Pathophysiology and Diagnosis of Varicella Zoster Virus (VZV) - PART-II

 

DESCRIPTION:

The highly contagious illness varicella, sometimes known as chickenpox, is caused by an early infection with the Varicella Zoster Virus (VZV). The disease results in a recognizable skin rash that grows into tiny, uncomfortable blisters before eventually scabbing over. Typically, it begins on the chest, back, and face. It then spreads all across the body. The disease often worsens more quickly in adults than in kids. When an infected individual coughs or sneezes, the airborne illness known as chickenpox can readily spread from one person to another. After an incubation period of 10 to 21 days, the characteristic rash appears. It may spread from one to two days before the rash appears until all lesions have crusted over. It might spread if someone touched the blisters. People with shingles may spread chickenpox to those who aren't immune by touching the blisters. However, in unusual cases, Polymerase Chain Reaction (PCR) testing of the blister fluid or scabs may be required to confirm the diagnosis. Usually, the condition can be diagnosed based on the presenting symptom. Antibodies can be checked to see if a person is immune. Usually, a person only gets chickenpox once. Despite the possibility of reinfection, the majority of the time there are no symptoms. 

Symptoms and signs:

In both adolescents and adults, the early (prodromal) symptoms include nausea, loss of appetite, painful muscles, and headache. After this, the usual rash or oral sores, sluggishness, and low grade fever that signal the disease's presence appear. On rare occasions, the disease's oral symptoms (enanthem) may manifest before the external rash. Children frequently develop a rash or mouth spots as their first symptoms of an illness. In children, prodromal signs are rare. The initial signs of the rash are small red dots that appear on the face, scalp, torso, upper arms, and legs. Small bumps, blisters, and pustules develop over the period of 10–12 hours, and are then followed by umbilication and the formation of scabs. 

Pathophysiology:

After being exposed to the Varicella Zoster Virus (VZV), healthy children create immunoglobulin G (IgG), immunoglobulin M (IgM), and immunoglobulin A (IgA) antibodies. IgG antibodies last a lifetime and offer immunity. Cell-mediated immune responses must cooperate in order to reduce the intensity and length of the primary varicella infection. After primary infection, it is believed that the Varicella Zoster Virus (VZV) spreads from adjacent sensory nerves to mucosal and epidermal sores. The Varicella Zoster Virus (VZV) then remains latent in the dorsal ganglion cells of the sensory nerves. The reactivation of the varicella zoster virus causes the clinically distinct syndromes of herpes zoster (shingles), postherpetic neuralgia, and sporadically Ramsay Hunt syndrome type II (VZV). Varicella zoster can damage the arteries in the neck and head and cause stroke in infancy or after a protracted latency period. 

Diagnosis and treatment:

Examining the fluid within the vesicles of the rash or testing blood for signs of an acute immune response can also help confirm the diagnosis. Using a Tzanck smear or a direct fluorescent antibody test, vesicular fluid can be analysed. Additionally, the fluid can be "cultured," which entails making an effort to develop the virus from a sample of the fluid. Blood tests can be performed to determine an acute infection response (IgM) or a prior infection and subsequent immunity (IgG). It is recommended to wait five weeks after the first maternal infection before utilising ultrasonography to diagnose foetal varicella. It is also possible to test the mother's amniotic fluid for PCR (DNA), although this approach has a higher risk of spontaneous abortion than it does of foetal varicella syndrome development. 

Children: Children with chickenpox are treated for the symptoms while the immune system fights the infection. Because they are more likely than adults to scratch their blisters more deeply, children under the age of 12 should have their fingernails clipped short and kept clean. 

Epidemiology:

It is unclear where the word "chickenpox" came from, however it could have something to do with how mild the illness was. On the basis of the vesicles' likeness to chickpeas or the rash's resemblance to chicken pecks, it has been suggested that it originated from chickpeas. Other theories include the term "chicken pox" (meaning "kid pox"), a misspelling of "itching pox," or the hypothesis that poultry may have carried the disease in the past. The designation was made, according to Samuel Johnson, "from its being of no very great risk." 

Source: Department of Pulmonary and Critical Medicine, Oregon Health and Sciences University, Portland, USA

Chickenpox (varicella) Diagnosis, Pathophysiology and Treatment - PART-I

 

Chickenpox is an infection caused by the varicella-zoster virus. Most children have chickenpox at some stage. Most commonly, children get chickenpox before the age of 10 years. The immune system makes proteins called antibodies during the infection. These fight the virus and then provide lifelong protection against it (immunity). Therefore, it is uncommon to have more than one bout of chickenpox in your lifetime.

