’s commonly associated with fruit bats and pig farms doesn’t top your list of things to think about today, you may want to read this story in the current issue of Inside Stanford Medicine. The piece focuses on Nipah virus – a disease that has no known treatment or vaccine - and discusses a recent commentary on it from Steve Luby, MD, director of research for Stanford’s Center for Innovation in Global Health. In his piece, Luby explains how global travel can spread diseases and lists some of the reasons why diseases that affect low-income countries should be of global concern.

From the Inside Stanford Medicine article:

Discovered in 1999, Nipah can be traced to Pteropus bats, commonly known as fruit bats, which carry the virus but are immune to it. In Bangladesh, these bats transmit the virus to humans through raw date palm sap, which the bats are known to lick and urinate in as it is harvested for human consumption. Children love the treat with puffed rice in the morning.

Sustained person-to-person transmission of Nipah through contact with bodily secretions has been limited so far. Still, there is significant cause for concern that Nipah could spread faster and wider. Fruit bats can be found over a range stretching from Pakistan across South and Southeast Asia, up the coast of Southern China and down into Australia. Climate change and other environmental factors could expand the bats’ range.

Rich countries need to help improve poor countries’ health-care systems — specifically, making sure health-care workers have access to protection such as gloves and hand washing — to help prevent spread, Luby said. In densely populated Bangladesh, health-care providers who treat Nipah patients typically lack gloves and masks, while patient attendants often lack soap and water for hand washing.

Beyond stopping the spread of Nipah, such measures would reduce the risk of influenza and other disease pandemics, according to Luby. “I think it’s important that taxpayers in the U.S. recognize that investments in prevention in low-income, high-risk countries can protect their own lives.”

Luby’s commentary appears in the journal Antiviral Research.

Holly MacCormick is a writing intern in the medical school’s Office of Communication & Public Affairs. She is a graduate student in ecology and evolutionary biology at University of California-Santa Cruz.

Previously: H7N9 got you aflutter? Wired offers help sorting fact from fictionClosing the net on malariaWhat I did this summer: Stanford medical student works to improve pediatric surgical care in TanzaniaImproving treatment for infant respiratory distress in developing countriesWHO’s math may not add up for developing nations and Stanford pump project makes clean water no longer a pipe dream
Photo of fruit bat by Joachim Muller

Infectious Disease, Microbiology, Nutrition, Research, Stanford News

Joyride: Brief post-antibiotic sugar spike gives pathogens a lift

Joyride: Brief post-antibiotic sugar spike gives pathogens a lift

candy shackLet’s be clear: Antibiotics are a modern miracle. They’re also ancient history: During ancient times, moldy bread was traditionally used in Greece and Serbia to treat wounds and infections. Russian peasants used warm soil to cure infected wounds. Sumerian doctors gave patients beer soup mixed with turtle shells and snake skins. Babylonian doctors healed the eyes using a mixture of frog bile and sour milk. You get the drift.

At the same time, it’s not exactly breaking news that a course of antibiotics can wreak havoc with your gastrointestinal tract, where infamous intestinal pathogens such as salmonella and C. difficile can run amok.

“Antibiotics open the door for these pathogens to take hold,” according to Stanford microbiologist Justin Sonnenburg, PhD.

As I wrote in my press release about some exciting recent work by Sonnenburg, a healthy person’s large intestine is a menagerie teeming with miniature lifeforms:

The thousands of distinct bacterial strains that normally inhabit this challenging but nutrient-rich niche have adapted to it so well that we have difficulty living without them. They manufacture vitamins, provide critical training to our immune systems and even guide the development of our own tissues.

In return, our gut pays these industrious Oompa-Loompas salaries made of sugar – not common table sugar, but more exotic types, with names like fucose and sialic acid. Cells lining the intestine extrude long chains of such sugar varieties (these chains go by a familiar name: “mucus”) to feed its one-celled workhorses – as well as to keep them at arm’s length, so that they don’t get into the bloodstream and cause sepsis.

