TABLE 1

Characteristics of study participants by group including subgroups of Giardia-exposed individuals

CharacteristicGiardia-exposed groupLow-risk controlsP valuea
AllSubgroup with giardiasis:
CurrentlyFor <8 wkFor >8 wk
No. of individuals/group21511512NAf
No. (%) of females11 (52.4)2 (40.0)8 (72.7)1 (20.0)8 (66.7)0.486b
Mean age, yr (SD)38.7 (17.1)31.0 (14.5)46.9 (16.9)28.4 (12.2)43.0 (17.8)0.389c
Mean no. of wk infected (range)12.5 (1–61)20.2 (7–61)3.36 (1–7)25.0 (11–57)NANA
Mean no. of wk since giardiasis (range)33.9 (0–112)NA57.4 (1–112)16.0 (5–32)NANA
No. (%) with Giardia assemblage A6 (35.3)d2 (40.0)4 (36.4)0 (0)eNANA
  • a P values are for comparisons of all Giardia-exposed groups with low-risk controls.

  • b Fisher's exact test was used for comparisons of categorical variables.

  • c The Mann-Whitney U test was used for comparisons of continuous variables between two groups.

  • d The Giardia assemblage responsible for infection could not be determined for 4 of the participants by TPI sequencing, and the percentage represents the ratio for 17 individuals. All of the assemblages were detected in the current-giardiasis group.

  • e The Giardia assemblage of two participants in this subgroup could not be characterized; the other three had assemblage B.

  • f NA, not applicable.