Listeria A Microbiologist Bacterium Behind Recent Deadly Foods

Listeria A Microbiologist Bacterium Behind Recent Deadly Foods

Bacteria do, and will, end up in foods. Everyone eats intentionally or unintentionally millions to billions of live microbes every day. Most are completely harmless, but some can cause serious illnesses in humans. Because of these potential pathogens.

There is a long list of foods to avoid, including uncooked eggs. Raw fish and unwashed fruits and vegetables, particularly for pregnant women. The foods themselves are not bad, but the same cannot said for certain bacterial passengers. Such as Listeria monocytogenes, or listeria for short.

This particular pathogen has found ways to indiscriminately get into our foods. While deli and dairy foods like cold cuts, cheese, milk and eggs are frequently. Culprits for causing listeriosis the general name for listeria-cause infections fresh vegetables and fruits have also been implicate.

Variety Of Foods

The variety of foods responsible for U.S. listeria outbreaks in the past decade. Shows just how easily these bacteria get around. Listeria has turned up in hard-boiled eggs, enoki mushrooms, cooked chicken and, in 2021, packaged salad twice.

Even the frozen aisle is not spare from listeria contamination. Contaminated ice cream in Florida was behind this year’s listeria outbreak. With 25 reported cases spanning 11 states since January 2021. According to an early August 2022 report from the Centers for Disease Control and Prevention. Those who fell ill ranged in age from less than 1 to 92 years old. And 24 of the cases have involved hospitalizations.

How can such a tiny organism bypass extensive disinfection efforts and wreak such havoc? As a microbiologist who has been working with listeria and trying to solve these mysteries, I’d like to share some insider secrets about this unique little pathogen and its strategies of survival inside and outside our bodies.

Farm To Foods Table

To prevent consumer exposure to listeria, the foods industries follow stringent disinfection and surveillance guidelines from the Food and Drug Administration and the U.S. Department of Agriculture. Any detection of listeria triggers a recall of potentially contaminated food products.

Since 2017, there have been over 270 listeria-relate food recalls. These are incredibly costly and can sometimes lead to fears in consumers as well as nationwide disruptions in food services. However, the recalls represent one of the few tools that the food industry has to protect consumers from foodborne infections.

Not all listeria strains are create equal. Genetic variations in listeria make a big difference in whether the pathogen ends up being involve in multistate outbreaks or simply hitching a ride harmlessly through our digestive tract. Essentially, based on the different methods used, listeria can be subtype into different lineages, with some associated with outbreaks more frequently than others.

Researchers are investigating ways to tell these listeria strains apart, distinguishing the less harmful ones from those that are particularly dangerous, or hypervirulent. Being able to accurately identify them can help policymakers assess risks and make economically feasible decisions to improve food safety.

Listeria Is Tough

Listeria can live in any place where food is grown, packaged, stored, transported, prepared or served. Our research team has even found listeria in organic lettuce harvested from a backyard garden.

Listeria can survive and grow in temperatures as cold as 24 degrees Fahrenheit (-4.4 Celsius) because it has adapted to cold temperatures and developed tricks for overcoming cold stress. Considering the average refrigerator maintains a temperature range of 35 F to 38 F (1.7 C to 3.3 C), even when the food is stored properly at refrigeration temperatures, a harmless few listeria can grow to dangerous levels of contamination over time.

Listeria is also extremely versatile in adapting to and surviving all kinds of disinfection processes. When it grows on surfaces, listeria protects itself with a biofilm structure, a kind of coating that forms a physical and chemical barrier and prevents disinfectants from reaching the bacteria within.

Surviving the harsh conditions outside our body is only the first part of the story. Before even beginning to cause infections, listeria needs to get to the intestines without getting caught and destroyed by the body’s defenses.

Traveling And Surviving Foods Passage

Traveling and surviving passage through a human digestive tract is not easy for bacteria. Saliva enzymes can degrade bacterial cell walls. So can stomach acids and bile salts. Antibodies in our digestive tract can recognize and target bacteria for degradation. Moreover, resident gut microbes are strong competitors for the limited amount of space and nutrients in our intestines.

