Plasmodium falciparum merozoite surface antigen-specific cytophilic IgG and control of malaria infection in a Beninese birth cohort

Table 2 Clinical and parasitological characteristics for infants in CAIG and NCIG groups

	Malaria infection groups^a
	Asymptomatic infection clearance without anti-malarial treatment group (CAIG) N = 53	Control group (NCIG) N = 183
Infections during the follow-up asymptomatic infections, no (%)
No infection	0	121 (66)
1	24 (45)	48 (26)
2–3	29 (55)	13 (7)
> 3	0	1 (0)
Symptomatic infections, no (%)
No infection	6 (11)	0 (0)
1	17 (32)	26 (14)
2–3	18 (34)	102 (56)
> 3	12 (23)	55 (30)
Parasite density^b in asymptomatic infections, median (IQR)	38.6 (6.2–143.9)	60.2 (6.4–168.8)
Parasite density in symptomatic infections, median (IQR)	255.7 (8.0–806.8)	180.3 (10.1–698.8)
Time until malaria attacks (days)^c, median (25th–75th)	34 (26–47)	13.5 (6–31)
Environmental risk of exposure to malaria^d during the follow-up, median (25th–75th)	3.06 (2.15–4.60)	3.89 (2.54–5.70)

^aCAIG was composed by 53 infants with spontaneous clearance of at least one asymptomatic infection. Among these 53 infants, six never had febrile malaria during the follow-up while 47 also developed at least one malaria attack. Among the 168 asymptomatic infections, 88 and 80 respectively occurred in CAIG and NCIG during the whole follow-up. 64/88 were followed by a negative of thick blood smears in the time, 17/88 were followed by a malaria attacks and 7/88 occurred at the end of the follow-up for which it was not possible to determine the outcome. Concerning NCIG, 62/80 were followed by a malaria attacks and 18/80 occurred at the end of the follow-up for which it was not possible to determine the outcome
^bParasite density was expressed in number of Pf-infected red blood cells for 100 leucocytes
^cThe time expressed in days between the detection of asymptomatic infection and the occurrence of febrile malaria was higher in CAIG than NCIG. All infants (n = 30) with only one malaria infection were considered as not sufficiently exposed to belong to both groups and excluded
^dEnvironmental risk of exposure to malaria was estimated for each infant once a month. No significant difference of exposure to malaria was observed between infants from CAIG and NCIG (p = 0.11; Mann–Whitney test)

ISSN: 1475-2875