all epidemiology stories

Eating whole-grain cereals may help men lower heart failure risk

404132862 — Mon, 22 Oct 2007 15:14:44 -0400

Men who consume a higher amount of whole grain breakfast cereals may have a reduced risk of heart failure, according to a report by Harvard researchers published in the October 22 issue of Archives of Internal Medicine.

"The lifetime risk of heart failure is estimated at 20 percent (one in five) for both men and women aged 40 years," according to background information in the article. Studies have suggested that the risk of hypertension, coronary heart disease, hypercholesterolemia (high blood cholesterol) and mortality can be reduced with a diet rich in grain products.

Eradicating polio better option than control

Tue, 10 Jul 2007 14:40:28 -0400

Concerns about the high perceived costs of eradicating the relatively low number of polio cases worldwide have led to recent suggestions that it is time to shift from a goal of eradication to control: abandoning eradication and allowing wild poliovirus to continue to circulate, which proponents of control believe can sustain the low number of cases. In a new study, researchers from the Harvard School of Public Health (HSPH) analyzed the costs and health outcomes of control and eradication options. They found that the relatively high short-term costs of global polio eradication will ultimately be much lower than the long-term financial and human health costs required to control polio forever.

Noninfectious pathway for HIV found by HSPH team

Tue, 10 Jul 2007 16:39:28 -0400

HIV is a crafty virus. It attacks the body by invading and taking over the very cells meant to protect humans from infection. Hiding within cells such as macrophages and lymphocytes, the virus uses the body's natural machinery to replicate itself, destroying the immune system and leaving patients open to a range of debilitating and deadly opportunistic infections.

Now, a team led by Harvard School of Public Health (HSPH) researchers has described a previously unappreciated pathway used by HIV to enter macrophages and has shown that the virus, once in the cells through this entryway, doesn't appear to replicate. Rather than causing infection, the virus is destroyed, and an immune response may be triggered.

Spray-dry vaccine for TB developed

Wed, 11 Jul 2007 10:47:14 -0400

Bioengineers and public health researchers have developed a novel spray-drying method for preserving and delivering the most common tuberculosis (TB) vaccine. The low-cost and scalable technique offers several potential advantages over conventional freezing procedures, such as greater stability at room temperature and use in needle-free delivery. The spray-drying process could one day provide a better approach for vaccination against TB and help prevent the related spread of HIV/AIDS in the developing world.

Study: Gap in energy among teens

Wed, 11 Jul 2007 16:06:40 -0400

A new study by researchers at the Harvard School of Public Health (HSPH) shows that America's overweight teens consumed an average of 700 to 1,000 calories more than required each day over a 10-year period. This "energy gap" - or the imbalance between the number of calories children consumed each day and the number they required to support normal growth, physical activity, and body function - resulted in an average of 58 extra pounds for overweight teens.

The study, the first to look at the energy gap among children and youth, was published in the December 2006 issue of the journal Pediatrics. The study shows that U.S. children and teens overall consumed an average of 110 to 165 more calories than they required each day. Over a 10-year period, this energy gap led to an excess 10 pounds of body weight on average among teens.

"Our research indicates that early prevention may be critical," said Y. Claire Wang, the HSPH researcher who led the study. "The energy gap becomes bigger and harder to close as kids accumulate more excess weight." This suggests that strategies to prevent excess weight gain from occurring during childhood may be more effective than attempting to treat overweight teens.

"We must find ways to help kids eat well and move more," said Tracy Orleans, a distinguished fellow and senior scientist at the Robert Wood Johnson Foundation, which sponsored the study. "That means acting now to create environments that support healthy eating and increased physical activity in schools and communities, and at home."

For the study, researchers examined height and weight data for 5,000 children in the National Health and Nutrition Examination Survey (NHANES) between 1988 and 1994. They projected what the height and weight gains for this group would be 10 years later, based on normal growth patterns, and compared that projection to actual height and weight data from a similar group of teens in the most recent NHANES (1999 to 2002). Children were defined as overweight (sometimes called obese) if their body mass index was greater than or equal to the 95th percentile of the Centers for Disease Control and Prevention (CDC) growth charts.

Obesity begins in the womb

Thu, 12 Jul 2007 15:06:37 -0400

The obesity epidemic in the United States has spread to include children under 6 years old and particularly infants, according to a Harvard study.