Everybody’s having fun until along come antibiotics and somebody gets hurt. The decimated gut-microbe ecosystem begins bouncing back within a few days, but  for as much as a month after a round of antibiotics we’re at heightened risk for infection by some bad, bad bugs.

In a new study, Sonnenburg and his colleagues snared some clues about how that works. They found that antibiotics’ inadvertent but inevitable gut-bugicide generates a transient surplus of sugars, including sialic acid and fucose, that have been liberated from gut mucus by good bugs who bit the dust before they got a chance to munch their lunch.

Salmonella lacks the equipment for carving sialic acid and fucose loose from the intestine’s extruded mucus, but it knows how to eat them. The bonanza, Sonnenburg’s team found, gives the pathogen the energy it needs to gain a toehold and launch a toxic takeover, leaving our gut in its hands.

Sonnenburg thinks there may be ways to slam the door that antibiotics open for unwanted intruders. For example, specialized probiotics with big appetites for fucose or sialic acid could be co-administered along with the antibiotics, cutting off the the nasty bugs’ stash until the nice ones repopulate the gut.

Sonnenburg’s work appears online in Nature.

Previously: The future of probiotics, Eat a germ, fight an allergy, What if gut-bacteria communities “remember” past antibiotic exposures? and Researchers manipulate microbes in gut
Photo by Lee Cannon

Health Disparities, Infectious Disease, Public Health, Research, Women's Health

Study shows racial disparities in HPV vaccination

Study shows racial disparities in HPV vaccination

Much has been written here and elsewhere about the lower-than-ideal number of women and girls who get vaccinated for human papillomavirus (HPV). (The concern, of course, is that these patients are missing out on the opportunity to reduce their risk of sexually transmitted disease and cancer.) Now, a study out of University of Pittsburgh School of Medicine appearing in the Journal of Adolescent Health shows (as has past research) that some young women of color are even less likely than their white counterparts to get vaccinated.

As described in a press release:

Led by [Sonya Borrero, MD], researchers used data from the 2006-2010 National Survey of Family Growth (NSFG), a nationwide cross-sectional survey administered by the U.S. Department of Health and Human Services, to examine the effect of race/ethnicity on HPV vaccine initiation in adolescent girls and young women and to determine whether access to health care influences this relationship.

In this nationally representative sample of 2,168 females aged 15 to 24, African-Americans were significantly less likely than whites to have initiated HPV vaccination, 18.2 percent vs. 33.1 percent respectively. That disparity persisted even after taking into account socio-demographic factors and access to health care. Observed disparities in HPV vaccination for Hispanics, on the other hand, were largely explained by socio-demographic and health care access variables, the researchers found.

Referencing their finding that African-American patients are also less likely than white patients to have a health-care provider recommend the vaccine, Borrero and her co-authors suggest that improving access to health care among this population might not do the trick in solving the problem. “Perhaps, addressing negative attitudes and beliefs and increasing provider recommendation for HPV vaccination will be fruitful in increasing HPV vaccination rates in this population,” they write.

Previously: HPV-associated cancers are rising, HPV vaccination rates still too low, new national report says, Only one-third of teenage girls get HPV vaccine to prevent cervical cancer and The cost of forgoing routine vaccinations

History, Infectious Disease, Microbiology, Public Health, Research, Stanford News

Did microbes mess with Typhoid Mary’s macrophages?

Did microbes mess with Typhoid Mary's macrophages?

macrophage with salmonella insideMary Mallon (a.k.a. “Typhoid Mary“) didn’t mean any harm to anybody. An Irish immigrant, she made her living for several years about a century ago by cooking for better-off families in the New York City area. Strangely, the people she cooked for kept on coming down with typhoid fever – but not Mary.

Mallon, alas, turned out to be a chronic asymptomatic carrier of Salmonella typhi, the bacterial strain that causes typhoid fever. Typhoid is a deadly disease that, while no longer a huge problem in the United States, infects tens of millions – and kills hundreds of thousands – of people around the world every year.

