TABLE 2.
Proportions of serum samples agglutinating P. falciparum parasites from the RP5 strain and from isolates obtained from pregnant or nonpregnant subjectsa
| Isolate | % (No.) of serum samples agglutinating parasites
|
||||
|---|---|---|---|---|---|
| Nonpregnant subjects | Women delivering babies
|
||||
| Nonparasitized placenta
|
Parasitized placenta
|
||||
| Parity = 1 | Parity ≥ 4 | Parity = 1 | Parity ≥ 4 | ||
| Nonpregnant subjects | |||||
| 501 | 38.3 (47) | 73.0 (37) | 78.3 (60) | 73.9 (23) | 70.0 (10) |
| 543 | 22.9 (48) | 38.9 (36) | 35.6 (59) | 39.1 (23) | 30.0 (10) |
| 538 | 54.2 (48) | 63.9 (36) | 69.5 (59) | 91.3 (23) | 100 (10) |
| Pregnant women | |||||
| 1237 | 5.4 (56) | 5.2 (38) | 27.0 (63)* | 46.2 (25) | 40.0 (15) |
| 1396 | 20 (10) | 15.4 (13) | 44.0 (25) | 80.0 (10) | 100 (7) |
| 1492 | 6.6 (15) | 23.1 (13) | 52.9 (17) | ND | ND |
| RP5 | 7.8 (64) | 22.3 (76) | 50.0 (143)* | 61.0 (41) | 75.9 (29) |
a
P. falciparum isolates and the RP5 strain were cultured in vitro until the culture presented a majority of mature stages. Acridine orange-labelled parasites were rotated for 90 min in a 1/10 dilution of serum, and the level of agglutination was determined under UV microscopy. The result was considered as negative if fewer than five agglutinates of at least three IEs were counted. *, between parity 1 and parity ≥4, P < 0.05 (chi-square test or Fisher’s exact test). ND, not determined.