The study of 120,680 kids is the largest to date to report on such young children. During the 22-year period covered, medical records reveal that the prevalence of overweight children less than 6 years old jumped 59 percent, from 6.3 to 10 percent.

The results show surprising increases in the number of overweight children up to 6 months old. From 1980 to 2001, the increase in overweight infants ballooned 74 percent.

"The obesity epidemic has spared no age group," says Matthew Gillman, an associate professor at Harvard Medical School. "These results show that efforts to prevent obesity must start even before birth."

Exercise boosts health of HIV-infected women

Thu, 12 Jul 2007 16:41:57 -0400

Betsy Lincoln felt pregnant all the time. Loss of muscle tone in her face, arms, and legs made her look so bad, she didn't want to leave her apartment. She had little strength or endurance. Lifting one of her children or climbing a flight of stairs exhausted her.

Lincoln (not her real name) is representative of many of the estimated 250,000 women in the United States infected with HIV (human immunodeficiency virus), or the deadly AIDS it causes. And that number is rising. In this country, most of the women are minorities and poor, with limited access to medical care. Recent research also suggests that they may be at increased risk for heart disease. Even the drugs they take to keep their infection under control can cause unwanted changes in body fat and loss of energy.

Study: Hope alive for AIDS vaccine

Fri, 13 Jul 2007 10:35:21 -0400

Researchers from the Dana-Farber Cancer Institute and Harvard Medical School (HMS) have prompted human immune cells to attack HIV protein fragments, showing that the long-sought vaccine to protect against AIDS is still a possibility.

Researchers using advanced data-analysis programs identified five protein fragments from HIV - the virus that causes AIDS - that promote a strong immune response from the cells of people who have never been exposed to the HIV virus before.

That means, researchers said, that creation of a vaccine to protect unexposed individuals from infection with HIV appears possible. Researchers conducted their study using fragments from HIV-1, the more virulent of the two strains known to cause AIDS.

For 20 years, scientists have fought the disease and sought ways to prevent the AIDS virus from devastating patients' immune systems. It is the virus's destruction of the body's immune response that opens patients to a variety of opportunistic infections that run rampant and, ultimately, cause death.

Researchers had thought that human immune system cells don't fully recognize the HIV-1 virus and so can't eliminate it from the body after infection. The new study shows that isn't the case and suggests shifting efforts toward creating a vaccine aimed at uninfected individuals.

The study, published in the online journal Medical Immunology, was led by Dana-Farber's Pedro Reche, an instructor in medicine at HMS, and by Derin Keskin, a research fellow in medicine at HMS.

"It has been unknown for 20 years why HIV-1 becomes persistent and isn't cleared from the bodies of AIDS patients," says Medical Immunology's editor, Kendall Smith, chief of the Division of Immunology at Weill Medical College at Cornell University. "This study suggests that in HIV-positive people, the immune system cells that respond to HIV-1 are either deleted or have lost the ability to recognize and home in on major parts of the virus."

If these findings hold true in follow-up studies, they suggest that exposing healthy people to HIV-1 proteins might train their immune system to attack the virus and prevent them from developing AIDS if exposed to HIV-1 in the future, Reche said.

Senior author of the study is Professor of Medicine Ellis Reinherz, of Dana-Farber and Harvard Medical School. Other co-authors, all of Dana-Farber and Harvard Medical School, are Rebecca Hussey, research associate in pathology; Petronela Ancuta, research fellow in pathology; and Professor of Neurology Dana Gabuzda.

Study offers new hope for preventive vaccine for AIDS

70652986 — Mon, 26 Mar 2007 06:27:37 -0400

New research by Dana-Farber Cancer Institute scientists suggests that it may one day be possible to immunize healthy individuals against HIV-1, the virus that causes AIDS.

In a study published in the online journal Medical Immunology, investigators led by Dana-Farber's Pedro Reche, Ph.D., and Derin Keskin, Ph.D., upend the long-held view that human immune system cells do not fully recognize HIV-1 following infection, and thus are unable to eliminate it from the body. The researchers found that lab-grown immune system cells from uninfected individuals are able to distinguish and respond to key HIV proteins. Cells taken from infected individuals, by contrast, were much less responsive to the virus.

