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Description:
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In March of 1995 , the United States Food and Drug Administration approved a vaccine for the varicella -zoster virus (VZV ) infection [7] . This vaccine was developed in the 1970's in Osaka , Japan and has been used extensively in the Asian and European continents . Prior to March 1995 , the United States had restricted the use of the VZV vaccine to immunocompromized patients (chemotherapy and AIDS patients ) .
The varicella -zoster virus causes varicella , or chickenpox , in the majority of the population at a young age . Estimates range from 3 .5 to 4 million cases of chickenpox per year in the United States [3 , 7] . For most children who contract varicella , few complications arise . Yet for infants ,steroid or immunocompromized patients or women who are pregnant , the varicella infection may cause complications ranging from severe rashes , congenital varicella syndrome to death [3 , 16 , 26] .
After an individual has been infected and survives varicella infection , the virus travels to the dorsal root ganglia at the base of the spinal cord and becomes dormant [7 , 16] . The virus remains latent in this location usually for decades [7 , 16] . If the virus reactivates , it causes an acute infection , herpes -zoster , similar to the original varicella infection except for the intensity . Herpes -zoster or shingles , usually affecting only a single dermatome [16] , increases in incidence with age [14 , 20 , 25 , 27 , 34] . There have been 300 ,000 to 850 ,000 cases of zoster per year reported in the United States in recent years [14 , 30 , 33] . A syndrome known as postherpetic neuralgia , (PHN ) , pervasive pain , which can last from one month up to one year is considered the worst comphcation associated with zoster [14] . There is also an age -related incidence of PHN with zoster patients : at 60 years old , an individual with zoster has a 50 % chance of developing PHN , but at 90 years , PHN occurs in 90 % of zoster patients [31] . Although treatments for PHN have increased in effectiveness over the years , this still represents a sizable risk for the elderly . |