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Evaluation of ivermectin mass drug administration for malaria transmission control across different West African environments.

Alout H, Krajacich BJ, Meyers JI, Grubaugh ND, Brackney DE, Kobylinski KC, Diclaro JW, Bolay FK, Fakoli LS, Diabaté A, Dabiré RK, Bougma RW, Foy BD - Malar. J. (2014)

Bottom Line: The effect of MDA was then analysed against the time relative to the MDA, the distributed drugs and environmental variables.Anopheles gambiae survivorship was reduced by 33.9% for one week following MDA and parity rates were significantly reduced for more than two weeks after the MDAs.These data provide a comprehensive and crucial evidence base for the significant reduction in malaria transmission following single ivermectin MDAs across diverse field sites.

View Article: PubMed Central - PubMed

Affiliation: Arthropod-borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO, USA. haoues.alout@colostate.edu.

ABSTRACT

Background: Mass drug administration (MDA) of ivermectin to humans for control and elimination of filarial parasites can kill biting malaria vectors and lead to Plasmodium transmission reduction. This study examines the degree and duration of mosquitocidal effects resulting from single MDAs conducted in three different West African countries, and the subsequent reductions in parity and Plasmodium sporozoite rates.

Methods: Indoor-resting, blood-fed and outdoor host-seeking Anopheles spp. were captured on days surrounding MDAs from 2008-2013 in Senegalese, Liberian and Burkinabé villages. Mortality was assessed on a portion of the indoor collection, and parity status was determined on host-seeking mosquitoes. The effect of MDA was then analysed against the time relative to the MDA, the distributed drugs and environmental variables.

Results: Anopheles gambiae survivorship was reduced by 33.9% for one week following MDA and parity rates were significantly reduced for more than two weeks after the MDAs. Sporozoite rates were significantly reduced by >77% for two weeks following the MDAs in treatment villages despite occurring in the middle of intense transmission seasons. These observed effects were consistent across three different West African transmission dynamics.

Conclusions: These data provide a comprehensive and crucial evidence base for the significant reduction in malaria transmission following single ivermectin MDAs across diverse field sites. Despite the limited duration of transmission reduction, these results support the hypothesis that repeated MDAs with optimal timing could help sustainably control malaria as well as filarial transmission.

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Related in: MedlinePlus

Mosquito parity rate over time in treated and control villages. Significant differences in parity rates between the control (blue bars) and the treated villages (red bars) are denoted by stars above the column pairs and derived using a Chi-squared test (N.S. = not significant). Error bars are the standard error of the mean. Sample sizes were 103 and 119 pre-MDA, 55 and 75 on week 1, 62 and 50 on week 2 and 107 and 136 on week 3 in the control and the treated villages, respectively.
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Fig2: Mosquito parity rate over time in treated and control villages. Significant differences in parity rates between the control (blue bars) and the treated villages (red bars) are denoted by stars above the column pairs and derived using a Chi-squared test (N.S. = not significant). Error bars are the standard error of the mean. Sample sizes were 103 and 119 pre-MDA, 55 and 75 on week 1, 62 and 50 on week 2 and 107 and 136 on week 3 in the control and the treated villages, respectively.

Mentions: Figure 2 represents the variation in parity rate by week and shows no significant variation over time in the control village (χ2df=3 = 3.96, p = 0.265, N = 327), ranging between 80 and 89.72% (mean of 85.4% ±2.3). In contrast, the proportion of parous female An. gambiae s.l. varied significantly over time in the treated village (χ2df=3 = 14.36, p = 0.0024, N = 380). While 80.7% ±3.6 of host-seeking females were parous before MDA in the treatment village and showed no significant difference with the control village (χ2df=1 = 0.033, p = 0.856, N = 222), this proportion significantly decreased to 60.0% ±5.6 (χ2df=1 = 4.98, p = 0.0255, N = 130) over the first week post-MDA and to 58.0% ±7.0 (N = 50, χ2df=1 = 5.78, p = 0.0161, N = 112) over the second week post-MDA. By the third week post-MDA, the parity rate in the treated villages increased to 73.5% ±3.8 but remained significantly lower than in the control villages (χ2df=1 = 9.05, p = 0.0026, N = 243).Figure 2


Evaluation of ivermectin mass drug administration for malaria transmission control across different West African environments.

