Listeriosis in humans

Listeria is a special type of bacteria that causes diseases called anthropozoonoses. They can be infected from animals that themselves are sick or only carry the pathogen.

What is listeriosis

This disease belongs to a group of infections that are called saprozoonotic (that is, animals and people get sick). It affects blood cells (mononuclear cells) and the nervous system. The course of the disease can be severe, up to the development of septic forms.

Forms of listeriosis in humans

Depending on what symptoms and organ damage occur in patients, several forms of the disease are distinguished:

• angina-septic with a predominance of symptoms similar to mononucleosis;
• oculo-glandular, when the organs of vision and lymph nodes are predominantly affected;
• typhoid with skin lesions and attacks of fever;
• mixed option.

In addition, a congenital form of listeriosis is isolated separately, which is noted in the fetus and newborn if the mother became infected with listeria during pregnancy.

The causative agent of listeriosis

The causative agent of the infection is Listeria. This is a small mobile coccoid rod. Listeria are quite resistant to adverse environmental factors, they can remain viable at low and moderate temperatures in the soil for several years. They are well preserved in forage, they survive for a long time in meat and dairy products in a refrigerator. But they do not withstand boiling and the action of disinfectants.

Ways of transmission of listeriosis in humans

Bacteria are widely distributed, birds and mammals are considered their main source in nature.

The main route of infection is food, when eating vacuum-packed prepared meat and fish products, dairy products (soft cheeses, butter, ice cream, unboiled milk).

Contact-household transmission is possible when interacting with domestic (cats, dogs, chickens) and wild animals (foxes, rodents, wild boars).

A person can become infected with listeriosis through direct contact with animals or birds, through the surface of the skin or mucous membranes (for example, during butchering of carcasses), from food contaminated with bacteria, through the air when working with grain, or during pregnancy, during childbirth. The disease is especially severe in newborns, in patients with immunodeficiencies and in the elderly.

Symptoms of listeriosis in humans

Listeriosis can occur both in the form of manifest, and in the form of abortive and asymptomatic forms.

The acquired manifest form of listeriosis is typical for adult patients. It can occur in different ways, each with its own set of symptoms.

In the anginal form (its second name is mononucleosis-like), a high temperature occurs, appetite decreases, headache and severe weakness appear, sore throat symptoms (tonsil damage) and an increase in lymph nodes in the neck and under the jaw are also typical.

If the pathogen penetrates from the conjunctiva of the eye, an oculo-glandular form occurs (bathers’ disease). It is characterized by fever, loss of appetite and headache, pronounced symptoms of asthenia, severe swelling and severe redness in the eyelids, a sharp narrowing of the palpebral fissures, the appearance of a purulent secret in the corners of the eyes, an increase in lymph nodes in size, pain in the lymph nodes.

In the typhoid form of infection, the following symptoms occur: high and prolonged fever, a rash on the skin both in the form of spots and bruises, but there are no signs of tonsillitis or conjunctivitis. This form is typical for children, especially those suffering from immunodeficiencies, as well as in newborn babies and toddlers in the first year.

If the nervous system suffers, meningitis or encephalitis may develop, which leads to severe mental disorders, paralysis, developmental delay (if these are children). But this form is most often found in adults.

In pregnant women, listeriosis can proceed quite easily with a variety of symptoms, for example, flu-like symptoms – conjunctivitis, runny nose, cough, muscle pain. But even mild forms of the disease in the mother can lead to intrauterine infection of the fetus.

Congenital listeriosis has its own characteristics – it can occur even in the womb at any stage of pregnancy after the 5th week, or during childbirth. Therefore, spontaneous abortions, stillbirth, malformations in babies are possible if it was the first half of gestation. If this is the second half of pregnancy and a baby is born, he may develop congenital listeriosis. It is characterized by high fever, refusal to eat, vomiting or regurgitation, constant lethargy and lethargy, pulse fluctuations, marbling or cyanosis of the skin, nodular rash or bruising, liver damage with jaundice, meningitis or encephalitis.

Treatment of listeriosis in humans

Treatment of listeriosis should only be under medical supervision. Sometimes it is acceptable to stay at home with all the recommended drugs, but if there is a threat of damage to the internal organs or the central nervous system, hospitalization is indicated.

Diagnostics

The basis of the diagnosis is laboratory tests, since it is not easy to suspect an infection based on symptoms alone. In the blood test, especially against the background of angina, a sharp monocytosis is possible. The volume of monocytes can reach 60% of all leukocytes.

In order to identify the bacterium, bacteriological and molecular genetic research methods are carried out. Blood samples, nasopharyngeal mucus, cerebrospinal fluid, eye swabs are taken. Also, a biopsy of enlarged lymph nodes, a sample of amniotic fluid, particles of the placenta are performed.

The most commonly used enzyme immunoassay with the determination of antibodies to Listeria and molecular genetic study – PCR diagnostics with the determination of Listeria DNA in various biological media. If a diagnosis of damage to the nervous system is carried out, an electroencephalogram, a puncture with the collection of cerebrospinal fluid, MRI or CT of the brain is necessary.

Modern treatments

At the time of acute manifestations of the disease, strict bed rest, a sharp restriction of activity and isolation of the patient from others are indicated. To suppress the activity of bacteria, antibiotics of various groups are used. The prescription of drugs is carried out taking into account the age of the patient. The duration of the course of therapy and its volume depend on the localization of the process and the severity of the disease.

In addition, symptomatic drugs are prescribed, which are individually selected by the doctor. For example, at elevated temperatures – antipyretics, in the case of eye problems – drops.

Prevention of listeriosis in humans at home

Specific preventive measures in the form of a vaccine for listeriosis have not been developed. Therefore, the observance of strict sanitary standards and control by the veterinary service in livestock farms, the food industry and catering establishments will help prevent infection.

It is also necessary to control rodents, to carry out the necessary heat treatment of products.

Popular questions and answers

We discussed with pediatrician, infectious disease specialist and hepatologist Tatyana Kovaleva danger of listeriosis, warning signs of infection and the need to see a doctor.