Larval Source Management in Africa: Case Studies

Charles M. MbogoKenya Medical Research Institute, Centre for

Geographic Medicine Research, Kilifi

Case studies

• Dar-es-Salaam, Tanzania• Malindi and Nyabondo, Kenya• Zambia• ECOWAS position• Discussion and conclusion

Larval Control studies in Africa

Western Kenya

Malindi, Kenya

Dar-es-Salaam

Zambia

Nigeria

Accra, Ghana

Case study 1: Dar-es-Salaam, Tanzania

• Large-scale, community-based but vertically managed operational program using Bti in Dar-es-Salaam, Tanzania– Mapping & surveillance of potential Anopheles breeding

sites– Monitoring of adult mosquito densities– Cluster –sampled household surveys of parasite infection

rates– Weekly application of Bti

Area: 55 km2 Target Population: 612,000 people

Study area in Central Dar-es-Salaam, Tanzania

Dar-es-Salaam, Tanzania

Reduction of malaria infection and risk in under 5 years old children

Crude prevalence of malaria infection in u5s.

Conclusion

• Significant reduction in malaria prevalence, vector density and abundance

• Concluded that “protective effectiveness can be achieved under routine, real-world programmatic conditions and that Bti was applied on a substantial operational scale by CORPs to achieve a dramatic reduction of malaria prevalence”

Case 2: Adaptive integrated malaria control in urban Malindi, Kenya

Developed a community-based vector control plan which focuses on prevention strategy

Integrated Vector Management strategies ◦ Monitor epidemiological factors (malaria cases from HF)◦Monitoring larvae and adult mosquitoes◦ Capacity Building-Inform, educate & empower◦Regular application of Bti/Bs

◦Study area: 32 km2

Main strategy: Adaptive management principles stipulate active participation of the communities

Components of LSM• Biolarviciding - Bti

• Environmental management – filling and draining

An. gambiae Larval densities

There has been a steady decline in larval densities overtime (56.2%). Most productive habitats such as abandoned swimming pools and wells have been well managed

An. gambiae indoor resting densities

o The Mosquito densities were highest between Jun – Oct 2006o Overtime there has been a steady decline of Anopheles (65.32%)o Small upsurges (peaks) are seen coinciding with rainfall season

IVM: Mosquito

control activities

Malaria cases in under 5 years in Malindi, 2002-2009

A 62% reduction in malaria cases was achieved between 2002-2009

Case 3: Success in sustained malaria control in Zambia

• Successful programmes to control malaria transmission by A. gambiae — the predominant vector in sub-Saharan Africa — were initiated in the 1930s and 1940s and their effects sustained for two decades or more in Brazil, Egypt and Zambia

• There were three common features to these outstanding successes: They had integrated control, emphasizing; – Environmental management and regular insecticidal suppression of larval

stages of the vector;– Rigorous surveillance and adaptive tuning of the intervention package over

time; and– Employed multi-sectoral programme staff with expertise in clinical,

ecological, entomological and epidemiological aspects of malaria

• Integrated malaria control in Africa will rely on basic and applied environmental science.

Malaria incidence rates at Konkola copper mines, Zambia, 1999-2010

IRS is integrated with larval control through active community participation. Larval control involves draining mosquito breeding habitats and larviciding using temephos.

IVM in Zambia

• The Ministry of Health integrate and scale up the Larval Source Management as one of the strategies in the control of malaria to complement the existing interventions (LLINs & IRS).

• Ministry of Health has approved Larval control using environmentally friendly larvicides as an alternative and effective way for malaria control if complemented with adult control interventions.

Integrating LSM in the National Malaria Control Programme in Zambia: Steps taken

• 2005: Implementation of LSM was launched within the context of IVM.

• 2007: Efficacy studies of larvicides including Bacillus thuringensis var israelensis were conducted.

• 2008: A feasibility assessment for integrating larviciding in the malaria control programme was conducted

• 2009: A stakeholders’ consensus meeting and launch of biological control using Gambusia affinis fish were conducted followed by implementation in 8 urban districts.

• 2010 : LSM programme scaled up to 15 districts to complement ITNs and IRS

• Entomological and epidemiological surveillance including insecticide resistance are conducted routinely.

Case 4: ECOWAS- LARVAL CONTROL Campaign

• Use of biolarvicides against malaria vectors to be promoted in West Africa

• The Economic Commission of West African States (ECOWAS) launched a bio-larvicide campaign aimed to eliminate malaria in the region by 2015.– The campaign focuses on strengthening the vector control

component in the fight against malaria in the region through the use of bio-larvicides.

• The current strategy is being adopted because of the evidence of its success in other parts of the world where malaria has since ceased to exist as it uses an integrated approach.

LABIOFARM: CURRENT LSM ACTIVITIES IN AFRICA

Discussion• All case studies unequivocally demonstrated that

integrated control using existing tools (IRS & ITNs) and larval control has a significant add-on effect over a single intervention.

• LSM synergy in combination with other Vector control tools may be effective for outdoor biting and transmission (plus biting nuisance).

• Larval control is likely to be cost-effective only in situations where the breeding sites are particularly few, fixed and easily identifiable.

Discussion • LSM is being used as part of IVM in many

countries at present. However, we need to know which products are effective.

• LSM is highly effective with active community participation

• Program and organization management is key --- technical leadership, monitoring and evaluation (entomological surveillance), guidelines, policies, institutional strengthening for financial management and procurement

Conclusion

• There is need to conduct an impact evaluation into Larviciding programme in different epidemiological settings in Africa.