Transmission of Chickenpox in a School Setting Prior to the Observed Exanthem

Communicability of varicella before rash onset: a literature review

“…Included articles originated from the United States (7), Japan (5), United Kingdom (2), Australia (1) and Czechoslovakia (1). Seven articles addressed VZV transmission before varicella rash onset using epidemiologic data [12][13][14][15][16][17][18] and 10 with laboratory data [11,12,[19][20][21][22][23][24][25][26]; one epidemiologic study had a laboratory component [12].…”

“…The authors reported that patients with varicella were infectious at various intervals before the rash appeared: <1 day (9 h) before (one report) [ 17 ], at least 1 day before (two reports) [ 14 , 18 ], at least 2 days before (two reports) [ 12 , 16 ], at least 4 days before (one report) [ 15 ]; one report described potential infectiousness ‘a few days’ before rash onset, but no source of exposure could be identified [ 13 ] ( Table 1 ). Exposure of contacts before rash onset in the index patient was determined based on reports of index patients and contacts being in the same setting a number of days or hours before rash onset in the index patient and not while the index patient had rash: two reports described transmission among siblings, two in hospitals (ward contacts), two in schools (in one report parents denied that the child with varicella attended school when the rash was present and in a second, a person-time analysis, exposure was defined as the day before a classmate stayed home with varicella) and one in jail (putative source not identified).…”

“…Exposure of contacts before rash onset in the index patient was determined based on reports of index patients and contacts being in the same setting a number of days or hours before rash onset in the index patient and not while the index patient had rash: two reports described transmission among siblings, two in hospitals (ward contacts), two in schools (in one report parents denied that the child with varicella attended school when the rash was present and in a second, a person-time analysis, exposure was defined as the day before a classmate stayed home with varicella) and one in jail (putative source not identified). In one report, a patient with varicella who was considered to have transmitted the virus to a schoolmate was monitored daily clinically and with laboratory studies [ 12 ]. VZV was not detected in specimens of pharyngeal or nasal secretions obtained daily from ~4 days before to 2 days after rash onset (the same experience for his two younger siblings).…”

“…VZV was not detected in specimens of pharyngeal or nasal secretions obtained daily from ~4 days before to 2 days after rash onset (the same experience for his two younger siblings). However, VZV was detected (based on the characteristic cytopathic effect in cell culture) in vesicular fluid collected on days 2 and 3 of the rash in two of the three siblings [ 12 ].…”

“…Of the 10 articles that addressed VZV transmission before rash onset with laboratory evidence, five were published during 1966–1989; they reported results of virologic techniques (culture) to identify virus in the oropharynx [ 11 , 12 , 24 – 26 ]. Five articles were published during 1991–1999 and examined evidence of VZV DNA presence in the oropharynx using polymerase chain reaction (PCR) [ 19 – 23 ].…”