Salmonellosis is a common intestinal infection. It mainly affects the organs of the gastrointestinal tract (GIT), namely the small intestine and stomach. Pathogenic microbes enter the human body mainly through products of animal origin.
The disease is characterized by severe intoxication and dehydration. The largest number of cases of infection with this infectious disease are recorded in the summer. In order to prevent or minimize the likelihood of infection, it is important to know how salmonellosis is transmitted.
The causative agent of the disease
The causative agent of salmonellosis is a bacterium called salmonella. It is a gram-negative, anaerobic, motile rod-shaped microorganism. The reservoir and main source of salmonellosis spread is poultry and livestock. Salmonellosis is a disease transmitted by the fecal-oral route.
Most often it occurs due to eating undercooked meat or raw chicken eggs. The causative agent of salmonellosis exhibits increased resistance and persists for a long time in environmental conditions. In reservoirs, salmonella persists for up to 4 months, in soil for up to 1.5 years, in sea water for up to 6 months, in dusty rooms for one and a half years.
Salmonella also persists in food products for a long time:
- in kefir 60 days;
- in milk 20 days;
- in sausages up to 4 months;
- in frozen meat up to 1 year;
- in butter 4 months;
- in eggshell 3 weeks;
- in cheese 1 year.
If you store chicken eggs in the refrigerator for a long time, longer than 1 month, then salmonella can penetrate the yolk through the shell and actively multiply there. Meat and dairy products are also a favorable environment for this bacterium. At the same time, they do not change their appearance and the taste of the product does not deteriorate. Therefore, using these criteria, it is impossible to recognize that a product contains a pathogen.
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Salmonella settles in the small intestine and actively produces toxins in this section of the gastrointestinal tract. This leads to the removal of fluid from it, disruption of vascular tone and damage to the nervous system. The bacterium produces enterotoxins, cytotoxins and endotoxins. The former disrupt the functioning of the small intestine, removing water and salts through it.
Cytotoxins have a destructive effect on the cell membrane, disrupting protein synthesis. The production of endotoxins leads to a deterioration in the general well-being of the patient. Salmonella is characterized by the following features:
- resistant to environmental factors;
- survives at very low temperatures, withstands up to minus 82 degrees;
- resistant to disinfectants;
- viability at room temperature up to 3 months;
- persists in animal feces for up to 4 years;
- is not destroyed in products by salting or smoking;
- actively reproduces in milk and meat dishes;
- produces toxins;
- can only be destroyed by long-term heat treatment.
After the Salmonella microbe enters the human body, the disease manifests itself within 6–72 hours. This means that the incubation period lasts up to 3 days. If the disease is recognized in a timely manner and treatment measures are taken, recovery can be expected within a week or 10 days.
Clinical manifestations of salmonellosis depend on the state of a person’s immunity, and, accordingly, symptoms can be pronounced or practically absent. But even a mild course of the disease does not prevent a person from being a source of infection for others.
Salmonella is often transmitted through raw chicken eggs.
Therapeutic measures
Patients suffering from severe salmonellosis or complications must be hospitalized. Adults and children experiencing mild infection are treated at home.
The basic procedure is washing the stomach and intestines of an infected person, the so-called. "siphon enemas". The next stage of treatment for salmonellosis is restoring the balance of electrolytes in the patient’s body and correcting the water-salt balance. Dehydration is eliminated by frequent (but not copious) ingestion of saline solution orally. For severe dehydration, intravenous infusion therapy is performed, which includes polyionic solutions.
Antibacterial therapy is indicated for patients with a generalized form of salmonellosis. Doctors prescribe drugs from the fluoroquinolone group. Gastrointestinal forms of infection require the use of antibiotics if the pathogen is not susceptible to other drugs. With the standard treatment regimen, patients are prescribed enzymes (pancreatin, dry bile). During acute attacks of salmonellosis, clinical recommendations provide for diet No. 4. After eliminating the intestinal manifestations of the infection, the patient can switch to diet No. 13.
Routes of infection
There are 4 ways of transmitting salmonellosis, these are:
- nutritional;
- contact and household;
- airborne dust;
- water.
The nutritional route is considered the main one when the disease is transmitted through food through the fecal-oral route. More than 80% of all diagnosed cases of salmonellosis are transmitted in this way. The most common source of infection is meat. Eggs, dairy products, and less often fish, are factors in the transmission of salmonellosis.
All of these foods become contaminated if they contain salmonella bacteria and are not cooked properly. You can also become infected through raw vegetables and fruits. When there is a high concentration of Salmonella that has entered the human body, the infection quickly spreads and signs of the disease begin to appear within the first day after infection.
