Anthrax in animals
The findings from the field investigation showed that the first cattle death occurred on the 12th of June 2013. Sporadic cattle death occurred between June 2013 and October 2013, but the situation worsened end of November 2013, and most of the cattle deaths occurred in December 2013. The Veterinary Department collected specimens from a few cattle that were dying and sent them to the Provincial Veterinary Laboratory on the 24th of December 2013 where a laboratory diagnosis of anthrax was confirmed. The anthrax diagnosis in the rest of the animals was clinical. An estimation of 180 cattle died in both Ward 22 and 23. The exact number could not be ascertained since the Veterinary Department was not on the ground. Reports on the deaths of other animals other than cattle were made and these included goats, pigs and chicken but the actual numbers were also not ascertained.
Anthrax in humans
a) Study participants
Through active surveillance and from the hospital line list, we identified 64 cases in both Ward 22 and 23; all were "probable" based on their clinical characteristics and epi-linkage to animal cases that were laboratory confirmed. Of the 64 cases, we managed to reach and interview 37 of them.
b) Baseline Characteristics of cases and controls
We interviewed 37 cases and 37 controls. The median age in years for cases and controls was 34 (interquartile range-IQR: 22 – 42) and 28 (IQR: 25 – 46) respectively. Males constituted 73% (27) of cases and 70.3% (26) of controls. Most of both cases (67.6%) and controls (59.5%) had secondary education and above. Most of the cases and controls were not employed (59.5%). Generally, the baseline characteristics for cases and controls were comparable (Table 1).
Table 1: Baseline characteristics of cases and controls for the anthrax outbreak in Makoni District Ward 22 and 23 in 2014
Characteristic
|
Categories
|
Controls
|
Cases
|
p-value (χ2)
|
Sex
|
Female
|
11 (29.7)
|
10 (27.0)
|
0.797
|
|
Male
|
26 (70.3)
|
27 (73.0)
|
|
Median Age (IQR)
|
|
28 (25 – 46)
|
34(22 – 42)
|
0.998*
|
Marital Status
|
Has partner
|
15 (40.5)
|
22 (59.5)
|
0.104
|
|
No partner
|
22 (59.5)
|
15 (40.5)
|
|
Education
|
Primary and below
|
15 (40.5)
|
12 (32.4)
|
0.469
|
|
Secondary and above
|
22 (59.5)
|
25 (67.6)
|
|
Employment
|
Employed
|
5 (13.5)
|
9 (24.3)
|
0.343
|
|
Peasant farmer
|
10 (27.0)
|
6 (16.2)
|
|
|
Unemployed
|
22 (59.5)
|
22 (59.5)
|
|
Religion
|
a Traditional churches
|
18 (48.7)
|
19 (5.4)
|
0.330
|
|
Apostolic
|
13 (38.1)
|
8 (21.6)
|
|
|
Others
|
6 (16.2)
|
10 (27.0)
|
|
|
|
|
|
|
a Traditional churches – Anglican, Methodist, Roman Catholic and Reformed Church of Zimbabwe
|
*Wilcoxon rank-sum, IQR: Interquartile range
|
c) Case Fatality Rate
One community death suspected to have been due to anthrax disease was reported. The person never reported to a health facility. According to witnesses, he developed an eschar on the chest wall which was followed by swelling of the left arm and shortness of breath. The victim was known to have been involved in the skinning of cattle and consumed roasted meat during skinning. He died at the age of 40 years on the 13th of January 2014. This gave the outbreak an estimated case fatality rate of 0.016 (1/64).
d) Clinical characteristics
All the 37 cases had never had anthrax disease before and reported a depressed eschar. The other signs and symptoms experienced are summarized in Figure 1.
Most of the depressed eschar affected the hands (41%) while the back of the trunk was least affected (Figure 2).
Three of the interviewed cases were admitted in a hospital, and they spent 2, 5 and 12 days respectively. None of the cases had any laboratory tests done, including the test for anthrax when they presented to health facilities. Thirty-four cases (89%) were managed according to national guidelines on the management of anthrax (Doxycycline for mild cases and Benzyl or Procaine Penicillin for severe cases) [7]. Eleven of the cases admitted being aware of and tried to use traditional herbs to treat anthrax before going to the health facilities. The mentioned traditional or local herbs included Chikohwa, Muzeze, Changamire, Gakakava, Chimutara and leaves of gumtree.
e) Distribution of cases - place
The anthrax outbreak affected Ward 22 and 23 of Makoni District. The two wards had 64 cases of anthrax reported in total, and Ward 23 was the worst affected with 78% (50) of the cases. Of the 37 cases interviewed, 28 were from Ward 23 and 9 from Ward 22. Twenty-six (26) villages were affected in the two wards. Figure 3 shows the spot map of the outbreak.
