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Research
Jacklin Franklin Mosha
National Institute for Medical Research Mwanza Research Centre
Corresponding Author
ORCiD: https://orcid.org/0000-0001-7940-8903
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Background Long lasting insecticide nets (LLIN) are the intervention most widely deployed in Sub-Saharan Africa to prevent malaria. Recent reports indicate selection of pyrethroid insecticide resistance is widespread in mosquito vectors. This paper explores the risk factors associated with malaria infection prevalence and vector density between mass distribution campaigns of LLIN in Northern Tanzania.
Methods A cross sectional malaria survey of 3,456 children was undertaken in 2014. Vector density was assessed using indoor light traps and outdoor tent traps. Anophelines were identified to species using PCR and tested for falciparum circumsporozoite protein. Logistic regression was used to identify household and environmental factors associated with malaria infection and vector density.
Results LLIN use was 27.7%. Only 16.9% of households had sufficient nets to cover all sleeping places. Malaria infection was independently associated with access to LLIN (OR: 0.57; 95%CI 0.34 – 0.98), age group, altitude and house construction quality. LLIN less than 2 years old were more protective than older LLIN (53% vs 65% prevalence of infection); however, there was no evidence that LLIN in good condition (hole index <65) were more protective than LLIN which were more holed. Independent risk factors for vector density were consistent with malaria outcomes and included altitude, wind, livestock, house quality, open eaves and LLIN access. Indoor collections comprised 4.6% Anopheles funestus and 95.4% An. gambiae of which 4.5% were An. arabiensis and 93.5% were An. gambiae s.s .
Conclusion Three years after the mass distribution campaign and despite top-ups, LLIN usage had fallen considerably. While children living in households with access to LLIN were at lower risk of malaria, infection prevalence remained high even among users of LLIN in good condition. While effort should be made to maintain high coverage between campaigns, distribution of just standard pyrethroid LLIN appears insufficient to prevent malaria transmission in this area of intense pyrethroid resistance.
Keywords
Malaria, LLIN, Effectiveness, Vectors, Tanzania
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CURRENT STATUS: Published
View the published article at Malaria Journal.
No community comments so far
Editorial decision: Accept
On 08 Aug, 2020
Editor assigned
On 04 Aug, 2020
Submission checks complete
On 03 Aug, 2020
Editor invited
On 03 Aug, 2020
No comments provided
Editorial decision: Minor Revision
On 16 Jun, 2020
Editor assigned
On 15 Jun, 2020
Submission checks complete
On 14 Jun, 2020
Editor invited
On 14 Jun, 2020
Version 1
Posted 06 Apr, 2020
No comments provided
Review #2 received
Received 17 May, 2020
Editorial decision: Minor Revision
On 17 May, 2020
Reviewer #3 agreed
On 05 May, 2020
Review #1 received
Received 17 Apr, 2020
Reviewer #2 agreed
On 14 Apr, 2020
Reviewers invited
Invitations sent on 13 Apr, 2020
Reviewer #1 agreed
On 13 Apr, 2020
Editor assigned
On 03 Apr, 2020
First submitted
On 02 Apr, 2020
Submission checks complete
On 02 Apr, 2020
Editor invited
On 02 Apr, 2020
Metrics
Comments: 0
PDF Downloads: ...
HTML Views: ...
Subject Areas
Infectious Diseases
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A new preprint design is coming!
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See the published version of this preprint at Malaria Journal.
This is a preprint, a preliminary version of a manuscript that has not completed peer review at a journal. Research Square does not conduct peer review prior to posting preprints. The posting of a preprint on this server should not be interpreted as an endorsement of its validity or suitability for dissemination as established information or for guiding clinical practice.
Learn more about In Review
Research
Jacklin Franklin Mosha
National Institute for Medical Research Mwanza Research Centre
Corresponding Author
ORCiD: https://orcid.org/0000-0001-7940-8903
Badges
Prescreen
This manuscript passed our Prescreen assessment
Complete author information
Appropriate declaration statements
Potential risks to human health
Prescreen
Peer Review Timeline
CURRENT STATUS: Published
View the published article at Malaria Journal.
No community comments so far
Editorial decision: Accept
On 08 Aug, 2020
Editor assigned
On 04 Aug, 2020
Submission checks complete
On 03 Aug, 2020
Editor invited
On 03 Aug, 2020
No comments provided
Editorial decision: Minor Revision
On 16 Jun, 2020
Editor assigned
On 15 Jun, 2020
Submission checks complete
On 14 Jun, 2020
Editor invited
On 14 Jun, 2020
Version 1
Posted 06 Apr, 2020
No comments provided
Review #2 received
Received 17 May, 2020
Editorial decision: Minor Revision
On 17 May, 2020
Reviewer #3 agreed
On 05 May, 2020
Review #1 received
Received 17 Apr, 2020
Reviewer #2 agreed
On 14 Apr, 2020
Reviewers invited
Invitations sent on 13 Apr, 2020
Reviewer #1 agreed
On 13 Apr, 2020
Editor assigned
On 03 Apr, 2020
First submitted
On 02 Apr, 2020
Submission checks complete
On 02 Apr, 2020
Editor invited
On 02 Apr, 2020
Metrics
Comments: 0
PDF Downloads: ...
HTML Views: ...
Subject Areas
Infectious Diseases
License:
This work is licensed under a CC BY 4.0 License. Read Full License
View the published article at Malaria Journal.
Background Long lasting insecticide nets (LLIN) are the intervention most widely deployed in Sub-Saharan Africa to prevent malaria. Recent reports indicate selection of pyrethroid insecticide resistance is widespread in mosquito vectors. This paper explores the risk factors associated with malaria infection prevalence and vector density between mass distribution campaigns of LLIN in Northern Tanzania.
Methods A cross sectional malaria survey of 3,456 children was undertaken in 2014. Vector density was assessed using indoor light traps and outdoor tent traps. Anophelines were identified to species using PCR and tested for falciparum circumsporozoite protein. Logistic regression was used to identify household and environmental factors associated with malaria infection and vector density.
Results LLIN use was 27.7%. Only 16.9% of households had sufficient nets to cover all sleeping places. Malaria infection was independently associated with access to LLIN (OR: 0.57; 95%CI 0.34 – 0.98), age group, altitude and house construction quality. LLIN less than 2 years old were more protective than older LLIN (53% vs 65% prevalence of infection); however, there was no evidence that LLIN in good condition (hole index <65) were more protective than LLIN which were more holed. Independent risk factors for vector density were consistent with malaria outcomes and included altitude, wind, livestock, house quality, open eaves and LLIN access. Indoor collections comprised 4.6% Anopheles funestus and 95.4% An. gambiae of which 4.5% were An. arabiensis and 93.5% were An. gambiae s.s .
Conclusion Three years after the mass distribution campaign and despite top-ups, LLIN usage had fallen considerably. While children living in households with access to LLIN were at lower risk of malaria, infection prevalence remained high even among users of LLIN in good condition. While effort should be made to maintain high coverage between campaigns, distribution of just standard pyrethroid LLIN appears insufficient to prevent malaria transmission in this area of intense pyrethroid resistance.
Figure 1
This is a list of supplementary files associated with this preprint. Click to download.
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