Evaluation of the national tuberculosis surveillance and response systems, 2018 to 2019: National Tuberculosis, Leprosy and Buruli Ulcer Control Programme, Abuja, Nigeria

Introduction Nigeria is among the countries with high Tuberculosis (TB) burden by global rating signifying the relevance of TB surveillance system evaluation in improving performance and capacity of the existing system. Hence, this evaluation was conducted in order to determine the gaps and proffer solution to enhance the TB surveillance system performance. Methods questionnaires were administered to eight key informants using face-to-face interview method; data obtained was analyzed. Total number of TB cases and estimated number of cases for year 2018 was obtained. Percentage of positive cases using the GeneXpert test for 6 months (January to June 2019) was obtained. Available documents and publications on the National Tuberculosis, Leprosy and Buruli Ulcer Control Programme (NTBLCP) were also sought for information. Results the NTBLCP has over 5,300 TB service points and 1,602 microscopy Centre’s distributed across the country. Acceptance for the standard TB case definition was 100%, forms used are easy to fill and diagnosis is laboratory-based requiring specialized trainings for laboratory personnel. The system had 25% sensitivity, high data quality with 100% timeliness. The TB surveillance system is representative of all ages. The system was first designed as TB and Leprosy Control Programme but later Buruli ulcer was incorporated into the Programme. First quarter supervisory visits are skipped due to late funding and delayed budget approval. Major share of the funding comes from donor partners. Conclusion the system is useful, representative, acceptable, has good data quality, timely, and sensitive. The system is stable but needs to be funded more by the government. There is need for early funding and budget approval to avoid skipping of supervisory visits due to funding challenges. The system is not simple due the various test that need to be conducted before, during and after treatment to detect and verify that the patient is cured. We recommend continuous training of health workers, routine monitoring and evaluation, integration of TB care and prevention into other health services programmes like HIV/AIDS and active case search at all levels to increase the sensitivity of the system. Speed up the process of integration of NTBLCP surveillance system with IDSR for data harmonization in the country.


Introduction
Tuberculosis is a global treat and Nigeria is among the high TB, TB/HIV and DR-TB countries globally. The country ranks 7 th among the 30 high TB burden countries globally and 2nd in Africa, accounting for 4% of the estimated incidence cases globally [1]. In 2015, the global estimate for new (incident) TB cases was estimated at 10.4 million. People living with HIV accounted for 1.2 million (11%) of the incident cases [2]. An estimated 460,000 cases of tuberculosis occur in Nigeria annually [1]. TB prevalence among HIV/AIDS patients rose up to 27% due to increased association of TB with HIV/AIDS [3]. The TB incidence and mortality rates for the country is 219/100,000 and 39/100,000 population respectively. The treatment coverage for the country in 2016 was 24% making it the lowest TB treatment coverage rate globally [1]. Nigeria  among drug resistance TB patients by the human capital catastrophic cost estimation threshold of 20% [1] indicating the severity of TB in the country.
Public health surveillance systems are instituted for data collection, analysis, interpretation and dissemination of information to relevant authorities for action to improve public health [4,5]. Currently, the human, animal and environmental health have instituted surveillance systems which are progressively being integrated into the One Health (OH) approach component [4]. Surveillance system evaluation enhances efficient utilization of data collection resources and optimizes the systems operation. It defines the usefulness of a specific system for a particular public health initiative based on the goals of the public health program and the data collection objectives [6]. The aim of surveillance system evaluation is to assess whether the system achieves the purpose and objectives of the programme [6]. The variation of public health surveillance systems in their methods, scope, purpose and objectives brings about the disparity of what is important in the system being evaluated [7]. The need for effective surveillance systems has long been recognized with increasing international pressure to improve the effectiveness of these systems [8]. The capacity of surveillance systems to accurately describe patterns of diseases is of public health importance. Therefore, regular and relevant evaluations of these systems are critical in order to improve their performance and efficiency [9]. This study aimed at assessing the national tuberculosis surveillance and response systems to determine if the system meets its goals and objectives and to recommend way of improving the system capacities. Currently, the operating guideline for the programme is the Sixth Edition (2015) of the "National Tuberculosis, Leprosy and Buruli Ulcer Management and Control Guidelines [11]. At the national level, NTBLCP has National Coordinator, the Programme Manager and the Monitoring and Evaluation (M&E) unit for data management [11]. The  Figure 2 and Table 1).

