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Chickenpox

Updated : January 29, 2024





Background

Chickenpox is a highly contagious infection caused by the varicella-zoster virus and is primarily spread through respiratory droplets. The disease primarily affects non-immune individuals and results in symptoms such as a blister-like rash, itching, and fever.

Chickenpox is common in children under 10 years of age and is usually mild but severe in adolescents and adults and can get complicated in immunosuppressed adults and pregnant women. After an individual has recovered from chickenpox, the virus can remain dormant in the body and later reactivate, causing herpes zoster or shingles.

 

Epidemiology

The epidemiology of chickenpox varies by region and population. In areas where immunization is not widespread, chickenpox is most common in children under the age of 10, with the highest incidence occurring in children between the ages of 1 and 4. In the United States, chickenpox typically peaks during the late winter and early spring and accounts for 9000 hospitalizations annually.

In countries where vaccination is routine, the incidence of chickenpox has decreased significantly and is less common. The varicella-zoster virus is highly contagious, with an infection rate of 90% among non-immune individuals. When a primary case of varicella occurs in a household, the secondary cases tend to be more severe.

In tropical regions, varicella affects older individuals and may cause more serious complications. With the widespread use of the vaccine, deaths due to chickenpox have decreased significantly. With vaccination, the risk of death from chickenpox is rare but still exists, particularly in individuals with underlying health conditions.

 

Anatomy

Pathophysiology

The pathophysiology of chickenpox involves the replication and spread of the varicella-zoster virus (VZV) within the body. After exposure to the virus, it enters the body through the airways and replicates in the lymph nodes. The virus then spreads through the bloodstream to the skin and other organs. It infects local sensory nerves, becomes latent in the dorsal ganglion cells, and causes the characteristic symptoms of chickenpox.

The virus infects cells in the skin, known as keratinocytes, and causes them to produce inflammatory mediators that form a blister-like rash. In addition to the skin, the virus can infect other organs, such as the lungs, causing pneumonia, and the nervous system, leading to encephalitis or meningitis. After the primary infection, the virus can remain dormant in the sensory ganglia of spinal or cranial nerves.

Later in life, the virus can reactivate, causing herpes zoster or shingles, postherpetic neuralgia, and in some cases, Ramsay Hunt syndrome type II. Additionally, varicella zoster can damage the blood vessels in the head and neck, increasing the risk of stroke. The immune system plays a crucial role in controlling the replication of the virus and alleviating the infection. However, the virus can evade the immune response and lead to severe disease in some instances.

 

Etiology

The varicella-zoster virus is highly contagious and is primarily spread through respiratory droplets when an infected person coughs or sneezes or through direct contact with the fluid from chickenpox blisters. Chickenpox is caused by the varicella-zoster virus (VZV), which is a herpesvirus that is found globally. The virus establishes latency after the primary infection, which is unique among herpes viruses.

The varicella-zoster virus is highly contagious and is primarily spread through respiratory droplets when an infected person coughs or sneezes or through direct contact with the fluid from chickenpox blisters. The initial infection occurs in the mucous membranes of the upper respiratory tract.

Within 2-6 days, the virus enters the bloodstream and causes another round of viral replication, which occurs 10-12 days later, at this point that the characteristic vesicles appear. The body produces IgA, IgM, and IgG antibodies, but the IgG antibodies provide lifelong immunity. Following the primary infection, varicella localizes to sensory nerves and may reactivate in the future, causing shingles.

 

Genetics

Prognostic Factors

The prognosis for chickenpox is generally good, as the disease is usually self-limiting and resolves without complications. Most people recover fully within 7-10 days, and the symptoms usually resolve within 2-4 weeks. However, some individuals may experience complications from chickenpox, particularly those with weak immune systems, HIV/AIDS, cancer, pregnancy, and other chronic illnesses.

Complications can include bacterial infections of the skin and soft tissues, pneumonia, encephalitis, and meningitis. Additionally, after recovery from chickenpox, the virus can remain dormant in the body and later reactivate, causing herpes zoster or shingles. This condition can result in chronic pain, nerve damage, and scarring. In rare cases, the varicella-zoster virus can cause more severe complications, such as stroke, especially in older adults.

 

Clinical History

Clinical History

The clinical history of chickenpox typically includes an incubation period of 10-21 days after exposure to the varicella-zoster virus. The onset of symptoms is usually gradual, commencingwith fever, fatigue, and loss of appetite. These symptoms are followed by the development of a rash, which is the most characteristic symptom of the disease. In children, the onset of the disease is usually sudden, and there is no prodrome.

However, in adults and adolescents, the onset of chickenpox may be preceded by nausea, muscle aches, loss of appetite, and headache. The patient is usually infectious for 1-2 days prior to the development of the rash. The symptoms of the rash begin with the appearance of small, red bumps, which quickly develop into papules, clear vesicles, and pustules. These vesicles often cause itching and may be accompanied by pain or tingling sensations.