If these findings hold true in follow-up studies, they suggest that exposing healthy people to HIV-1 proteins might train their immune systems to attack the virus and prevent them from developing AIDS if exposed to HIV-1 in the future, Reche said.

The research was funded in part by grants from the National Institutes of Health.

Obesity levels in U.S. states are grossly underestimated

70652986 — Mon, 26 Mar 2007 06:26:44 -0400

The prevalence of obesity in the U.S. states has been greatly underestimated. Researchers at the Harvard School of Public Health analyzed data from health surveys, which are used to estimate obesity levels in states. Because people tend to provide incorrect information about their weight and height, especially in telephone surveys, the researchers concluded that estimates of obesity in individual states have been too low, by more than 50 percent. Their study, which corrects for misreporting in those surveys, appears in the May 2006 issue of the Journal of the Royal Society of Medicine.

Obesity is one of the leading causes of morbidity and mortality, causing some 2.6 million deaths worldwide each year. In the U.S., survey data on obesity on a national and state level is obtained using information gathered by the Behavioral Risk Factor Surveillance System (BRFSS), which uses telephone interviews; national data is also collected using the National Health and Nutrition Examination Survey (NHANES), which does in-person interviews and follow-up height and weight measurements on people who agree to a clinical exam. Lead author Majid Ezzati , associate professor of international health at HSPH, and his colleagues analyzed and compared the data from the two surveys in order to quantify the level of bias when people self-report their height and weight, especially in a telephone interview.

Based on this new understanding of the survey data, the authors found that, on average, women tend to underestimate their weight while men do not. When it comes to height, young and middle-aged men tend to overestimate their height more than women in the same age group.

In 2002, the corrected prevalence of obesity in the U.S. population was 28.7 percent for adult men and 34.5 percent for adult women, more than 50 percent higher than previously estimated.

The research, which presents the first-ever corrected estimates of obesity for individual states, found that Southern states have the highest levels of obesity in the country.

This work was supported by a cooperative agreement from the Centers for Disease Control and Prevention through the Association of Schools of Public Health and by the National Institute on Aging.

RNA sequence restrains fatal encephalitis

70652986 — Mon, 26 Mar 2007 06:25:17 -0400

One short sequence of RNA protected mice from deadly brain inflammation caused by West Nile virus and Japanese encephalitis virus, report Priti Kumar, Manjunath Swamy, and Premlata Shankar. The findings, which appear online and in the April 2006 PLoS Medicine, underscore the therapeutic potential of the fast-moving field of RNA interference. It has only been four years since scientists first showed that RNA interference, which protects plants, flies, and worms from viral infections, also works in mammalian cells. Now, at least two experimental siRNA therapies already have advanced to phase I safety trials in people. Short interfering RNA (siRNA) silences genes most commonly by triggering the destruction of RNA before proteins can be made.

Containment buys time but...

50443248 — Thu, 19 Jul 2007 11:58:35 -0400

Containing an emerging bird flu pandemic at its source will probably only delay - not stop - the illness' spread because of likely multiple introductions of the pathogen, assert researchers from the Harvard School of Public Health (HSPH) and the University of Washington in a policy paper in PLoS Medicine. The paper will appear in the open access journal online on Feb. 20 after 8 p.m.

"If a single introduction of a pandemic-capable strain is likely to happen, then multiple introductions are also likely," said HSPH Associate Professor of Epidemiology Marc Lipsitch. "If there are multiple introductions, then there are numerous chances for containment, and the strategy only has to fail once to result in a pandemic."

Containment describes attempts to reach a pandemic source as early as possible and then apply public health tools such as vaccination (if available), antiviral drugs, and quarantine to curb a pathogen's spread. Containment is one component of federal and World Health Organization planning for a possible flu pandemic.

The researchers argue that resources would be strained with each new effort at containment, making subsequent control strategies more and more difficult to implement. Under good circumstances, containment efforts may only double the time before a pandemic emerges, the researchers have calculated. That time could drop even further if efforts underpinning the containment, such as surveillance for human cases, are inadequate.

Alternative screening could cut cervical cancer deaths in poor nations

70652986 — Mon, 26 Mar 2007 05:43:12 -0400

In the right hands, a swab of vinegar and a flashlight may detect more cervical cancer around the world than the recommended cytological screening known as a Pap smear. At the right time, a single DNA test for the virus that causes cervical cancer may also outperform repeated Pap smears.

