Typhoid fever. Symptoms, diagnosis, tests and vaccination against the disease. Blood test for typhoid fever Ses test for typhoid fever

Diagnosis of typhoid fever is difficult due to the difficult differentiation of the disease from similar symptoms of intestinal disorders, tuberculosis or cholera. Tests for the presence of typhoid fever and other studies are usually prescribed at the stage of fixing a constant febrile (38-39 0 C) temperature and stable characteristic signs. In addition to determining the diagnosis of illness, an analysis for typhoid fever is mandatory for catering workers, employees of children's and medical institutions, representatives of the hotel or sanatorium services.

Causes and symptoms of typhoid fever

The causative agent of the infectious disease, the bacterium Salmonella typhi, enters the human body through common objects - for example, toys in kindergarten or personal hygiene items, poorly processed dairy products, dirty water. At whatever age the infection occurs, once ill, a person acquires a stable immunity to re-infection.

According to statistics, the threat of Salmonella bacteria penetration is highest in younger schoolchildren, but this does not exclude the fact that older people are carrying the causative agent of typhoid or the disease in an acute form.

An analysis for typhoid fever is given in the presence of all the characteristic signs of the following (with the exception of a rash, which does not occur in all cases of infection):

• constant thirst with a constant feeling of tightness, dry mouth, blanching and peeling of the skin of the face and body, swelling and covering with a whitish coating of the tongue;
• acute recurrent abdominal pain;
• symptoms of intoxication - vomiting, nausea, poor appetite, loss of strength, sweating;
• difficulty in defecation or diarrhea;
• the occurrence of a rash such as roseola, which become faint when pressed.

Symptoms are characterized by a gradual increase, but in a third of all cases, an acute onset of the disease is possible, with the presence of several symptoms at the same time and, necessarily, a temperature in the range of 38-39 0 C. If the course of the disease is standard, then it will follow this algorithm:

• sudden weakness, poor sleep, problems with stools;
• headaches, increased general malaise, fever;
• the temperature within 3-5 days reaches indicative values ​​up to 39 0 and stops at this mark;
• there are severe pains in the abdomen, gas formation, a person’s reaction to external stimuli is dulled, his condition can be called “inhibited”. In the same period, the appearance of roseola is possible.

Since the onset of symptoms of infection occurs no earlier than the seventh day from the entry of typhoid bacillus into the intestines, it is almost impossible to determine the origin of the infectious agent.

Types of tests for typhoid fever

Even before receiving the results of laboratory tests, the clinical picture of the totality of symptoms allows the doctor to diagnose typhoid fever and begin treatment of the patient in isolation from patients of other groups of diseases. Despite the fact that the diagnosis is based on a comprehensive study of blood, if typhoid is suspected, other samples will be needed - for example, urine, bile, feces.

• you can not take medicines for three days before the delivery of the material;
• no alcoholic beverages should be consumed 24 hours prior to sampling;
• 2-4 hours before the tests, you can not smoke, physically overstrain and refrain from experiences and negative emotions;
• all samples are taken in the morning, on an empty stomach of the patient;
• on the eve of the delivery of biological material, you can not eat: eggs, dairy and sour-milk products, smoked meats, pork, lamb, spicy and salty dishes.

All types of additional examinations that may cause discomfort or require separate preparation should be done after taking laboratory tests.

General blood analysis

A clinical blood test helps to determine the change in the main indicators of the state of the body as a whole. The leading values ​​that indicate the activity of the causative agent of typhoid in the body are the distortion (compared with the norm) of the following data:

• decrease in the level of leukocytes;
• absence of eosinophils in the blood;
• lymphocytosis of relative parameters, which indicates a low immune response;
• high erythrocyte sedimentation rate (ESR indicators);
• critically high values ​​of neutrophils;
• low criteria for the presence of platelets.

Blood sampling for research is carried out from the patient's vein immediately upon admission to the infectious diseases department of the hospital. Subsequently, blood will be taken several more times during the treatment process and before discharge.

