Health

After investigating the eating habits of thousands of Americans, one factor was found to account for a significant difference in the healthiness of Americans: cooking meals at home. In a recent study from Johns Hopkins Center for a Livable Future, people who cooked meals at home were found to eat consume fewer calories, fat, sugar and carbohydrates.

“A difference of 150 calories per day over time can make a significant difference in dietary intake and health,” Julia Wolfson, MPP, PhD Candidate Johns Hopkins Bloomberg School of Public Health, Johns Hopkins Center for a Livable Future-Lerner Fellow, and one of the authors of the study, told The Speaker.

And a difference of 150 calories per day was the finding. After analyzing data from over 9,000 participants aged 20 and older, the researchers found that when adults who cooked dinner once or less a week were compared with adults who cooked six to seven times a week, the people who cooked at home were eating a lot healthier. Those who cooked at home consumed 2,164 calories, 81 grams of fat and 119 grams of suger on average daily, while those who more often ate out consumed an average of 2,301 calories, 84 grams of fat and 135 grams of sugar.

“This difference indicates that a person who starts cooking more does not need to make drastic changes to their diet in order to see a beneficial impact, Wolfson told us. “These results show that just the act of cooking more frequently is associated with reduced intake of calories, fat, sugar and carbohydrates.”

The researchers also made other significant findings. Blacks were found to be more likely than whites to live in households where there was less home cooking, and individuals who worked over 35 hours per week outside the home were also found to cook less often at home.

“There are very real barriers to frequent cooking,” explained Wolfson. “Time constraints, cost of ingredients, resources and equipment to cook, and lack of access to fresh, healthy, and affordable ingredients. These barriers are more likely to impact lower-income populations, who… are more likely to be black.”

Americans are familiar with the 40 hour work week associated with full-time employment, but recent polls have found that full-time workers in the US actually work an average of 47 hours per week–and 40 percent of full-time workers work over 50 hours per week.

“Long work hours, inflexible schedules definitely make cooking very frequently more difficult for many people,” Wolfson told us. “Because encouraging more cooking at home has the potential to have a positive impact on obesity rates and diet quality, we need to find ways to support more frequent cooking at home. However, for those individuals for whom cooking at home is not feasible, we also need to invest in ways to make eating healthfully outside the home easier and more affordable.

“The most important takeaway is that more frequent cooking at home is associated with a healthier diet, regardless of whether one is trying to lose weight. If a person starts cooking more meals at home, they will be eating healthier by default.”

The report, “Is cooking at home associated with better diet quality or weight-loss intention?” was authored by Julia A. Wolfson and Dr Sara N. Bleich, an associate professor in the Department of Health Policy and Management at the Bloomberg School, was supported by the National Heart, Lung, and Blood Institute, and was published in the journal Public Health Nutrition.

By Heidi Woolf

Photo: Ryan McVay

A recent study by Yale University has found that isolating Ebola victims within four days of symptom onset could achieve disease elimination in Liberia. Setting out to determine how to best use scare resources to combat the Ebola outbreak overwhelming West Africa, and after analyzing the incidence and case fatality of the outbreak, the team concluded that the best hope for ending the spread of Ebola was isolation of Ebola victims very early in the progression of symptoms–although the time window suggested by the research was smaller than current time to hospital reporting in West Africa.

“The Ebola outbreak in Western Africa is spiraling out of control. The need to determine how to deploy scarce resources to end this crisis is urgent,” Dr Dan Yamin, Postdoctoral Associate in Epidemiology at Yale School of Medicine and lead author of the report, framed the study.

The goal of the study was to “evaluate the contribution of disease progression and case fatality to transmission and to examine the potential for targeted interventions to eliminate the disease,” according to the report.

The team used both clinical and epidemiological data–incidence and case fatality records–from the Liberian Ministry of Health and Social Welfare, and found that secondary infections occurred during the infectious period of an Ebola victim at an average rate of 1.73. That is, each infected person passed on Ebola to 1.73 healthy individuals.

