Research Article
Austin J Pulm Respir Med 2017; 4(2): 1054.
Seasonality and Trend Analysis of Pulmonary Tuberculosis at St. Paul Hospital Millennium Medical College, Addis Ababa, Ethiopia
Bikila D*, Yohannes W, Abdeta A, Lejisa T, Tolcha Y, Habtu W, Alemu J and Girma J
Department of Medical Laboratory Sciences, Addis Ababa University, Ethiopia
*Corresponding author: Bikila D, Department of Medical Laboratory Sciences, Addis Ababa University, Addis Ababa, Ethiopia
Received: July 24, 2017; Accepted: August 22, 2017; Published: August 29, 2017
Abstract
Background: Tuberculosis (TB) is a respiratory infectious disease caused by Mycobacterium tuberculosis which shows seasonality. However the situation is not well studied in poor setting countries like Ethiopia.
Objectives: To determine the seasonality and trend analysis of TB incidence at St. Paul Hospital Millennium medical college, Addis Ababa, Ethiopia.
Methods: A retrospective study was conducted by collecting data from laboratory log book at St. Paul Millennium medical college from December, 2011 to June 2015. Data was collected by using data collection sheet which contains code, age, sex, residence and TB test result by using convenience sampling technique from December 2015 to June 2016. The data was cleaned, edited, checked for completeness and entered into SPSS version 20 for analysis. The result was presented with tables accordingly.
Result: Out of a total of 471 (6%) sputum smear positive cases among a total of 7, 870, the highest cases 205 (2.6%) were reported during summer season. Out of a total of 471 (6%) sputum smear positive cases among a total of 7, 870, 266 (3.4%) cases were reported among females. Out of a total of 471 (6%) sputum smear positive cases among a total of 7, 870, the highest cases 111 (1.4%) were reported among the age group of 25 - 44 years.
Discussion: In this study, the seasonality of TB case notification with a peak in the Fourth season has been observed from the computed data. These results were observed to be more or less consistent for the whole study period.
Keywords: Trends; Seasonality; Time series; Tuberculosis; Ethiopia
Abbreviations
DOTS: Directly Observed Treatment-Short course; EPTB: Extra-Pulmonary Tuberculosis; HIV: Human Immunodeficiency Virus; PTB: Pulmonary Tuberculosis; TB: Tuberculosis; UK: United Kingdom; WHO: World Health Organization
Background
Introduction
Tuberculosis (TB) is a respiratory infectious disease caused by bacillus Mycobacterium tuberculosis and spreads through air droplets by sneezing and coughing of the infected person [1]. It is one of the biggest health challenges which the world is facing and is the second major cause of mortality, particularly in poor and low economic countries [2,3]. About one-third of the world's population has latent TB, people who are infected with TB bacteria have a lifetime risk of getting ill with TB of 10% (people with compromised immune systems have a much higher risk) and two third of people ill with TB will die without proper treatment. TB typically attacks the lungs (known as pulmonary TB), can also affect other parts of the body (known as extra-pulmonary TB) [4].
Globally, 8.6 million people developed TB throughout the world in 2012; 1.1 million (13%) were co infected with Human Immunodeficiency Virus (HIV) [5]. Throughout the world, 6.1 million cases of TB were registered to the national TB program, and of these, 5.7 million were newly diagnosed cases [6]. In WHO Global TB report, Ethiopia ranked 7th among 22 High Burden Countries and 3rd in Africa in 2011 [7,8]. Moreover, TB is one of the most important infectious diseases responsible as 3rd cause of hospital admission and the second top causes of death in Ethiopia [7,9].
It is a well-known fact that TB demonstrates seasonality. Seasonality of TB has been reported in many studies, such as in Kuwait, where the peak of case notification is in summer, in India with summer as the peak season, and in China where summer is the peak season. In Iran, a high number of TB cases were observed in spring and summer [10].
The review of various studies has shown a rise in TB case notification at the end of the winter and the start of summer [11]. The exact mechanism underlying this seasonality is not known, but it has been suggested that various environmental, social, and host-related risk factors such as temperature, humidity, rainfall, sunlight, indoor activity, crowding, pollution, immune suppression, and diagnostic delays are involved in TB seasonality, specially, in winter [12]. Various demographic and epidemiological factors have been characterized that explain the trend and seasonality of TB [13,14].
