An Evaluation of the National Malaria Surveillance System of Bhutan, 2006–2012 as It Approaches the Goal of Malaria Elimination

Abstract

IntroductionBhutan is progressing toward malaria elimination. The purpose of this evaluation was to assess the ability of the surveillance system from 2006 to 2012 to meet the objectives of the Bhutan Vector-borne Disease Control Program (VDCP) and to highlight priorities requiring attention as the nation transitions to elimination.MethodsThe evaluation was conducted using the Center for Disease Control guidelines for evaluating public health surveillance systems. Data sources included a search of publically available literature, VDCP program data, and interviews with malaria surveillance personnel. Blood slide quality assurance and control through formal assessment of slide preparation and measures of between-reader correlation were performed.ResultsTotal malaria cases declined from 2006 to 2012. The average slide positivity rate decreased from 3.4% in 2006 to 0.2% in 2012. The proportion of non-residents in all cases increased to its highest value of 22.6% in 2012, and significant clustering in the border regions of India was noted, with Sarpang accounting for more cases than any other district from 2009 onward. Case detection was almost exclusively passive, but flexibility and sensitivity was demonstrated by the later addition of active case detection and specification of imported and locally acquired cases. Spatial data were limited to the village level, not allowing identification of transmission hotspots. For blood smears, statistical measures of between-reader agreement and predictive value were not computed. Blood smear quality was suboptimal by at least one criterion in over half of evaluated smears. Timeliness in reporting of cases was on a weekly to monthly basis, and did not meet the WHO goal of immediate notification.ConclusionAs of 2012, the national malaria surveillance system demonstrated flexibility, representativeness, simplicity, and stability. The full potential for data analysis was not yet realized. Attaining the goal of malaria elimination will require system function enhancement through increased and more accurate case detection and rapid investigation, improved health worker training and accountability, focally targeted response measures, and, in particular, the challenge of finding re-introductions of infections from India. Many such measure have been undertaken or planned as part of the next phase of the Bhutan’s National Strategic Plan.

Demonstration of indigenous malaria elimination through Track-Test-Treat-Track (T4) strategy in a Malaria Elimination Demonstration Project in Mandla, Madhya Pradesh

“…early diagnosis and complete treatment, vector control using LLIN/IRS/Larvivorous fishes, IEC/BCC, Mass Screening and Treatment (MSAT). Evidence shows that strengthening surveillance may control the malaria leading to elimination [ 8 , 33 – 35 ].…”

Malaria elimination in Bhutan: asymptomatic malaria cases in the Bhutanese population living in malaria-risk areas and in migrant workers from India

“…Bhutan launched active case finding strategies targeting asymptomatic plasmodial infections as early as 2012. For the preparation towards the malaria elimination, the program included reactive case detection methods for the identification of parasite transmission foci, and proactive case detection methods in the screening of all migrant workers at border districts 10 , 33 - 36 . The LLIN’s coverage exceeded 90% since 2006, and successive surveys on indicators have also reported very high coverages 13 , 34 , 35 .…”

“…Among these States, Assam and West Bengal borders have intense cross-border activity, and most cases are reported in areas bordering Assam 5 , 11 , 12 . Percentages of imported malaria cases have increased from 79.7% of the total malaria cases detected in Bhutan in 2016 to 82.33% in 2017, and 88.9% in 2018 4 , 10 , 13 .…”

“…The geographical distribution of malaria infection has also decreased from 15 of the 20 districts in 2006 to only two districts in 2018 4 , 6 . The dramatic decline in malaria cases is believed to be due to the high coverage of LLINs, intensified surveillance and early diagnosis and treatment 5 , 6 , 9 , 10 . Bhutan plans to eliminate malaria by 2025 9 .…”

Evaluation of Malaria Blood Smears Sent to National Malaria Reference Laboratory

“…Other deficits were less common (91% normal size, 88% equal and 93% satisfactorily stained). Sixty smears (2.4%) were broken in Vector-borne Disease Control Program and could not be evaluate for cross control (9). In our study, of the 16.827 smears, 12 smears sent to our laboratory for confirmation were found to be broken which made the evaluation impossible and it was found that 97 smears did not reach our laboratory despite being included in the sent lists.…”