The household contact method of infection is characterized by human contact with sick animals or with animals that are carriers of salmonella. Infection is also possible when caring for a sick animal. People who work in meat processing plants, as well as those who work on agricultural farms, have an increased risk of contracting this infectious disease.
The most active carriers of salmonellosis are birds. A person becomes infected if he eats their meat or comes into contact with objects contaminated with their droppings. Salmonellosis can also be contracted through unwashed hands after contact with pets. Salmonella can be transmitted through kitchen utensils used to cut raw meat.
How to detect salmonellosis?
Contaminated water is also a source of infection. You don’t have to drink it, just swim in it. Even more rare, compared to the waterborne method of transmission of salmonellosis, is airborne dust.
Direct infection through an aerosol mechanism is suspected. Researchers believe that pathogenic bacteria can enter the body through the conjunctiva.
The mucous membrane of the eyes is considered a favorable environment for the activation of pathogens. Salmonella bacteria transit through the conjunctiva into the intestines. However, airborne and waterborne transmission of Salmonella is quite rare, accounting for no more than 5% of reported Salmonella cases.
With all the variety of ways of infection with salmonellosis, the most common is the food mechanism of penetration of the pathogenic bacterium through the consumption of contaminated meat, milk and eggs. This happens when these products are not properly cooked. You can get sick from rare steaks, raw eggs, and fried eggs. The source of infection is domestic animals, in particular cattle, cats, dogs, pigs.
The causative agent of salmonellosis persists in meat for a long time
A little history
A. Bollinger was the first to trace the connection between diseases of domestic animals and food poisoning of people who consumed their meat in 1876.
- The discovery of pathogens of “meat poisoning” began in 1885, when veterinarians D. Salmon and Th. Smith isolated from the internal organs of pigs Bacteria
- In 1888, A. Gartner isolated similar microorganisms from cow meat and the spleen of the person who consumed it. The bacteria were named Bacteria enteritidis Gartneri? later named Salmonella
- In 1892, F. Loffler isolated Bacteria typhimurium (S, typhimurium) from sick mice.
- The name of the genus “Salmonella” was approved by the International Association of Microbiologists in 1934 in honor of the discoverer of bacteria D. Salmon, and the term “Salmonellosis” began to refer to diseases caused by this group of bacteria.
- In 1954, the international Kauffman-White classification was adopted. It includes more than 1,500 different serological types of Salmonella bacteria.
Rice. 2. American veterinarian, in whose honor the genus of enterobacteria Salmonella is named, Daniel Elmer Salmon.
Features of infection from humans and main signs
Infection can also occur from a person with salmonellosis. A carrier of salmonella is also someone who has already had the disease. It is still contagious to others. When infected with salmonellosis from person to person, contact and household transmission of the infection occurs.
The mechanism of infection is characterized by the following stages:
- Live salmonella bacteria enter the human body.
- Salmonella attacks the intestinal walls.
- Bacteria are captured by macrophages, where their active reproduction begins.
- When bacteria die, they release endotoxin, which affects the blood vessels and nerve endings of the intestine. This, in turn, favors the spread of salmonella.
- Bacteria penetrate the lymph nodes and blood vessels. The infection spreads throughout the body through the bloodstream.
- Salmonella multiply in various organs.
- Under the influence of toxins, the human condition is disrupted.
Despite the insidiousness of salmonella, the penetration of bacteria into the body does not always lead to illness. Bacteria enter the stomach before passing into the small intestine. Hydrochloric acid can kill salmonella, or rather, some of it. But people who have diseases associated with impaired secretion of gastric juice are most sensitive to salmonellosis.
If the bacteria have safely passed the gastric barrier, their next refuge is the intestines. There they begin their active destructive activities.
A person with salmonellosis is dangerous to others for the entire duration of his illness. Even for some time after recovery, he continues to excrete bacteria. Despite the fact that there are no symptoms of the disease and the person is in good health, he still continues to excrete salmonella. This period can last up to 3 months or more. A person can be a carrier of salmonella, but not know it. Such latent carriage can last up to 1 year.
The risk of salmonella infection is increased in the following categories of people:
- children under 5 years old;
- aged people;
- people who have had their spleen and stomach removed;
- persons with reduced immunity;
- poultry and farm workers;
- lovers of raw food, especially meat and eggs.
In children, the clinical manifestations of the disease are most severe and have a long course. Often acute salmonellosis in a small child can develop into long-term carriage of the bacteria. Family members caring for a sick child must carefully maintain personal hygiene.
In addition to bacterial excretion, there are two forms of salmonellosis: gastrointestinal and generalized. In the first case, the intestines and stomach are affected. The generalized form is characterized by the involvement of other organs and systems in the pathological process. Usually the disease begins acutely. Symptoms of salmonellosis infection are as follows:
- nausea and vomiting;
- stomach ache;
- frequent profuse loose stools;
- bloating;
- rumbling in the stomach.