After digestion, the body’s intestinal movement sends traffic one way out of the body. In order to stick around and cause infections, bacteria have to attach themselves and hang on against the bowel movement while competing for nutrients. Successful pathogens can establish these survival and attachment tasks while undermining our immune defenses.

Listeria that manage to stick around in our intestines can trigger an immune response. In healthy people, that might manifest as minor diarrhea or vomiting that goes away without medical attention.

However, those with compromised immune systems or immune systems temporarily weakened as a result of medication or pregnancy can be more susceptible to severe infections. In the absence of an effective immune system, listeria can invade other tissues and organs by creating an efficient niche for growth.

Listeria In Stealth Mode

Listeria is what we microbiologists call an intracellular pathogen. In an infected individual, listeria can grow inside a cell and spread to neighboring cells. Hiding inside our cells this way, listeria avoids detection by antibodies or other immune defenses that are designed to detect and destroy threats that exist outside of our cells.

Once in stealth mode, listeria can move into and infect different organs. Wherever it goes, inflammation follows as the body’s immune system tries to go after the bacteria. The inflammation eventually results in collateral damage in nearby tissues.

In fact, deaths from listeria infections are often associated with the more invasive forms of the disease in which the microbes have breached the intestinal barriers and moved to other body parts. Life-threatening illnesses that can result from listeria include meningitis inflammation around the brain and spinal cord that can occur when these microbes infect the brain or endocarditis, infection of the heart’s inner lining. And in pregnant individuals, if the pathogen reaches the placenta, it can spread to the fetus and cause stillbirth or miscarriage.

As such, invasive listeria cases often have an alarmingly high hospitalization rate of more than 90% and a fatality rate that can reach 30%. The scary statistics argue for a proactive and effective infection control to protect vulnerable populations, such as elderly or pregnant individuals, from listeria exposure.

Think, Cook And Eat Foods

If you have risk factors and want to take extra precautions, maybe turn that unpasteurized. Cider into a hot, mulled cider to kill the bacteria with boiling and simmering. Eat soft cheeses on foods that get cooked, such as pizzas or grilled sandwiches. Instead of eating them cold, straight from the refrigerator. Essentially, use heat to bring out the delicious flavors and eliminate potential listeria contamination in your food.

Ultimately, it’s nearly impossible to live in a completely sterile environment, eating food devoid of all living microorganisms. So enjoy your favorites, but stay up to date with ongoing recalls. And follow the expiration guidelines, especially for ready-to-eat food.

Diet Influence Mood, Behavior And More A Neuroscientist Explains

Diet Influence Mood, Behavior And More A Neuroscientist Explains

During the long seafaring voyages diet of the 15th and 16th centuries. A period known as the Age of Discovery, sailors reported experiencing visions of sublime foods and verdant fields. The discovery that these were nothing more than hallucinations after months at sea was agonizing. Some sailors wept in longing; others threw themselves overboard.

The cure for these harrowing mirages turned out to be not a concoction of complex chemicals. As once suspected, but rather the simple antidote of lemon juice. These sailors suffered from scurvy, a disease caused by a deficiency of vitamin C. An essential micronutrient that people acquire from eating fruits and vegetables.

Vitamin C is important for the production and release of neurotransmitters, the chemical messengers of the brain. In its absence, brain cells do not communicate effectively with one another, which can lead to hallucinations.

As this famous example of early explorers illustrates, there is an intimate connection. Between food and the brain, one that researchers like me are working to unravel. As a scientist who studies the neuroscience of nutrition at the University of Michigan. I am primarily interest in how components of food and their breakdown. Products can alter the genetic instructions that control our physiology.

Beyond that, my research is also focus on understanding how food can influence our thoughts, moods and behaviors. While we can’t yet prevent or treat brain conditions with diet, researchers like me are learning a great deal. About the role that nutrition plays in the everyday brain processes that make us who we are.

Perhaps not surprisingly, a delicate balance of nutrients is key for brain health. Deficiencies or excesses in vitamins, sugars, fats and amino acids can influence brain. And behavior in either negative or positive ways.