Methods
Case definition: a suspected pulmonary TB case is defined as any person coughing for 2 weeks or more, with or without symptoms of weight loss, tiredness, fever, night sweats, chest pain, shortness of breath, loss of appetite and coughing up blood while a suspected extra-pulmonary TB case is a person with symptoms depending on the affected organ, vertebral spine (back pain, swelling on spine); bone (long standing pain and swelling of the bone); Joints (painful joint swelling, usually affecting one joint); kidney and urinary tract (painful urination, blood in urine, frequent urination, lower back pain/loin pain); upper respiratory tract (hoarseness of voice, pain on swallowing); pleural membrane of lungs (chest pain, difficulty in breathing, fever); meninges of the brain (headache, persistent fever, neck stiffness, vomiting, irritability, convulsions, loss of consciousness); lymph node (painless swelling of the node, may drain pus); skin (longstanding ulcer despite antibiotic treatment, draining pus) and some general symptoms (weight loss, persistent fever, night sweats). In children, a suspect case is defined as any or combination of the following symptoms: low grade fever not responding to malaria treatment, night sweats, loss of weight, loss of appetite, failure to thrive, lymph node swellings, joint or bone swellings, angle deformity of the spine, listlessness and neck stiffness, headache, vomiting (TB meningitis) [13]. A confirmed TB case must be laboratory diagnosed.
Case detection is done through screening of TB symptoms, along with sputum microscopy for AFB. Two positive smears out of three define positivity for TB. For sputum smear-negative cases, diagnosis is made after three negatives, along with X-ray and confirmation by medical officer. Extra-pulmonary TB cases in children are diagnosed by medical officers using clinical examination, X-ray, and/or any other investigation deemed necessary to establish a diagnosis [10].
Study design and data collation: we conducted a descriptive evaluation of the National TB surveillance system using Centers for Disease Control and Prevention (CDC) updated guidelines for evaluating public health surveillance systems [14] and the CDC Overview of Evaluating Surveillance Systems [6]. Questionnaire used for this study was adapted from the WHO generic questionnaire for central level (national), protocol for the assessment of national communicable disease surveillance and response [15] with minor modifications to suit the surveillance system being evaluated. The Data analysis: data obtained from questionnaires and key informant interviews were cleaned and analyzed. We presented the descriptive statistic and also determined the sensitivity and predictive value positive as well as the other attributes of the surveillance system.
Ethical issues: this study was conducted based on approval by the national coordinator of the NTBLCP after a letter for the release of data was sent. Secondary data was used for this study and no ethical clearance was required. Verbal consent of the key informants was obtained before the face-to-face interview was conducted.

Results
Usefulness of the system: at the end of 2014, there were over 5,300 TB service points and 1,602 microscopy Centre's distributed across the entire country [11]. The system detects TB in health facilities from the 774 local government areas of the federation nationwide. Gene Expert machines are used in the detection of drug resistant tuberculosis nationwide. For new cases where there are no GeneXpert machines, AFB test are used to diagnose TB. It is mandatory for re-occurring cases to use GeneXpert test to detect DR-TB cases. Data obtained from the surveillance are used to measure performance of the system, determine the health indicators for needs assessments and accountability of the system. Aside TB detection, other diseases detected by the system are leprosy and buruli ulcer.
Data is also shared with WHO (Table 2).  Table 3). The system of reporting at the central level is computerized, has a central data based server, data storage and analysis. The system is linked with the electronic TB (E-TB) manager for alerting of new TB cases and the GXalert messages for detected DR-TB cases from GeneXpert ® MTB/RIF assay machine (Table 3).
Representativeness: the TB surveillance system is representative of all ages. Children below and above the age of 15 years are covered nationwide ( Table 2). There is regimen for the treatment of children that are diagnosed with TB. Nationwide all age group and every district is under surveillance. Therefore, data obtained from the surveillance is representative of the entire national population. Data obtained is described in terms of person (sex and age), place (distribution using tables, charts and maps) and time (trend analysis and period of occurrence), (Table 3).
Acceptability: there exist TB manual which includes other diseases; leprosy and buruli ulcer. The standard TB case definition is well accepted (100%) by the staff (Table 1). There was full participation of all stakeholders in the programme and a good public-private partnership with the programme. Data quality: case definition is consistent with WHO guidelines. The TB surveillance system was designed to capture a minimum set of variables for reported TB cases which was met by evaluation (core variables are captured; age, sex, case type, distribution) ( Table 3) (Table 3). Power point presentations are delivered and information is shared with the state epidemiologist who in turn disseminate the information to LGA supervisors and subsequently to the health facilities concerned (Table 3). were positive. Hence, the sensitivity of the system was 25% while the PVP for DR-TB using the GeneXpert test was 12.7%. There were no frequent cases of misdiagnosis (Table 2)

