Table 2. Baseline characteristics of the subjects, considering only Plasmodium vivax infections.
| Current vivax malaria | ||||
| Variables | Non-infectedn = 205 | Symptomatic infectionn = 190 | Asymptomatic infectionn = 173 | P valueχ2 |
| n (%) | n (%) | n (%) | ||
| Gender | 0.0741 | |||
| Male | 88 (42.93) | 102 (53.68) | 77 (44.51) | |
| Age (years) | <0.0001 | |||
| 5 to 15 | 14 (6.83) | 24 (12.63) | 1 (0.58) | |
| 16 to 30 | 50 (24.39) | 63 (33.16) | 25 (14.45) | |
| 31 to 59 | 98 (47.80) | 77 (40.53) | 120 (69.36) | |
| ≥60 | 21 (10.24) | 18 (9.47) | 17 (9.83) | |
| Years residing in the area | <0.0001 | |||
| ≤2 | 44 (21.46) | 51 (26.84) | 27 (15.61) | |
| 3 to 10 | 20 (9.76) | 38 (20.0) | 17 (9.83) | |
| >10 | 119 (58.05) | 93 (48.95) | 119 (68.79) | |
| Residents per household | <0.0001 | |||
| 1 to 5 | 141 (68.78) | 107 (56.32) | 118 (68.21) | |
| >5 | 42 (20.49) | 75 (39.47) | 45 (26.01) | |
| HBV infection | <0.0001 | |||
| Non-infected | 89 (43.41) | 132 (69.47) | 74 (45.40) | |
| Previous HBV | 65 (31.70) | 47 (24.74) | 64 (39.26) | |
| Current HBV | 29 (14.15) | 03 (1.58) | 25 (15.34) | |
| Vaccinated | 22 (10.73) | 08 (4.21) | 10 (5.78) | |
| Malaria episodes | <0.0001 | |||
| None | 24 (11.71) | 25 (13.16) | 03 (1.73) | |
| 1 to 4 | 07 (3.41) | 52 (27.37) | 02 (1.16) | |
| 5 to 10 | 29 (14.15) | 45 (23.68) | 04 (2.31) | |
| >10 | 123 (60.0) | 60 (31.58) | 154 (89.01) | |
| Serum IL-10 (pg/mL) § | <0.0001 | |||
| ≤46 | 175 (85.37) | 139 (73.16) | 42 (24.28) | |
| >46 | 08 (3.90) | 43 (22.63) | 121 (69.94) | |
| Serum IFN-γ (pg/mL) § | <0.0001 | |||
| ≤198 | 154 (75.12) | 111 (58.42) | 118 (68.21) | |
| >198 | 29 (14.15) | 71 (37.37) | 45 (26.01) | |
A Chi-square test was performed to compare the distribution of each variable between the groups.
Individuals presenting AgHBS−/anti-HBS+/anti-HBc+ with no HBV DNA amplification by quantitative RT-PCR (qPCR) were considered to have previous HBV infection, those presenting AgHBS+/anti-HBS− and detectable viremia by qPCR were considered currently infected with HBV and those with AgHBS−/anti-HBS+/anti-HBc− were considered vaccinated against the virus.
§Cut-off IL-10 and IFN- γ plasma levels were determined by choosing the values that which implied the highest likelihood ratio in discriminating asymptomatic from symptomatic malaria infection using a ROC analysis.