Blood chemistry

A biochemical blood test is also taken from a vein before starting antibacterial treatment. The results of the study obtained within 24 hours determine the presence of acute phase proteins synthesized in the liver as a response to an infectious lesion.

Serological blood test

For serological studies, plasma is isolated from the blood of a sick person, where the presence of characteristic antibodies is of decisive importance.

An analysis taken no earlier than the fifth day from the moment the typhoid bacillus enters the intestine is considered effective, since it is this period that the body needs to produce antibodies to the infectious agent.

Overestimated values ​​of detected antibodies indicate a high level of immune response to infection, which is specific in two cases:

• in the process of recovery;
• if a sick person is a carrier of typhoid bacillus.

To obtain a reliable answer, serological studies are carried out on the 7-10th day from the onset of initial symptoms.

Bacterial culture

Bacterial seeding of biological material allows you to detect the disease at an early stage of infection. Blood is most often used as the examined fluid - this is called seeding for blood culture. Blood sampling is preferably done at the moment when the patient's body temperature is above 38 0 C. Rappoport's nutrient medium is used for seeding, into which 15-20 ml of the patient's blood is placed. Then, for ten days, laboratory staff daily observe the growth of bacterial colonies in the sample and, in case of detecting a dynamic development of such, make the next inoculation in a Petri dish. Here, bacteria are analyzed for 24 hours under constant testing, including sensitivity to antibacterial drugs.

Urine culture is indicative at any stage of the disease, but the best period to detect the pathogen is from the 21st day from the moment of infection. The principle of conducting test studies of uroculture is the same as when monitoring the patient's blood.

The study of feces is carried out between the third and fifth week of the disease, while only the liquid substance of the feces is considered suitable for sowing. For infectious patients, this type of analysis is rarely used, but it is considered reasonable for periodic examinations of workers with health records.

Immune fluorescence reaction (RIF) and enzyme immunoassay (ELISA)

RIF is an emergency research method performed for suspected typhoid fever, when symptoms are mild or there is reason to believe that a person could become infected. A biological sample taken from a patient is injected with special antibodies stained with fluorescent elements, which, when combined with the antigens of an infectious agent, begin to produce a glow. This characteristic feature, clearly visible when examining the sample under a microscope, allows us to conclude that there is a typhoid bacillus.

ELISA, unlike the previous method for determining antigens and antibodies, can even accurately estimate their number. Based on the data obtained, the doctor concludes that the treatment regimen is correct.

The reaction of indirect hemagglutination (RIHA)

RNGA is one of the most accurate types of diagnostics for suspected typhoid fever, since this reaction is sensitive to 3 antigens of typhoid bacillus. When carrying out this type of analysis, erythrocytes that have a strong immunity to pathogen antigens are evaluated. RNHA is diagnosed several times, and an increase in O-antibody titers is considered normal for a positive response. If increased titers of H- and Vi-antibodies are detected, this indicates an imminent recovery of the patient or his status as a carrier of a bacterial pathogen.

Prevention of typhoid fever

Prevention of typhoid fever adheres to the most strict control in relation to employees of preschool and health institutions, employees of food points and health care institutions. If a carrier of infection is found among the employees of these institutions, two disinfection measures are carried out at the place of work of a sick person.

Individual prevention of an infectious disease is personal hygiene, which includes the mandatory isolation of personal items from public places. To prevent infection through food, you can not eat unwashed fruits and vegetables, unheated dairy products, raw eggs. A great danger is the unboiled tap water or drawn from dubious sources, water.

Since children of younger or school age are more susceptible to typhoid infection than the adult population, parents should be more careful to ensure that the employees of the institution visited by their child have all the necessary medical reports on the state of health. This will almost 100% eliminate the possibility of infecting a child with a dangerous typhoid bacillus.

