Demography: regions; districts, communities (CHA), and population

Overall, 1610 community health areas from 79 districts belongs to 14 regions have been analyzed. The districts cover a population of 17,156,624 habitants. SAC and adults’ populations represent 4,855,303 (28.3%) and 9,041,556 (52.7%) respectively.

1610 community implementation units (IUs) were categorized using the decision tree for schistosomiasis endemicity at district and community level (Fig. 2).

Fig. 2

Different data sources used for disaggregation at community level. hbts habitants

Evaluation of schistosomiasis risk transmission and the determination of endemicity categories were mainly based on the use of most recent JRSM endemicity data (40.5%) followed the use of district-IU endemicity (33.5%). Community-IU endemicity was in 10.5%. Highest adjacent endemicity was not used. According to the regions, same tendency was observed (Table 1).

Table 1 Sources of data for endemicity categories by regionsNumber of community health areas according to the endemicity categories by region

The results showed that 41.1% of community IUs (n = 666) have been classified as non-endemic. 282 (17.5%) and 398 (24.7%) community IUs have been classified as moderate and high endemicity respectively.

According to regions, high endemicity communities were in Tambacounda (n = 114), Saint Louis (n = 97), Matam (n = 78), Louga (n = 57) and Kedougou (n = 43) whereas the highest number of non-endemic areas were found in Thies (n = 153), Dakar (n = 152), Fatick (n = 96), Diourbel (n = 91) and Sedhiou (n = 44). Low endemicity was also found in 264 communities (16.4%). It was more important in Kaolack (n = 61) and Louga (n = 56) (Table 2).

Table 2 Number of community health areas (CHA) and targeted population according to endemicity categories by regions (n = 1610)

In high endemic settings, the proportion of SAC and adults represents 20.8% and 38.8% respectively. In moderate endemicity settings, the proportion of SAC and adults was 16.5% and 6.1% respectively. In low endemicity, only school aged children were concerned with a total number of 720, 257 (17.7%) (Table 4).

According to regions, Saint Louis, Matam and Louga have the highest number of SAC and adults exposed to schistosomiasis. In moderate endemic regions, the number of SAC exposed was more important in Ziguinchor (53.6%), Sédhiou (56.8%), Kolda (49.0%) and Diourbel (49.1%). In low endemic areas, only SAC were exposed (Table 2).

Changes in community endemicity categories from district IU to community level implementation

The Fig. 2 illustrates the changes in endemicity category from district level to community level. At district level, 324 IUs (20.1%) were classified non endemic. When analyzing at community level, the number of non-endemic IU was almost twice more important (n = 666) (41.4%). Number of low endemic IU was high at district level was 352 (21.9%) while that at community level was 264 (16.4%). Same tendency was noted concerning high endemicity at district level compared to community level: 33.5% vs 24.7% (Fig. 3).

Fig. 3 

Comparison of endemicity categories from district level implementation to community level implementation (N = 1610)

When looking the changes in endemicity category from district implementation level to community level implementation, the results have demonstrated that among 324 IUs classified as non-endemic at district level, 314 (96.9%) remain non endemics. However, 8 IUs (2.5%) considered non endemic become low at community level. In areas classified low endemic at district level (n = 352), 153 (43.5%) IUs remain low at community level. However, 186 (52.8%) and 13 (3.7%) become non endemic and moderate respectively. At district level, 394 IUs were classified moderate. The analysis at community level showed that only 176 (44.7%) remain moderate whereas 153 (38.8%), 60 (15.2%) and 5 (28.0%) IUs became respectively non endemic, low, and high. Among areas classified as high endemic at district level, 392 (72.6%) remain high, while 92 (17.0%) became moderate, 43 (8.0%) low and 13 (2.4%) non-endemic at community level (Table 3).

Table 3 Final endemicity category at community levelCommunity level endemicity and population requiring treatment

According to the target population and drug quantity, the number of areas requiring preventive chemotherapy is more important at district level (1286) compared to community level (944). The number of SAC requiring treatment is also more important at district level compared to community level. The difference between two levels is 144,850 SAC, representing (9.3%). This mean that less praziquantel drugs are required in community IU compared to districts IU (Table 4).

Table 4 Comparison of target population and drug quantities between district level implementation and community level implementationTreatment adequacy according to the endemicity category

Concerning the under treatment, at district level 10 IUs were classified non endemic (not requiring treatment). When analyzing at community level, the results showed that 8 IUs became low endemic, one became moderate and one high. IUs classified low and moderate at district level, became moderate and high at community level.

When regarding areas over treated, the results showed that areas classified moderate (213 IUs) at district level were not moderate at community level. 153 IUs (71.8%) were non endemic, and 60 IUs (28.2%) were low. Similar result was observed in high endemicity. Among 148 IUs classified high endemic, 13 IUs (8.8%) were non endemic, 43 IUs (29%) low and 92 IUs (62.2%) were moderate (Table 5).

Table 5 Treatment adequacy for community health areas by endemicity category, n (%)Treatment adequacy according to the target population

Table 6 shows the treatment adequacy at district level and community level. Concerning the under treatment, the results showed that among 52,228 targeted population considered as non-endemic at district level, 43,143 (82.6%) remain non endemic but 4529 (8.7%) and 4556 (8.7%) became moderate and high respectively at community level. However, population considered low and moderate at district level keep same status at community level. For 282,869 people considered at high risk at district level, none of them was at high risk at community level. 30.2% were classified low and 69.8% were considered as moderate (Table 6).

Table 6 Treatment adequacy for target populations by endemicity category, n (%)School aged children adequatly treated according to the regions

According to regions, SAC living in Louga, Saint Louis and Kaolack were more treated adequately with 15.6%, 15.2% and 14.7% respectively. Thiès, Kaolack and Dakar have the highest proportion of SAC under treated. Over treatment was highly found in Kolda (28.9%) and Kaffrine (13.8%).

The quantity of drugs underestimated was more important in Thiès (30.8%), Fatick (21.9%), Dakar (17.9%) and Kaolack (16.4%). Drugs overestimated were more frequent in Kolda (20.4%) and Tambacounda (19.4%) (Table 7).

Table 7 Treatment adequacy according to the regions

According to the new WHO guidelines on control and elimination of human schistosomiasis (2022), the results (see Table 8) showed that the annual treatment with praziquantel concerned only population living in endemic areas with the prevalence ≥ 10%. It concerns 680 (42.2%) of communities with a total of 1,515,242 (34.9%) SAC and 2,821,682 (65.1%) adults. The mains regions with community health areas requiring the annual treatment are Saint Louis, Louga, Matam, Tambacouda, Kédougou and Kolda (Table 8).

Table 8 Number of communities health areas by treatment regime and target population