Herpes simplex virus
HSV or Herpes simplex virus causes a transmissible infection that affects around 60-95% of adults worldwide. The two type of the virus (HSV-1 and HSV-2) mainly infect humans. HSV-1 is associated primarily with infections of the oral area specifically the mouth, the pharynx, eye, face, and CNS (central nervous system), and HSV-2 is associated mainly with anogenital region infections, though both serotypes could infect any body part.
The majority of adults have HSV and carry dormant viruses, yet the severity of symptoms, serotype, and transmission mode vary according to with age. Kids are infected chiefly with oro-labial HSV-1 by five years of age, with 33% infection rates in populations of lower socioeconomic status as well as 20% in people of higher socioeconomic status. By adulthood, HSV-1 affects 70-80% in the lower socioeconomic population as well as 40-60% in the improved socioeconomic population. The occurrence of HSV-1 increases consistent with age, by age fifteen years, reaching 40% and rising to 60-90% in older adults.
In the USA, the occurrence of HSV-1 increases consistent with age, from 26.3% in children 6 to 7-years-old and 36.1% in children 12 to 13-years-old to 90% among people older than 70. Take note that the overall occurrence of HSV-1 in the USA has been demonstrated to be diminishing over time.
Globally, the occurrence of HSV-1 infection is higher than HSV-2 in the majority of geographic areas. HSV-2 is mainly sexually transmitted and, thus, isn’t as common in children. But, HSV-2 can be passed on from mother to baby during pregnancy, with such incidence from 1/3,000 to 1/20,000 live births and around 1,500 new cases per year in the United States. Around 2% of women contract genital herpes during pregnancy, and approximately 20-30% of pregnant women are HSV-2 seropositive.
The occurrence of HSV-2 varies across age, sex, and country. The HSV-2 occurrence is highest in parts of South and Central America and regions of Sub-Saharan Africa. The occurrence typically is lower in southern and western Europe than in northern Europe as well as in North America. Asia has the lowest occurrence rates of HSV-2.
The occurrence is lower in men than in women. Yet, the occurrence increases with age from small levels in children below 12 years to 20-40% by 40 years old and a soaring 80% among populations that have a higher risk.
In the USA, the occurrence of HSV-2 infection in African-Americans is higher than in Mexican Americans or whites. Though time trends in herpes simplex prevalence are limited, the majority of studies indicate that the HSV-2 occurrence has risen over the past many years in countries like the USA from 16.0% (late 1970s) to 20.8% (early 1990s); in other populations, HSV-2 occurrence has either remained constant or decreased.
As stated before, HSV-2 is associated mainly with anogenital region infections, whereas HSV-1 is found extra-genitally. However, recent research has demonstrated a 30% rise in the HSV-2 infection prevalence, with HSV-2 being as common as HSV-1 in the extra-genital areas but the orofacial region. Additionally, HSV-1 seems to be rising in occurrence in the anogenital region, formerly known to be mainly HSV-2 infected.