Typhoid fever is a rare pathology that is accompanied by a harmful infection in the intestines. The treatment period is at least 1 month. To detect this disease, the doctor prescribes appropriate tests, which we will discuss in more detail in our material.

For the first time the name "typhus", which means clouding of consciousness, was introduced in 460 BC. Hippocrates. In 2017, typhoid fever (hereinafter referred to as BT) is an infectious disease associated with damage to the stomach and intestines due to the appearance in the body of a harmful bacterium called Salmonella typhi - a bacillus that exists in the outside world for up to 3 months, especially in the presence of a favorable environment for reproduction.

So, the signs of BT include: fatigue; heat; migraine; loss of appetite; sleep disturbance; pallor, dry skin; skin rash; dry cough.

Typhoid fever can only exist in the human body. So, every year about 20 million people become infected with this disease, of which 40% die. In the Russian Federation, the number of patients with a similar diagnosis does not exceed 1000 people per year.

There are 4 types of infection:

• Food - when eating meat, milk.
• Contact - touching contaminated household items, non-compliance with hygiene rules, as well as direct contact with a sick patient.
• Water - consumption of water from reservoirs or industrial water from enterprises.
• Insects - flies are carriers of harmful bacteria.

In addition, BT has several features:

What tests are required?

If BT is suspected, tests are performed before taking medications, since after 3 days the tests may show a negative result.

The initial study will be a complete blood count (hereinafter CBC), which does not guarantee a 100% result in the detection of BT. But the KLA establishes the presence of bacteria in the patient's body. So, when BT is confirmed, the ESR value increases, and the level of leukocytes decreases.

The downside is that KLA is taken if any type of infectious disease is suspected, so doctors prescribe additional studies, such as:

Blood sampling for medical records

Employees who are constantly in contact with other people are required to undergo a medical examination in order to obtain a sanitary or medical book. A similar document is received by employees of such areas as:

1. Medicine.
2. Food production.
3. Trade.
4. Educational institutions.

One of the laboratory tests is a test for typhoid fever, which is allowed to be taken in both private and public hospitals.

The frequency of tests for typhoid fever depends on the place of work. So, educators and catering workers are required to take a similar analysis at least once a year. In this case, a certificate of a study on BT is issued on the basis of any of the above types of analysis.

To obtain reliable information on the analyzes, the patient must prepare for the procedure. So, 2 days before blood sampling, it is forbidden to drink alcohol, fatty foods, and take medications.

How much is the price?

The cost of the analysis directly depends on a number of factors:

Testing for typhoid

The main source of the BT pathogen is a person with the presence of a harmful bacterium (hereinafter referred to as the carrier) or a sick person. According to statistics, the infection is transmitted in 95% of cases through the carrier, and in 5% through the sick patient.

In this case, bacteriocarrier can be chronic or acute. In the first variant, the release of harmful bacteria into the surrounding atmosphere lasts for 3–10 years or a lifetime, and in the second, up to 3 months.

In this case, the infection is transmitted in one of the following ways:

1. Water - consumption of dirty water, as well as seafood from a contaminated source.
2. Food - the infection enters the body of a healthy patient through the consumption of raw foods, milk, meat. In addition, the bacterium enters food through the carrier, which is engaged in the storage, preparation or sale of products.
3. Household items – such as using a toilet that is contaminated with bacteria. In this case, infection occurs when dirty hands touch the mouth. Also, the infection spreads when hygiene rules are not observed when changing bed linen, especially in medical institutions.
4. Personal contact - includes intimate relationships, including oral and anal sex.

Typhoid fever is common in countries with poor sanitation, such as Africa, South America or Asia. In Russia, this disease spreads after the patient travels to the above countries. But when an outbreak of infection is registered, BT can get sick up to 50% of the general population. At the same time, a lethal outcome is more often observed among people who have not left their country.

Important! Carriers are more often women than men over the age of 50 years - 88%.