Season of
the yearSputum Smear Status
Date of laboratory diagnosis in years
Total
2011
2012
2013
2014
2015
Autumn
Sputum smear positive
8
11
15
14
23
71
Sputum smear Negative
152
309
225
466
457
1609
Total
160
320
240
480
480
1680
Winter
Sputum smear positive
8
16
14
33
24
95
Sputum smear Negative
352
344
306
407
458
1867
Total
360
360
320
440
482
1962
Spring
Sputum smear positive
9
9
31
21
30
100
Sputum smear Negative
351
391
209
379
408
1738
Total
360
400
240
400
438
1838
Summer
Sputum smear positive
26
18
46
65
50
205
Sputum smear Negative
254
342
664
415
510
2185
Total
280
360
710
480
560
2390
Total
Sputum smear positive
51
54
106
133
127
471
Sputum smear Negative
1109
1386
1404
1667
1833
7399
Total
1160
1440
1510
1800
1960
7870
*Out of a total of 471(6%) sputum smear positive cases among a total of 7, 870 reported sputum smear cases, the highest cases 205(2.6%) were reported during Summer season.
Table 1: Season wise sputum smear status notification cases, 2011-2015.
One dominant hypothesis in the literature suggests that spring surges in tuberculosis result from increased activation of latent tuberculosis due to late winter nadirs in vitamin D [15], an immune regulator synthesized in sun-exposed skin that enhances cellular immunity against Mycobacterium tuberculosis in vitro [16]. An alternative hypothesis proposes that spring time peaks in tuberculosis diagnosis are due to increased transmission of tuberculosis rather than an increase in activation of latent disease, perhaps due to wintertime indoor crowding [17,18].
TB case notification has been reported with different peaks in different seasons, such as in South Africa where it peaks from winter to early spring [19], in the UK and Hong Kong where summer is the peak season [19,20], and in Spain and Japan, where the maximum numbers of cases were reported in summer and autumn [21,22].
Statement of the problem
Despite Tuberculosis (TB) being a long-standing, worldwide disease the global burden of disease attributable to TB continues to be a major public health concern. In 2013 alone there were an estimated 9.0 million new cases of TB worldwide and 1.5 million deaths attributable to TB, 80 % of which were occurring from 22 High-Burden Countries (HBCs) [23].
In 2012, the incidence of TB were 8.6 million globally, equivalent to 122 cases per 10,000 population. The estimated prevalence of TB were 12 million, equivalent to 169 cases per 100,000 population. The deaths from TB were estimated 1.3 million, equivalent to 18 cases per 100,000 population. Most TB cases and deaths occur in men, but the burden of TB is also high among women and children. South-East Asia and Western Pacific Regions accounted for 58% of the world's TB cases and India and China had the largest number of cases representing 26% and 12% of the global total respectively [24]. In 2012, the TB notification cases in Hong Kong was 4858, or a notification rate of 67.9 per 100,000 population. The number of TB deaths were 199 and the corresponding TB mortality rate was 2.8 per 100,000 population. TB is still a major infectious disease, accounting for 0.5% of the total registered deaths in Hong Kong [25].
Sex of the patient
Sputum Smear Status
Date of laboratory diagnosis in years
Total
2011
2012
2013
2014
2015
Male
Sputum smear positive
28
21
56
70
30
205
Sputum smear Negative
597
717
533
639
830
3316
Total
625
738
589
709
860
3521
Female
Sputum smear positive
23
33
50
63
97
266
Sputum smear Negative
512
669
871
1028
1003
4083
Total
535
702
921
1091
1100
4349
Total
Sputum smear positive
51
54
106
133
127
471(6%)
Sputum smear Negative
1109
1386
1404
1667
1833
7399((94%)
Total
1160
1440
1510
1800
1960
7870
*Out of a total of 471(6%) sputum smear positive cases among a total of 7, 870 reported sputum smear cases, 266(3.4%) cases were reported among females.
Table 2: Sex-wise sputum smear status notification cases, 2011-2015.
Globally, the trend of TB incidence, prevalence and mortality rate was descending of all categories and the trend of TB treatment successes and detection rates is growing. However, there was still a long way to reach the goal of "TB Stop Strategy" conducted by WHO [24,26]. The incidence rate was relatively stable from 1990 to 2001, and then it started to fall until 2013. The number of TB case notifications per 100,000 populations in the diagnosis and notification was relatively stable between 1990 and 2000, rose sharply from 2000 to 2008, and then began to decline slowly [24]. Besides, the declining trend of mortality rates was faster than that of incidence rates of TB [27].
The seasonal pattern of TB has been observed in many countries, including Spain, United Kingdom, India and so on [17,19,21]. Also, the pattern can be seen in some cities like Birmingham in United Kingdom and Delhi in India [26,28]. Different studies show different results of the questions of if the seasonality of TB varies with latitude, sex, age and various disease forms of TB [26,29,30]. Vitamin D deficiency, sunlight, other respiratory diseases, delay of diagnosis and indoor activities are the possible reasons of seasonality of TB. However, these questions related to seasonality of TB remain controversial [21,28,31].
