Description of the malaria outbreak by person
A total of 109 cases of malaria were reported from week 36 to week 44 of 2017 and no deaths occurred in the study area during this period. Four of the sampled cases could not be located since they had travelled outside Ward 6 and four refused to be interviewed thus, a total of 75 cases and 75 controls were interviewed of which 52% (n=39) of the cases were females and the mean age of the malaria cases was 29+13 years while most (35%) cases were in the age-group 20-29 years.
Study participants who had long lasting insecticide-treated nets (LLINs) (n=85) reported that the LLINs were donated in 2015 and researchers noted that 45% of these had since developed holes which were potential entry points for the malaria vector. Of those who had LLINs, 26% (n=22) did not use them because the treated nets were perceived to cause suffocation (n=11), itchiness (n=4), or individuals were not interested in using the nets (n=7).
Although the community knowledge of malaria transmission was not significantly associated with contracting malaria, the majority (97%) managed to recall the use of LLINs while 35% mentioned IRS as a way of protecting self from malaria. 83% of participants agreed that one can protect self from getting malaria and all the participants reported that malaria disease is curable and they would visit the clinic upon suspecting any signs and symptoms of malaria. 93% of participants correctly identified that malaria is more common during the hot and wet season. 12% of the cases had travelled outside Ward 6 approximately four weeks before they were diagnosed of malaria while none of the controls had travelled outside Ward 6. The mean number of days taken from onset of malaria symptoms to visiting the clinic by the malaria cases was 3. Table 1 shows the sociodemographic characteristics of the study participants.
Table 1. Study participants’ socio-demographic information.
Variable
|
Category
|
Cases n=75 (%)
|
Controls n=75 (%)
|
Gender
|
Male
|
36 (48)
|
33 (44)
|
|
Female
|
39 (52)
|
42 (56)
|
Education level
|
None
|
9 (12)
|
10 (13)
|
|
Primary
|
43 (57)
|
42 (56)
|
|
Secondary
|
23 (31)
|
23 (31)
|
Income source
|
Dependent
|
21 (28)
|
22 (29)
|
|
Formal
|
15 (20)
|
15 (20)
|
|
Informal/self
|
39 (52)
|
38 (51)
|
Religion
|
Apostolic
|
12 (16)
|
21 (28)
|
|
Pentecostal
|
12 (16)
|
13 (17)
|
|
Protestant
|
15 (20)
|
8 (11)
|
|
None
|
36 (48)
|
33 (44)
|
Description of the malaria outbreak by place
The residents of Ward 6 of Beitbridge District mainly lived in rural villages and farm compounds where the walls of the houses were made from bricks or mud and pole while roofing material was mainly thatch, asbestos or corrugated zinc sheets. 36%, 32%, 29% and 3% of the participants resided in houses made from brick and asbestos/corrugated sheets, mud and thatch, brick and thatch, and mud and asbestos/corrugated sheets, respectively.
Although 45% of the participants slept in houses with conventional windows, some of the windows did not have panes or the panes were broken exposing the inhabitants to mosquitoes. The majority of malaria cases from the clinic line list for week 36 to week 44 were from Bishopstone farm compound (18%; n=20) and Mzingwane village (17%; n=19). Figure 1 shows the spot map of Ward 6 of Beitbridge District showing the distribution of the 109 cases for week 36 to week 44 of 2017 according to the Mtetengwe Clinic line list. 33% (n=49) of the participants had IRS done more than eight months earlier and 47% (n=23) of these were malaria cases.
Description of the Malaria Outbreak by time
Figure 2 displays an epidemiological curve reporting the gradual increase in number of individuals who presented with clinical symptoms of malaria and tested positive for the disease. The curve shows a common source outbreak with intermittent exposure. The irregular peaks represents the timing and extent of exposure to the malaria parasite. Malaria positive cases started to increase gradually from the 9th of September 2017, peaked on the 3rd of October 2017 and steadily began to decline thereafter. Although malaria cases identification continued after the outbreak period, the frequencies ranged below the threshold level.
