As shown in Fig. 1, the northeast, northwest, north-central, and southwest regions showed higher SCH endemicity compared to the southeast and south-south regions. Three northern states (Kebbi and Sokoto in the northwest and Niger in the north-central region) were the most endemic for SCH in Nigeria, as a high prevalence of SCH was often reported in these states. However, most states in Nigeria showed a low to moderate prevalence of SCH, especially those in the northeast and north-central regions. Akwa Ibom and Rivers states were non-endemic for SCH while Abia, Imo and Anambra states had a mix of non-endemic and low prevalence of SCH.
The depiction of preventive chemotherapy coverage for schistosomiasis among school-aged children across Nigeria is illustrated in Fig. 2. The map indicates that there was no preventive chemotherapy delivery in most states in the northeast, northwest, and North-central regions, as well as certain areas within the southwest region. Preventive chemotherapy was also not delivered in areas with high endemicity.
Figure 3 illustrates the proportion of children affected by SCH in relation to the endemicity level. Among school-aged children, SCH was absent in 22.48% of cases. The percentages of children with low, moderate, and high infections were 38.24%, 37.98%, and 1.29%, respectively.
In the year 2021, out of the 774 IUs for preventive chemotherapy (PC) in Nigeria, PC was carried out in 68 units (8.79%) targeting school children. Among these, successful implementation (achieving ≥ 75% coverage) of PC was observed in 33 units (4.26%), as indicated in Table 1.
Table 1
The children’s proportion with preventive chemotherapy implementation. PC preventive chemotherapy.
Groups
|
PC implemented (%)
|
Effective (≥ 75%) PC implemented (%)
|
Yes
No
Total
|
68 (8.79)
706 (91.21)
774
|
33 (4.26)
741 (95.74)
774
|
Table 2 displays the cumulative implementation of PC and effective PC within the SCH IUs in Nigeria during the year 2021. The findings revealed that in the period spanning 2013 to 2021, PC was conducted only once among school children in 150 (19.38%) IUs, while a larger proportion (23.51%) of IUs executed PC at least three times. Despite this, 241 (31.14%) of the IUs successfully carried out effective PC (≥ 75%) once from 2013 to 2021. Conversely, a higher percentage (31.91%) of IUs indicated PC coverage below 75%, signifying ineffectiveness. Notably, when the frequency of PC interventions ranged from 5 to 8 times, the proportion of SCH IUs implementing effective PC substantially decreased (EffPC-n, 0.9–0%; PC-n, 8.27–0.13%) (Table 2).
Table 2
Cumulative PC implemented and effective PC implemented since 2013 based on programme coverage.
Treatment frequency (n)
|
Cumulative PC implemented since 2013 based on the programme
coverage—PC-n (%)
|
Cumulative Effective PC implemented since 2013 based on
programme coverage—EffPC-n (%)
|
0
1
2
3
4
5
6
7
8
Total
|
132 (17.05)
150 (19.38)
130 (16.80)
182 (23.51)
79 (10.21)
64 (8.27)
27 (3.5)
9 (1.16)
1 (0.13)
774
|
247 (31.91)
241 (31.14)
155 (20.03)
82 (10.50)
37 (4.78)
7 (0.90)
5 (0.65)
0 (0)
0 (0)
774
|
Table 3
Associations between different intervention indices and endemicity of SCH in school-aged children. Preventive chemotherapy implemented (PC), Cumulative preventive chemotherapy implemented (PC-n), Effective preventive chemotherapy implemented (EffPC), Cumulative effective preventive chemotherapy implemented (EffPC-n).
