A total of 449 cases of measles were reported between January 2014 and December 2018. There were 245 (54.6%) males and most number of cases occurred in the age-group 1-4 years (64.1%), followed by the children aged between 5-14 years (18.3%) (Table 1).
Table 1: Socio-demographic characteristics of reported measles cases in Bayelsa State, 2014-2018
|
Variables
|
No. of suspected cases n (%)
|
No. of confirmed cases n (%)
|
|
|
|
|
|
|
|
|
|
Sex
|
|
|
|
|
|
Females
|
204 (45.4)
|
134 (46.4)
|
|
|
|
Males
|
245 (54.6)
|
155 (53.6)
|
|
|
|
|
|
|
|
|
|
Age group(years)
|
|
|
|
|
|
<1
|
59 (13.1)
|
40 (13.8)
|
|
|
|
1-4
|
288 (64.1)
|
173 (59.9)
|
|
|
|
5-14
|
82 (18.3)
|
59 (20.4)
|
|
|
|
≥ 15
|
20 (4.5)
|
17 (5.9)
|
|
|
|
|
|
|
|
|
|
Place of Residence
|
|
|
|
|
|
Urban
|
168
|
118
|
|
|
|
Rural
|
281
|
171
|
|
|
|
Total
|
449
|
289
|
|
|
Table 2: Confirmed Measles cases in Bayelsa State, 2014 – 2018
S/N
|
Category
|
No. of cases
|
1.
|
Laboratory confirmed
|
42
|
2.
|
Epidemiologic Linkage
|
245
|
3.
|
Clinically compatible
|
2
|
|
Total
|
289
|
Of the 449 cases recorded within the five-year period, 289 (9.35%) were confirmed (Table 1) by laboratory diagnosis, epidemiological linkage and clinical compatibility (Table 2). The highest proportion of laboratory confirmed cases in a year was 19 (45.23%) in 2018. No laboratory confirmed cases were recorded in 2015 (Figure 1).
There was an all-year transmission, with peaks in May and July. Reports for some months were not available (Figure 2), for 2016 completeness of reporting was 58.3% while in 2017 it was 91.6% (Table 4). The time trend series analysis forecasted expected number of cases for quarters 1-4 in 2019 as 49,30,37 and 32 respectively. There was a rise in cases in the 4th quarter of each year as well as in the forecast for 2019, however the model was only slightly significant (Figure 3).
Yenegoa LGA had the highest number of reported cases within the five-year period; however, incidence rate per 100,000 was high in Kolokuma/Opokuma, Nembe, Yenegoa (Urban area) and Southern Ijaw LGA over the five years under review (Figure 4).
Data on the number of vaccine doses received was not collected for all reported cases; only 145 (32.29%) of all cases had that information, of which only 70 (48.27%) had received at least
one dose of measles vaccine and more than half (51.72%) of the cases had not received any measles vaccine at all (Table 3). However, 304 cases had missing information on vaccination status.
Table 3: Measles vaccine doses received in Bayelsa State from 2014-2018
|
|
|
No. of vaccine doses
|
Frequency
|
%
|
0
|
75
|
51.7
|
1
|
62
|
42.8
|
2
|
8
|
5.5
|
Total
|
145
|
100
|
There is an improvement in majority of the indicators over the years (Table 4), Non-Measles Febrile Rash illness and Timeliness of case investigation within 3 days was not calculated for 2016, 2017 and 2018 as the data was not available.
Table 4: Measles case-based surveillance indicators for Bayelsa State, 2014-2018
Measles Surveillance Indicators
|
Target
|
2014
|
2015
|
2016
|
2017
|
2018
|
Non-Measles Febrile Rash Illness Rate
|
At least 2 per 100,000 population
|
1.2
|
1.7
|
0
|
0
|
0
|
Proportion of districts that have reported at least 1 suspected case of measles with a blood specimen per year
|
At least 80%
|
100%
|
100%
|
100%
|
100%
|
100%
|
Incidence rate of confirmed measles
|
|
15.4
|
15.4
|
18.9
|
22.7
|
53.1
|
Proportion of Specimen reaching Laboratory in good condition
|
At least 90%
|
96%
|
96%
|
100%
|
100%
|
100%
|
Timeliness of case investigation within 3 days
|
>80%
|
84.7%
|
73%
|
0
|
0
|
0
|
Completeness of reporting
|
|
58.3%
|
91.6%
|
100%
|
100%
|
100%
|
Timeliness of specimen reaching the laboratory within 3 days of specimen collection, was persistently low below the WHO recommended target of 80% for the five years (Figure 5).
The proportion of specimens received at the laboratory with results sent to the national level on time (within 7 days of specimen receipt at the laboratory) was below the recommended WHO target of 80% throughout 2014-2018. However, a general increase in proportion of specimens with results sent out timely from the laboratory was noted in the period of 2015 and 2016, followed by a decline in 2017 and then an increase in 2018 (Figure 6).
People greater than 5 years were significantly more likely to have measles infection compared to those less than five years, also the odds of having measles was significantly higher in those residing in the Urban areas than in the rural areas. The odds of having measles was higher among females although this association was not statistically significant (Table 5). People not vaccinated were more likely to have measles although this association was not statistically significant (Table 5).
After controlling for age and sex, the logistic regression of exposure factors for measles showed that age less than 5 years remained a significant protective factor while residing in an urban area remained a significant exposure factor (Table 5).
Table 5: Exposure factors for Measles in Bayelsa State, 2014 – 2018
|
S/N
|
Variable
|
Frequency
|
OR
|
95% CI
|
AOR
|
95% CI
|
|
|
|
|
Yes
|
No
|
|
|
|
|
|
|
1
|
Age (years)
|
|
|
|
|
|
|
|
|
|
<5
|
199
|
126
|
0.57
|
0.36-0.90
|
0.57
|
0.36 – 0.91
|
|
|
|
≥5
|
91
|
33
|
1
|
|
1
|
|
|
|
|
|
|
|
|
|
|
|
|
|
2
|
Sex
|
|
|
|
|
|
|
|
|
|
Male
|
156
|
89
|
0.91
|
0.62-1.35
|
|
|
|
|
|
Female
|
134
|
70
|
1
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
3
|
Place of residence
|
|
|
|
|
|
|
|
Urban
|
118
|
49
|
1.54
|
1.02-2.32
|
1.55
|
1.02 – 2.34
|
|
|
|
Rural
|
172
|
282
|
1
|
|
1
|
|
|
|
4
|
Vaccination Status
|
|
|
|
|
|
|
|
|
|
None
|
36
|
39
|
1.03
|
0.53-1.98
|
|
|
|
|
|
At least one dose
|
33
|
37
|
1
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|