Coverage
Four MTTT interventions were conducted in July 2017, November 2017, March 2018 and July 2018. Of the 5,000 participants initially targeted across communities for each intervention, coverage ranged from 77.8% (3891/5000) to 98.8% (4,941/5,000) (Table 1). A total of 2,669 participants received all four MTTTs (53%) and the median number of MTTTs participants received was 3. The proportions represent those who were effectively reached and tested. Females made up 50.4% and 52.4% of participants in July 2017 and July 2018, respectively (Table 1). The fluctuation in coverage was largely due to movement of people in and out of the intervention area, and the proportion represents those who were effectively reached. If a household was visited three times and the participant could not be contacted, (s)he was considered not available for the survey/intervention or reported to have moved.
Asymptomatic parasitaemia prevalence
Considering the different time points across the intervention period, asymptomatic malaria parasite carriage was found to be 36.3% in July 2017, 22.1% in November 2017, 23.2% in March 2018 and 32.9% in July 2018. These observations reflect the seasonality of malaria in the district and across the country.
Table 1: Parasite carriage across different communities at different time points in the Pakro sub-district
|
Prevalence of asymptomatic parasitaemia among community members N (%)
|
Characteristics
|
July 2017 Survey n/N (%)
|
November 2017 Survey n/N (%)
|
March 2018 Survey n/N (%)
|
July 2018 Survey n/N (%)
|
Community
|
|
|
|
|
Abease
|
282/888 (31.8)
|
124/712 (17.4)
|
77/709 (10.9)
|
161/721 (22.3)
|
Adesa
|
158/406 (38.9)
|
85/323 (26.3)
|
62/351 (17.7)
|
121/342 (35.4)
|
Adjanase
|
514/1342 (38.3)
|
191/957 (20.0)
|
283/1070 (26.5)
|
387/1037 (37.3)
|
Fante Town
|
543/1530 (35.5)
|
306/1238 (24.7)
|
347/1284 (27.0)
|
392/1236 (31.7)
|
Odumtokro
|
101/245 (41.2)
|
42/213 (19.7)
|
43/190 (22.6)
|
63/180 (35.0)
|
Piem
|
80/220 (36.4)
|
35/183 (19.3)
|
50/157 (31.9)
|
57/160 (35.6)
|
Sachi/Tabankro
|
117/310 (37.7)
|
75/265 (28.3)
|
75/277 (27.1)
|
122/290 (42.1)
|
Total
|
1795/4941 (36.3)
|
858/3891 (22.1)
|
937/4038 (23.2)
|
1303/3966 (32.9)
|
Coverage
|
4941/5000(98.8)
|
3891/5000(77.8)
|
4038/5000(80.8)
|
3966/5000 (79.3)
|
Comparative analysis between the two time points, July 2017 to July 2018 revealed a decline in asymptomatic parasite carriage from 36.3% (1,795/4,941) to 32.9% (1,303/3,966) (p=0.001) (Tables 1 & 2)). The highest level of community-specific prevalence of asymptomatic parasitaemia per time point were 41.2%, 28.3%, 31.9% and 42.1% for July 2017, November 2017, March 2018 and July 2018 respectively (table 1). Parasite carriage significantly declined in both Abease and Fante Town between July 2017 and July 2018 (p<0.0001 and p=0.037 respectively), but, the decline in the other communities was not statistically significant. An increase in parasite carriage was observed for Sachi/Tabankro from July 2017 to July 2018. However, this was not significant, (Table 2).
The highest decline in parasitaemia carriage, was observed in Abease while the lowest decline was observed in Adesa. It is not clear what accounted for the heterogeneity as there were no other interventions in the area at the time of this study. Asymptomatic parasitaemia prevalence from July 2017 and July 2018 significantly decreased in both children and adults (p=0.002 for <15 children and p=0.001 for ≥15 years) (Table 2). As per age group, asymptomatic parasitaemia prevalence significantly declined in the age groups 5-14 and 15-45 years, but the decline was marginally significant in the age group 1-4. This decline in parasitaemia was not significant in the age groups 46-65 and >65 years. An increase in parasitaemia prevalence was observed among the <1 year old age group between July 2017 and 2018. But this was not significant.
Table 2: Univariate analysis of effect of MTTT interventions on prevalence of asymptomatic malaria parasitaemia over the time points July 2017 and 2018.