Cause:

The varicella-zoster virus may be spread through the air when an infected person coughs or sneezes or by direct contact with the blisters (lesions) of someone infected with chickenpox or shingles.

The risk of getting chickenpox is higher for people who have had contact with an infected person, are under 12 years old, have a weakened immune system, or who work or spend time in a school or daycare facility.

Once someone is infected, the virus usually incubates for 14 to 16 days before a rash appears, although incubation can last from 10 days to 21 days. There are no symptoms during incubation and a person doesn't become contagious until 1 to 2 days before the rash appears. The person remains contagious until all the blisters have dried and scabs have formed. 

To prevent the spread of the virus to others, people who have or are suspected to have chickenpox should avoid public places, such as school, until all blisters have scabbed over. 

Chickenpox Blisters: 

Symptoms:

The itchy blister rash caused by chickenpox infection appears 10 to 21 days after exposure to the virus and usually lasts about five to 10 days. Other signs and symptoms, which may appear one to two days before the rash, include:

• Fever
• Loss of appetite or feeding problems to child
• Headache
• Tiredness and a general feeling of being unwell (malaise)

 

Once the chickenpox rash appears, it goes through three phases:

• Raised pink or red bumps (papules), which break out over several days
• Small fluid-filled blisters (vesicles), which form in about one day and then break and leak
• Crusts and scabs, which cover the broken blisters and take several more days to heal

New bumps continue to appear for several days, so you may have all three stages of the rash — bumps, blisters and scabbed lesions — at the same time.

You can spread the virus to other people for up to 48 hours before the rash appears, and the virus remains contagious until all broken blisters have crusted over. 

The disease is generally mild in healthy children. In severe cases, the rash can cover the entire body, and lesions may form in the throat, eyes, and mucous membranes of the urethra, anus and vagina.

 Chickenpox Scabbing: 

 

Some children feel quite unwell for a few days. Others appear only mildly ill. Most are much better within a week. The blisters dry up and scab. They gradually fade but may take up to two weeks to go completely. 

Most of the time, children with chickenpox recover fully and have no complications. Uncommonly, one or more of the following complications can occur.

 

• The spots do not usually scar unless they are badly scratched.
• Some spots become infected with germs (bacteria) in some cases. This is the most common complication in children. If this occurs, the surrounding skin becomes red and sore. Antibiotics in the form of creams or medicine may then be needed.
• Inflammation of the lung (pneumonia) and inflammation of the brain (encephalitis) are rare complications.
• Vary rarely, other serious complications develop. For example: 

ü  Reye's syndrome. (A very rare condition with brain and liver problems).

ü  Inflammation of the heart muscle (myocarditis).

ü  Kidney inflammation (glomerulonephritis).

ü  Appendicitis.

ü  Ataxia (problems co-ordinating movements).

ü  Inflammation of the pancreas (pancreatitis).

ü  Henoch-Schönlein purpura (a condition that can affect the kidneys).

ü  Inflammation of the testes (orchitis).

ü  Inflammation of the joints (arthritis).

ü  Inflammation of various parts of the eye.

Therefore, although serious complications are rare, it is best to be watchful. Consult with Medical Practitioner if your child develops any worrying symptoms that you are unsure about such as:

 

• Breathing problems.
• Weakness such as a child becoming wobbly on his/her feet.
• Drowsiness.
• Fits (convulsions).
• Pains or headaches which become worse despite paracetamol.
• Being unable to take fluids, due to a severe rash in the mouth.
• A severe rash, or a rash which bruises or bleeds into the skin (haemorrhagic rash).
• Becoming generally more and more unwell.

 Shingles

Shingles is caused by the same virus that causes chickenpox and is a very delayed complication of chickenpox. Anyone who has had chickenpox in the past may develop shingles. Shingles is an infection of a nerve and the area of skin supplied by the nerve. It causes a rash and pain in a local band-like area along the affected nerve. About 1 in 5 people have shingles at some time in their lives. It can occur at any age, but it is most common in people over the age of 50.

 

The reason why shingles may occur is because the virus does not completely go after you have chickenpox. Some virus particles remain inactive in the nerve roots next to your spinal cord. They do no harm there and cause no symptoms. For reasons that are not clear, the virus may begin to multiply again (reactivate). This is often years later. The reactivated virus travels along the nerve to the skin to cause shingles.

Note: you can catch chickenpox from being exposed to a person with shingles if you have not had chickenpox yourself. However, you cannot catch shingles from a person with chickenpox, or catch shingles from a person with shingles.