To our knowledge, no study has described the seasonality of TB and Trend analysis at St. Paul Millennium Medical College. Therefore, the present study will reveal the seasonality and Trend analysis of TB in the study area [32-40].
Significance of the study
The study of seasonality and the trend pattern of TB are very important to find out the major risk factors involved in the spread of the disease and to plan the strategies to control the prevention of the disease. It is also important to identify possible seasonal pattern in the disease incidence, the knowledge of which may be used to predict the future magnitude of the health problem, to develop an effective public health program, and to set objectives and utilize available resources more effectively.
Objective
General objective
To determine the seasonality and trend of tuberculosis over the past five years among patients who were diagnosed at St. Paul Hospital Millennium Medical College.
Specific objective
To determine the seasonal variation of tuberculosis in the study area
To determine the trend of smear positive PTB among different ages, sex and living area
Hypothesis: The peak TB notification in this study area was not be different from the study conducted in Kuwait, India, China, Hong Kong, UK, which is reported during summer season [19,20].
Materials and Methods
Study area/setting
The study was conducted at St. Paul Hospital Millennium Medical College. St. Paul Hospital is found in Addis Ababa, capital city of Ethiopia. It is teaching and referral Hospital located western part of Addis Ababa, Gulelle sub-city, Woreda 9, House No 461. The hospital is built by Emperor Haileselassie in 1969 with the help of the German Evangelical church aimed to serve the poor. A Millennium medical college was started in 2007. It is teaching centre for Medicine. The Hospital serves an average of 700 Patients daily including private wing. The Hospital has 340 beds. The laboratory gives service on average 300 patients daily including private wing. The reason for selection of the study site was its accessibility, and this laboratory has implemented Laboratory Information System (LIS) and has to assess trend and seasonality of tuberculosis documents [41].
Study design
A Five year Retrospective study design was conducted between December 2015 to June 2016 at St. Paul Hospital Millennium Medical College to determine the seasonality and trend of Tuberculosis.
Study period
The study was carried out from December 2015 to June 2016.
Population
Source population: All patients who were examined for TB for the last five years.
Study population: Patients with complete demographic and laboratory data.
Inclusion and exclusion criteria
Inclusion Criteria: Patient with complete demographic and laboratory data.
Exclusion criteria: Patients with other chronic illnesses like Cancer, Diabetes Mellitus.
Age in years
Sputum Smear Status
Date of laboratory diagnosis in years
Total
2011
2012
2013
2014
2015
0-14
Sputum smear positive
3
4
7
9
14
37
Sputum smear Negative
56
72
55
73
125
381
Total
59
76
62
82
139
418
15-24
Sputum smear positive
7
9
29
11
18
74
Sputum smear Negative
114
235
393
380
379
1501
Total
121
244
422
391
397
1575
25-34
Sputum smear positive
7
10
32
29
33
111
Sputum smear Negative
231
248
214
310
321
1324
Total
238
258
246
339
354
1435
35-44
Sputum smear positive
8
12
13
42
36
111
Sputum smear Negative
214
293
349
400
378
1634
Total
222
305
362
442
414
1745
45-54
Sputum smear positive
13
9
23
17
21
83
Sputum smear Negative
244
299
261
351
350
1505
Total
257
308
284
368
371
1588
55-64
Sputum smear positive
8
7
1
25
3
44
Sputum smear Negative
168
161
125
149
198
801
Total
176
168
126
174
201
845
65 or Greater
Sputum smear positive
5
3
1
0
2
11
Sputum smear Negative
82
78
7
4
82
253
Total
87
81
8
4
84
264
Total
Sputum smear positive
51
54
106
133
127
471
Sputum smear Negative
1109
1386
1404
1667
1833
7399
Total
1160
1440
1510
1800
1960
7870
*Out of a total of 471(6%) sputum smear positive cases among a total of 7, 870 reported sputum smear cases, the highest cases 111(1.4%) were reported among the age group of 25-44 years.
Table 3: Age wise sputum smear status notification of cases, 2011-2015.
Sample size and sampling technique
Sample size: All available data that fulfil inclusion criteria from 2011 to 2015 was used.
Sampling technique: Convenient sampling method was used by using available data of patients recorded on the laboratory log book.
Study variables
Dependent variable
Prevalence of TB among different age and sex group
Number of TB cases notified
Independent variable
Age
Sex
Data collection
Data collection procedure: Data was collected by using data collection sheet which contains code, age, sex, residence, and AFB smear result from laboratory log book after the actual permission from DRERC (Department of Research and Ethics Review Committee).
Data quality assurance: During data collection the data collected was cleaned, edited checked for completeness, clarity and consistency by the PI on daily bases. Data was computerized using double data entry to minimize transcription errors.