f) Distribution of cases - time
The first reported probable human anthrax case was on the 19th of June 2013. This first human anthrax case sought medical attention at Makoni Rural Hospital and was referred to Rusape District Hospital, which further referred the case to Mutare Provincial Hospital, where a clinical diagnosis of cutaneous anthrax was confirmed. The human anthrax cases started to increase rapidly in December 2013, and a peak was reached in mid-January 2014. The last case was reported on the 29th of January 2014. These field findings were contrary to the report by the District Veterinary Office and District Medical Office. The District Veterinary Office reported that the first cattle death occurred on the 6th of December 2013 and the District Medical Office reported that the first case of human anthrax was reported on the 21st of December 2013. Figure 4 shows the epidemiological curve of the outbreak.
g) Risk factors for contracting anthrax
On multivariable analysis, source of meat from other villagers [vs butchery, OR = 15.21, 95% CI (2.32-99.81)], skinning [OR = 4.32, 95% CI (1.25-14.94)] and belonging to a religion which permits eating meat from a cattle slaughtered due to unknown illness or died alone [OR = 6.12, 95% CI (1.28-29.37)] were associated with contracting anthrax during the outbreak (Table 2).
Table 2: Bivariate and multivariable logistic regression for factors associated with contracting anthrax in Makoni District Ward 22 and 23 in 2014
Variables
|
Categories
|
Controls
|
Cases
|
OR
|
95% CI
|
p-value
|
aOR
|
95% Cl
|
Sex
|
Female
|
11 (29.7)
|
10 (27.0)
|
1
|
|
|
1.14
|
0.42 - 3.14
|
|
Male
|
26 (70.3)
|
27 (73.0)
|
1.14
|
0.42 - 3.14
|
0.797
|
|
|
Marital Status
|
Has partner
|
15 (40.5)
|
22 (59.5)
|
1
|
|
|
|
|
|
No partner
|
22 (59.5)
|
15 (40.5)
|
0.46
|
0.18 – 1.18
|
0.106
|
|
|
Education
|
Primary and below
|
15 (40.5)
|
12 (32.4)
|
1
|
|
|
|
|
|
Secondary and above
|
22 (59.5)
|
25 (67.6)
|
1.42
|
0.55 – 3.68
|
0.469
|
|
|
Employment
|
Employed
|
5 (13.5)
|
9 (24.3)
|
1
|
|
|
|
|
|
Peasant farmer
|
10 (27.0)
|
6 (16.2)
|
0.33
|
0.07 -1.48
|
0.352
|
|
|
|
Unemployed
|
22 (59.5)
|
22 (59.5)
|
0.56
|
0.16 – 1.93
|
|
|
|
Religion
|
a Traditional churches
|
18 (48.7)
|
19 (5.4)
|
1
|
|
|
|
|
|
Apostolic
|
13 (38.1)
|
8 (21.6)
|
0.58
|
0.20 – 1.74
|
0.337
|
|
|
|
Others
|
6 (16.2)
|
10 (27.0)
|
1.58
|
0.48 – 5.24
|
|
|
|
b Ate meat
|
No
|
17 (46.0)
|
4 (10.8)
|
1
|
|
|
|
|
Yes
|
20 (54.0)
|
33 (89.2)
|
7.00
|
2.06 – 23.82
|
0.002
|
|
|
Source of meat
|
Butchery
|
11 (29.7)
|
2 (5.4)
|
1
|
|
|
|
|
|
Other villagers
|
10 (27.0)
|
27 (73.0)
|
14.85
|
2.79 – 79.06
|
0.001
|
15.21
|
2.32 – 99.81
|
|
Own cattle
|
6 (16.2)
|
6 (16.2)
|
5.5
|
0.84 – 36.20
|
|
7.25
|
0.84 – 62.57
|
|
Missing
|
10 (27.1)
|
2 (5.4)
|
-
|
-
|
-
|
-
|
-
|
c Cutting meat
|
No
|
20 (54.1)
|
7 (18.9)
|
1
|
|
|
|
|
|
Yes
|
17 (45.9)
|
30 (81.1)
|
5.32
|
1.91 – 14.77
|
0.002
|
|
|
Skinning
|
No
|
29 (78.4)
|
15 (40.5)
|
1
|
|
|
|
|
|
Yes
|
8 (21.6)
|
22 (59.5)
|
5.04
|
1.77 – 14.36
|
0.001
|
4.32
|
1.25 – 14.94
|
Cooking
|
No
|
23 (62.2)
|
12 (32.4)
|
1
|
|
|
|
|
|
Yes
|
14 (37.8)
|
25 (67.6)
|
3.42
|
1.32 – 8.91
|
0.012
|
|
|
d Cuts
|
No
|
31 (83.8)
|
22 (59.5)
|
1
|
|
|
|
|
|
Yes
|
6 (16.2)
|
15 (40.5)
|
3.50
|
1.18 - 10.51
|
0.024
|
|
|
Hide preparation
|
No
|
26 (70.3)
|
21 (56.8)
|
1
|
|
|
|
|
|
Yes
|
11 (29.7)
|
16 (43.2)
|
1.80
|
0.69 – 4.70
|
0.229
|
|
|
Heard of anthrax before
|
No
|
10 (27.0)
|
19 (51.4)
|
1
|
|
|
|
|
Yes
|
27 (77.0)
|
18(48.6)
|
0.35
|
0.13 – 0.93
|
0.034
|
|
|
e Religion which permits
|
No
|
33 (89.2)
|
21 (56.8)
|
1
|
|
|
|
|
Yes
|
4 (10.8)
|
16 (43.2)
|
6.29
|
1.85 – 21.39
|
0.003
|
6.12
|
1.28 – 29.37
|
|
|
|
|
|
|
|
|
|
OR: odds ratio, aOR: adjusted odds ratio, CI: confidence interval
|
a Traditional churches – Anglican, Methodist, Roman Catholic and Reformed Church of Zimbabwe
|
b Ate meat from a cattle slaughtered due to unknown illness or butchered after an unobserved death
