Tests for latent infections: types, delivery rules
The content of the article:
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Types of tests for latent infections
- Bacterioscopy and bacterial culture
- PCR
- ELISA
- REEF
- Indications for testing for latent infections
- Preparation for the analysis for latent infections
- Latent infections
Tests for latent infections are most often prescribed when health worsens, the appearance of suspicious symptoms, or planning a pregnancy. For prevention, the study is indicated for persons at risk.
Latent infections are infectious diseases that do not have pronounced clinical manifestations. Usually, speaking of latent infections, they mean mainly sexually transmitted diseases (STDs, or STIs - sexually transmitted infections), which may not manifest themselves in any way for many months or even years. The causative agents are gonococci, chlamydia, Trichomonas, etc. Usually, the presence of a latent infection is discovered by chance during diagnosis for another reason (for example, when identifying the cause of infertility).
Tests for latent infections allow them to be detected in time and cured before serious complications develop
STIs are widespread even in countries with a high standard of living, which is explained by the predominant absence of severe symptoms in infected patients. The risk of infection increases significantly if a person leads a promiscuous sex life.
Latent infections can affect the joints, eyes, cause the development of pathologies of the cardiovascular system, significantly reduce immunity. In case of infection during pregnancy, there is a risk of infection of the fetus, which may entail adverse consequences for its development and life.
If diagnosed early, latent infections tend to respond well to treatment. Self-medication or lack of treatment if an STI is suspected is unacceptable, as this can cause an aggravation of the pathological process and the development of serious complications that can lead to irreversible health consequences.
In order to prevent hidden infections, first of all, it is necessary to avoid casual sexual intercourse, especially unprotected sexual intercourse.
Types of tests for latent infections
There are a number of laboratory diagnostic methods that can detect asymptomatic infections.
Bacterioscopy and bacterial culture
A general smear (gynecological smear, urogenital smear for microflora, bacterioscopy) is the main method for laboratory diagnosis of bacterial infections, based on microscopy of the contents of the genital tract.
For bacteriological analysis, biological material taken from the urogenital tract is inoculated on nutrient media. In the course of bacteriological research, it is also possible to determine the sensitivity of the isolated cultures of microorganisms to antibiotics (antibioticogram). The analysis is often used in gynecology and urology when an STD is suspected, for preventive purposes for people at risk, as well as when planning a pregnancy.
PCR
The most accurate studies to identify the causative agents of latent infection is the polymerase chain reaction (PCR) method. The essence of the method is to identify the DNA and RNA of infectious agents. For the analysis, blood, genital secretions, saliva, etc. can be used. The advantage of PCR is that the method is effective already in the early stages of the disease, when other, less sensitive tests still show a negative result.
ELISA
The enzyme-linked immunosorbent assay (ELISA) is based on a specific antigen-antibody reaction and, like PCR, is mainly used to identify viral pathogens. For this, blood, semen, amniotic fluid, etc. can be used. The ELISA accuracy is approximately 90%.
REEF
Latent viral infections can also be detected using the reaction of immunofluorescence (RIF), which is a highly sensitive diagnostic method. For research, as a rule, material is taken from the urethra, which is stained and examined using a fluorescent microscope. The accuracy of the immunofluorescence reaction is about 80%.
Depending on which of the research methods is used, the result may be ready in 1-10 days.
Indications for testing for latent infections
For prophylactic purposes, persons belonging to the risk group are recommended to undergo a study for latent infections at least once a year.
A few weeks after unprotected intercourse with an unverified partner, it is recommended to get tested for STIs. Otherwise, you can not only harm your own health, but also endanger your sexual partners.
The reason for testing for STIs may be planning a pregnancy, a change in well-being, the appearance of symptoms suspicious of STDs. The main signs that may indicate the presence of latent infections in the body include pain in the lower abdomen, weight loss, discomfort during intercourse and / or urination, unusual discharge from the genitals, burning and itching in the external genitals.
Preparation for the analysis for latent infections
To get reliable results, you need to properly prepare for the study.
If the examination is planned, then the analysis should be carried out no earlier than a month after antibiotic therapy. For several days before the study, you should refrain from sexual intercourse. On the eve of the delivery of the material for analysis, local contraceptives, vaginal suppositories, ointments, and douching cannot be used.
In women, a smear is taken from the urethra; material from the vagina, cervical canal may also be needed. Unless otherwise indicated, it is recommended to take this test on the fifth or sixth day of the menstrual cycle. The study is not performed during menstrual bleeding. In men, biomaterial for analysis is taken from the urethra. One and a half to two hours before taking the material, you should not urinate.
For tests for latent infections in women, a swab is taken from the vagina or urethra
Blood for latent infections is usually taken from the cubital vein.
The list of indicators that need to be investigated is compiled by a doctor who writes a referral to the laboratory where the study will be conducted.
If the result is doubtful, re-analysis is performed. If a positive result is obtained, that is, if hidden infections are detected, additional research may be needed.
Latent infections
Chlamydia is one of the most common latent STDs. The asymptomatic course of chlamydia is observed in about 67% of female patients and 45% of male patients, but even if there are symptoms, in most cases they are not pronounced. Chlamydia in men leads to the development of inflammation of the urethra, prostatitis, in women - to inflammatory processes in the pelvic organs, obstruction of the fallopian tubes and infertility. Chlamydiae can affect the external and internal genital organs, the mucous membrane of the respiratory tract, the cardiovascular system, joints, teeth, hearing and vision organs. Women are more susceptible to this infection. The main routes of transmission are sexual and contact-household (especially in baths, saunas, etc.). Children can become infected when passing through the birth canal of a sick mother. Untreated chlamydia can cause premature termination of pregnancy. In addition to scraping (in men - from the urethra, in women - from the vagina, cervical and urethra), blood, urine, and ejaculate can be used to test for chlamydia. To control the recovery, as a rule, enzyme immunoassay is used, as well as a study by the polymerase chain reaction method.
Trichomoniasis, which occupies a leading position in the general structure of STIs, also refers to diseases with a latent course. The causative agent is Trichomonas vaginalis. To identify it, the culture method is usually used, i.e. bacterial sowing. Also, a microscopic examination of an unstained and / or colored preparation, PCR is carried out.
Latent infections sometimes include gardnerellosis, mycoplasmosis and ureaplasmosis. Doctors have no consensus on this matter. The fact is that gardnerella, mycoplasma and ureaplasma are present in the body of healthy people, without leading to any inflammatory process. The inflammation caused by these pathogens usually develops only in severely immunocompromised patients. Some experts attribute the detection of gardnerella, mycoplasma and ureaplasma to overdiagnosis, considering gardnerella, mycoplasmosis and ureaplasmosis as commercial diagnoses. In other words, the pathogenicity of these pathogens has not been proven, and their identification, as a rule, does not require treatment, with the exception of immunodeficiency states.
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Anna Aksenova Medical journalist About the author
Education: 2004-2007 "First Kiev Medical College" specialty "Laboratory Diagnostics".
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