There was a total of 225 samples of a malaria cases and throughout the outbreak there were no death occur. From the total of malaria confirmed cases the most affected age group was > 15 years, 54 (72%) followed by 5–14, 17(22.7%). From the total 50% of them were > 15 years of age. Males 38 (51%) were slightly more affected than females. And nobody refused to be interviewed. The other socio demographic parts are expressed below.
Laboratory
From April 15 to August 25, 2019 a total of 4,380 blood smear positive (confirmed positive) of Bolosso Sore Woreda. Of which, 3,281 (75%) were positive for P. Falciparum, 1,100 (25%) were P. Vivax. This is from a weekly report of the zone and the wereda.
Descriptive Epidemiology
Description of the overall epidemic situation
Five years woreda data was shows that there was no outbreak within those five years. Bolosso Sore woreda Weekly malaria case passed the threshold level on WHO Week 18 (from April 22) and the health office has detected the outbreak on Week 18 based on the established threshold and writing letters about the outbreak to health centers for alerting the outbreak then similarly to Zonal health department. And the wereda was actively worked for the response of the outbreak and they controlled it. There was no death reported. At woreda and Zonal level no investigation was done until the national team conduct investigation.
Description of cases by Time
The number of cases passed the threshold level in epi. Week of 18 /2019 continued consistently increasing and reached peak on week (20) and then with sharp decrease on each week and steadily decreasing from week 29 up to Week 35 and it was decreased and controlled. The outbreak started on Week 18 of the epidemiologic week by crossing the threshold and reached peak on week 20. The intervention was started lately by mass treatment and ten kebeles of focal points or areas Profoxer/IRS sprayed and stagnant water were larvicide by Abet chemical.
Epi curve of the Outbreak
The outbreak was started from week 18, peaks at week 20 and then stopped or controlled from week 34 till this investigation done.
Clinical features of cases
A total of 75 active cases from Gurmo kosha H/C cluster, Achura H/C cluster, Gara Gudo H/C cluster, Woybo H/C cluster, Legama H/C cluster, D/Salata H/C cluster and selected kebelese of each cluster of Bolosso Sore woreda enrolled in the study from the bigining of the outbreak April 2019 till week 35. This is only the cases that interviewed by questionnaire.
The most frequently manifested clinical feature among the cases were fever, shivering, vomiting, headache, Anorexia, rigor and back pain 73(97%), 51(68%), 48(64%), 70(93%), 60(80%), 58(77%) and 59(79%) respectively. There were complications or severe malaria happened according to the sign and symptoms they answered. Those were altered consciousness 1%, not able to fed or drunk 5%, severe dehydration 6 %, persistent fever 9%, frequent vomiting 7% and unable to sit or stand up 4%.
Description of Cases by person
Bolosso Sore Woreda has a total population under surveillance of 211,145 out of this 120,252 are at risk of malaria. The overall attack rate (AR) for the woreda was 36.4/1000. From the cases Males are more affected than females (38: 37) .The most affected age group is > 15 years, 54 (72%) followed by 5–14, 17(22.7%). The educational status of the study participants were illiterate (7) and 31 attended school at primary level. Regarding Marital status of study participants, 52% were married, 16% NA or underage and 32% single.
Description of cases by place
Most active cases were from Gurmo Koysha cluster. The wereda has 8 clusters in which in each cluster has three to five kebeles. Embecho and Afama Bancha clusters were not included in case controls study because of their topography difficulty and the number of cases somehow small. We interviewed 75 a case from six clusters (G/koysha H/C, Gara Gudo H/C, Achura H/C, D/salata H/C, Legama H/C and Woybo H/C). The investigation team treated a total of serologically confirmed (positive) 75 cases.
Analytical Epidemiology (Case -Control)
A total of 75 malaria cases and 150 apparently healthy controls were included into this analysis. We assessed possible risk factors that contribute to contracting malaria. In another bi-varate analysis who staying overnight 43% (P-value 0.028) is less likely affected by malaria than those not staying overnight. ITN who have used sometimes (COR 2.343) and those have ITN and they never use ITN (COR 2.248) were identified as a risk factor for malaria or more likely affected by malaria two times each respectively than those used ITN always.