Endemicity
|
|
Intervention indices
|
Non-endemic (0%)
|
Low prevalence (< 10%)
|
Moderate prevalence (10–49%)
|
High prevalence (≥ 50%)
|
Total
|
P value
|
PC
|
|
|
|
|
|
|
Yes
No
Total
|
0 (0)
174 (24.7)
174 (22.5)
|
37 (54.4)
259 (36.7)
296 (38.2)
|
28 (41.2)
266 (37.7)
294 (37.9)
|
3 (4.4)
7 (0.9)
10 (1.3)
|
68
706
774
|
0.000
|
EffPC
|
|
|
|
|
|
|
Yes
No
Total
|
0 (0)
174 (23.5)
174 (22.5)
|
11 (33.3)
285 (38.5)
296 (38.2)
|
20 (60.6)
274 (36.9)
294 (37.9)
|
2 (6.1)
8 (1.1)
10 (1.3)
|
33
741
774
|
0.000
|
PC-n
|
|
|
|
|
|
|
0
1
2
3
4
5
6
7
8
Total
|
125 (94.7)
24 (16.0)
21 (16.1)
4 (2.2)
0 (0)
0 (0)
0 (0)
0 (0)
0 (0)
174 (22.5)
|
3 (2.3)
112 (74.7)
78 (60.0)
78 (42.9)
22 (27.8)
3 (4.7)
0 (0)
0 (0)
0 (0)
296 (38.2)
|
4 (3.0)
13 (8.7)
31 (23.8)
100 (54.9)
54 (68.4)
58 (90.6)
25 (92.6)
8 (88.9)
1 (100)
294 (37.9)
|
0 (0)
1 (0.7)
0 (0)
0 (0)
3 (3.8)
3 (4.7)
2 (7.4)
1 (11.1)
0 (0)
10 (1.3)
|
132
150
130
182
79
64
27
9
1
774
|
0.000
|
EffPC-n
|
|
|
|
|
|
|
0
1
2
3
4
5
6
7
8
Total
|
135 (54.7)
22 (9.1)
16 (10.3)
1 (1.2)
0 (0)
0 (0)
0 (0)
0 (0)
0 (0)
174
|
85 (34.4)
137 (56.8)
44 (28.4)
28 (34.1)
2 (5.4)
0 (0)
0 (0)
0 (0)
0 (0)
296
|
26 (10.5)
81 (33.6)
94 (60.6)
51 (62.2)
30 (81.1)
7 (100)
5 (100)
0 (0)
0 (0)
294
|
1 (0.4)
1 (0.4)
1 (0.7)
2 (2.4)
5 (13.5)
0 (0)
0 (0)
0 (0)
0 (0)
10
|
247
241
155
82
37
7
5
0
0
774
|
0.000
|
Table 3 illustrates the correlations between PC intervention status and endemicity. In the units where PC was conducted, a greater proportion of school-age children exhibited low SCH prevalence (54.4%) compared to areas with no SCH PC implementation (36.7%). A similar pattern was noted among school children with moderate and high SCH endemicity (P < 0.05). The highest percentage of school-aged children with low SCH prevalence was observed in units where the PC programme was executed once (74.7%), in contrast to those with multiple implementations—twice (60%), three times (42.9%), four times (27.8%), or five times (4.7%).
The IU with the highest prevalence of moderate SCH infection among school-aged children (92.6%) was found in cases where PC was administered six times, while one IU with moderate endemicity received PC eight times. Conversely, IU with lower rates of moderate infections was observed when treatments were not administered (3%), compared to areas where treatment was administered once (8.7%), twice (23.8%), three times (54.9%), four times (68.4%), five times (90.6%), or seven times (88.9%) (Table 3).
Additionally, our findings indicated that the units with the highest percentage of significant SCH infection (11.1%) were those where seven treatment cycles were administered, in contrast to units where treatments occurred once (0.7%), four times (3.8%), five times (4.7%), or six times (7.4%) (Table 3).
There was a significant relationship between SCH endemicity levels and the number of effective treatments (P < 0.05). In areas with low SCH endemicity, there was a tendency for higher rates of effectiveness when treatments were administered once compared to 2–4 times or not at all. Among school-aged children, regions with moderate SCH prevalence had the highest rate (100%) of effective treatments occurring 5–6 times, while the lowest prevalence (10.5%) was observed in cases with no effective treatments. For areas with high SCH prevalence, the highest rate (13.5%) occurred when effective treatments were administered four times, while the lowest rates (0.4%) were recorded when no effective treatments were given or when it was done only once (Table 3).