Alout H, Krajacich BJ, Meyers JI, Grubaugh ND, Brackney DE, Kobylinski KC, Diclaro JW, Bolay FK, Fakoli LS, Diabaté A, Dabiré RK, Bougma RW, Foy BD - Malar. J. (2014)

Mosquito parity rate over time in treated and control villages. Significant differences in parity rates between the control (blue bars) and the treated villages (red bars) are denoted by stars above the column pairs and derived using a Chi-squared test (N.S. = not significant). Error bars are the standard error of the mean. Sample sizes were 103 and 119 pre-MDA, 55 and 75 on week 1, 62 and 50 on week 2 and 107 and 136 on week 3 in the control and the treated villages, respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4226880&req=5

Fig2: Mosquito parity rate over time in treated and control villages. Significant differences in parity rates between the control (blue bars) and the treated villages (red bars) are denoted by stars above the column pairs and derived using a Chi-squared test (N.S. = not significant). Error bars are the standard error of the mean. Sample sizes were 103 and 119 pre-MDA, 55 and 75 on week 1, 62 and 50 on week 2 and 107 and 136 on week 3 in the control and the treated villages, respectively.
Mentions: Figure 2 represents the variation in parity rate by week and shows no significant variation over time in the control village (χ2df=3 = 3.96, p = 0.265, N = 327), ranging between 80 and 89.72% (mean of 85.4% ±2.3). In contrast, the proportion of parous female An. gambiae s.l. varied significantly over time in the treated village (χ2df=3 = 14.36, p = 0.0024, N = 380). While 80.7% ±3.6 of host-seeking females were parous before MDA in the treatment village and showed no significant difference with the control village (χ2df=1 = 0.033, p = 0.856, N = 222), this proportion significantly decreased to 60.0% ±5.6 (χ2df=1 = 4.98, p = 0.0255, N = 130) over the first week post-MDA and to 58.0% ±7.0 (N = 50, χ2df=1 = 5.78, p = 0.0161, N = 112) over the second week post-MDA. By the third week post-MDA, the parity rate in the treated villages increased to 73.5% ±3.8 but remained significantly lower than in the control villages (χ2df=1 = 9.05, p = 0.0026, N = 243).Figure 2

Bottom Line: The effect of MDA was then analysed against the time relative to the MDA, the distributed drugs and environmental variables.Anopheles gambiae survivorship was reduced by 33.9% for one week following MDA and parity rates were significantly reduced for more than two weeks after the MDAs.These data provide a comprehensive and crucial evidence base for the significant reduction in malaria transmission following single ivermectin MDAs across diverse field sites.

View Article: PubMed Central - PubMed

Affiliation: Arthropod-borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO, USA. haoues.alout@colostate.edu.

ABSTRACT

Background: Mass drug administration (MDA) of ivermectin to humans for control and elimination of filarial parasites can kill biting malaria vectors and lead to Plasmodium transmission reduction. This study examines the degree and duration of mosquitocidal effects resulting from single MDAs conducted in three different West African countries, and the subsequent reductions in parity and Plasmodium sporozoite rates.

Methods: Indoor-resting, blood-fed and outdoor host-seeking Anopheles spp. were captured on days surrounding MDAs from 2008-2013 in Senegalese, Liberian and Burkinabé villages. Mortality was assessed on a portion of the indoor collection, and parity status was determined on host-seeking mosquitoes. The effect of MDA was then analysed against the time relative to the MDA, the distributed drugs and environmental variables.

Results: Anopheles gambiae survivorship was reduced by 33.9% for one week following MDA and parity rates were significantly reduced for more than two weeks after the MDAs. Sporozoite rates were significantly reduced by >77% for two weeks following the MDAs in treatment villages despite occurring in the middle of intense transmission seasons. These observed effects were consistent across three different West African transmission dynamics.

Conclusions: These data provide a comprehensive and crucial evidence base for the significant reduction in malaria transmission following single ivermectin MDAs across diverse field sites. Despite the limited duration of transmission reduction, these results support the hypothesis that repeated MDAs with optimal timing could help sustainably control malaria as well as filarial transmission.

Show MeSH
Related in: MedlinePlus