Discussion
The TB surveillance system was found useful in the detection of drug susceptible and DR-TB cases as well as in evaluating the TB health indicators. This was based on the CDC assessment of usefulness of a surveillance system by its ability to determine adverse health event that contributes to performance measures such as health indicators that are used for need assessment and system accountability [16].
Data obtained has signified that the case definition is simple and easy to use but a confirmed case has to do with laboratory test which may be fairly easy or complex to conduct. This require specialized and trained personnel making the system a bit complex to operate. Test also need to conducted at the end of treatment to verify if the patient is cured or not. The simplicity of a public health surveillance system refers to both its structure and ease of operation. Surveillance systems should be as simple as possible while still meeting their objectives [14]. In 2018, 25% of the projected number of cases was detected by the surveillance system, indicating the need for improved active case search at all levels for early case detection to meet the objective and goal of the surveillance system in reducing the prevalence of TB to a level that no longer constitute public health problems in the country which will significantly diminish the socioeconomic impact and rate of transmission. The system is not yet integrated with other systems. Discussion on data integration and harmonization with IDSR is ongoing.
Integration and harmonization of data from NTBLCP and IDSR through collaboration will increase the validity of TB data obtained and distributed across the country and at international level. Differences in data obtained indicates a missing link between the two organizations. Hence, the dare need to harmonize data obtained. Data obtained has indicated that the TB surveillance system is representative of the TB cases in the country based on the CDC guideline that was used to evaluate the credibility of the system which states that a public health surveillance system is representative when it accurately describes the occurrence of a health-related event over time and its distribution in the population by place and person [16].
In 2016, at least one million children were estimated to have acquired tuberculosis annually, representing about 10% of all tuberculosis (TB) cases globally, while 250,000 children died of TB (including those coinfected with HIV) [17]. During the same period, there were an estimated 56,000 cases of TB in children in Nigeria [18] indicating that children are well captured in the TB surveillance system in the country.
When cases notified to a surveillance system are not representative of the events in the general population, there is poor reflection of national and global situation of the disease [14].
Over time, the representativeness of surveillance data may change due to changes in legislation, surveillance infrastructure, clinical practice and reimbursement policies leading to wrong conclusions. For example, when trends in surveillance data are compared between countries. Hence the need for stability in the representativeness on the national surveillance level needs to be monitored, and the quantitative effect of changes on representativeness assessed [14].
There are 32 supervisory visits to be made in a year at the central level, 8 visits in each quarter but the visit in the first quarter is usually skipped due to late funding of the budget. Thus, the need for early funding to avoid the skipping of the first quarter supervisory visits.
The system demonstrated stability based on reliability; signifying the systems´ ability to collect, manage, and provide data properly without failure and availability; ability to be operational when needed.
However, the funding of the programme is mainly by the donor partners. This indicates that the Nigerian government needs be the major funder of the programme for sustained stability in the future because funding plays a major role in the performance and sustenance of a system. Peradventure there is withdrawal from any of the major donors in the future, this may lead to a major setback in the programme. Studies have indicated prospects for TB control in Nigeria with the existence of a 30 year old TB control programme and the willingness of development partners to assist [19].
Limitation of the study: evaluation of validity and available resources in terms of funding was not done.

Conclusion
The system was found to be useful, representative, acceptable, good data quality, timely, and sensitive. The system is also stable but needs to be funded more by the government. The stability of the programme largely depends on the funding from donor partners which needs to be corrected. There is need for early funding to avoid the skipping of the first quarter supervisory visits. The system is not simple due the various test that need to be conducted before, during and after treatment to verify that the patient is cured. Recommendations include training and re-training of health workers, constant monitoring and evaluation of the TB surveillance system, integration of TB care and prevention into other health services and programmes like HIV/AIDS and active case search at all levels. Speed up the process of integration of NTBLCP surveillance system with IDSR for data harmonization and better output in case detection. Findings will be communicated to partners and stakeholders in order to improve on the existing TB surveillance system and response.
What is known about this topic  Surveillance system evaluation is conducted to improve public health;  Evaluation is done based on the type of system instituted;  The instituted system for surveillance should be able to meet its set goals and objectives.
What this study adds  The TB surveillance system was found to be useful, representative, acceptable, has good data quality, timely and sensitive. Nevertheless, 25% sensitivity of the surveillance system indicates the need for improved active case search at all levels for early case detection to meet the objective and goal of the surveillance system;  There is need for government to increase funding of the TB surveillance system because majority of the funds is from donor partners;  There is need for early funding and budget approval to avoid the skipping of the first quarter supervisory visits.

Competing interests
The authors declare no competing interests.

Acknowledgments
Our gratitude goes to the National Coordinator and staff of the NTBLCP in their willingness to share the system data and participated as respondents for the questionnaires administered.      Collaborative activities nationwide. USAID has been actively involved in 17 states in the northern part of the country, including Lagos and the FCT. USAID is also supporting the MDRTB survey and implementation of MDR-TB activities, including strengthening the zonal and national reference laboratories. USAID is also supporting the national TB logistic systems, community TB care, Public -Private Mix (PPM)-DOTS, and ACSM, and is strengthening the health system through renovation of facilities, human capacity building, and supply of microscopes and laboratory commodities. USAID has supported the development of a costing tool for provision of TB services, NTP strategic plan, and HRD plan 2010 -2015 and is strengthening supportive supervision through the use of person al digital assistants (PDAs). WHO Technical support in policy formulation, strategic planning, supervision, monitoring, and program evaluation at national and state levels. Resource mobilization and supply of anti-leprosy drugs.