Assessing Thailand's 1-3-7 surveillance strategy in accelerating malaria elimination

Abstract

Background: Thailand's strong malaria elimination programme relies on effective implementation of its 1-3-7 surveillance strategy, which was endorsed and implemented nationwide in 2016. For each confirmed malaria patient, the Ministry of Public Health's Division of Vector Borne Diseases (DVBD) ensures completion of case notification within 1 day, case investigation within 3 days, and foci investigation within 7 days. To date, there has not been a comprehensive assessment of the performance and achievements of the 1-3-7 surveillance strategy although such results could help Thailand's future malaria elimination strategic planning.

Methods: This study examined adherence to the 1-3-7 protocols, tracked progress against set targets, and examined geographic variations in implementation of the 1-3-7 strategy in the programme's initial 5 years. An auto-regressive integrated moving average (ARIMA) time series analysis with seasonal decomposition assessed the plausible implementation effect of the 1-3-7 strategy on malaria incidence in the programme's initial 5 years. The quantitative analysis included all confirmed malaria cases from public health and non-governmental community facilities from October 2014 to September 2021 (fiscal year [FY] 2015 to FY 2021) (n = 77,405). The spatial analysis included active foci with known geocoordinates that reported more than five cases from FY 2018 to FY 2021.

Results: From FY 2017 to FY 2021, on-time case notification improved from 24.4% to 89.3%, case investigations from 58.0% to 96.5%, and foci investigations from 37.9% to 87.2%. Adherence to timeliness protocols did not show statistically significant variation by area risk classification. However, adherence to 1-3-7 protocols showed a marked spatial heterogeneity among active foci, and the ARIMA model showed a statistically significant acceleration in the reduction of malaria incidence. The 1-3-7 strategy national indicators and targets in Thailand have shown progressive success, and most targets were achieved for FY 2021.

Conclusion: The results of Thailand's 1-3-7 surveillance strategy are associated with a decreased incidence in the period following the adoption of the strategy although there is notable geographic variation. The DVBD will continue to implement and adapt the 1-3-7 strategy to accelerate progress toward malaria elimination. This assessment may be useful for domestic strategic planning and to other countries considering more intensive case and foci investigation and response strategies.

Keywords: 1-3-7 Strategy; Elimination; Surveillance.

Fig. 1

Malaria annual parasite incidence in GMS, FY 2021. Source: Malaria Elimination Database, Mekong Malaria Elimination Programme, 2021 (pers. commun.)

Fig. 2

Number and percentage of malaria cases reported within 1 day, by month, FY 2017–FY 2021

Fig. 3

Number and percentage of malaria cases investigated within 3 days, by month, FY 2017–FY 2021

Fig. 4

Number and percentage of foci investigated and responded to within 7 days, FY 2017–FY 2021

Fig. 5

District-level improvements in malaria free status from FY 2017 and FY 2021. Source: DVBD, MOPH, 2021 (pers. commun.)

Fig. 6

Observed and forecast malaria incidence per 1000 population at risk in active foci areas FY 2015–FY 2024

Fig. 7

Spatial pattern of adherence to 1-3-7 protocols among active foci in Thailand, FY 2018–FY 2021

Fig. 8

Active foci with significantly lower adherence to 1-3-7 protocols, FY 2018–FY 2021 The red dots indicate significant hot spots (p < 0.05) of low adherence to 1-3-7 timing identified by the G* local spatial test