|
c Cutting meat already skinning or before cooking
|
d Developed cuts during skinning or cutting meat
|
e Religion which permits eating meat from a cattle slaughtered due to unknown illness or butchered after an unobserved death
|
Environmental assessment
Most of the cattle that died were not buried properly, and the burials were not supervised. Animal carcasses were seen left on open spaces which allowed dogs and vultures to consume them. Reports of people throwing infected meat in the nearby Osborne Dam were made. There was a game reserve in Ward 22 and close to Osborne Dam which bordered some of the affected villages. Cattle from the surrounding communities mixed and grazed in the same areas with the game animals because the game reserve fence was not intact. Generally, there was inadequate grazing land and pastures in both Ward 22 and 23. Most of the grazing area had short grass. Ward 23 bordered Mutasa District which experienced an anthrax outbreak in the previous year and cattle from the two districts shared grazing land. A former Army Base which was no longer functional was noted in Ward 22 near Makoni Rural Hospital.
District preparedness and response
The rural hospital which services the two wards had an adequate stock of drugs (Doxycycline for mild cases and Benzyl or Procaine Penicillin for severe cases) used to treat anthrax during the outbreak period. This was assessed using the stock cards as of the 31st of November 2013. The EHTs on the field had no personal protective equipment (PPE), i.e. overalls/work suits, gumboots and heavy-duty gloves to use during the outbreak. The rural hospital had only 40 kgs of chloride of lime for use to disinfect sites where animal carcasses died. The EHTs were also not provided with allowances. There was no information, education and communication materials during the early stages of the outbreak response and only became available later. The district had no Emergency preparedness response plan, and the zoonotic committees were not functional. The cumulative period of the outbreak was seven months. The concrete response started after six months despite the first case having been reported in June 2013. The line list of cases was incomplete.
Outbreak prevention and control measures
The district started concrete outbreak control measures on the 21st of January 2014. The team dispatched to institute outbreak control measures comprised of two EHTs, Veterinary Officer and a Public Health Officer from the University of Zimbabwe, Field Epidemiology Training Programme. Health education was offered at 15 of the 16 primary and secondary schools in both wards. A meeting was organized through the Chief of the area with Village Heads of the two wards. Of the 53 Village Heads, 14 managed to attend the meeting were health education, advocacy and lobbying to control the outbreak were discussed. A total of 5896 people were reached with health education in both wards. Active case finding was conducted in the community, and a total of 8 cases more were identified. An outreach clinic to treat new cases and review old cases was performed at Dope Secondary School in Ward 22.
Disinfection of areas where cattle deaths occurred was done with sodium of lime. The team also assisted in the supervised burial of new cattle deaths and reburial of carcasses which were disposed improperly. Two butcheries in the wards were barred from selling meat during the outbreak period. Slaughtering of cattle was stopped for the butcheries and in the surrounding communities. Dried meat was confiscated from the villages. The amount of meat confiscated and destroyed was not be ascertained since there was no scale to weigh the meat. The Veterinary Department vaccinated the cattle against anthrax in the wards. The registered number cattle at the three wards dip tanks was about 5000 of which 4000 were vaccinated (80%). The department also stopped issuing of permits for cattle movement during the period.