Varicella zoster virus in American Samoa: seroprevalence and predictive value of varicella disease history in elementary and college students.

The epidemiology of varicella is believed to differ between temperate and tropical countries. We conducted a varicella seroprevalence study among elementary and college students in the US-territory of American Samoa before introduction of a routine varicella-vaccination program. Sera from 515 elementary and 208 college students were tested for the presence of varicella-zoster virus (VZV) IgG antibodies. VZV seroprevalence increased with age from 76.0% in the 4–6 year-olds to 97.7% in those ≥23 years-old. Reported history of varicella disease for elementary students was significantly associated with VZV seropositivity. The positive and negative predictive values of varicella disease history were 93.4% and 36.4% in elementary students and 97.6% and 3.0% in college students. VZV seroprevalence in this Pacific island appears to be similar to that in temperate countries and suggests endemic VZV circulation.