What are the clinical manifestations of VZV infection in children?
The primary VZV infection results in chickenpox, which has characteristic clinical manifestation. It presents with a rash, low-grade fever and malaise. Few patients may have prodromal symptoms for 1-2 days prior to the appearance of the exanthem. The rash usually starts on the face, scalp or trunk. It is often the first manifestation of illness. Lesions that are hidden by hair can often be detected by running the hands along the scalp, before the appearance of large number of lesions in other areas. Occasionally a group of two to three lesions appear on the trunk a day or two before the generalized eruption. The skin manifestations, the hallmark of infection, consist of maculopapules, vesicles and scabs in varying stages of evolution. The lesions initially contain clear vesicular fluid, but over a short period of time they pustulate and scab. Most lesions are small having an erythematous base with a diameter of 5-12 mm. The lesions can be round or oval. As healing progresses, central umbilication occurs in them. Successive crops of lesions generally appear over a period of 2-4 days as the rash spreads centripetally. These successive crops are responsible for lesions of various stages of evolution. The crusts completely fall off within a week or two after the onset of infection, leaving behind a slightly depressed scar over skin.
The rash may be accompanied by constitutional symptoms such as malaise, pruritis, anorexia and listlessness. These symptoms generally resolve as the illness abates. There could be lesions on the mucosa of the oropharynx and the vagina. However, these are relatively uncommon.
What are the manifestations and complications of chickenpox in adults?As is true of many viral diseases, chickenpox may be much more severe in adults than in children. The lesions are frequently confluent and systemic symptoms such as myalgia, arthralgia and malaise are much more common. The complication of chickenpox are usually more severe too and occur more frequently than in children. Respiratory complications like pneumonitis manifesting with cough, fever, dyspnea and sometimes, pleuritic pain and hemoptysis within 5 days of the appearance of the rash; are especially common. Varicella infection in adult is associated with a 15-fold rise in mortality than that seen in children.
What are the effects of varicella infection in immunocompromised individuals?Immunocompromised children and adult are prone to severe form of varicella infection. The constellation of manifestations is referred to as "progressive varicella syndrome ". It has a shorter incubation period than usual. The rash is severe, confluent, involves even palms and soles and is likely to last longer. The fever and constitutional symptoms are more severe and complication rate is much higher. Almost one-third of these individuals have involvement of multiple organs including the lungs, liver and central nervous system. The fatality rate is higher (15-18%) and accounts for 70% of deaths due to varicella.
What are the effects of varicella infection during pregnancy?A woman who develops varicella during pregnancy is more prone to develop pneumonitis. Some authorities believe that pregnant women usually tend to have more have a more severe from of varicella.
The consequences for the fetus and the newborn baby depend upon the timing of varicella infection. If a women develops varicella infection during the first trimester, the fetus may have defective organogenesis and the baby may have congenital varicella syndrome. If the infection is developed during the second trimester, the baby is normal but is likely to develop herpes zoster within the first 1-2 years of life. This is an unusual event, given the fact that zoster generally develops in adults above the age of 55 years. If the mother develops varicella infection within 5 days preceding the delivery or within 2 days after the delivery , the neonate receives the virus but does not receive maternal antibodies, given the underdeveloped immune system in neonates, a baby born to such a mother is prone to develop progressive varicella syndrome with severe manifestation, higher chance of developing serious complications and at an enhanced risk of death from the infection.
What is congenital varicella syndrome?When a fetus gets infected with varicella due to maternal infection occurring during the first trimester of pregnancy, there is a probability of virus disrupting organogenesis in the fetus. Such an infected fetus shows multiple abnormalities at birth and constellation of these manifestations are referred to as congenital varicella syndrome. Such a baby has characteristic abnormalities (chorioretinitis, Horner's syndrome, microphthalmia, cataract and nystagmus) and abnormalities of the central nervous system (cortical atrophy). Other abnormalities that have been described include equinovarus, abnormal or absent digits, prematurity and low birth weight. These children have mental retardation, poor sphincteric control and are at risk to develop clinical zoster in infancy and early childhood.
Herpes zoster in immunocompetent individualsHerpes zoster occurs frequently in adults, but is not uncommon in children. Adults have a painful vesicular eruption. The rash consists of grouped vesicles surrounded by an erythematous base. Vesicles may coalesce to form bullous lesions. The rash is unilateral and limited to the distribution of one of the nerves or dermatomes. It more commonly affects the thoracic and lumber regions. The next most commonly affected site is the trigeminal nerve affecting the face and possibly the eye. The lesions may continue to form over 3-5 days with the total duration of diseases being 10-15 days. However, it may take up to 1 month before the skin returns to normal. The rash is unaccompanied by systemic symptoms other then mild fever.
Pain within the affected region may precede the appearance of rash by 48-72 hours and produce a diagnostic problem. Normal children infrequently experience severe pain with their eruption. Although herpes zoster has a self-limited course, it is followed by neuralgia (post- herpetic neuralgia), even in immunocompetent individuals. This painful condition may last for several months or even for years. The pain can be excruciating and is notoriously unresponsive to routinely used analgesics. At its worst, neuralgia can be incapacitating.
Herpes zoster ophthalmicus associated with keratitis is a potentially sight threatening complication. Keratitis may be followed by severe iridocyclitis, secondary glaucoma or neuroparalytic keratitis. Encephalitis and pneumonia are rare complications of herpes zoster.
Immunocompromised states that make the child prone to develop progressive varicella syndrome or severe complications following varicella infection.The following immunodeficiency states predispose a child to develop progressive varicella syndrome or severe complication following varicella infection :
- Malignancy: Leukemia
- Therapy-related: Children on corticosteroid therapy, radiotherapy, cancer chemotherapy or immunosuppressive drugs prior to or after organ transplants.
- Infection: HIV infection.
Clinical features of herpes zoster in immunocompromised childrenHerpes zoster causes a disseminated infection in immunosuppressed children. Usually, two to three days after the appearance of localized lesions, vesicles appear in other areas of the trunk and extremities. The appearance of remote lesion may continue for up to 2 weeks after that. There may be visceral involvement as well, including varicella pneumonitis, hepatitis and meningoencephalitis. Certain categories of immunocompromised children may suffer from chronic herpes zoster. Complications such as VZV retinitis, acute retinal necrosis and chronic progressive encephalitis have been reported.