2015 | 2016 | 2017 | 2018 | 2019 | 2020* | |
Cases notified by health facilities | 4325 | 3856 | 4252 | 5494 | 6766 | 6678 |
No of index cases followed up to health facilities by DMSOs | 3745 | 2596 | 2940 | 3647 | 5747 | 4011 |
No of investigated index cases (%) | 2592† (69.2) | 2096 (80.7) | 2081 (70.8) | 2736 (75.0) | 4259 (74.1) | 2630 (65.6) |
Median age (years) of investigated index cases | 20 (IQR: 11–29) | 19 (IQR: 9–28) | 21 (IQR: 13–29) | 20 (IQR: 11–29) | 22 (IQR: 13–31) | 23 (IQR: 15–31) |
Fraction of investigated index cases who were male (%) | 59.3 | 57.6 | 62.6 | 59.3 | 64.8 | 69.8 |
Fraction of investigated index cases reported in Unguja (%) | 81.6 | 69.7 | 84 | 77.1 | 82.9 | 80.2 |
No of index cases with travel history outside Zanzibar (%) | 1926 (51.4) | 1195 (46.0) | 1223 (41.6) | 1938 (53.1) | 3536 (61.5) | 1365 (34.0) |
No of index cases with travel history within Zanzibar (%) | 139 (3.7) | 87 (3.4) | 87 (3.0) | 154 (4.2) | 197 (3.4) | 220 (5.5) |
No of index cases with no travel history outside their shehia (%) | 1680 (44.9) | 1314 (50.6) | 1630 (55.4) | 1555 (42.6) | 2014 (35.0) | 2426 (60.5) |
‡Fraction of index cases reported during January–April who have travel history outside Zanzibar | 62.7 | 51.0 | 55.2 | 58.6 | 69.0 | 35.1 |
‡Fraction of index cases reported during January–April who have travel history within Zanzibar | 4.4 | 4.9 | 3.0 | 4.6 | 3.0 | 5.7 |
Weekly rainfall year in mm (median (IQR)) | 9.8 (1.9–30.7) | 2.9 (0.0–18.3) | 15.5 (3.1–72.6) | 21.8 (6.9–63.5) | 16.6 (2.4–88.9) | 10.9 (6.0–12.9) |
Weekly rainfall during the masika season in mm, mid-March to May (median (IQR)) | 52.4 (12.5–96.3) | 19.8 (3.7–55.1) | 125.6 (62.7–175.7) | 56.3 (25.2–129.3) | 43.3 (13.3–84.6) | – |
Weekly rainfall during the vuli season in mm, November to mid-January (median (IQR)) | 11.8 (4.5–43.8) | 13.3 (2.6–19.3) | 19.2 (9.1–66.3) | 17.9 (9.9–24.8) | 43.8 (15.7–74.4) | – |
*Time period 1 January to 30 April.
†Data available from 1 January to 16 September.
‡Calculated to make comparison among all years from 2015 to 2020.
DMSO, District Malaria Surveillance Officer.