Vitamins And Mineral Deficiencies Diet

As with vitamin C, deficits in other vitamins and minerals can also precipitate nutritional diseases. That adversely impact the brain in humans. For example, low dietary levels of vitamin B3/niacin typically found in meat and fish cause pellagra. A disease in which people develop dementia.

Niacin is essential to turn food into energy and building blocks. Protect the genetic blueprint from environmental damage and control how much of certain gene products are made. In the absence of these critical processes, brain cells, also known as neurons, malfunction and die prematurely, leading to dementia.

In animal models, decreasing or blocking the production of niacin in the brain promotes neuronal damage and cell death. Conversely, enhancing niacin levels has shown to mitigate the effects of neurodegenerative diseases such as Alzheimer’s, Huntington’s and Parkinson’s. Observational studies in humans suggest that sufficient levels of niacin may protect against these diseases, but the results are still inconclusive.

Niacin Deficiency Diet

Interestingly, niacin deficiency caused by consumption of excessive amounts of alcohol can lead to similar effects as those found with pellagra.

Another example of how a nutrient deficiency affects brain function can be found in the element iodine, which, like niacin, must be acquire from one’s diet. Iodine, which is present in seafood and seaweed, is an essential building block for thyroid hormones signaling molecules that are important for many aspects of human biology, including development, metabolism, appetite and sleep. Low iodine levels prevent the production of adequate amounts of thyroid hormones, impairing these essential physiological processes.

Iodine is particularly important to the developing human brain. Before table salt was supplement with this mineral in the 1920s, iodine deficiency was a major cause of cognitive disability worldwide. The introduction of iodize salt is thought to have contribute to the gradual rise in IQ scores in the past century.

Ketogenic Diet For Epilepsy

Not all dietary deficiencies are detrimental to the brain. In fact, studies show that people with drug-resistant epilepsy a condition in which brain cells fire uncontrollably can reduce the number of seizures by adopting an ultralow-carbohydrate regimen, known as a ketogenic diet, in which 80% to 90% of calories are obtained from fat.

Carbohydrates are the preferred energy source for the body. When they are not available either because of fasting or because of a ketogenic diet – cells obtain fuel by breaking down fats into compounds called ketones. Utilization of ketones for energy leads to profound shifts in metabolism and physiology, including the levels of hormones circulating in the body, the amount of neurotransmitters produced by the brain and the types of bacteria living in the gut.

Researchers think that these diet-dependent changes, especially the higher production of brain chemicals that can quiet down neurons and decrease levels of inflammatory molecules, may play a role in the ketogenic diet’s ability to lower the number of seizures. These changes may also explain the benefits of a ketogenic state either through diet or fasting on cognitive function and mood.

Sugar, Saturated Fats And Ultra Processed Foods

Excess levels of some nutrients can also have detrimental effects on the brain. In humans and animal models, elevated consumption of refined sugars and saturated fats a combination commonly found in ultra processed foods promotes eating by desensitizing the brain to the hormonal signals known to regulate satiety.

Interestingly, a diet high in these foods also desensitizes the taste system, making animals and humans perceive food as less sweet. These sensory alterations may affect food choice as well as the reward we get from food. For example, research shows that people’s responses to ice cream in brain areas important for taste and reward are dulled when they eat it every day for two weeks. Some researchers think this decrease in food reward signals may enhance cravings for even more fatty and sugary foods, similar to the way smokers crave cigarettes.

High-fat and processed-food diets are also associated with lower cognitive function and memory in humans and animal models as well as a higher incidence of neurodegenerative diseases. However, researchers still don’t know if these effects are due to these foods. Or to the weight gain and insulin resistance that develop with long-term consumption of these diets.

Time Scales

This brings us to a critical aspect of the effect of diet on the brain: time. Some foods can influence brain function and behavior acutely such as over hours or days while others take weeks. Months or even years to have an effect. For instance, eating a slice of cake rapidly shifts the fat-burning. Ketogenic metabolism of an individual with drug-resistant epilepsy into a carbohydrate-burning metabolism.

Increasing the risk of seizures. In contrast, it takes weeks of sugar consumption for taste and the brain’s reward pathways to change. And months of vitamin C deficiency to develop scurvy. Finally, when it comes to diseases like Alzheimer’s and Parkinson’s. Risk is influenced by years of dietary exposures in combination with other genetic or lifestyle factors such as smoking.

