​Kembara Xtra - Medicine - Varicella Zoster Virus ( Chickenpox)

​Kembara Xtra - Medicine - Varicella Zoster Virus ( Chickenpox)  
Introduction 
Following exposure to the varicella-zoster virus (VZV), a highly contagious widespread exanthem with crops of itchy vesicles on the skin and mucous membranes develops.
VZV establishes latency in the dorsal root ganglia and is transmitted through direct contact with vesicles and inhalation of respiratory droplets from an infected host. Reactivation of the virus causes herpes zoster (shingles).
In temperate climes, outbreaks often happen from late winter to early spring.

● After exposure to varicella OR shingles rash, the typical incubation period lasts 14 to 16 days (within a range of 10 to 21 days).
From around 48 hours prior to the emergence of vesicles until the last lesions have crusted, patients are contagious.
● In the past, most people contracted chickenpox as children and obtained permanent immunity. In 1995, the varicella vaccination was made accessible (1). The recommended primary immunization schedule for kids presently includes varicella.
System(s) impacted: exocrine, nervous

Epidemiology (Incidence and Prevalence): Males predominate over females; Peak incidence occurs between the ages of 3 and 9; may occur at any age.
Incidence
Varicella cases reported in the United States: 1991: 147,076; 2017: 8,775 cases Prior to the vaccine, about 100 deaths per year were reported in the United States; in 2015, only 6 reported deaths U.S. rates: 1994, prior to the vaccine: 136/100,000 persons; 2013 to 2014: 0.001/100,000 persons In developing countries, varicella is still a common disease.

Pathophysiology and Etiology 
Viral particles enter the respiratory epithelium through respiratory droplets. Primary viremia occurs 4–6 days after exposure and is triggered by replication in local lymph nodes of the respiratory tract. 14–16 days after exposure, a secondary viremia and a second phase of viral replication contribute to epidermal invasion and the recognizable skin lesions.
Histologically, skin lesions and herpes simplex virus are identical.
Intranuclear inclusions are observed in the majority of organs and vascular endothelium of fatal patients.
VZV is a double-stranded DNA virus that primarily affects humans. It belongs to the herpesviridae subfamily.
RISK ELEMENTS
Immune, immunocompromised, and pregnancy (particularly in kids with leukemia/lymphoma in remission or getting large doses of corticosteroids)

Aspects of Geriatrics
Adults experience more severe illness; shingles is brought on by reactivating a latent infection.
All immunocompetent people under the age of 50 should receive the recombinant varicella vaccination (Shingrix), according to the CDC. The recombinant zoster vaccine (Shingrix) is delivered as a 2-dose series spaced by 2 to 6 months; the live attenuated vaccine (Zostavax) is no longer available for use in the United States as of 2020. Primary viral pneumonia is the most prevalent cause of mortality from varicella, however patients with a history of shingles or those who have already had a dose of the live attenuated zoster vaccination can receive this vaccine.

Child Safety Considerations
Varicella-zoster immune globulin (VZIG) should be given to newborns whose mothers experience chickenpox between five days before and two days after giving birth to reduce their risk of contracting a serious illness.

The first month of a baby's life is when they are most at risk for developing a serious illness, especially if the mother is seronegative.
Varicella bullosa is typically encountered in children under the age of two.
Bullae rather than vesicles represent lesions. Other than that, the clinical course is comparable.
The two most typical reasons for zoster-related deaths in children are encephalitis and septic complications.
Due to the association with Reye syndrome, children should not take aspirin or acetylsalicylic acid.

Considerations During Pregnancy: 25% Risk of Transplacental Infection
Congenital malformations, including limb hypoplasia, localized muscle atrophy, encephalitis, low birth weight, cutaneous scarring, cortical atrophy, chorioretinitis, and microcephaly, are seen in 2% of patients when the fetus contracts the infection during the first or second trimester.
Women who get chickenpox can still nurse normally. To reduce transmission, open vesicles on the breast should be covered.

Prevention 

Hospitalized patients should be kept apart, and if necessary, passive vaccination with VZIG should be given within 96 hours after exposure. VZIG is advised for patients who are immunocompromised and have been exposed to chickenpox or shingles, newborns whose mothers first developed chickenpox less than five days before or two days after giving birth, premature infants (born before 28 weeks) who have been exposed during the neonatal period and whose mothers are not immune, and infants who weigh less than 1,000 g regardless of maternal immunity.
If administered within 72 hours of exposure, active vaccination can prevent or lessen the severity of varicella.
Varicella virus vaccine (Varivax), a live attenuated vaccine recommended by ACIP for immunization of healthy patients aged 12 months or older who have never had chickenpox, should be administered twice, the first time at 12 to 15 months and the second time at 4 to 6 years of age. A single dose has an 85–94% success rate in preventing serious illness.
The 2-dose regimen has an efficiency of 96–98%. A sickness that has made a breakthrough lasts less time and experiences fewer fevers (2)[A].
- Seroconversion rates are 78-82% after one dose and 99% after two doses for children under 13 years old, with adult efficacy falling toward the lower end of this range. - 2014 U.S. estimate: 91% of children aged 19 to 35 months have received one or more doses of vaccination (3)
- Pain and redness at the vaccination site are common side effects (19% of children; 24% of teens and adults).
1 in 10 people get a fever. A minor rash resembling varicella will appear in 1 in 25 people up to one month following vaccination.
- Contraindications to vaccines
Severe immunodeficiency (e.g., HIV patients with low CD4 levels, chemotherapy, congenital immunodeficiency, long-term immunosuppressive medication), severe allergic reaction (such as anaphylaxis) to a previous dose or vaccine component, and congenital immunodeficiency. 