Characteristics
|
July 2017 Survey
|
July 2018 Survey
|
χ2 value
|
P value
|
Community
|
n/N (%)
|
n/N (%)
|
|
|
Abease
|
282/888 (31.8)
|
161/721 (22.3)
|
17.1
|
<0.001**
|
Adesa
|
158/406 (38.9)
|
121/342 (35.4)
|
1
|
0.319
|
Adjanase
|
514/1342 (38.3)
|
387/1037 (37.3)
|
0.2
|
0.624
|
Fante Town
|
543/1530 (35.5)
|
392/1236 (31.7)
|
4.4
|
0.037**
|
Odomtokro
|
101/245 (41.2)
|
63/180 (35.0)
|
1.7
|
0.193
|
Piem
|
80/220 (36.4)
|
57/160 (35.6)
|
0
|
0.882
|
Sachi/Tabankro
|
117/310 (37.7)
|
122/290 (42.1)
|
1.17
|
0.279
|
All Communities
|
1795 (36.3)
|
1303 (32.9)
|
11.71
|
0.001**
|
Age_group (years)
|
n/N (%)
|
n/N (%)
|
|
|
0 - 11 months
|
14/56 (25.0)
|
22/57 (38.6)
|
2.4
|
0.121
|
1 - 4 years
|
270/541 (49.9)
|
216/491 (44.0)
|
3.6
|
0.057
|
5 - 14 years
|
759/1387 (54.7)
|
582/1180 (49.3)
|
7.5
|
0.006**
|
15 - 45 years
|
5852092 (28.0)
|
360/1523 (23.6)
|
8.5
|
0.003**
|
46 - 65 years
|
129/640 (20.2)
|
97/544 (17.8)
|
1
|
0.310
|
> 65 years
|
38/225 (16.9)
|
26/171 (15.2)
|
0.2
|
0.352
|
Total # of <15
|
1043/1984 (52.6)
|
820/1728 (47.5)
|
9.7
|
0.002**
|
Total # of ≥15
|
752/2957 (25.4)
|
483/2238 (21.6)
|
10.4
|
0.001**
|
Mean axillary Temperature
|
36.0
|
36.2
|
|
<0.001**
|
Use ITN
|
|
|
|
|
No
|
1595/4574 (34.9)
|
380/1166 (32.5)
|
0.0012
|
<0.001
|
Yes
|
200/367 (54.5)
|
923/2800 (33.0)
|
|
|
** Significance level at α =0.05
All percentages represent proportions of parasite carriage compared to the population tested. The comparison is made only between July 2017 and July 2018 which depicts the same season.
A logistic regression was performed to determine the predictors of malaria parasitaemia and the magnitude of the effect of the intervention on the outcome of interest, which is malaria parasitaemia. Age, use of ITN and axillary temperature were predictors of malaria parasitaemia at the univariate level (α =0.05) (Table 3) and were included as confounders in predicting the magnitude of effect of the intervention on malaria parasitaemia prevalence. The intervention reduced parasitaemia by 24% a year, after the mass treatment in July 2018, following adjusting for confounders (OR=0.76, CI=0.67, 0.85 p value ≤ 0.001) and by 9.4% a year, unadjusted. A unit increase in age reduces malaria prevalence by 3% after adjusting for confounders (OR=0.97, CI=0.97, 0.97, p value≤0.001). The use of ITN was not a statistically significant predictor of malaria parasitaemia prevalence after adjusting for confounders (OR=1.11, CI=0.98, 1.26, p value ≤ 0.001). The implementation of MTTT reduced symptomatic parasitaemia by 9% from July 2017 to July 2018 after adjusting for age, though not statistically significant (OR=0.91, CI=0.67, 1.38 p value = 0.672) (Table 4).