In the end, the relationship between food and the brain is a bit like the delicate Goldilocks. We need not too little, not too much but just enough of each nutrient.

Hunger Increasing Worldwide But Women Bear The Brunt Of Food

Hunger Increasing Worldwide But Women Bear The Brunt Of Food

Recent UN data on food insecurity paints a bleak picture of a growing international problem. Global hunger is not only growing but it disproportionately affects women. Similarly, the international humanitarian aid organization, CARE, estimates that 150 million more women than men went hungry in 2021.

Despite gains in global food security since 2015, food security has gone backwards. With an increase of 150 million people experiencing hunger since 2019. The UN reports that globally, 2.3 billion people were food insecure. In 2021 with 276 million (12%) facing severe food insecurity. This rapid and sustained increase in hunger over a short time is highly concerning. So too, is the growing gender gap, with 32% of women compared to 27.5% of men going hungry.

Why Are Women More Affect By Food Insecurity Than Men?

To answer this question, the global food system needs to be understood as a mirror of society. It reflects income inequalities and the uneven distribution of goods and services and. As such, is likely to show the same underlying structural inequalities as society at large.

The causes of food insecurity are complex and multi-dimensional. However, two important dimensions are the availability of food and the accessibility of foods.

Recently, the availability of foods has been challenged by climate crises, conflicts, and disruptions due to the COVID-19 pandemic. At the same time, cost of living pressures have pushed the accessibility of food. Beyond the means of many people in both developed and developing countries.

On official measures of gender equality, women tend to experience a lower socio-economic status than men. Globally, 388 million women and girls live in extreme poverty right now, compared to 372 million men and boys. Oxfam reports that women earn 24% less than men, work longer hours. Have more precarious work and do at least twice as much unpaid work.

The Impact Of Other Forms Of Inequality

Income disparities are also important to consider. Even when foods is in abundance, with a few exceptions, it cannot be accessed without money. Accordingly, a bigger gender gap in income equality also means women have fewer means to purchase foods.

The disadvantage of women has also been described in terms of their lack of agency to change their circumstances. In developing countries where subsistence farming is a key means of foods provision, structural inequalities in land tenure and access to credit undermine women’s ability to generate income. Women make up 43% of the agricultural workforce, yet own less than 15% of land.

Improved women’s agency is strongly correlate with a reduction in poverty and has been recognize by the Higher Level Panel of Experts on Food Security as a critical dimension of foods security.

Australia Also Has Severe Food Insecurity, But Women Aren’t Count

Despite being the lucky country, Australia does not have a foods security policy, nor does it collect the data necessary for an informed and targeted response. In fact, the Department of Agriculture, Fisheries and Forestry argues that concerns about foods security are understandable, yet misplaced because Australia produces substantially more foods than it consumes.

The narrative might work in terms of availability of foods but overlooks key issues regarding its accessibility, including gender dimensions, the difference between individual, household and domestic food security, and the link between poverty and foods insecurity.

Some of these data gaps have been fill by Food Bank, a food relief organization, that conducts annual surveys on foods insecurity in Australia. Their recent data reveals 17% of Australian adults are severely food insecure. While the data is not segregate by gender, we can surmise a foods insecurity gap if we use income as a proxy.

Indeed, the Australian parliament reports that women’s median weekly earnings were 25% lower than men’s in 2019, suggesting women may also have reduced access to foods. We may also expect a foods security gap with other marginalized groups such as the aged, people with disabilities, sole parents, and Indigenous populations.

Future Responses

Severe levels of foods insecurity are currently increasing in all regions of the world. And women are faring worse than men. Gender inequality worldwide intensifies the lack of access to foods for women.

Recognizing that women’s foods security cannot separate from broader concerns of agency. Policies must consider the specific issues of gender equality, women’s rights and empowerment

To do this, governments must also institute funded, systematic data collection, segregated by gender. Improved knowledge and transparency is central to policies aiming to strengthen women’s agency. Lift women out of poverty and ensure the food security gender gap does not widen.