In multi variate logistic regression some times and never ITN usage (AOR 10.214, 95 % CI1.163-89.725 and AOR 32.098, 95% CI 3.570-288.133 respectively ) were found to be independent risk factors of malaria infection in the study area or they were the highest risk factors. In general, those who have an AOR < 1 they were found to be preventive or had less risk for malaria infection (Table 6).
Table 1
; Socio demographic Characteristics of Bolosso Sore Woreda,Wolayta zone, SNNPR, September,2019
SNO. | Variables | Case | Control | AR | | Total | % | |
1 | Occupation | Employed | 2 | 23 | 3% | | 25 | 11% | |
Unemployed | 5 | 8 | 7% | | 13 | 6% | |
Student | 31 | 38 | 41% | | 69 | 30.7% | |
Pastoralist | 5 | 1 | 5% | | 6 | 2.7% | |
Farmer | 32 | 81 | 44% | | 113 | 50.2% | |
2 | Total family Size | 2–5 members | 30 | 40 | 40% | | 70 | 31% | |
> 5 members | 46 | 109 | 61% | | 155 | 69% | |
3 | Marital Status | Married | 39 | 80 | 52% | | 119 | 53% | |
Single | 24 | 51 | 32% | | 75 | 33% | |
NA | 12 | 19 | 16% | | 31 | 14% | |
4 | Education | Ilitrate | 7 | 24 | 9% | 31 | 14% | |
Primary | 31 | 58 | 41% | | 89 | 40% | |
Secondary | 16 | 23 | 21% | | 39 | 17% | |
Tertiary | 4 | 11 | 5% | | 15 | 7% | |
Non-formal | 8 | 21 | 11% | | 29 | 13% | |
NA | 5 | 17 | 7% | | 22 | 10% | |
Table 2
; distributions of Total malaria positivity by age group and sex in Bolosso Sore Wereda, Wolayta Zone, August 2019 (from the interview of cases)
Characteristics | Catagory | Total Malaria | PF | PV |
Sex | Male | 38 | 35 | 3 |
Female | 37 | 27 | 10 |
Total | 75 | 62 | 13 |
Age | < 5 years | 5 | 5 | 0 |
5–14 years | 17 | 15 | 2 |
> 15 years | 53 | 42 | 13 |
Table 3
Distribution of malaria cases by cluster and AR in Bolosso Sore Wereda, Wolayta zone, SNNRP, April 21 to August 25, 2019 (from WHO epi week 17–35)
SNO | Name of H/C | Total population | Number of PF | Number of PV | Total number of cases | AR per 1000 |
01 | G/koysha H/C | 23,225 | 785 | 257 | 1,042 | 45% |
02 | Gara gudo H/C | 37,106 | 378 | 63 | 441 | 11.9% |
03 | Achura H/C | 17,309 | 131 | 78 | 209 | 12% |
04 | Dangra Salata H/C | 19,473 | 741 | 157 | 898 | 46.1% |
05 | Legama H/C | 20,470 | 524 | 116 | 640 | 31.3% |
06 | Woybo H/C | 25,381 | 111 | 41 | 152 | 6% |
07 | Embecho H/C | 33,883 | 232 | 276 | 508 | 15% |
08 | Afama Bancha H/C | 32,589 | 110 | 119 | 229 | 7% |
Table 4
; Socio-demographic Bi-varate Analysis of Bolosso Sore Wereda, SNNPR, 2019
SNO | Variables | Case in % | control in % | 95% CI | COR | P-value |
Lower | Upper |
1 | Age group | < 5 years | 5(6%) | 18(12%) | 1 | 1 | 1 | 1 |