Factors associated with Malaria Transmission
Table 2 shows the bivariate analysis of factors associated with contracting malaria in Ward 6, Beitbridge District between week 36 and week 44 of 2017.
Table 2: Bivariate analysis for factors associated with contracting malaria in Ward 6 of Beitbridge District for Week 36 to Week 44, 2017.
Variable
|
Category
|
Cases
|
Controls
|
OR
|
95% CI
|
p-value
|
Gender
|
Male
|
36
|
33
|
0.85
|
0.45-1.62
|
0.62
|
|
Female
|
39
|
42
|
|
|
|
Education
|
None/primary
|
52
|
52
|
1
|
0.50-2.0
|
1
|
|
Secondary
|
23
|
23
|
|
|
|
Age (years)
|
>20
|
54
|
61
|
0.59
|
0.27-1.27
|
0.18
|
|
<20
|
21
|
14
|
|
|
|
Income status
|
Employed
|
54
|
53
|
1.07
|
0.53-2.17
|
0.86
|
|
Dependent
|
21
|
22
|
|
|
|
Religion
|
Apostolic
|
13
|
21
|
0.54
|
0.25-1.18
|
0.12
|
|
Non-apostolic
|
63
|
54
|
|
|
|
Village/farm
|
Mzi/Bishopstone
|
35
|
38
|
0.85
|
0.45-1.62
|
0.62
|
|
Other
|
40
|
37
|
|
|
|
House had visible open eaves
|
Yes
|
60
|
43
|
2.97
|
1.44-6.16
|
0.0028*
|
|
No
|
15
|
32
|
|
|
|
Residents closed eaves before sunset
|
No
|
15
|
20
|
0.45
|
0.20-1.02
|
0.055*
|
|
Yes
|
45
|
27
|
|
|
|
House has conventional windows
|
No
|
40
|
34
|
1.38
|
0.73-2.62
|
0.60
|
|
Yes
|
35
|
41
|
|
|
|
Sleeping in a poorly constructed house
|
Yes
|
64
|
43
|
4.33
|
1.97-9.51
|
0.000*
|
|
Noa
|
11
|
32
|
|
|
|
Has LLINs
|
No
|
27
|
38
|
0.55
|
0.28-1.05
|
0.07
|
|
Yes
|
48
|
37
|
|
|
|
Slept under LLIN last night
|
No
|
10
|
9
|
0.81
|
0.29-2.28
|
0.70
|
|
Yes
|
38
|
28
|
|
|
|
Wearing long clothes at night
|
No
|
67
|
60
|
2.10
|
0.83-5.29
|
0.11
|
|
Yes
|
8
|
15
|
|
|
|
Spent evenings
|
Outdoors
|
62
|
51
|
2.24
|
1.04-4.85
|
0.037*
|
|
Indoors
|
13
|
24
|
|
|
|
Lived <1km from water source
|
Yes
|
44
|
36
|
1.54
|
0.81-2.93
|
0.19
|
|
No
|
31
|
39
|
|
|
|
IRS done in last 8months
|
No
|
52
|
49
|
1.20
|
0.61-2.38
|
0.60
|
|
Yes
|
23
|
26
|
|
|
|
History of traveling outside Ward 6
|
Yes
|
12
|
0
|
0
|
|
|
|
No
|
63
|
75
|
|
|
|
*Statistically significant p-value
a Sleeping in a house made from bricks walls and a roof made from asbestos or corrugated roof.
