Chickenpox and shingles tests

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Chickenpox and shingles are common infections caused by viruses. These two diseases are usually diagnosed on clinical grounds, however, in some cases, diagnostic testing is required. Tests for chickenpox and shingles such as serological tests, fresh swabs,...

1. The causative agent of chickenpox and shingles

1.1. Chickenpox Chickenpox is an infectious disease caused by the varicella zoster virus (VZV) that affects the skin and mucous membranes directly. Chickenpox is transmitted by inhalation and direct contact with the source of the disease. Chickenpox is common in children because their immune systems are still weak, the disease occurs mainly in spring and winter, and can even spread into an epidemic.
1.2. Shingles Shingles, also known as shingles, is the result of a reactivation of the herpes zoster virus (varicella-zoster virus). The herpes zoster virus is also the causative agent of chickenpox in children. The chickenpox virus resides inside the sensory nerves of the body in a dormant state. In one person who has had chickenpox, the virus becomes active after causing chickenpox many years ago in the body. The herpes zoster virus then travels along sensory nerves into the skin and creates the painful rash known as shingles.

2. Hydrodynamic and shingles tests

Testing for chickenpox and shingles is usually diagnosed on a clinical basis, but diagnostic testing is needed in some cases. Chickenpox tests and shingles tests include the following:
2.1. Serology test Serological test is a blood test method, using centrifugation technique to extract serum and then analyze for the presence of IgM, IgG antibodies present in the blood. The presence of antibodies means infection with the virus but also protection against future infection. Some experts have concluded that serologic tests are suitable for screening for varicella zoster virus susceptibility. Because the risk of vaccinating people with false-negative results is much lower than the risk of spontaneous infection in people with false-positive results.
The chickenpox test uses a primary specimen, which is a blood sample taken from a patient's vein. After the sample is taken, the patient's blood is placed in a test tube containing an anticoagulant to prevent the formation of blood clots. After that, the patient samples are numbered, recorded with the patient's name and sent to the laboratory for testing.
IgM antibodies are detected in the plasma of patients 5 to 7 days after the onset of symptoms. For those who are negative for IgM antibodies, there is still the possibility of acute chickenpox infection. IgG antibodies are found 10 to 12 days after the onset of symptoms, or can be found in people who have had chickenpox or the varicella vaccine. Chickenpox and shingles antibody test results show specific IgM and IgG values ​​for each case as follows:
Positive and negative IgM: healthy body without signs of chickenpox infection. A positive IgG index may be due to the patient's previous disease or the immune effect of the vaccine. Negative IgG, negative IgM: healthy body does not show signs of chickenpox infection, but need to be vaccinated against chickenpox. Positive or negative IgG index, positive IgM: the body is infected with chickenpox, shingles need to take immediate treatment measures and avoid leaving complications. The results of serological tests for antibodies are very important for pregnant women in deciding to receive the chickenpox vaccine to prevent infection and prevent birth defects.
2.2 Cytological smear test To perform a smear test for cytology, the specimen must first be obtained from:
Blisters appear on the skin: Specimen must be taken from newly grown blisters, turn the roof over. vesicles, then infiltrate and scrape with a medical knife. Injured sores: Use a knife to scrape the bottom of the sores on the patient's body. Cyst lesions: use needle aspiration. Relatively benign superficial tumor: Using a knife to make a moderate incision, scrape both edges of the wound. Then spread the collected specimen on the slide, let it dry naturally and fix it with alcohol. Then stain Giemsa by diluting Giemsa with distilled water in a ratio of 1:10. Coat the giemsa on the slide and keep for 15 minutes. Then rinse with water and examine the slide under the microscope. The color of the color nucleus can vary from purple red, blue to pink. The cytoplasm has a bluish color.
The results of the fresh smear test for zank cells are as follows:
Aberrant squamous cells: are epithelial cells with large size, large round nucleus accounting for nearly 2/3 of cells, round shape, border of cell membrane. and the nuclear border is clearly visible, the cytoplasm of the cell is base colored, forming a halo around the nucleus. Giant multinucleated cells: Multinucleated cells with very large size, relatively smooth cell borders, syncytial nucleus (due to many nuclei of epithelial cells fused).

2.3 Polymerase Chain Reaction Real-time polymerase chain reaction (PCR) techniques consistently give fast and sensitive confirmation of varicella zoster virus from patient samples taken from skin lesions and muscle fluids. selective as bronchoalveolar lavage and cerebrospinal fluid. In a study comparing viral culture isolates with real-time polymerase chain reaction, 110 skin lesions were analyzed by both methods. The varicella zoster virus isolated by culture in 15 samples accounted for 14%, while the varicella zoster virus DNA detected by PCR in 51 samples accounted for 46%. In another study of patients with clinically suspected shingles, the real-time polymerase chain reaction assay was very sensitive compared with culture (92% vs 53%). In addition, the polymerase chain reaction test is highly specific and does not show cross-reactivity with many other viruses.
The real-time PCR polymerase chain reaction assay allows rapid viral amplification, lowers the risk of infection, provides greater sensitivity than isolating varicella zoster virus from a wide range of clinical specimens, and time returns results faster than conventional culture techniques. In addition, the polymerase chain reaction test is also useful for a variety of other indications, for example in the diagnosis of patients with post-vaccination atypical infections. Serum or blood PCR testing may also be useful in transplant patients with organ disease prior to the appearance of skin lesions.
2.4 Direct Fluorescent Antibodies The Direct Fluorescent Antibody (DFA) test can rapidly diagnose varicella zoster virus infection on scraped specimens from active vesicular skin lesions that have not yet crusted over. Direct fluorescent antibody tests are widely available, cheaper than culture and quicker to return results. The direct fluorescent antibody technique can simultaneously detect HSV and varicella zoster virus with a response time of 1.5 hours.
2.5 Viral culture It is sometimes possible to isolate the virus by culture, but it is less sensitive and detectable (approximately 60% to 75%) when compared with polymerase chain reaction assays. Isolation of specific cultures of varicella zoster virus from vesicular lesions of the skin or sterile body fluids, such as cerebrospinal fluid, usually requires prolonged incubation with a response time of 1-2 weeks. The sensitivity of viral culture also decreased as the lesions progressed beyond the vesicular stage.
In summary, there are many methods of testing for chickenpox and shingles. These are two common infectious diseases and testing is done when the patient has epidemiological factors or shows typical symptoms of the disease. Tests for chickenpox and shingles such as antibody tests, cytology,...
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