Table 3: Logistic regression for asymptomatic parasitaemia
Characteristics
|
Unadjusted OR
|
P value
|
Adjusted OR
|
P value
|
Timeline
|
|
|
|
|
July 2017 survey
|
Ref
|
0.001
|
Ref
|
<0.001
|
July 2018 survey
|
0.86 (0.78, 0.94)
|
|
0.76 (0.67, 0.85)
|
|
Age (years)
|
0.97 (0.97, 0.97)
|
<0.001
|
0.97 (0.97, 0.97)
|
<0.001
|
Mean axillary Temperature
|
1.19 (1.14, 1.25)
|
<0.001
|
1.19 (1.12, 1.26)
|
<0.001
|
ITN Use
|
|
|
|
|
No
|
Ref
|
0.034
|
|
0.086
|
Yes
|
0.92 (0.87, 0.99)
|
|
1.11 (0.98, 1.26)
|
|
Asymptomatic versus symptomatic malaria parasite carriage
Records show that in July 2017, the Pakro Health Centre was visited by 4.4% (219/4941) of the study population who became febrile. Of these, 1.9% (96/4,941) were confirmed to be positive for malaria. This means that 43.8% (96/219) of all those presenting with fever were positive for symptomatic parasitaemia carriage in July 2017 and were treated. In July 2018, 5% (197/3,966) of the population that became febrile, visited the Health Centre and 2% (78/3,966) of the population were confirmed to be positive for malaria. Prevalence of symptomatic parasitaemia among those presenting with fever was 39.6% (78/197) representing a 4.2% reduction in symptomatic parasitaemia between July 2017 and July 2018 (Table 5). Implementing MTTT interventions significantly reduced asymptomatic parasite carriage by 24% (OR = 0.76, CI = 0.67, 0.85 p = ≤0.001) after adjusting for age, use of ITNs and axillary temperature, compared to a non-significant reduction of 9% (OR = 0.91, CI = 0.67, 1.38, p = 0.672) in confirmed symptomatic malaria cases who attended the health facility over the same period (Table 4). This demonstrates that implementing MTTT interventions could reduce the asymptomatic malaria prevalence, which may not necessarily be reflected to the same extent in the outpatient consultations within the first year.
Table 4: Logistic regression for symptomatic parasitaemia
Characteristics
|
Unadjusted OR (CI)
|
P value
|
Adjusted OR (CI)
|
P value
|
Timeline
|
|
|
|
|
July 2017 survey
|
Ref
|
0.381
|
Ref
|
0.672
|
July 2018 survey
|
0.83 (0.57, 1.24)
|
|
0.91 (0.67, 1.38)
|
|
Age_group (years)
|
|
|
|
0 - 11 months
|
Ref
|
<0.001
|
Ref
|
<0.001
|
1 - 4 years
|
1.72 (1.41, 2.11)
|
<0.001
|
0.67 (0.64, 6.91)
|
0.53
|
5 - 14 years
|
3.31 (2.70, 4.08)
|
<0.001
|
1.62 (0.44, 5.92)
|
0.469
|
15 - 45 years
|
0.72 (0.59, 0.89)
|
0.002
|
0.54 (0.15, 1.86)
|
0.328
|
46 - 65 years
|
0.46 (0.38, 0.58)
|
<0.001
|
0.31 (0.08, 1.16)
|
0.082
|
> 65 years
|
0.49 (0.40, 0.61)
|
<0.001
|
0.34 (0.09, 1.23)
|
0.111
|
Table 5: Comparative analysis of asymptomatic and symptomatic prevalence in the Pakro sub-district
|
MTTT Data
(Asymptomatic parasitaemia)
|
Hospital Data for clinical malaria (symptomatic parasitaemia)
|
|
RDT +
|
Total tested
|
%
|
RDT +
|
Total OPD attendance
|
%
|
Jul-17
|
1,795
|
4,941
|
36.3
|
96
|
219
|
43.8
|
Jul-18
|
1,303
|
3,966
|
32.9
|
78
|
197
|
39.6
|
Confirmed parasitaemia was found to have decreased across all the age groups except the 0-11 months and 15-45 years age group where the proportion increased. However, neither the observed increase nor decrease in parasitaemia was significant in all age groups (Table 5).
Table 5: Confirmed symptomatic parasitaemia across all age groups N (%)
Age group
|
July 2017 Survey
|
July 2018 Survey
|
χ2 value
|
P Value
|
0 - 11 months
|
2/5 (40.0)
|
4/6 (66.7)
|
0.7822
|
0.567
|
1 - 4 years
|
28/60 (46.7)
|
16/38 (42.1)
|
0.1957
|
0.658
|
5 - 14 years
|
24/33 (72.7)
|
17/29 (58.6)
|
1.3713
|
0.242
|
15 - 45 years
|
26/73 (35.6)
|
23/51 (45.1)
|
1.1293
|
0.288
|
46 - 65 years
|
6/18 (33.3)
|
11/45 (24.4)
|
0.5156
|
0.473
|
> 65 years
|
10/30 (33.3)
|
7/28 (25.0)
|
0.4854
|
0.486
|
Total # of <15
|
54/98 (55.1)
|
37/73 (50.7)
|
0.3279
|
0.567
|
Total # of ≥15
|
42/121 (34.7)
|
41/124 (33.1)
|
0.0741
|
0.785
|