Symptoms of intoxication depend on the severity of the disease. In mild cases it is absent. With an average degree, the temperature rises to 39 degrees, the patient is bothered by dizziness and headaches, cramps in the limbs may appear, and aches are felt throughout the body. Severe salmonellosis is characterized by a high temperature of more than 40 degrees, chills, severe weakness and a sharp loss of strength.
Salmonella primarily affects the gastrointestinal tract
Symptoms
The symptoms of salmonellosis in adults and children are identical. The incubation period lasts from several hours to 2 days. The most common form of infection remains the gastroenteric type. It is characterized by impaired water-salt metabolism and extensive intoxication. The body temperature rises sharply, severe pain, heaviness in the head, and weakness appear.
Stool upset due to salmonellosis is one of the main symptoms. The stool becomes watery, foamy and extremely foul-smelling. Defecation is accompanied by the urge to vomit.
The patient's skin is pale. The mucous membrane of the oral cavity and tongue are dried out and covered with a white coating. Children experience bloating. Palpation causes moderate pain. The heart rate is higher than the age norm.
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How to prevent infection
The causes of salmonellosis infection are varied and multivariate. Most outbreaks occur in summer and spring. Bacteria actively multiply in hot weather, which is when food storage rules are violated. Infection is possible under the following conditions:
- insufficient heat treatment of meat;
- improper storage of products, namely dairy and meat;
- consumption of raw milk and products containing raw eggs;
- failure to comply with personal hygiene rules when in contact with a carrier of the disease.
You can protect yourself and others from acute intestinal infection caused by salmonella by following a number of recommendations. In particular, it is necessary to purchase meat products only from trusted retail outlets. It is important to follow the technology for preparing dishes from those products that most often contain salmonella.
Meat and eggs must be thoroughly cooked. Only in this case can the causative agent of salmonellosis be destroyed. You cannot swim in bodies of water in which birds swim or from which cattle drink water. All rules regarding food storage must be followed. If signs of salmonellosis appear, you should immediately contact a medical facility. Lack of timely treatment can lead to the development of toxic-infectious shock.
Diagnostics
Diagnostic measures involve collection and microscopy of vomit and feces after bacterial culture. Laboratory tests can detect the presence of pathogenic bacteria in the patient’s biological materials. If a generalized form of salmonellosis is suspected, a blood test is performed.
Laboratory tests allow doctors to determine the degree of dehydration of the patient’s body, blood viscosity, and electrolyte balance. These data are necessary to formulate an effective strategy for the treatment of salmonellosis. In case of complicated infection, consultation with a cardiologist, nephrologist, urologist and doctors of other specializations may be required.
Medicines
Complex therapy is prepared by an infectious disease specialist; salmonellosis is treated with various means. The basis of therapy is antibacterial drugs that lead to the death of pathogenic microorganisms.
The remaining medications support the child, helping him cope with unpleasant symptoms, reducing the severity of signs of the disease.
Symptoms of salmonellosis in children
An infected child experiences symptoms such as abdominal pain (localized in the navel area), frequent fatty stools, vomiting, and loss of appetite. Weakness, headache, and fever are also noted.
In the gastrointestinal form of the disease, symptoms usually subside within a week. However, parents need to remember that prolonged diarrhea and repeated vomiting can lead to dehydration, which is especially dangerous for children in the first three years of life. Signs of dehydration include increased dryness of the skin and mucous membranes, rare urination, crying without tears, and retraction of the fontanel. In severe cases of the disease, loss of consciousness, convulsions, and a sharp decrease in blood pressure are possible.
Antibiotics
More often, doctors resort to broad-spectrum medications. Although antibiotics are toxic, they help provide assistance to the patient before identifying the causative agent of the infection.
If the causative agent of the infection is identified, then they resort to the help of narrowly targeted means, they are less toxins, but more effective.
Since salmonellosis is considered a dangerous disease, the choice of antibiotics is made by a doctor. Otherwise, the therapy will not be highly effective and may lead to death.
Preventive measures
Prevention of salmonellosis is based on compliance with sanitary and hygienic standards. Owners of livestock and poultry should carefully monitor the storage conditions of their products and the timeliness of their heat treatment. Remember the importance of washing your hands before eating and after returning home.
When preparing homemade dishes, you need to monitor the temperature. Products with expiring dates should be disposed of promptly. Adults should conduct preventive conversations with children of preschool and primary school age.
Specific measures to prevent salmonellosis - in the form of vaccination - are not used due to low effectiveness. The pathogen is heterogeneous, and acquired immunity has low resistance.