Ebola victims who did not survive passed the disease on to 0.66 people, while nonsurvivors passed the disease on to 2.36 people. Survivors of Ebola, the study found, infected at least one healthy person in 32 percent of cases. Nonsurvivors infected at least one healthy person with a 67 percent probability rate.

“Consequently, nonsurvivors, who made up 63% (CI, 60% to 64%) of the population, were responsible for 86% (CI, 63% to 98%) of transmissions,” the researchers found.

Left alone, “the number of newly reported cases will be doubled every 20 days,” Yamin told The Speaker, pointing out that the number of newly reported cases should not be misconstrued to be the total number of cases.

The conclusion reached by the team was that isolation of infected individuals offered a chance of eliminating the disease. Isolation of 75 percent of nonsurviving infected individuals within four days after symptoms began created a 74 percent chance of disease elimination. Isolation of all infected people offered a marginal reduction beyond the 74 percent. Isolation of asymptomatic people, however, made no practical sense, the researchers found.

“There is no medical sense in quarantining asymptomatic people,” Yamin told us. “All evidence shows that asymptomatic people (and people that were exposed and are in the “incubation period”) can’t transmit.

“Isolating all individuals before symptoms onset is not practical,” said Yamin, noting that, of course, it “would obviously lead to disease elimination.”

The most pragmatic way to actually combat Ebola in West Africa, Yamin told us, was isolation of only those people who were already symptomatic.

“In the absence of sufficient isolation units, our model emphasizes that targeted isolation of those who are mostly responsible for transmission may be the most efficient way to contain Ebola. Specifically, because infectiousness increases greatly with disease progression we found that that isolating 75% of infected individuals (particularly, the more severe cases) within four days of symptom onset has a high chance of eliminating the spread of the disease.

The researchers found that the current average period from symptom onset to hospitalization in Liberia was approximately 5 days–significantly beyond the requirements suggested by the study.

The researchers also evaluated the effectiveness of self-quarantine–a pragmatic strategy in areas where there were not sufficient isolation units. Self-quarantine of 75 percent of all infected could eradicate Ebola with 78 percent probability.

“Effectively, we tested self-quarantine by contact reduction of an infected person beyond what was currently reported,” Yamin told us. “The data provided by the Liberian Ministry of Health suggests that, an infected individual contacts, on average, with 6 people–this

number seems to be substantially lower than the number of contacts of a healthy person.

“Our results suggest that to achieve 78% for elimination, additional 60% reduction in contacts should occur following the first day from symptoms onset. Practically, implementing even this strategy seem to be challenging, which highlights the importance of increasing isolation units in Liberia.”

The conclusion of the researchers was that the massive international support directed at helping in West Africa “should be directed towards expanding the capacity of hospitalized case isolation.”

“Targeted isolation may offer the best hope of ending the Ebola epidemic.”

The report, “Effect of Ebola Progression on Transmission and Control in Liberia,” was authored by Dan Yamin, PhD; Shai Gertler; Martial L. Ndeffo-Mbah, PhD; Laura A. Skrip, MPH; Mosoka Fallah, PhD; Tolbert G. Nyenswah, MPH; Frederick L. Altice, MD, MA; and Alison P. Galvani, PhD, was published in Annals of Internal Medicine, and was funded primarily by the National Institute of Health.

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By Andrew Stern

Photo: International Federation of Red Cross and Red Crescent Societies

The Ebola Virus and the related Marburgvirus have been diverging for over 16 million years, according to a recent study by the University of Buffalo. Although filoviruses were once thought to date back only 10,000 years, new research using more reliable dating methods has shown that the origins of the virus go much deeper than the beginnings of large-scale human agriculture.

“An understanding of the timescale of evolution is critical for comparative virology but remains elusive for many RNA viruses,” wrote the authors of the report.

Experts had at one time believed that filoviruses came about around 10,000 years ago, and coincided with the rise in human agriculture.

According to the research of Professor Derek Taylor and others at the University of Buffalo, the viruses date back to the Miocene Epoch–16 to 23 million years ago.

