Sociodemographic and clinical characteristics of patients
A total of 416, 259 and 131 patients with suspected malaria were enrolled at the CSI «Maman Mboualé», Hôpital de Mfilou and the LNSP respectively. Sociodemographic as well as clinical characteristics of these patients are summarized in Table1.
Out of 259 patients enrolled at the Hôpital de Mfilou, gender and age were recorded for 257 of them, while with regards to the CSI « Maman Mboualé», out of the 416 recruited patients, 410 had records on gender. Both proportion of malaria cases and geometric mean parasite density were higher at the CSI «Maman Mboualé» compared to over sites (P-value ˂0.001).
Table 1: Characteristics of patients
Characteristics
|
CSI « Maman Mboualé»
|
Hôpital de Mfilou
|
LNSP
|
P-value
|
Total number
Gender (F/M)
Groups of age (n, %)
˂5 years
≥5 years
Mean age ± ET
|
416
207/203
99(23.8)
317(76.2)
14.5±13.49
|
259
131/126
38(14.8)
219(85.2)
28.6±19.82
|
131
68/63
0(0.0)
131(100.0)
42.31±14.84
|
|
Malaria cases (n, %)
Geometric mean parasite density (Min-Max)
|
173(41.6)
2399.30 (16-164800)
|
62(23.9)
1905.10 (16-100000)
|
12(9.2)
189.46 (16-8720)
|
˂0.001
˂0.001
|
Multiplicity of infection
MSP1
MSP2
MSP1+2
|
1.70
1.33
2.55
|
2.05
1.51
3.23
|
1.13
1.00
1.89
|
˂0.001
˂0.001
˂0.001
|
Relationship between the multiplicity of infection, parasite density and age
Regardless the molecular marker used, the MOI was higher at the Hôpital de Mfilou compared to the CSI « Maman Mboualé», and the LNSP (Table 1), with the overall MOI of 3.23, 2.55 and 1.89 respectively (P-value ˂0.001). While the MOI was not influenced by age, patients with less than 5 years had significantly higher parasite densities compare to those with the age more than 5 years old (Table 2). Moreover, the MOI was not associated with parasite density.
Table 2: Relationship between the multiplicity of infection, parasite density and age
Center
|
Characteristics
|
Mean parasite densities
|
P-value
|
MOI
|
P-value
|
Hôpital de Mfilou
|
Age groups
˂ 5 years
≥ 5 years
|
22167.18
9847
|
0.037
|
3.25
3.15
|
0.956
|
CSI « Maman Mboualé»
|
Age groups
˂ 5 years
≥ 5 years
|
32109.11
15816.28
|
0.012
|
2.18
2.63
|
0.469
|
LNSP
|
Age groups
˂ 5 years
≥ 5 years
|
--
1320.33
|
--
|
--
1.89
|
--
|
Variation of proportion of malaria cases and parasites density throughout the year
During the year, Plasmodium falciparum was the only specie identified in all positive slides confirmed by the quality control expert.
A particular profile has been found at the LNSP with very low malaria cases without impact of different seasons (P-value =0.477). However, the difference of the mean parasite density was statistically significant (P-value ˂0,01) with the highest pick in November, corresponding to the rainy season.
At the Hôpital de Mfilou, highest proportions of malaria cases have been found at the beginning of the study in May and June (50%), November (40%), February (38.9%) and April (33.3%) corresponding to the months of rainy seasons and the beginning of dry season for June (Table 3). However, lowest proportions of cases were noticed in September (3.4%), and January (18.8%) corresponding to the peak of dry seasons. The variation of these proportions within the year was statistically significant (P-value ˂0.004). A contrasting profile was observed at the CSI « Maman Mboualé», where the highest proportion of malaria cases were obtained during the main rainy season, in April, May including the beginning of dry season in June. Progressive diminution of malaria cases has been noticed from July to March, reaching the lowest proportion in December and March corresponding to the beginning of dry season and main rainy season respectively (P-value ˂0.01). When tacking all tree sites together the highest proportions of malaria cases were confirmed during the rainy seasons, while lowest proportions were registered in September, December and March (P-value ˂0.01).
