Methods: Self-report of varicella infection, was compared to serology in 606 adult ICE detainees. The positive predictive value (PPV) of oral history for evidence of immunity to varicella was calculated separately for 400 participants who volunteered for a prospective surveillance project at a single detention facility, and 206 detainee contacts of a varicella case-patient across four facilities.
Results: The overall seroprevalence of varicella was 87.5%. The PPV of self-reported history of varicella infection among prospective survey participants was 95% (95% C.I.: 92%,98%), and did not significantly differ from a PPV of 93% (95% C.I.: 88%,99%) among detainees exposed to a varicella case-patient. Detainees who reported having a history of varicella infection were 75 times greater odd of having detectable antibodies against varicella than those who denied ever having a varicella infection (p<0.0001).
Conclusion: The seroprevalence of varicella among detainee participants is sufficiently low to enable outbreaks. The high PPV of self-report of prior varicella could obviate serologic testing and cohorting among individuals who affirm prior illness. These findings also underscore the importance of continued testing of detainees who report an unsure or negative history of varicella. Utilizing a positive history to assist with management decisions could save resources and expedite legal proceedings.
J. Freiman, None
S. Brodine, None
K. Ferran, None
S. Waterman, None
D. Elson, None
E. Lederman, None
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