Sequential dengue virus infections detected in active and passive surveillance programs in Thailand, 1994–2010

BMC Public Health

Table 1 Demographic, serologic, and clinical characteristics of individuals with repeat dengue virus infections

	All data (n = 502 individuals)^a	Cohort extended dataset (n = 205)
Gender
Female	252	100
Male	237	95
Unknown	13	10
Age
At infection one (mean years ± SD)	7.6 ± 3.0	9.0 ± 1.7
At infection two (mean years ± SD)	11.2 ± 3.0	11.2 ± 2.0
Serologic response at infection one ^b
Primary	84	6
Secondary	263	59
Unknown (symptomatic)	15	-
Unknown (Subclinical/nonhospitalized)	56	56
Unknown (Subclinical)	84	84
Clinical category at infection one ^c
Symp. (DHF)	201	24
Symp. (DHF/hospitalized DF)	16	3
Symp. (hospitalized DF)	123	16
Symp. (non-hospitalized DF)	19	19
Symp. (hospitalized/non-hospitalized DF)	3	3
Subclinical/non-hospitalized	56	56
Subclinical	84	84
Clinical category at infection two ^c
Symp. (DHF)	201	17
Symp. (DHF/hospitalized DF)	13	-
Symp. (hospitalized DF)	112	16
Symp. (non-hospitalized DF)	33	29
Symp. (hospitalized/non-hospitalized DF)	1	1
Subclinical/non-hospitalized	42	42
Subclinical	100	100

^a488 individuals had two detected infections; 14 had three detected infections.
^bThe serologic response could not be categorized in 155 individuals; 140 could not be categorized because they were either subclinical (n = 84) or had seroconversion outside the active surveillance period in cohort studies (n = 56); 15 were symptomatic but had inadequate samples to determine serologic response.
^cSubclinical infections in cohort studies were identified by ≥ four-fold rise in dengue hemagglutination inhibition (HAI) titers without detection of symptomatic infection during the intervening surveillance period. Infections captured outside the active study surveillance period by HAI without a recognized hospitalization were marked as ‘subclinical/non-hospitalized’. Hospitalized cases that did not have sufficient clinical information for clinical categorization were marked ‘DHF/hospitalized DF.’ Four infections categorized as DF but with uncertain hospitalization status were marked as ‘hospitalized/non-hospitalized DF’.

ISSN: 1471-2458