LLTNs-Long lasting insecticide-treated nets
IRS-Indoor residual spraying
Mzi/Bishopstone: Mzingwane village or Bishopstone Farm
Multivariate analysis
Backward stepwise regression analysis was conducted to estimate the variables associated with contracting malaria while controlling for confounding factors. Only variables with p<0.1 in bivariate analysis were used in constructing a mathematical model to describe the association between exposure and disease and other variables that may confound the effect of the exposure. The results of the logistic regression are presented in Table 3. While controlling for the presence of open eaves and having an LLIN, sleeping in a poorly constructed house remained statistically significant. Thus, individuals who slept in a poorly constructed houses were three times more likely to contract malaria than individuals sleeping in a well-constructed house. To control for multicollinearity while reducing omitted variable bias, the variable ‘house had visible eaves was excluded from the regression analysis because it had high partial correlations which inflated standard errors for ‘closing eaves at sunset’ and ‘sleeping in a poorly constructed house’
Table 3. Multivariate analysis of the factors associated with contracting malaria in Ward 6, Beitbridge District for week 36 to week 44, 2017.
Variable
|
Coefficient
|
AOR
|
95% CI
|
p-value
|
|
Spending the evening outdoors
|
0.80
|
2.23
|
0.81-6.10
|
0.12
|
Closing eaves at sunset
|
-0.64
|
0.53
|
0.21-1.28
|
0.16
|
Having an LLIN
|
-0.36
|
0.70
|
0.30-1.61
|
0.40
|
Sleeping in a poorly constructed house
|
2.13
|
8.40
|
1.69-41.66
|
0.009*
|
|
|
|
|
|
|
|
|
*p>0.05, result is statistically significant
Malaria Outbreak preparedness and response
Before the outbreak, malaria cases were being reported to the district office on a weekly basis. The clinic staff notified the District Health Team (DHT) of the sudden increase in malaria cases on the 9th of September, 2017. The Emergency Preparedness Response (EPR) team which used to converge every Wednesday, met immediately and recommended mobilization of resources in preparation for a potential malaria outbreak. An Environmental Health Technician (EHT) from Makakabule Clinic and 2 Laboratory technicians from the district office were deployed by the DHT to establish the possibility of an outbreak in Ward 6 within 48 hours since there was no EHT at Mtetengwe Clinic. The clinic staff collected blood specimens from cases identified by RDT and the blood specimens were collected daily from the clinic to the district laboratory.
Mtetengwe Clinic had a staff complement of two primary care nurses and one community-hired nurse aide. All the nurses at the clinic were trained in malaria surveillance and response as well as malaria case management. Utilizing the epidemic preparedness and rapid response guidelines, the nurses at Mtetengwe Rural Health Centre monitored malaria trends and drafted malaria threshold graphs. Mtetengwe Clinic did not experience stock outs of supplies and antimalarial medications during the period of the outbreak.
The EHT and local VHWs, conducted active case finding by visiting the surrounding communities, identifying risk factors and giving information on malaria. Health education and promotion on use of LLINs and early seeking of treatment was ongoing. Some malaria positive cases were accompanied by the Village Health Worker to the clinic. Farm owners from distant farms such as BK Cawood and Bishopstone offered free transport for ill workers and their relatives. Indoor residual spraying was conducted in the area during the last two weeks of November 2017. The district team was in constant contact with the clinic staff throughout the outbreak period and the outbreak was declared over on the 20th of November 2017.
Malaria case management
Due to the unavailability of microscopy tests and microscopists in the rural areas, health workers relied on malaria rapid diagnostic test (RDT) to confirm diagnosis and this test can be conducted by nurses and village health workers (VHWs). The VHWs were equipped with RDT kits for rapid testing as well as artemisinin-based combination therapy (ACT) treatment for uncomplicated cases. Uncomplicated cases who visited the clinic were also given ACT with the first dose being directly observed by a healthcare worker before they were discharged home. All cases reported to have completed the full course of antimalarial medication. The complicated cases were referred to Beitbridge District Hospital for further management. The two cases who were referred during this study period, recovered well. At Mtetengwe Clinic, malaria treatment and diagnostic testing is free for all age groups.