5–14 y | 17(23%) | 37(25%) | 0.192 | 1.9 | 0.605 | 0.389 |
> 15 | 53(71%) | 95(63%) | 0.18 | 1.417 | 0.498 | 0.191 |
2 | Occupation | Employee | 2(2.7%) | 23(15%) | 1.024 | 20.656 | 4.600 | 0.046 |
unemployed | 5(6.7%) | 8(5.3%) | 0.195 | 2.104 | 0.640 | 0.462 |
Student | 31(41%) | 38(25%) | 0.262 | 0.918 | 0.490 | 0.026 |
Pastoralist | 5(7%) | 1(0.7%) | 0.009 | 0.712 | 0.080 | 0.024 |
Farmer | 33(44%) | 80(54%) | 1 | 1 | 1 | 1 |
3 | Education | Ilitrate | 10(13%) | 21(14%) | 1 | 1 | 1 | 1 |
Primary | 31(41%) | 58(39%) | 0.373 | 2.127 | 0.891 | 0.795 |
Secondary | 17(23%) | 22(15%) | 0.23 | 1.648 | 0.616 | 0.335 |
Teritiary | 4(5%) | 11(7%) | 0.333 | 5.153 | 1.31 | 0.7 |
Non formal | 8(11%) | 21(14%) | 0.412 | 3.79 | 1.25 | 0.693 |
NA | 5(7%) | 17(11%) | 0.464 | 5.648 | 1.619 | 0.45 |
Table 5
; Risk factors Bi-varate Analysis of Bolosso Sore Wereda, SNNPR, 2019
1 | Travel History | Yes | 5(7%) | 0 | 0 | 0 | 0 | 0.999 |
No | 70(93%) | 150(100%) | 1 | 1 | 1 | 1 |
2 | Staying overnight | yes | 32(43%) | 42(28%) | 0.293 | 0.933 | 0.523 | 0.028 |
No | 43(57%) | 108(72%) | 1 | 1 | 1 | 1 |
3 | Having ITN | yes | 70(93%) | 129(86%) | 0.159 | 1.214 | 0.439 | 0.113 |
No | 5(7%) | 21(14%) | 1 | 1 | 1 | 1 |
4 | ITN Usage | Always | 36(48%) | 30(20%) | 1 | 1 | 1 | 1 |
Sometimes | 34(45%) | 99(66%) | 1.240 | 4.425 | 2.343 | 0.009 |
Never | 5(7%) | 21(14%) | 1.007 | 5.021 | 2.248 | 0.048 |
5 | Number of ITN | One | 6(8%) | 57(38%) | 0.788 | 9.354 | 2.714 | 0.114 |
2–3 ITN | 53(71%) | 70(47%) | 0.142 | 1.000 | 0.377 | 0.050 |
4–6 ITN | 10(13%) | 2(1%) | 0.010 | 0.335 | 0.057 | 0.002 |
Non have | 6(8%) | 21(14%) | 0.164 | 1 | 1 | 1 |
6 | IRS | Yes | 35(47%) | 28(19%) | 0.242 | 0.844 | 0.452 | 0.013 |
No | 40(53%) | 122(81%) | 1 | 1 | 1 | 1 |
7 | Open deep wel | Yes | 39(52%) | 57(38%) | 1.009 | 3.095 | 1.768 | 0.046 |
No | 36(48%) | 93(62%) | 1 | 1 | 1 | 1 |
8 | Broken glass | Yes | 36(48%) | 43(29%) | 0.245 | 0.774 | 0.435 | 0.005 |
No | 39(52%) | 107(71%) | 1 | 1 | 1 | 1 |
9 | Plastic container | Yes | 61(81%) | 59(39%) | 0.109 | 0.411 | 0.212 | 0.00 |
No | 14(19%) | 91(61%) | 1 | 1 | 1 | 1 |
10 | Gutter | Yes | 24(32%) | 42(28%) | 0.453 | 1.509 | 0.826 | 0.535 |
No | 51(78%) | 108(72%) | 1 | 1 | 1 | 1 |
11 | Stagnant water | Yes | 58(77%) | 88(59%) | 0.221 | 0.782 | 0.416 | 0.006 |
No | 17(23%) | 62(41%) | 1 | 1 | 1 | 1 |
12 | Intermittent River | Yes | 41(55%) | 61(41%) | 1.032 | 3.162 | 1.806 | 0.038 |
No | 34(45%) | 89(59%) | 1 | 1 | 1 | 1 |
13 | Tick grass | Yes | 6(8%) | 14(9%) | 0.436 | 3.216 | 1.184 | 0.741 |
No | 69(92%) | 136(91%) | 1 | 1 | 1 | 1 |
