Indoor Residual Spraying for Malaria Control in Sub-Saharan Africa 1997 to 2017: An Adjusted Retrospective Analysis

Abstract Background: Indoor residual spraying (IRS) is a key tool for controlling and eliminating malaria by targeting vectors. To support the development of effective intervention strategies it is important to understand the impact of vector control tools on malaria incidence and on the spread of insecticide resistance. In 2006, the World Health Organization (WHO) stated that countries should report on coverage and impact of IRS, yet IRS coverage data are still sparse and unspecific. Here we estimated the subnational coverage of IRS across sub-Saharan Africa for the four main insecticide classes from 1997 to 2017. Methods: Data on IRS deployment were collated from a variety of sources, including the President’s Malaria Initiative spray reports and National Malaria Control program reports, for all 46 malaria-endemic countries in Sub-Saharan Africa from 1997 to 2017. The data were mapped to the applicable administrative divisions and the proportion of households sprayed for each of the four main insecticide classes; carbamates, organochlorines, organophosphates and pyrethroids was calculated. Results: We found that the number of countries implementing IRS increased considerably over time, although the focal nature of deployment means the number of people protected remains low. From 1997 to 2010, DDT and pyrethroids were commonly used, then partly replaced by carbamates from 2011 and by organophosphates from 2013. IRS deployment since the publication of resistance management guidelines has typically avoided overlap between pyrethroid IRS and ITN use. However, annual rotations of insecticide classes with differing modes of action are not routinely used. Conclusion: This study highlights the gaps between policy and practice, emphasizing the continuing potential of IRS to drive resistance. The data presented here can improve studies on the impact of IRS on malaria incidence and help to guide future malaria control efforts.

Download Full-text

Indoor residual spraying for malaria control in Sub-Saharan Africa 1997 to 2017; an adjusted retrospective analysis

10.21203/rs.2.17606/v1 ◽

2019 ◽

Author(s):

Julie-Anne Tangena ◽

Chantal M.J. Hendriks ◽

Maria Devine ◽

Meghan Tammaro ◽

Anna E. Trett ◽

...

Keyword(s):

Malaria Control ◽

Malaria Incidence ◽

Resistance Management ◽

Indoor Residual Spraying ◽

Control Program ◽

Sub Saharan Africa ◽

World Health ◽

Policy And Practice ◽

Sub Saharan ◽

The Impact

Abstract Background: Indoor residual spraying (IRS) is a key tool for controlling and eliminating malaria by targeting vectors. To support the development of effective intervention strategies it is important to understand the impact of vector control tools on malaria incidence and on the spread of insecticide resistance. In 2006, the World Health Organization (WHO) stated that countries should report on coverage and impact of IRS, yet IRS coverage data are still sparse and unspecific. Here we estimated the subnational coverage of IRS across sub-Saharan Africa for the four main insecticide classes from 1997 to 2017. Methods: Data on IRS deployment were collated from a variety of sources, including the President’s Malaria Initiative spray reports and National Malaria Control program reports, for all 46 malaria-endemic countries in Sub-Saharan Africa from 1997 to 2017. The data were mapped to the applicable administrative divisions and the proportion of households sprayed for each of the four main insecticide classes; carbamates, organochlorines, organophosphates and pyrethroids was calculated. Results: We found that the number of countries implementing IRS increased considerably over time, although the focal nature of deployment means the number of people protected remains low. From 1997 to 2010, DDT and pyrethroids were commonly used, then partly replaced by carbamates from 2011 and by organophosphates from 2013. IRS deployment since the publication of resistance management guidelines has typically avoided overlap between pyrethroid IRS and ITN use. However, annual rotations of insecticide classes with differing modes of action are not routinely used. Conclusion: This study highlights the gaps between policy and practice, emphasizing the continuing potential of IRS to drive resistance. The data presented here can improve studies on the impact of IRS on malaria incidence and help to guide future malaria control efforts.

Download Full-text

Impact of seasonality and malaria control interventions on Anopheles density and species composition from three areas of Uganda with differing malaria endemicity

Malaria Journal ◽

10.1186/s12936-021-03675-5 ◽

2021 ◽

Vol 20 (1) ◽

Author(s):

Henry Ddumba Mawejje ◽

Maxwell Kilama ◽

Simon P. Kigozi ◽

Alex K. Musiime ◽

Moses Kamya ◽

...