Serological testing for typhoid fever

Serological blood sampling is an analysis of capillary blood, according to the results of which the doctor detects not only infectious diseases like BT, but also microbial, viral infections. In the presence of an infectious disease, the analysis is performed at the beginning of the development of the pathology when the patient enters the hospital and after 8-10 days.

In this case, there are several ways to detect specific bodies in the blood:

• Immunoenzymatic (ELISA) - antibodies are fixed in a specially prepared tablet.
• Agglutination reaction - provides information 14 days after the onset of the disease.
• Indirect hemagglutination reaction - helps in the diagnosis of BT 7 days after the development of pathology.
• The reaction of fluorescent antibodies - helps to determine any type of antibodies to the pathogen antigens.

For more information on typhoid fever, see the following video:

Thus, typhoid fever is a serious disease that requires timely treatment. The first stage is the delivery of all tests, which are discussed in more detail in our material.

In the old days, epidemics of such a serious infectious disease as typhoid fever led to the death of thousands of human lives. Thanks to strict sanitary and epidemiological control, outbreaks of this dangerous intestinal infection in our country have not been observed for a long time. However, in African, Asian and South American countries with a hot climate, the incidence of typhoid fever is still very high. The ideal habitat for the causative agent of this disease (typhoid salmonella from the family of enterobacteria) are polluted water bodies, poorly purified drinking water, improperly stored dairy and meat products, where harmful microorganisms begin to multiply actively at high air temperatures. The bacterium is excreted with the feces of the bacillus carrier and enters the mouth of a healthy person through dirty hands, food, or common items (fecal-oral route of infection). To identify this infectious agent, conduct laboratory tests of urine, feces, bile, and also prescribe a blood test for typhoid fever.

Indications for passing the analysis

First of all, typhoid salmonella affects the intestines, then regional (nearby) lymph nodes, after which it enters the circulatory system and causes general intoxication of the body. Indications for blood donation to identify this bacterium are high body temperature, headache, depression, weakness, dry tongue, pain in the right hypochondrium, red rashes on the abdomen (roseola), clouding of consciousness. Laboratory blood tests when diagnosing this pathology are carried out without fail, since similar symptoms are also characteristic of pneumonia, malaria,.

Hemogram

This term hides a general clinical blood test, which is an integral part of the diagnostic procedures for any infectious diseases. The following indicators may indicate the presence of typhoid fever: the level of leukocytes (leukopenia) is greatly reduced in the blood, there are no eosinophils, and the erythrocyte sedimentation rate (ESR) is increased.

Bacteriological research

Next comes the turn of the direct detection of the typhoid pathogen (hemoculture). For this purpose, venous blood is taken, sown on a special nutrient medium and placed in a thermostatic apparatus, in which a high temperature is created. Under the influence of heat, whole colonies of bacteria are formed, suitable for microscopic examination. Hemoculture is considered the most accurate early diagnostic method for detecting typhoid fever.

Immunological study

Since the immune system must respond to the introduction of a foreign agent, by the end of the first week of the disease, antigens and antibodies to the infectious agent begin to form in the blood. For immunological studies, blood serum is separated, in which the titer (level) of antibodies is determined. Such an analysis is called a passive hemagglutination test (RPHA). In a sick person, the antibody titer can be 1:40, and in a convalescent person it can reach up to 1:2000, so this blood serum test is performed every 5 days.

Preparation for the delivery of the analysis

In order for the results of general clinical, bacteriological and immunological studies for typhoid fever to be reliable, it is necessary to properly prepare for the blood test. If possible, then three days before the procedure, it is advisable to stop taking any medications. Two days before laboratory tests, the intake of alcoholic beverages is prohibited. On the day of visiting the blood donation point, you will have to stop eating dairy products, eggs, butter, fried, smoked and spicy foods. An hour before the tests, you need to refrain from the bad habit of smoking. All these factors can cause biochemical, metabolic and hormonal changes in the body that can change laboratory parameters.

