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Where does listeriosis hide?

Modern society teaches people from an early age to observe sanitary norms. And if you ask an elementary question: "Do you wash your hands before eating?", the answer will probably be "Of course, yes!" But if we slightly modify this question: "Do you always have the opportunity to wash your hands before eating", then a person is bound to think about the answer. Doctors do not call for fanatical sterilisation of the environment, but warn about the consequences that a patient may face if he or she does not adhere to elementary rules. This article is about listeriosis, a disease that can occur anywhere, with a wide range of clinical manifestations, which makes it difficult to diagnose. The relevance of the topic is related to the recent outbreak of listeriosis in Denmark, which killed 15 people [1].

And so, listeriosis is an infectious disease caused by listeria bacteria and characterised by multiple sources of the causative agent, a variety of symptoms, routes and factors of transmission.

Many people think that listeriosis is a rare disease. However, this is not entirely true. Firstly, a low detection rate does not necessarily mean a low incidence. Secondly, clinical symptoms can be masked by common acute respiratory infections and intestinal disorders. The main danger of the disease lies in the fact that listeriosis is able to pass into a chronic form and make itself known only when the immune defence of the patient is reduced. This is especially true for pregnant women - 30% of listeriosis cases in the United States occur in pregnant women[2], with listeriosis responsible for 28% of food poisoning deaths[3].

So where does listeriosis "hide"? Listeria is ubiquitous and lives in the soil and therefore in the bodies of domestic animals. This is the main route of infection:

1. Foodborne route - through consumption of animal products without proper heat treatment: milk, cottage cheese, soft cheeses, sausages, processed meats, sausages and butter meat. Unwashed fruit and vegetables contaminated with bacteria from the soil also fall into this category

2. Contact route - infection from sick animals

3. Aerogenic route - by inhalation of bacteria during the processing of hides and wool

4. The vertical pathway is from the sick pregnant woman to the foetus

5. Transmissible route - by tick bite

The incubation period lasts from 1-2 days to 1.5-2 months. Symptoms depend on a number of factors: age, sex, comorbidities, localisation of the pathogen in the body and immune status. Below we list all clinical forms of the disease.

The glandular form runs like a sore throat

The ocular glandular form is characterised by unilateral purulent conjunctivitis. The lymph nodes on the corresponding side may be enlarged.

The gastroenteric form is accompanied by an acute onset, a sharp rise in body temperature to high figures and increasing weakness. After a few hours, nausea, vomiting, frequent liquid stools, the abdomen may be painful in the area of the appendix.

The nervous form manifests itself as meningitis with characteristic symptoms in the form of severe headache.

The septic form is one of the most severe, as blood poisoning occurs with all its consequences.

Listeriosis of pregnant women and newborns is distinguished separately. Acute and chronic listeriosis can cause termination of pregnancy at different stages.

Chronic listeriosis is difficult to suspect, as the symptoms of exacerbation are very non-specific: short-term fever and sore throat, digestive disorders in the form of nausea, vomiting or liquid stools, as well as symptoms of pyelonephritis: pain in the lower back and increased body temperature.

In acute forms of the disease (even without identification of the causative agent), doctors prescribe broad-spectrum antibiotics that cope with listeria, so the patient gets better. But the chronic form is not easy enough to diagnose and treat.

Diagnosis without laboratory data is impossible due to the lack of specific signs of the disease. Microscopy of biomaterial with direct detection of bacteria is considered the gold standard. This method is limited by the fact that it is difficult to predict in which biomaterial (blood, urine, feces, cerebrospinal fluid and pharyngeal swab) the pathogen will be found. It is therefore recommended to perform serological diagnosis by blood: determination of IgG to Listeria monocytogenes. This test detects the chronic process in the body caused by listeriosis, regardless of where the microbe is located in the body.

In conclusion, it is worth noting that compliance with sanitary rules and timely referral to a doctor at the onset of these signs of disease will help to minimise the likelihood of chronic listeriosis. Be healthy!

Warning! If you have signs of listeriosis, we recommend you to consult a primary care physician or an infectious disease specialist. You can also undergo an ELISA test for listeriosis in any treatment room of the OLYMP CDL branch

1. http://foodcontrol.ru/news/7250 with reference to the Danish State Serum Institute (SSI)

2. Center for Infectious Disease Research and Policy, University of Minnesota –Listeriosis

3. Robert-Koch-Institut : Epidemiologisches Bulletin. 8 Dezember 2006/Nr: 49