Keyword(s):

Species Composition ◽

Vector Control ◽

Malaria Control ◽

Mosquito Species ◽

Density Ratio ◽

Indoor Residual Spraying ◽

Sub Saharan Africa ◽

Malaria Vector Control ◽

Vector Density ◽

Llin Distribution

Abstract Background Long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) are the malaria control interventions primarily responsible for reductions in transmission intensity across sub-Saharan Africa. These interventions, however, may have differential impact on Anopheles species composition and density. This study examined the changing pattern of Anopheles species in three areas of Uganda with markedly different transmission intensities and different levels of vector control. Methods From October 2011 to June 2016 mosquitoes were collected monthly using CDC light traps from 100 randomly selected households in three areas: Walukuba (low transmission), Kihihi (moderate transmission) and Nagongera (high transmission). LLINs were distributed in November 2013 in Walukuba and Nagongera and in June 2014 in Kihihi. IRS was implemented only in Nagongera, with three rounds of bendiocarb delivered between December 2014 and June 2015. Mosquito species were identified morphologically and by PCR (Polymerase Chain Reaction). Results In Walukuba, LLIN distribution was associated with a decline in Anopheles funestus vector density (0.07 vs 0.02 mosquitoes per house per night, density ratio [DR] 0.34, 95% CI: 0.18–0.65, p = 0.001), but not Anopheles gambiae sensu stricto (s.s.) nor Anopheles arabiensis. In Kihihi, over 98% of mosquitoes were An. gambiae s.s. and LLIN distribution was associated with a decline in An. gambiae s.s. vector density (4.00 vs 2.46, DR 0.68, 95% CI: 0.49–0.94, p = 0.02). In Nagongera, the combination of LLINs and multiple rounds of IRS was associated with almost complete elimination of An. gambiae s.s. (28.0 vs 0.17, DR 0.004, 95% CI: 0.002–0.009, p < 0.001), and An. funestus sensu lato (s.l.) (3.90 vs 0.006, DR 0.001, 95% CI: 0.0005–0.004, p < 0.001), with a less pronounced decline in An. arabiensis (9.18 vs 2.00, DR 0.15 95% CI: 0.07–0.33, p < 0.001). Conclusions LLIN distribution was associated with reductions in An. funestus s.l. in the lowest transmission site and An. gambiae s.s. in the moderate transmission site. In the highest transmission site, a combination of LLINs and multiple rounds of IRS was associated with the near collapse of An. gambiae s.s. and An. funestus s.l. Following IRS, An. arabiensis, a behaviourally resilient vector, became the predominant species, which may have implications for malaria vector control activities. Development of interventions targeted at outdoor biting remains a priority.

Download Full-text

Competing interests, clashing ideas and institutionalizing influence: insights into the political economy of malaria control from seven African countries

Health Policy and Planning ◽

10.1093/heapol/czaa166 ◽

2020 ◽

Author(s):

Justin Parkhurst ◽

Ludovica Ghilardi ◽

Jayne Webster ◽

Robert W Snow ◽

Caroline A Lynch

Keyword(s):

Decision Making ◽

Malaria Control ◽

Qualitative Interviews ◽

Sub Saharan Africa ◽

African Countries ◽

Health Community ◽

Control Programmes ◽

Control Decision ◽

Sub Saharan ◽

Economic Considerations

Abstract This article explores how malaria control in sub-Saharan Africa is shaped in important ways by political and economic considerations within the contexts of aid-recipient nations and the global health community. Malaria control is often assumed to be a technically driven exercise: the remit of public health experts and epidemiologists who utilize available data to select the most effective package of activities given available resources. Yet research conducted with national and international stakeholders shows how the realities of malaria control decision-making are often more nuanced. Hegemonic ideas and interests of global actors, as well as the national and global institutional arrangements through which malaria control is funded and implemented, can all influence how national actors respond to malaria. Results from qualitative interviews in seven malaria-endemic countries indicate that malaria decision-making is constrained or directed by multiple competing objectives, including a need to balance overarching global goals with local realities, as well as a need for National Malaria Control Programmes to manage and coordinate a range of non-state stakeholders who may divide up regions and tasks within countries. Finally, beyond the influence that political and economic concerns have over programmatic decisions and action, our analysis further finds that malaria control efforts have institutionalized systems, structures and processes that may have implications for local capacity development.