Statistical data analysis
Data was coded and double entered by principal investigators into SPSS version 20 for data checking, cleaning, and analysis, to determine the seasonal variation. Descriptive analyses and frequency table was computed as appropriate. The result was presented with tables accordingly.
Ethical consideration
Ethical clearance to conduct the study was obtained from the Research Ethics Review Committee at the Department of Medical Laboratory Sciences, Addis Ababa University. Permission will also obtain from St. Paul Hospital Millennium Medical College where the study was conducted. In addition, all the information obtained from laboratory logbook was strictly kept confidential and was not accessible to any third party and privacy of the study population was respected and kept as will. Moreover, to ensure confidentiality the name of the study subjects was not written on the data collection format or any written material concerning the research or in discussions of the research project instead code is used as identification number which is known only by the principal investigator of the study and all the information obtained was stored in a safe place that no one save the researchers can access.
Result dissemination
The findings of the study were forwarded to the Department of Medical Laboratory Science, College of Health Science, School of Allied Health Science, Addis Ababa University. The findings were presented to St. Paul Hospital Millennium Medical College staffs and Managers. We were also proposing to submit the study for publication in various Medical Journals.
Results
The study period from 2011–2015 constituted 20 seasons during which a total of 7,870 suspected Pulmonary TB cases were registered. The average number of cases notified/season was 393.5. The annual number of cases varied over the period of the study, with a maximum of 1960 in 2015 and a minimum of 1160 in 2011. Increasing trends of 10% of TB cases were observed. Within the calendar year, the maximum number of patients was observed in the fourth season of 2013 (710 cases) and the minimum of cases was observed in the first season of 2011 (160 cases), as shown in Table 1. In general, the maximum number of cases was reported in summer, then winter. More cases were reported among females than males as shown in Table 2. When grouped into similar age groups, males predominated at the age of 65 or < years (male to female ratio of 1.15). In the rest of the age groups, the incidence predominated in females as shown in Table 3.
Discussion
In this study, as one can observe from the computed data the seasonality of peak TB case notification were during the Fourth season. These results were observed to be more or less consistent for the whole study period. Similar results have already been shown in different studies in the UK [19] and Hong Kong [4], where TB cases notification was high in summer. In developing countries such as Ethiopia, the TB incidence rate is quite high in rural populations as compared to urban populations, because of poor healthcare facilities and unawareness, which may account for seasonal variation in case notification [44]. A rise in TB notification in summer is basically influenced by the winter season, mainly because of two reasons. In winter, overcrowding, indoor pollution, and vitamin D deficiency increase the probability of duration of contact with infection. This probability is increased when other seasonal infections like flu, pneumonia, asthma, fever, etc. reduce immunity, which increases the susceptibility to the infection if exposed to an infected person [45]. Secondly, mycobacteria are slow growing and take 7 - 8 weeks to proliferate and show symptoms in favorable conditions [46]. Hence, at the onset of spring and with the rise in temperature in summer, the TB case notification increases. It is believed that in winter, symptoms of TB may possibly not be seen immediately after becoming infected, but when summer approaches and the temperature increases, the bacterium starts proliferating and growing with positive symptoms of the infection. It has been generally observed that, during summer most of infected people seek healthcare assistance, which results in increased case notification. It is also possible that all infected individuals may not be notified, so it is important to find infected and exposed persons to control the spread of infection [47]. In the present study, it was also observed that at the age of 65 or < years, more cases were reported among males than females (M: F ratio 0.81), which matches well with the previous findings [44]. At present, it is not fully understood why TB notification has been observed to be high among females in Ethiopia, but this is an important epidemiological finding from the point of view of public healthcare. Inequitable access to healthcare facilities and reporting biases are not the only reason for observed differences in case notifications and there are genuine gender differences in the biology and epidemiology of TB.
Conclusion/Recommendation
The increments of TB cases in summer clearly show that temperature has a direct relationship with the increasing rate of infection, which is shown by the seasonality of the disease in the study area. These results showed that transmission of the disease was higher in winter and the infection notification was higher in summer. Investigation of risk factors responsible for increased transmission of the disease during winter months can help to control the spread of the infection. In general clinicians need to educate people on health issues. Healthcare facilities should be improved for timely diagnosis, treatment, and prevention of the disease.
Acknowledgment
First of all we would like to thank the almighty God and Saint Virgin Mary who gave us the courage and power to finish this research project. Our gratitude also goes to our advisors Jemal Alemu and Jigssa Girma who have spent their precious time in advising and correcting our research paper.
We would also like to extend our deepest gratitude to Kasu Desta for giving us invaluable information regarding our research project.
We would like to thank our family and friends for their support and to raise our morale throughout this work. We would like to extend our thanks to School of Medical Laboratory Sciences, College of Health Sciences, Addis Ababa University, for their support.
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