A blood test for typhoid fever is a necessary procedure for making a correct diagnosis, but it is better to prevent the development of this dangerous disease. It is necessary to keep your hands clean, wash fruits and vegetables thoroughly, avoid eating street food, and fight flies - active carriers of this infection. It is especially important to strictly observe the sanitary and hygienic rules for workers in the food industry, preschool and medical institutions.

Diagnostic serological analysis to detect antibodies to Vi-antigens of the causative agent of typhoid fever in the blood serum is intended to confirm or deny the fact of carriage.

Deadlines	7-8 days
Synonyms (rus)	Serological analysis for Vi-antibodies of the causative agent of typhoid fever in blood serum
Synonyms (eng)	Indirect hemagglutination assay for Salmonella typhi Vi antibodies
Analysis method	The reaction of indirect hemagglutination (RIHA)
Study preparation	The analysis is carried out in the morning, on an empty stomach. At least 8 hours must have elapsed since the last meal.
	Exclude alcohol intake at least 24 hours before taking the biomaterial.
	It is not recommended to donate blood for serology after fluorography, x-rays, physiotherapy procedures.
Biomaterial and methods of taking it	Deoxygenated blood

General information about typhoid fever and its detection

Typhoid fever refers to acute infectious intestinal diseases. It is characterized by a cyclic course with systemic damage to the intestinal organs, central nervous system, liver, lymphatic system; general intoxication of the body, stable bacteremia, in which the presence of bacteria is detected in the blood. The source of infection are sick, ill carriers.

The causative agent of typhoid fever - Salmonella typhi, refers to intestinal bacteria.

The antigenic system of the pathogen is represented by antigens O, H, Vi.

The Vi antigen is the virulence antigen, forming the resistance of the causative agent of typhoid salmonella to the protective reactions of the body. The presence of antibodies to Vi-antigens of Salmonella typhi during a serological study of blood samples serves as a marker of bacteriocarrier.

Vi-antigen blood test method

Detection of antibodies to erythrocyte Vi antigens is carried out using serological reaction of indirect hemagglutination, RNGA using special diagnostics.

RNGA method:

• based on the ability of the interaction of blood serum antibodies and antigens that are fixed on erythrocytes (erythrocyte diagnosticum); the result of the reaction is the aggregation of red blood cells, followed by sedimentation, agglutination;
• by the nature of the erythrocyte sediment, the presence of antibodies is judged (a characteristic "umbrella"), or their absence (a precipitate in the form of a "dot");
• is semiquantitative; to carry out the reaction, dilutions of blood serum are used to detect a diagnostic titer;
• the minimum diagnostic titer during the reaction is 1:40;
• an increase in the diagnostic value of the reaction is observed when using repeated analysis (paired sera method);
• the reaction is highly sensitive and specific, can be used on the fifth to seventh days of the disease.

The main purpose of the study is to identify the bacteriocarrier of typhoid salmonella.

Analysis results and their interpretation

The test results may be positive or negative.

A positive response:

• detection of antibodies to Vi-antigens of the typhoid pathogen in the blood (the minimum value of the diagnostic titer is 1:40) is considered as an indication of the fact of a bacteriocarrier and the need for re-testing;
• the value of the titer is fixed in the answer;
• may indicate the course of an acute infection, a past illness, a vaccination;
• in rare cases, it can be false positive due to cross-reactivity.

Negative answer issued if no antibodies are detected. A similar situation is possible both in the absence of infection with a typhoid pathogen, and in the early stages of the disease.

Conducting this study is of particular importance to prevent cases of the spread of typhoid fever by bacteria carriers.

Typhoid fever is a serious infectious disease that, if left untreated, can lead to the death of the patient. The causative agent of the disease is a rod-shaped bacterium, a type of salmonella, also known as "E. coli". This is a very tenacious microorganism that poses a threat to any person. When characteristic symptoms appear, the doctor immediately prescribes an analysis for typhoid fever.

