Table 2.

Laboratory evidence for VZV presence in the oropharynx before and after rash onset in patients with varicella

Study	Method	Results of oropharyngeal specimen testing		Other results
		Before rash onset	After rash onset
Gold [11]	Culture; specimens frozen and stored at −70°C before being tested. Study included exposed patients.	3/3 patients VZV negative; specimens collected daily from 9, 6 and 6 days before rash onset	5/5 patients VZV negative; specimens collected from day of rash onset to 3−5 days after	5/5 patients VZV positive; vesicular fluid collected within 3 days of rash onset; 23/25 specimens positive
Nelson and Geme [26]	Culture; most specimens stored at −50 °C for 1–2 weeks before inoculation. Source of patients not indicated.	45 specimens from 29 children tested VZV negative; specimens collected from 8 days before to 4 days after rash onset (one specimen was collected 3 days before and four were collected 1 day before)		1/1 patient VZV positive; vesicular fluid from herpes zoster lesions, repetitive isolation
Trlifajova et al. [25]	Culture; specimens inoculated at most 1 h incubation at room temperature in collecting medium. Study included exposed patients.	57/57 nasal and 56/56 oropharyngeal specimens collected during the entire incubation period VZV negative (11 patients); 11 nasal and 11 oropharyngeal specimens were collected in the last 3 days before rash onset	3/23 pharyngeal and 2/22 nasal specimens VZV positive during the first 3 days after rash onset; none of the 13 samples collected on the first day of rash tested positive	11/11 patients VZV positive; vesicular fluid collected during the first 3 days after rash onset (12/12 specimens)
Ozaki et al. [24]	Culture; specimens inoculated at most 4 h incubation at 4 °C in collecting medium. Study included paediatric outpatient patients with varicella, of whom 5 children during the incubation period, exposure source unknown.	5/5 patients VZV negative; specimens collected 6, 4, 2 and 1 day(s) before rash onset	5/117 patients with varicella VZV positive; specimens collected 1–2 days after rash onset	>90% VZV positivity rate; vesicular fluid collected during the first 3 days after rash onset
Brunell [12]	Culture; swabs placed in partially frozen (4 °C) medium; up to 30 min between collection of specimens and inoculation. Study included children exposed to a parent with varicella.	3/3 patients VZV negative; nasopharyngeal and oropharyngeal specimens obtained daily from ~4 days before rash onset	3/3 patients VZV negative; nasopharyngeal and oropharyngeal specimens obtained daily on days 1 and 2 after rash onset	2/3 patients VZV positive; vesicular fluid collected on days 2 and 3 of the rash
Koropchak et al. [22]	PCR; detection limit = 45 copies. Culture. Study included immunocompetent children and adults participants in a clinical trial evaluating oral acyclovir for treatment of varicella.		PCR: 1/30 patients VZV positive; specimens collected <24 h (mean 15.9 h) after appearance of skin lesions (most maculopapular); the VZV-positive patient had oral lesions typical of VZV Culture: 0/19 patients VZV positive during same collection interval	Skin lesion specimens collected <24 h after rash onset: PCR: 21/28 patients VZV positive Culture: 5/24 patients VZV positive
Ozaki et al. [23]	PCR; detection limit = 50 copies. Study included exposed siblings.	11/42 specimens collected from 15 days before rash onset VZV positive (18 children); 4/9 specimens collected within 5 days before rash onset VZV positive (3/7 children). A less sensitive assay (5 × 103 copies) did not detect viral DNA	90% specimens VZV positive during the first 3 days after rash onset (39 specimens); 26% VZV positive with the less sensitive assay
Hondo et al. [21]	PCR; estimated number of copies by comparing with the standard curves. Study included exposed siblings.	Two patients; throat swabs; DNA in low titres during the entire incubation period (<2 copies/swab); moreover, within 3 days before rash onset, VZV DNA detected only in 1/6 specimens	Titres abruptly increased to high levels when rash occurred; levels >100-fold higher than during the incubation period
Asano et al. [19]	PCR; detection limit = 100 copies. Study included exposed siblings.	0/2 patients VZV DNA positive in throat swabs collected daily from 8 days before rash onset or on the day of rash onset	2/2 patients VZV DNA positive in throat swabs for 4 days starting the day after rash onset
Asano et al. [20]	PCR; detection limit = 100 copies. Study included daycare contacts.		1/13 children VZV DNA positive; throat swabs collected 4 h after recognised onset of varicella in a contact (only a few maculopapular lesions)	All children were vaccinated postexposure and none developed varicella (including the one with the VZV DNA positive throat swab). Several environmental samples collected at the same time as the throat swabs were positive