Listeria is caused by Listeria monocytogenes, a gram positive bacterium found in soil, water and in animal digestive system including in humans. The infection is caused by eating contaminated food. Listeria is commonly seen in ready-to eat processed food items.
Can Listeria Kill You?
Yes, Listeria can kill you, but not everyone who get the Listeria infection will die. First let’s talk about the pathogenesis of Listeria infection briefly. This will help you understand how the disease can be fatal.
Listeria infection can cause severe infection in people with low immunity like neonates, pregnant women, elderly people and people with immunodeficiency. These people can get septicemia, central nervous system infection, and other organ infections. These infections of blood and other organs are the reason for the deaths (mortality). Septicemia has a mortality rate of 70%, CNS infections have a mortality of 20% and can increase up to 40 to 60% with other disease at the same time and endocarditis is the third cause for deaths.
Pathogenesis of Listeria Monocytogenes
When contaminated food with Listeria is consumed it enters the small intestinal lining cells and multiplies. The bacteria move, first intracellular then from cell to cell. Then the bacteria are carried to the liver and spleen and most of them destroyed in the liver and spleen. Some bacteria will escape and go to other organs, but host T cell-mediated immune system will activate and destroy the bacteria and if that happens then the person will develop gastroenteritis which can be self-limiting or may need treatment.
If the immune response of the host is inadequate, Listeria monocytogenes multiply in hepatocytes (liver cells) and macrophages (cell of the immune system) freely and reach other organs via blood. The bacteria particularly infect the brain and uterus right through the blood-brain barrier and placental barrier. The exact mechanism how the organism penetrate the blood-brain barrier or placental barrier is unknown. It can also spread to other organs and infect those organs as well.
The Diseases An Adult Will Get With Invasive Listeria Infection
- Septicemia – serious blood infection, 15-50% of adults can get septicemia
- Central nervous system (CNS) infection, seen in 55-70% of cases
- Meningitis – inflammation of the membranes surrounding the brain which are called meninges
- Encephalitis – inflammation of the brain
- Meningoenchephalitis – inflammation of both brain and meninges
- Brain abscess – localized area of infected material, occurs about 10% of CNS infection
- Rare diseases that manifest with listeriosis (5-10%)
- Endocarditis – inflammation of the inner lining of the heart
- Myocarditis – inflammation of the muscle layer of the heart
- Arteritis – inflammation of the inner walls of the arteries
- Pneumonia – infection of the lung
- Pleurisies – inflammation of the membranes that surround the lung
- Hepatitis – infection of the liver
- Osteomyelitis – infection of the bone
- Peritonitis – inflammation of the peritoneum which is the inner lining of the abdomen
Symptoms of Gastroenteritis
Symptoms of Brain Inflammation
- High fever
- Nausea and vomiting
- Neck pain/neck stiffness
- Loss of consciousness
- Paralysis of the cranial nerves
Other symptoms can occur according to the organ involved.
People At Increased Risk Of Getting Invasive Listeriosis
Listeriosis occurs when the T-cell mediated immunity is not adequate to fight off the infection. So basically Listeria is an opportunistic organism. The infection becomes severe and affects the brain, blood and other organs when the immunity in the body is low.
People with low immunity are:
- Elderly people
- Immunocompromised people
- Malignancies – leukemia, lymphoma or sarcoma
- On chemotherapy
- On immunosuppressant therapy – organ transplantation or corticosteroid use
- Chronic liver disease – cirrhosis or chronic alcoholism
- Kidney disease
- Diabetes mellitus
- Collagen disease – Systemic lupus erythematosus
- HIV (Human Immunodeficiency Virus) / AIDS (Acquired Immune Deficiency Syndrome)
- Pregnant women are at increased risk of getting listeria infection but the disease remains less sever in them, if they do not have any other disease. But the infection can be transmitted to the baby.
Risk of Death (Mortality) with Listeria Infection
- Septicemia – has a high mortality rate of 70%
- CNS Infection – has a 20% mortality rate, but it can increase up to 40-60% if associated with other disease at the same time.
- Endocarditis – this is the third most severe infection that can cause death.