Potential for reduction of burden and local elimination of malaria by reducing Plasmodium falciparum malaria transmission: a mathematical modelling study

Abstract

Summary Background Rapid declines in malaria prevalence, cases, and deaths have been achieved globally during the past 15 years because of improved access to first-line treatment and vector control. We aimed to assess the intervention coverage needed to achieve further gains over the next 15 years. Methods We used a mathematical model of the transmission of Plasmodium falciparum malaria to explore the potential effect on case incidence and malaria mortality rates from 2015 to 2030 of five different intervention scenarios: remaining at the intervention coverage levels of 2011–13 (Sustain), for which coverage comprises vector control and access to treatment; two scenarios of increased coverage to 80% (Accelerate 1) and 90% (Accelerate 2), with a switch from quinine to injectable artesunate for management of severe disease and seasonal malaria chemoprevention where recommended for both Accelerate scenarios, and rectal artesunate for pre-referral treatment at the community level added to Accelerate 2; a near-term innovation scenario (Innovate), which included longer-lasting insecticidal nets and expansion of seasonal malaria chemoprevention; and a reduction in coverage to 2006–08 levels (Reverse). We did the model simulations at the first administrative level (ie, state or province) for the 80 countries with sustained stable malaria transmission in 2010, accounting for variations in baseline endemicity, seasonality in transmission, vector species, and existing intervention coverage. To calculate the cases and deaths averted, we compared the total number of each under the five scenarios between 2015 and 2030 with the predicted number in 2015, accounting for population growth. Findings With an increase to 80% coverage, we predicted a reduction in case incidence of 21% (95% credible intervals [CrI] 19–29) and a reduction in mortality rates of 40% (27–61) by 2030 compared with 2015 levels. Acceleration to 90% coverage and expansion of treatment at the community level was predicted to reduce case incidence by 59% (Crl 56–64) and mortality rates by 74% (67–82); with additional near-term innovation, incidence was predicted to decline by 74% (70–77) and mortality rates by 81% (76–87). These scenarios were predicted to lead to local elimination in 13 countries under the Accelerate 1 scenario, 20 under Accelerate 2, and 22 under Innovate by 2030, reducing the proportion of the population living in at-risk areas by 36% if elimination is defined at the first administrative unit. However, failing to maintain coverage levels of 2011–13 is predicted to raise case incidence by 76% (Crl 71–80) and mortality rates by 46% (39–51) by 2020. Interpretation Our findings show that decreases in malaria transmission and burden can be accelerated over the next 15 years if the coverage of key interventions is increased. Funding UK Medical Research Council, UK Department for International Development, the Bill & Melinda Gates Foundation, the Swiss Development Agency, and the US Agency for International Development.

Antimicrobial Resistance Risks of Cholera Prophylaxis for United Nations Peacekeepers

“…These studies have typically used deterministic models and focused on endemic diseases. Stochastic models such as the one presented here allow modelers to account for randomness in transmission when case counts are low, and they have previously been used to inform policy in areas such as hospitalassociated infections, disease emergence and importation, and disease elimination (26)(27)(28). This study is unique in its use of a stochastic model to analyze the impact of prophylaxis on importation and epidemic spread of both DS and DR pathogens in an area where they are not endemic.…”

Priorities for Broadening the Malaria Vector Control Tool Kit

“…Yet in many locations vectors exhibit more diverse behaviors, feeding on other hosts, feeding and resting outdoors, and/or feeding in the early evening [6–8]. A consequence of both these challenges is that there are limits to how much LLINs and IRS alone can reduce transmission, even with further intensification and optimization [9]. This problem creates a pressing need for supplementary vector control tools.…”

“…The Global Technical Strategy is informed by a modeling analysis, which explores a range of future intervention scenarios that vary in terms of access to vector control (LLINS and IRS) and drug treatments (both seasonal malaria chemo-prevention and first line treatments with artemisinin combination therapy) [9]. The modeling analysis reveals a number of key insights (Figure 1).…”

“…The figure (modified from [9]) shows estimates of global malaria deaths from 2000–2045. The 50% decline in malaria related mortality recorded from 2000–2015 is largely attributable to the wide scale implementation of vector control tools (Long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS)) [1,2].…”

“…The 50% decline in malaria related mortality recorded from 2000–2015 is largely attributable to the wide scale implementation of vector control tools (Long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS)) [1,2]. The future projections are based on a model analysis that considers different scenarios of access to vector control, together with malaria drug treatments [9]. …”