Pregnancy
The MMRV vaccine, which includes the varicella, measles, and mumps vaccines, is equally effective. Rare reports indicate that in between 1,300 and 2,600 patients, 5 to 12 days after immunization, there is an elevated incidence of febrile seizures.

 Can be taken into account for a subpopulation of HIV-positive kids in CDC class I with CD4 levels above 25%.
– Immunization recipients who get a rash should stay away from babies, pregnant women without a history of chickenpox, and immunocompromised individuals.
– Children who require catch-up vaccinations should wait at least 3 months between doses 1 and 2.

History-telling Prodromal symptoms, including fever, malaise, anorexia, and headache
Adults are more likely to have fatigue, headaches, arthralgias, and muscle aches.
4% of cases are subclinical.
Rash that is typical of


clinical assessment 
A characteristic rash appears as consecutive crops of vesicles on an erythematous base.
Fever (typically 102°F) is present, and the pruritic rash is present at different stages of growth and healing. The lesions progress from macule to papule to vesicle before starting to crust.

Herpes zoster: shingles; insect bites; smallpox; impetigo; coxsackievirus infection; scabies; dermatitis herpetiformis; drug rash; differential diagnosis


Diagnostic tests and laboratory results 
The majority of a chickenpox diagnosis is clinical. Testing is typically saved for epidemiologic research or difficult cases.
Initial examinations (lab, imaging)
The preferred approach at the moment is the VZV polymerase chain reaction (PCR); fluid from an intact vesicle works best.
Multinucleated giant cells on Tzanck smear from vesicle scrapings indicate secondary infection.
Technically challenging to isolate virus from human tissue culture (positive in 40% of cases), direct immunofluorescence is more accurate and quick to conduct.


Tests in the Future & Special Considerations

Serologies demonstrate recent (IgG) or acute (IgM) infection.
Visualization using electron microscopy, tissue culture (expensive), and a number of techniques for collecting acute and convalescent sera, including latex agglutination (most readily available), enzyme immunoassay, indirect immunofluorescence antibody, fluorescent antibody to membrane assay, or PCR assay, which can identify wild viral strains from vaccines.
PCR testing of skin lesions is most sensitive and specific for identifying varicella, especially in vaccinated individuals. Vaccine-modified cases are challenging to diagnose.

Treatment 
Generally speaking, outpatient, excluding complex instances


Treatment options include supportive/symptomatic measures, oral antihistamines, oatmeal baths, calamine lotion, acetaminophen and/or ibuprofen for pain and fever, and fingernail trimming to avoid scarring or excoriations that could result in subsequent infections.

First Line of Medicine

Supportive: antipyretics for fever; prevent youngsters from taking aspirin.
For itching, local and/or systemic antipruritic medications
VZIG is available for passive immunization in the following situations: - Immunocompromised individuals; newborn infants to mothers who had varicella symptoms at the time of delivery; premature infants born at 28 weeks or more whose mothers do not have evidence of varicella immunity; premature infants 28 weeks' gestation or who weigh 1,000 g regardless of maternal immunity - Give VZIG within 96 hours after exposure.
Acyclovir reduces the length of fever and shortens the time that viruses are shed; it is advised for unvaccinated adolescents over the age of 12, children treated with intermittent oral or inhaled steroids, adults, and high-risk patients (immunocompromised); it is most effective when started within the first 24 hours of the onset of the illness.
- Patients aged 2 to 16: 20 mg/kg/dose (maximum 800 mg/dose) for 5 days, QID
Adults who have a healthy immune system should take 800 mg five times daily for five days. Adults who have a damaged immune system should take 10 mg/kg/dose intravenously every eight hours for seven days. If a patient is fat, use IBW.
 The bioavailability of IV acyclovir is superior to oral medications for more complex diseases.
 Precautions - Renal insufficiency with acyclovir - Concurrent use of probenecid increases halflife; increased effects with zidovudine (e.g., drowsiness, lethargy) Contraindication - Hypersensitivity to the drug
Next Line
Valacyclovir: 20 mg/kg/dose (maximum 1,000 mg/dose) for children under two.
for 5 days, TID

Admission 
Inpatient care may be necessary for severe sequelae such septicemia, necrotizing fasciitis, and osteomyelitis.
Infants and those with compromised immune systems are more likely to develop severe varicella and may require hospital care.


Patient Follow-Up Monitoring
Not required in minor situations. In the event of difficulties, intensive supportive care may be necessary. Activity as tolerated. When wounds have fully healed and scabbed over, kids can go back to school.
NOT SPECIFIC DIET
Native chickenpox normally imparts lifetime protection. A second attack is rare, but subclinical infection can happen; infrequently, after vaccination in children. Native chickenpox is rarely dangerous and the recovery is almost always complete.
Adults may experience latent infection years later as shingles, however fatalities are uncommon.

Complications Although just 2% of cases recorded after the second decade, this age group accounts for 35% of mortality.
Cellulitis, abscesses, erysipelas, sepsis, septic arthritis/osteomyelitis, or staphylococcal pyomyositis are examples of secondary bacterial infections. Pneumonia affects 20–30% of adults with chickenpox, and 1 in 400 of them require hospitalization.
Meningitis, encephalitis, and Reye syndrome

Thrombocytopenia, purpura

 Arthritis, hepatitis, and glomerulonephritis

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