When to take an analysis

When a mild ailment sets in, most people treat themselves and go to the doctor only when absolutely necessary. As a result, the doctor can begin treatment only after the disease has developed and seriously affected the body. Untimely admission to the hospital increases the chances of developing complications and serious pathologies, and also complicates treatment. You should undergo a medical examination and donate blood for analysis annually, and consult a doctor immediately after the appearance of unpleasant symptoms. In this case, doctors can detect the development of diseases in the early stages.

Indications for the study of typhoid fever are:

• General weakness, nausea, impotence, which is accompanied by an increase in body temperature, at first insignificant. After 3-5 days, the temperature rises strongly and can exceed 38 degrees.
• Signs of dehydration and extreme thirst.
• Malfunctions of the gastrointestinal tract. Gastrointestinal manifestations include constipation, diarrhea, and vomiting. Symptoms may appear alternately.
• Lack of appetite and even aversion to food.
• Red spots appear on the abdomen.
• With the development of typhoid fever, a person loses weight.
• Due to the toxic effect of the infection, the spleen and liver enlarge, which is especially noticeable in patients who have lost weight.
• Workers in the food industry and some other professions are regularly tested for typhoid fever as a preventive measure.

Symptoms of typhoid at the onset of the disease are very similar to the usual food poisoning, which can pass in a couple of days. However, the same signs accompany the development of sepsis, brucellosis and other serious diseases. If you experience a serious ailment, you should immediately consult a doctor and pass the necessary tests.

Research types

• A general study of the patient's blood sample is carried out at the first signs of typhoid fever. This is not a completely diagnostic method of research, since it cannot confirm the presence of the disease. The analysis aims to identify an inflammatory process that may explain the high temperature.
• A blood test for typhoid fever for bacterial culture is done to detect a specific type of bacteria. In a patient's blood sample, the number of microorganisms that cause intestinal infections is too small to detect them. The biological sample of the patient is placed in a nutrient medium in which bacteria begin to actively multiply. Then the sample is again examined under a microscope and the bacterium is identified using chemical reagents.
• Serological diagnosis of typhoid fever is used to look for antibody cells to the infection. Immediately after the alleged infection with a bacterium that causes typhoid fever, this type of research is meaningless, since the body has not yet begun to fight the foreign microorganism and produce specific antibodies. Serodiagnosis is effective only on the 4th-5th day of the disease.
• Detects typhoid fever urinalysis.
• Biochemistry can confirm the diagnosis, but this requires a blood sample to be taken before starting treatment, provided that the patient is not taking any medications.

There are other types of tests, such as the reaction of indirect hemagglutination, which may be referred to as RNHA or RPHA. Hemagglutination is based on the special properties of red blood cells to stick together over time. A passive approach using indirect exposure involves agglutination of erythrocytes by means of immune serum. This test is not given to patients with suspected typhoid fever, it is intended to evaluate the effectiveness of vaccination.

Preparation for analysis and interpretation of results

Serological examination is carried out on an empty stomach. The day before, it is not recommended to eat heavy food, which can have a negative impact on health. The use of alcohol, drugs and other substances that affect the blood is categorically excluded.

A negative test result indicates that the person is healthy. If the laboratory test result is negative, but the patient has characteristic symptoms of typhoid fever, the disease may be at an early stage.

The body has not yet begun to produce antibodies, and the number of bacteria is not large enough to be detected.

A positive result indicates that the patient has typhoid fever. If there are no symptoms of the disease, but the analysis is positive, the person may be a carrier of the disease. At the same time, the person himself may not have typhus, but it is contagious to other people.

Treatment of the patient involves taking medications prescribed by the doctor, as well as special nutrition, the consumption of large amounts of fluid and bed rest. In cases of severe disease, the typhoid patient is hospitalized. To prevent infection with typhoid fever, it is necessary to observe the norms of sanitary hygiene. Before traveling to hot countries, it is better to get vaccinated.

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