Impact of Implementation Interruptions of 1,7-Malaria Reactive Community-Based Testing and Response Approach on Malaria Control Efforts - Southern Tanzania.

Introduction: Surveys from the China-Tanzania Malaria Control Project demonstrated that the 1,7-malaria Reactive Community-Based Testing and Response (1,7-mRCTR) approach significantly reduced malaria incidence rates. However, implementation was disrupted by security concerns, infectious disease outbreaks, and supply shortages. This study evaluates how these interruptions affected intervention effectiveness to inform future malaria control strategies.

Methods: The study employed a two-phased design: Phase I (2016-2018) and Phase II (2019-2021). Weekly malaria incidence rates per 100 people were calculated from cases reported by local health facilities in the intervention areas during both phases. Seasonal and trend decomposition using loess (STL) and interrupted time series modeling with piecewise linear regression were used to evaluate the impact of disruptions on 1,7-mRCTR implementation effectiveness.

Results: In Tanzania's 1,7-mRCTR areas, malaria incidence peaked during November-December and June-July. Phase I's 8-month interruption reversed the weekly trend from a 0.17% decline to a 0.58% increase (P=0.001). After resumption, incidence dropped 8.96% (P=0.039) and maintained a 0.39% long-term decline (P=0.003). Even with seasonal adjustment, the interruption slowed the weekly decline from 0.08% to 0.07% (P=0.003). Phase II showed a similar pattern: a one-week interruption caused a 0.70% drop (P=0.007) but shifted the trend from a 0.02% decline to a 0.08% increase (P=0.001). After resumption, interventions stabilized the decline at 0.11% weekly (P=0.001).

Conclusions: This research demonstrates that Tanzania's malaria incidence is closely linked to seasonal patterns and consistent intervention efforts. Phase I's 8-month security-related interruption reduced 1,7-mRCTR effectiveness by 12.5%, while Phase II's 3-month pandemic-induced interruption caused only short-term fluctuations with minimal long-term impact. Rapid resumption of interventions after disruptions allowed for prompt recovery, highlighting the importance of adaptive strategies to maintain progress toward malaria control goals.