Results from the Gambian Survey of Tuberculosis Prevalence (GAMSTEP), a major collaborative study with the Ministry of Health and Social Welfare through the National Leprosy and Tuberculosis Programme (NTLP) has been published in the Bulletin of the World Health Organization. The study, ‘A tuberculosis (TB) nationwide prevalence survey in The Gambia, 2012’ shows that the burden of TB remains high in The Gambia and at 128 per 100,000 was much lower than earlier estimates of 350 and 490 per 100 000 population in 1990 and 2013 respectively. Less than half of all cases would have been identified if smear microscopy were the only diagnostic modality used. It also highlighted the significant burden of TB in men compared to women.
The key messages from this important survey are successful control efforts will require interventions targeting men, increased access to radiography and more accurate, rapid diagnostic tests. Based on the results of this survey, WHO in 2015 updated the TB prevalence estimates for The Gambia so the 1990 prevalence was revised downwards to 105 per 100 000, and the 2014 prevalence was 128 per 100 000 as reported. These estimates are expected to re-energize TB control efforts in the country. This study was funded by a grant from The Global Fund to Fight Acquired Immune Deficiency Syndrome (AIDS), TB and Malaria.
Tuberculosis killed 1.5 million people in 2014 and is the leading cause of death from an infectious disease worldwide. Sub-Saharan Africa, with 28% (9.6 million) of all notified TB cases in 2014, endures a disproportionate burden of the disease relative to its population. There are still significant undetected TB cases in The Gambia as only 5% of TB cases identified during the survey were already on treatment.
Given the need for improved, evidence-based interventions in TB control in The Gambia. The main aim of the study was to estimate the population prevalence of active pulmonary TB disease in The Gambia. Ethics approval to conduct this nationwide, multistage cluster TB prevalence survey was given by the joint ethics committee of the Gambian Government and MRC Unit The Gambia. The survey team enumerated 100 678 people aged ≥ 15 years (about 18% of Gambia’s population) and screened 43,100 participants for symptoms and by chest X-ray. All TB patients identified during the survey were promptly referred to the nearest treatment centre for treatment at no cost and notified to the national TB programme.
According to Dr Ifedayo Adetifa, Principal Investigator a former MRCG staff, “The Gambian Survey of Tuberculosis (TB) Prevalence is a significant milestone for TB control in The Gambia. It was the output of the long-standing collaborative partnership between the Medical Research Council Gambia Unit and the Gambian Ministry of Health and Social Welfare. It provides for the first time an accurate measure of TB burden in The Gambia thus meeting a critical need for data. The results have informed more realistic estimate of the trends for TB in The Gambia since 1990 and the formulation of practical targets for TB control. The results highlight the disproportionate burden of TB borne by men, limitations of the smear microscopy as the major diagnostic modality and the large numbers of undetected TB cases in the community.”
Male-targeted interventions and inclusion of more sensitive and specific tests into the diagnostic algorithm for TB are important for TB control in The Gambia.
Acknowledgements: The Gambian Government, The Gambian people, Ministry of Health and Social Welfare, Gambia; Gambian National Leprosy and TB Programme; MRC Unit The Gambia, WHO TB Impact Measurement Taskforce, Geneva, WHO representatives and offices, Ethiopia and The Gambia, Drs. Marina Tadolini, Sian Floyd and Ikushi Onozaki.
Authors: Ifedayo MO Adetifa, Lindsay Kendall, Adedapo Bashorun, Christopher Linda, Semeeh Omoleke, David Jeffries, Rahmatulai Maane, Beatrice Dei Alorse, William Dei Alorse, Catherine Bi Okoi, Kodjovi D Mlaga, Ma Ansu Kinteh, Simon Donkor, Bouke C de Jong, Martin Antonio, Umberto d’Alessandro