Salmonella poses a heightened risk for individuals over 65 years of age due to several key factors: Read more at the link above.
As people age, their immune systems naturally weaken, making them more vulnerable to infections, including those caused by Salmonella. The body’s ability to fight off harmful bacteria diminishes, increasing the chances of severe infection.
Listeria, specifically the bacterium Listeria monocytogenes, poses a significant risk to pregnant women due to several factors: Read more at the link above.
During pregnancy, a woman’s immune system undergoes changes to support the fetus, making her more susceptible to infections like listeriosis. This altered immune response means that even a small amount of bacteria that might not impact others can have serious effects on a pregnant woman.
Image CDC
University of Liverpool scientists have exploited the combined power of genomics and epidemiology to understand how a type of Salmonella bacteria evolved to kill hundreds of thousands of immunocompromised people in Africa.
Bloodstream infections caused by a drug-resistant type of Salmonella Typhimurium called ST313 are a major public health concern in Africa, where the disease is endemic and causes ~50,000 deaths each year. What was missing was an understanding of the timing of the major evolutionary events that equipped African Salmonella to cause bloodstream infections in humans.
In a new paper published in Nature Microbiology, a team of researchers from the UK, France and Malawi, sampled two comprehensive collections of Salmonella isolates from African patients with bloodstream infections, spanning 1966 to 2018, to piece together the evolutionary journey of the Salmonella over 50 years of human infections in Africa, including the discovery of a new lineage of antibiotic-susceptible ST313.
The study was led by Professor Jay Hinton at the University of Liverpool, who has been researching Salmonella for more than 30 years and leads the 10,000 Salmonella Genomes Project — a worldwide effort to understand the epidemiology, transmission and virulence of invasive non-Typhoidal Salmonellosis.
Professor Hinton said: “Through a remarkable team effort we have removed some of the mystery about the evolution of African Salmonella. We hope that by learning how these pathogens became able to infect the human bloodstream we will be better prepared to tackle future bacterial epidemics.”
The Australian Government Department of Health in collaboration with jurisdictions is currently investigating three cases of Listeria infections (listeriosis) occurring in Victoria, Queensland and New South Wales. All cases occurred in people aged over 70 years and all had significant underlying health conditions. Unfortunately two people (from NSW and Victoria) have died.
Investigations have implicated smoked salmon as the likely source. This is a timely reminder for people to ensure that food is handled, prepared and stored safely, and that those most at-risk of listeriosis avoid certain foods.
Listeriosis is an illness usually caused by eating food contaminated by the bacterium Listeria monocytogenes. The bacteria are widely distributed in the environment and can grow in food at refrigeration temperatures. Most people who are exposed to Listeria will only develop mild symptoms, though illness can be severe in those most at-risk. Those at increased risk of illness include pregnant women and their unborn babies, newborn babies, the elderly, and people of all ages with immune systems weakened by illness or medication.
If you (or someone in your household) have a weakened immune system or are pregnant, the best way to avoid Listeria is to eat freshly cooked or freshly prepared food.
Try to avoid foods that have a higher risk of Listeria contamination such as:
You can further reduce your risk by:
Listeria infection starts with flu-like symptoms such as fever, chills, muscle aches, nausea, and sometimes diarrhoea.
People can start experiencing symptoms within a few days, but symptoms can take a number of weeks to appear after eating a contaminated product.
For information on listeria and food visit the Food Standards Australia New Zealand website.
For more information see the Listeria fact sheet.
For information on foods to eat or avoid when pregnant visit the NSW Food Authority website.
For further information on the investigation into the cases of listeriosis please contact the relevant state health departments.
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