The rash typically starts on the face, scalp, trunk, and upper limbs before spreading to other areas of the body. The vesicles also appear on the palms, soles, and mucous membranes. As the vesicles heal, they form crusts, but new vesicles may continue to appear for several days. The individual remains contagious for four to five days after the rash develops, at which point the last group of vesicles forms crusts.

 

Physical Examination

Physical Examination

Chickenpox is a viral infection characterized by small, fluid-filled blisters, called vesicles, on the skin. These blisters are often surrounded by a red, itchy area and are said to resemble a dewdrop on a rose petal. The rash occurs simultaneously in all stages of development and usually heals without leaving scars, although scratching or secondary bacterial infections can cause scarring.

In adults, chickenpox tends to be more severe and can lead to complications such as pneumonia. Rarely, some individual may develop hemorrhagic blisters, usually when their immune system is compromised. When chickenpox reaches the blister stage, it is characterized by severe itching. Blisters may appear on different body parts, such as the palms, soles, and genital area.

It is also common to see blisters in the mouth and throat, which can be painful and itchy. These symptoms typically appear between 10 and 21 days after exposure to the virus. An infected person is contagious one to two days before showing chickenpox symptoms, typically characterized by a watery nasal discharge containing the virus.

 

Age group

Associated comorbidity

Associated activity

Acuity of presentation

Differential Diagnoses

Differential Diagnoses

Dermatitis herpetiformis

Herpes zoster

Impetigo

Insect bite

Measles

Smallpox

Syphilis

 

Laboratory Studies

Imaging Studies

Procedures

Histologic Findings

Staging

Treatment Paradigm

The treatment for chickenpox primarily focuses on symptomatic relief. This can include taking over-the-counter pain relievers, calamine lotion, and increased water intake. To prevent the spread of the virus, infected individuals are typically advised to stay in isolation until all blisters have crusted over.

Antiviral medications, such as acyclovir, and valacyclovir, may be prescribed in some instances, such as for adults and pregnant women who are more likely to experience complications. These medications are usually taken orally, but individuals with a compromised immune system may require intravenous antiviral treatment.

The varicella vaccine, which was first made available in 1995, has dramatically reduced the number of cases and complications of chickenpox. It effectively prevents 70-90% of infections and 95% of severe cases. Children are typically recommended to receive the vaccine through routine immunization. Even if given within three days of exposure, the vaccine can improve outcomes in children.

 

by Stage

by Modality

Chemotherapy

Radiation Therapy

Surgical Interventions

Hormone Therapy

Immunotherapy

Hyperthermia

Photodynamic Therapy

Stem Cell Transplant

Targeted Therapy

Palliative Care

Medication

 
 

valacyclovir 

For <2 years: safety or effectiveness not determined
For >2 years:
Take a dose of 20 mg/kg orally every 8 hours for 5 days



 

Media Gallary

References

https://www.ncbi.nlm.nih.gov/books/NBK448191/

Chickenpox

Updated : January 29, 2024




Chickenpox is a highly contagious infection caused by the varicella-zoster virus and is primarily spread through respiratory droplets. The disease primarily affects non-immune individuals and results in symptoms such as a blister-like rash, itching, and fever.

Chickenpox is common in children under 10 years of age and is usually mild but severe in adolescents and adults and can get complicated in immunosuppressed adults and pregnant women. After an individual has recovered from chickenpox, the virus can remain dormant in the body and later reactivate, causing herpes zoster or shingles.

 

The epidemiology of chickenpox varies by region and population. In areas where immunization is not widespread, chickenpox is most common in children under the age of 10, with the highest incidence occurring in children between the ages of 1 and 4. In the United States, chickenpox typically peaks during the late winter and early spring and accounts for 9000 hospitalizations annually.

In countries where vaccination is routine, the incidence of chickenpox has decreased significantly and is less common. The varicella-zoster virus is highly contagious, with an infection rate of 90% among non-immune individuals. When a primary case of varicella occurs in a household, the secondary cases tend to be more severe.

In tropical regions, varicella affects older individuals and may cause more serious complications. With the widespread use of the vaccine, deaths due to chickenpox have decreased significantly. With vaccination, the risk of death from chickenpox is rare but still exists, particularly in individuals with underlying health conditions.

 

The pathophysiology of chickenpox involves the replication and spread of the varicella-zoster virus (VZV) within the body. After exposure to the virus, it enters the body through the airways and replicates in the lymph nodes. The virus then spreads through the bloodstream to the skin and other organs. It infects local sensory nerves, becomes latent in the dorsal ganglion cells, and causes the characteristic symptoms of chickenpox.

The virus infects cells in the skin, known as keratinocytes, and causes them to produce inflammatory mediators that form a blister-like rash. In addition to the skin, the virus can infect other organs, such as the lungs, causing pneumonia, and the nervous system, leading to encephalitis or meningitis. After the primary infection, the virus can remain dormant in the sensory ganglia of spinal or cranial nerves.