With the regards to mean asexual parasite densities, a clear seasonality has been noticed at the Hôpital de Mfilou, with the highest peaks mainly observed at the beginning of dry seasons in June and December as well as in May (corresponding to the end of rainy season) at the end of the study (Figure 1). However the only one malaria case registered in September had also a high parasite density. Moreover, it is obvious from the result that the periods of low mean asexual parasite densities were observed at the peak of the dry season corresponding to the month of August with persistence during of rainy seasons (Figure1) corresponding to October and November as well as, February March and April for the short and main rainy seasons, respectively.
By considering the CSI «Maman Mboualé», tree high picks of mean parasite density have been identified in July, December and May; thereafter, persistence decrease has been noticed during the dry season, including the rainy seasons (Figure 1) corresponding to October and November as well as from February to April (P-value ˂0.043). When tacking all tree sites together, similar profile with the CSI «Maman Mboualé», has been observed (P-value ˂0.01).
Table 3: Relationship between different seasons and proportion of malaria cases
Seasons
|
Months
|
Hôpital de Mfilou
|
CSI «Maman Mboualé»
|
LNSP
|
All
|
N
|
n (%)
|
N
|
n (%)
|
N
|
n (%)
|
N
|
n (%)
|
Rainy
|
May-15
|
4
|
2(50,0)
|
8
|
6(75,0)
|
4
|
0(0,0)
|
16
|
8(50,0)
|
Dry
|
June-15
|
24
|
12(50,0)
|
36
|
29(80,6)
|
14
|
1(7,1)
|
74
|
42(56,8)
|
July-15
|
27
|
7(25,9)
|
36
|
17(47,2)
|
14
|
0(0,0)
|
77
|
24(31,2)
|
August-15
|
32
|
3(9,4)
|
34
|
15(44,1)
|
5
|
0(0,0)
|
71
|
18(25,4)
|
September-15
|
29
|
1(3,4)
|
36
|
11(30,6)
|
18
|
4(22,2)
|
83
|
16(19,3)
|
Rainy
|
October-15
|
25
|
6(24,0)
|
34
|
9(26,5)
|
7
|
0(0,0)
|
66
|
15(22,7)
|
November-15
|
15
|
6(40,0)
|
34
|
10(29,4)
|
6
|
1(16,7)
|
55
|
17(30,9)
|
Dry
|
December-15
|
23
|
6(26,1)
|
31
|
6(19,4)
|
14
|
2(14,3)
|
68
|
14(20,6)
|
January-16
|
16
|
3(18,8)
|
32
|
10(31,3)
|
11
|
1(9,1)
|
59
|
14(23,7)
|
Rainy
|
February-16
|
18
|
7(38,9)
|
34
|
14(41,2)
|
13
|
1(7,7)
|
65
|
22(33,8)
|
March-16
|
16
|
2(12,5)
|
37
|
9(24,3)
|
4
|
1(25,0)
|
57
|
12(21,1)
|
April-16
|
9
|
3(33,3)
|
32
|
16(50,0)
|
7
|
0(0,0)
|
48
|
19(39,6)
|
May-16
|
21
|
4(19,0)
|
32
|
21(65,6)
|
14
|
1(7,1)
|
67
|
26(38,8)
|
P-value
|
--
|
0,004
|
--
|
˂0,01
|
--
|
0,477
|
--
|
˂0,01
|
N: number of enrolled patients per month; n: number of malaria cases per month
Variation of multiplicity of Plasmodium falciparum infection throughout the year
Particular profile has also been found at the LNSP regarding the MOI with no infection in some alternative months (May, July, August, October and April), and the MOI did not vary significantly over the year (P-value =0,853).
At the Hôpital de Mfilou, significant variation of MOI was found over the year (P-value ˂0.01). From the beginning of the study in May, the MOI was increased reaching a pick in July, thereafter persistence of decrease was observed, with the lowest MOI in September (Figure 2). There was a permanent increase of MOI from October, reaching the highest picks in February and April, regardless the short dry season in December and January.
Concerning the CSI «Maman Mboualé», tree different picks were observed, with highest MOI registered at the beginning of the study in May; follow by those in October and the lowest in December (P-value ˂0.01). Persistence of decrease of MOI was observed in July and August, while the MOI stability was noticed from January to April. When taking all tree sites together, significant variation of MOI was also observed over the year (P-value ˂0.01) with similar profile with the CSI «Maman Mboualé» from May at the beginning of the study to November, but slightly increase of MOI from December to May at the end of the study.