Read more: Ebola Genome Sequencing Being Undertaken by Harvard Team to Discover Weaknesses in Virus Genome, Which Has Already Mutated Hundreds of Times 

“Filoviruses are far more ancient than previously thought,” said Taylor. “These things have been interacting with mammals for a long time–several million years.”

The science of measuring the age of diseases is still developing. Previous dating relied on mutation rates.

“Age estimates based on mutation rates can severely underestimate divergences for ancient viral genes that are evolving under strong purifying selection,” the researchers wrote in their report.

“Paleoviral dating, however, can provide minimum age estimates for ancient divergence, but few orthologous paleoviruses are known within clades of extant viruses.”

“For example, ebolaviruses and marburgviruses are well-studied mammalian pathogens, but their comparative biology is difficult to interpret because the existing estimates of divergence are controversial.”

The researchers looked at the paloviral elements of two genes in the ebolavirus family, and found that ebolavirus diverged from marburgvirus in the early Miocene.

The scientists searched within the viral genes in rodents preserved through fossilization.

“These rodents have billions of base pairs in their genomes, so the odds of a viral gene inserting itself at the same position in different species at different times are very small,” Taylor said. “It’s likely that the insertion was present in the common ancestor of these rodents.”

The knowledge may help scientists create better vaccines for Ebola victims. It could also help create programs that better identify emerging pathogens by providing insight into which host species serve the virus as “reseviors” for related pathogens.

“When they first started looking for reservoirs for Ebola, they were crashing through the rainforest, looking at everything–mammals, insects, other organisms,” said Taylor. The more we know about the evolution of filovirus-host interactions, the more we can learn about who the players might be in the system.”

By Andrew Stern

Photo: NIAID

According to a new report by scientists at the University of Bristol, additional daylight savings could have public health benefits. The study looked at daylight savings increases as a possible public health intervention, and found evidence that an increase would increase physical activity among children.

“This study provides the strongest evidence to date that, in Europe and Australia, evening daylight plays a role in increasing physical activity in the late afternoon and early evening – the ‘critical hours’ for children’s outdoor play. Introducing additional daylight savings measures would affect each and every child in the country, every day of the year, giving it a far greater reach than most other potential policy initiatives to improve public health,” said Dr. Anna Goodman, Lecturer at the London School of Hygiene & Tropical Medicine at the University of Bristol and one of the researchers on the project.

The study, “Daylight saving time as a potential public health intervention: an observational study of evening daylight and objectively measured physical activity among 23,000 children from 9 countries,” was authored by the University of Bristol’s Anna Goodman, Angie S Page and Ashley R Coope, and was published in the International Journal of Behavioural Nutrition and Physical Activity. The study was funded by the UK National Prevention Research Initiative, and Anna Goodman’s contribution was funded by the National Institute for Health Research.

In the research, over 23,000 children aged 5-16 years were studied in nine countries (England, Australia, USA, Norway, Denmark, Estonia, Switzerland, Brazil and Madeira, and Portugal). The scientists looked at physical activity data before and after the clocks changed. The data was matched to the time of sunset, as well as daily precipitation, humidity, wind speed, temperature and other weather characteristics.

Independent of weather factors, longer evening daylight was found to be associated with a modest but not insignificant increase in daily physical activity. The associations were consistently observed in five European, four English and two Australian samples, where children added two minutes of physical activity per day as a result of longer evening sunlight.

Although two minutes may at first seem a small amount of time, two minutes per child in a large population can amount to millions of minutes of extra physical activity per day, the researchers noted.

“We therefore conclude that, by shifting the physical activity mean of the entire population, the introduction of additional daylight saving measures could yield worthwhile public health benefits,” the researchers wrote.

“While the introduction of further daylight savings measures certainly wouldn’t solve the problem of low physical activity, we believe they are a step in the right direction,” said senior author Ashley Cooper, Professor of Physical Activity and Public Health at the University of Bristol.

By Heidi Woolf