Later in life, the virus can reactivate, causing herpes zoster or shingles, postherpetic neuralgia, and in some cases, Ramsay Hunt syndrome type II. Additionally, varicella zoster can damage the blood vessels in the head and neck, increasing the risk of stroke. The immune system plays a crucial role in controlling the replication of the virus and alleviating the infection. However, the virus can evade the immune response and lead to severe disease in some instances.

 

The varicella-zoster virus is highly contagious and is primarily spread through respiratory droplets when an infected person coughs or sneezes or through direct contact with the fluid from chickenpox blisters. Chickenpox is caused by the varicella-zoster virus (VZV), which is a herpesvirus that is found globally. The virus establishes latency after the primary infection, which is unique among herpes viruses.

The varicella-zoster virus is highly contagious and is primarily spread through respiratory droplets when an infected person coughs or sneezes or through direct contact with the fluid from chickenpox blisters. The initial infection occurs in the mucous membranes of the upper respiratory tract.

Within 2-6 days, the virus enters the bloodstream and causes another round of viral replication, which occurs 10-12 days later, at this point that the characteristic vesicles appear. The body produces IgA, IgM, and IgG antibodies, but the IgG antibodies provide lifelong immunity. Following the primary infection, varicella localizes to sensory nerves and may reactivate in the future, causing shingles.

 

The prognosis for chickenpox is generally good, as the disease is usually self-limiting and resolves without complications. Most people recover fully within 7-10 days, and the symptoms usually resolve within 2-4 weeks. However, some individuals may experience complications from chickenpox, particularly those with weak immune systems, HIV/AIDS, cancer, pregnancy, and other chronic illnesses.

Complications can include bacterial infections of the skin and soft tissues, pneumonia, encephalitis, and meningitis. Additionally, after recovery from chickenpox, the virus can remain dormant in the body and later reactivate, causing herpes zoster or shingles. This condition can result in chronic pain, nerve damage, and scarring. In rare cases, the varicella-zoster virus can cause more severe complications, such as stroke, especially in older adults.

 

Clinical History

The clinical history of chickenpox typically includes an incubation period of 10-21 days after exposure to the varicella-zoster virus. The onset of symptoms is usually gradual, commencingwith fever, fatigue, and loss of appetite. These symptoms are followed by the development of a rash, which is the most characteristic symptom of the disease. In children, the onset of the disease is usually sudden, and there is no prodrome.

However, in adults and adolescents, the onset of chickenpox may be preceded by nausea, muscle aches, loss of appetite, and headache. The patient is usually infectious for 1-2 days prior to the development of the rash. The symptoms of the rash begin with the appearance of small, red bumps, which quickly develop into papules, clear vesicles, and pustules. These vesicles often cause itching and may be accompanied by pain or tingling sensations.

The rash typically starts on the face, scalp, trunk, and upper limbs before spreading to other areas of the body. The vesicles also appear on the palms, soles, and mucous membranes. As the vesicles heal, they form crusts, but new vesicles may continue to appear for several days. The individual remains contagious for four to five days after the rash develops, at which point the last group of vesicles forms crusts.

 

Physical Examination

Chickenpox is a viral infection characterized by small, fluid-filled blisters, called vesicles, on the skin. These blisters are often surrounded by a red, itchy area and are said to resemble a dewdrop on a rose petal. The rash occurs simultaneously in all stages of development and usually heals without leaving scars, although scratching or secondary bacterial infections can cause scarring.

In adults, chickenpox tends to be more severe and can lead to complications such as pneumonia. Rarely, some individual may develop hemorrhagic blisters, usually when their immune system is compromised. When chickenpox reaches the blister stage, it is characterized by severe itching. Blisters may appear on different body parts, such as the palms, soles, and genital area.

It is also common to see blisters in the mouth and throat, which can be painful and itchy. These symptoms typically appear between 10 and 21 days after exposure to the virus. An infected person is contagious one to two days before showing chickenpox symptoms, typically characterized by a watery nasal discharge containing the virus.

 

Differential Diagnoses

Dermatitis herpetiformis

Herpes zoster

Impetigo

Insect bite

Measles

Smallpox

Syphilis

 

The treatment for chickenpox primarily focuses on symptomatic relief. This can include taking over-the-counter pain relievers, calamine lotion, and increased water intake. To prevent the spread of the virus, infected individuals are typically advised to stay in isolation until all blisters have crusted over.

Antiviral medications, such as acyclovir, and valacyclovir, may be prescribed in some instances, such as for adults and pregnant women who are more likely to experience complications. These medications are usually taken orally, but individuals with a compromised immune system may require intravenous antiviral treatment.

The varicella vaccine, which was first made available in 1995, has dramatically reduced the number of cases and complications of chickenpox. It effectively prevents 70-90% of infections and 95% of severe cases. Children are typically recommended to receive the vaccine through routine immunization. Even if given within three days of exposure, the vaccine can improve outcomes in children.

 

valacyclovir 

For <2 years: safety or effectiveness not determined
For >2 years:
Take a dose of 20 mg/kg orally every 8 hours for 5 days



https://www.ncbi.nlm.nih.gov/books/NBK448191/