Download Full-text

Spectrum-Malaria: a user-friendly projection tool for health impact assessment and strategic planning by malaria control programmes in sub-Saharan Africa

Malaria Journal ◽

10.1186/s12936-017-1705-3 ◽

2017 ◽

Vol 16 (1) ◽

Cited By ~ 7

Author(s):

Matthew Hamilton ◽

Guy Mahiane ◽

Elric Werst ◽

Rachel Sanders ◽

Olivier Briët ◽

...

Keyword(s):

Strategic Planning ◽

Impact Assessment ◽

Malaria Control ◽

Health Impact Assessment ◽

Health Impact ◽

Sub Saharan Africa ◽

Control Programmes ◽

Sub Saharan ◽

User Friendly

Download Full-text

Recent global updates in malaria control and situation in Sub-Saharan Africa region

Cukurova Medical Journal (Çukurova Üniversitesi Tıp Fakültesi Dergisi) ◽

10.17826/cutf.324572 ◽

2017 ◽

Vol 42 (3) ◽

pp. 592-593

Author(s):

Saurabh RamBihariLal Shrivastava ◽

Prateek Saurabh Shrivastava ◽

Jegadeesh Ramasamy

Keyword(s):

Malaria Control ◽

Sub Saharan Africa ◽

Sub Saharan

Download Full-text

Influence of Climatic Factors on Malaria Epidemic in Gulu District, Northern Uganda: A 10-Year Retrospective Study

Malaria Research and Treatment ◽

10.1155/2018/5482136 ◽

2018 ◽

Vol 2018 ◽

pp. 1-8 ◽

Cited By ~ 2

Author(s):

Ouma Simple ◽

Arnold Mindra ◽

Gerald Obai ◽

Emilio Ovuga ◽

Emmanuel Igwaro Odongo-Aginya

Keyword(s):

Retrospective Study ◽

Relative Humidity ◽

Malaria Control ◽

Malaria Infection ◽

Climatic Factors ◽

Indoor Residual Spraying ◽

Sub Saharan Africa ◽

Maximum Temperature ◽

Northern Uganda ◽

Gulu District

Background. Globally, 15 countries, mainly in Sub-Saharan Africa, account for 80% of malaria cases and 78% of malaria related deaths. In Uganda, malaria is endemic and the mortality and morbidity due to malaria cause significant negative impact on the economy. In Gulu district, malaria is the leading killer disease among children <5 years. In 2015, the high intensity of malaria infection in Northern Uganda revealed a possible link between malaria and rainfall. However, available information on the influence of climatic factors on malaria are scarce, conflicting, and highly contextualized and therefore one cannot reference such information to malaria control policy in Northern Uganda, thus the need for this study. Methods and Results. During the 10 year’s retrospective study period a total of 2,304,537 people suffered from malaria in Gulu district. Malaria infection was generally stable with biannual peaks during the months of June-July and September-October but showed a declining trend after introduction of indoor residual spraying. Analysis of the departure of mean monthly malaria cases from the long-term mean monthly malaria cases revealed biannual seasonal outbreaks before and during the first year of introduction of indoor residual spraying. However, there were two major malaria epidemics in 2015 following discontinuation of indoor residual spraying in the late 2014. Children <5 years of age were disproportionally affected by malaria and accounted for 47.6% of the total malaria cases. Both rainfall (P=0.04) and relative humidity (P=0.003) had significant positive correlations with malaria. Meanwhile, maximum temperature had significant negative correlation with malaria (P=0.02) but minimum temperature had no correlation with malaria (P=0.29). Conclusion. Malaria in Gulu disproportionately affects children under 5 years and shows seasonality with a generally stable trend influenced by rainfall and relative humidity. However, indoor residual spraying is a very promising method to achieve a sustained malaria control in this population.

Download Full-text