In fact, dime for dime, either test is a better deal for poor countries that want to emulate the success of wealthy countries in sharply reducing cervical cancer rates, says a cost- effectiveness analysis of the three screening methods in five developing countries.

If developing countries screened all women at least once in their mid-30s, they could cut the number of cervical cancer deaths by up to 25 percent, reports the paper in the Nov. 17, 2005 New England Journal of Medicine. With a second screening several years later, the two tests could potentially halve the number of women dying from cervical cancer.

"No matter which option - the high-tech DNA test or low-tech visual inspection - the most important point is the simple fact of being able to deliver the treatment with the screening in one or two visits," said lead author Sue Goldie, Harvard School of Public Health associate professor of health decision science.

Annual cytological testing of exfoliated cervix cells has been the global standard for decades, but the numbers tell the story of its failure to curb a highly preventable cancer in many regions. Cervical cancer tops the cancer mortality charts in poorer countries, which account for 80 percent of all cervical cancer deaths. It tends to kill women in their 40s, leaving large young families to fend for themselves.

Happily, abnormal cells destined to become cervical cancer are easily detected and safely treated in the earliest stages.

Warning labels on high-risk drugs inconsistently heeded by doctors

70652986 — Mon, 26 Mar 2007 05:42:20 -0400

In a survey of approximately 930,000 ambulatory care patients, researchers from the Department of Ambulatory Care and Prevention (of Harvard Medical School and Harvard Pilgrim Health Care) and colleagues found that 42 percent received prescriptions for drugs with Black Box Warnings (BBW), the Food and Drug Administration's strongest label for high-risk medication. Additionally, physicians' compliance with the recommendations of the BBWs was highly variable, which suggests that better methods are needed for ensuring the safe use of medications that carry serious risks.

In the categories studied, doctors' noncompliance to BBWs ranged from 0.3 percent to 49.6 percent. These results are reported online in the Nov. 18, 2005 issue of Pharmacoepidemiology and Drug Safety.

"In ambulatory care settings, approximately 1.4 billion prescriptions are written per year," said Anita Wagner, Harvard Medical School assistant professor at DACP. "Until now, there has been no information about how frequently doctors prescribe BBW drugs, nor whether prescribing is consistent with the warnings. This study tells us that these drugs are prescribed often and that in some categories, prescribing is inconsistent with the warnings."

Gingko may prevent ovarian cancer

70652986 — Mon, 26 Mar 2007 05:41:46 -0400

Researchers at Brigham and Women's Hospital have found initial laboratory and epidemiological evidence that, for the first time, demonstrates that ginkgo may help lower a woman's risk of developing ovarian cancer. The findings were presented at the American Association for Cancer Research's annual meeting in Baltimore on Oct. 31, 2005.

In a population-based study, which involved more than 668 ovarian cancer cases and 720 healthy, matched controls, women who took ginkgo supplements for six months or longer were shown to have a 60 percent lower risk of ovarian cancer.

Daniel Cramer, MD, ScD, director of the Obstetrics and Gynecology Epidemiology Center at BWH, and colleague Bin Ye, PhD, found that ginkgo, echinacea, St. John's wort, ginseng, and chondroitin were the most commonly used herbals among study participants. A further analysis of the data showed that ginkgo was the only herb linked to ovarian cancer prevention. The preventive effect was more pronounced in women with non- muncious ovarian cancers, with data showing that ginkgo may reduce the risk of this type of ovarian cancer by 65-70 percent.

The team then took the evidence demonstrated in the population study to the laboratory. In these experiments the researchers tested whether or not gingko, when introduced to ovarian cancer cells, may interfere with cell growth.

In vitro experiments showed that a low dosage of gingkolide caused ovarian cancer cells to stop growing. The researchers observed an 80 percent growth reduction in non-mucinious ovarian cancer cells. Gingkolides appeared to be less effective against the mucinous type of ovarian cancer cells, which paralleled the findings observed in the epidemiological study.

"Among the mixture of ginkgo chemicals," said Ye, "we found laboratory evidence that ginkgolide A and B, terpene compounds, are the most active components contributing to this protective effect."