“She didn’t know she had it,” says Stanford microbiologist Denise Monack, PhD. “To all outward appearances, she was perfectly healthy.”

Salmonella strains, including one called S. typhimurium, also cause food poisoning in people and pets, taking an annual human toll of 150,000 globally. While S. typhi infects only humans, closely related S. typhimurium can infect lots of mammals.

Between 1 and 6 percent of people infected with S. typhi become chronic, asymptomatic typhoid fever carriers. Nobody has known why this happens, but it’s a serious public-health issue. To address this, Monack has developed an experimental mouse model that mimicks asymptomatic typhoid carriers. In a new study published in Cell Host & Microbe, she and her colleagues put that model to good effect, showing that Salmonella has a sophisticated way of messing with our immune systems. The bacteria set up house inside voracious attack cells called macrophages (from the Greek words for “big eater”). Macrophages, are known for their ability to engulf and digest pathogens and are called to the front lines of an immune assault against invading microbes. Ornery critters that they are, macrophages would seem like the last thing bacteria bent on long-term survival would want to meet.

But, as I wrote in my release about this study, a macrophage has two faces, depending on its biochemical environment:

“Early in the course of an infection,” [Monack] said, “inflammatory substances secreted by other immune cells stir macrophages into an antimicrobial frenzy. If you’re not a good pathogen, you’ll be wiped out after several days of causing symptoms.” But salmonella is one tough bug. And our bodies can’t tolerate lots of inflammation. So, after several days of inflammatory overdrive, the immune system starts switching to the secretion of anti-inflammatory factors. This shifts macrophages into a kinder, gentler mode. Thus defanged, anti-inflammatory macrophages are more suited to peaceful activities, such as wound healing, than to devouring microbes.

And, sure enough, Monack and her colleagues showed that salmonella germs have a way (still mysterious, but stay tuned) of taming macrophages, flipping an intercellular switch inside of these thug-like cells that not only expedites their champ-to-chump shift but induces them to pump out tons of glucose, the bug’s favorite food. What better place to hide than in the belly of the beast?
Previously: TB organism’s secret life revealed in a hail of systems-biology measurements
Photo by AJC1

Infectious Disease, Public Health, Sexual Health, Stanford News

Packard Children’s adolescent and young adult specialist offers tips for college-bound students

Packard Children’s adolescent and young adult specialist offers tips for college-bound students

Stanford_freshmanIn addition to shopping for back-to-school supplies and mulling over course selections, college-bound students should also make time for an “off-to-college” health check-up before the start of the academic year. During such appointments, Sophia Yen, MD, MPH, and her colleagues at the Lucile Packard Children’s Hospital Teen and Young Adult Clinic, recommend students talk to their health-care providers about ways to stay healthy and safe while fully enjoying their college experience.

Yen suggested students ask their doctors about several topics, including specific vaccinations, in a recent press release.

“We urge all college students to get vaccinated against these diseases: tetanus, diphtheria and pertussis (Tdap); meningitis; and human papillomavirus (HPV), which is the No. 1 sexually transmitted infection (STI) in the United States. Even if a college student has only two sexual partners in his or her lifetime, they have a 70 percent or higher chance of contracting one of the four HPV strains if they haven’t received the vaccine,” says Yen, who is also a clinical assistant professor of pediatrics at the Stanford School of Medicine.

“In addition, all sexually experienced individuals under the age of 26 should get tested for chlamydia every year,” adds Yen, noting that 80 percent of people who have chlamydia – a sexually transmitted infection – don’t know that they have it and do not have symptoms.

Previously: Task force recommends HIV screening for all people aged 15 to 65, HPV-associated cancers are rising, HPV vaccination rates still too low, new national report, The costs of college binge drinking and Study estimates hospitalizations for underage drinking cost $755 million per year
Photo by L.A. Cicero/Stanford News Service

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