Table 6
; Multivariate analysis of risk factors for malaria outbreak Bolosso Sore wereda, Wolayta zone, SNNPR, Ethiopia, 2019
SNO | Variables | Category | | | AOR | 95 CI | P-Value |
Case in % | Control in % | Lower | Upper |
1 | Occupation | Employee | 2(2.7%) | 23(15%) | 1.832 | 0.318 | 10.537 | 0.498 |
unemployed | 5(6.7%) | 8(5.3%) | 0.079 | 0.013 | 0.501 | 0.007 |
Student | 31(41%) | 38(25%) | 0.187 | 0.070 | 0.515 | 0.001 |
Pastoralist | 5(7%) | 1(0.7%) | 0.027 | 0.001 | 0.535 | 0.018 |
Farmer | 33(44%) | 80(54%) | 1 | 1 | 1 | 1 |
2 | Staying overnight | yes | 32(43%) | 42(28%) | 0.372 | 0.149 | 0.930 | 0.034 |
No | 43(57%) | 108(72) | 1 | 1 | 1 | 1 |
3 | ITN Usage | Never | 36(48%) | 30(20%) | 32.098 | 3.570 | 288.633 | 0.002 |
Sometimes | 34(45%) | 99(66%) | 10.214 | 1.163 | 89.725 | 0.036 |
Always | 5(7%) | 21(14%) | 1 | 1 | 1 | 1 |
4 | Number of ITN | One | 6(8%) | 57(38%) | 0.112 | 0.010 | 1.217 | 0.072 |
2–3 ITN | 53(71%) | 70(47%) | 0.014 | 0.001 | 0.145 | 0.000 |
4–6 ITN | 10(13%) | 2(1%) | 0.002 | 0.000 | 0.044 | 0.000 |
Non have | 6(8%) | 21(14%) | 1 | 1 | 1 | 1 |
5 | IRS | Yes | 35(47%) | 28(19%) | 0.149 | 0.056 | 0.396 | 0.000 |
No | 40(53%) | 122(81) | 1 | 1 | 1 | 1 |
6 | Open deep well | Yes | 39(52%) | 57(38%) | 0.423 | 0.173 | 1.033 | 0.059 |
No | 36(48%) | 93(62%) | 1 | 1 | 1 | 1 |
7 | Broken glass | Yes | 36(48%) | 43(29%) | 0.193 | 0.074 | 0.506 | 0.001 |
No | 39(52%) | 107(71) | 1 | 1 | 1 | 1 |
8 | Plastic container | Yes | 61(81%) | 59(39%) | 0.134 | 0.050 | 0.361 | 0.000 |
No | 14(19%) | 91(61%) | 1 | 1 | 1 | 1 |
9 | Intermittent river | Yes | 41(55%) | 61(41%) | 0.166 | 0.065 | 0.425 | 0.000 |
No | 34(45%) | 89(59%) | 1 | 1 | 1 | 1 |
In addition to the above analysis in the study area not only in the study area in the whole country there were no repellents and there were no screening of houses for malaria.
Environmental Assessment
Observation was conducted for availability of stagnant water, building for fish breeding, broken glass, intermittent river near to the community and other potential mosquito breeding sites. In all assessed kebeles, it was identified that there was larvae of mosquitoes in observed stagnant water by naked eye.
Public health intervention
A Total of 10 kebeles were sprayed with profoxer chemical. Communities were mobilized and taught on prevention and control measures of malaria disease. Active case search and early management were done at community and health facility level. Larvicide was done those had stagnant water and larvae were seen by Abet chemical.