Potential herd protection against Plasmodium falciparum infections conferred by mass antimalarial drug administrations
- University of California, United States
- Mahidol University, Thailand
- University of Oxford, United kingdom
- University of Montpellier, France
- Centre Hospitalier Universitaire de Montpellier, France
- Harvard University, United States
Figures
Figure 1
Map indicating the locations of the study villages along the Myanmar-Thailand border; and the distribution of houses, mosquito catch sites and malaria posts within study sites.
https://doi.org/10.7554/eLife.41023.003
Figure 2
Clinical P.falciparum episodes (yellow square points) and uPCR-detected P. falciparum infections (blue dots) at house level over time (by survey month; month 0 (M0) through month 24 (M24)) for each of the four study villages.
Statistically significant clusters (detected using SaTScan) are indicated for both clinical episodes (underlying yellow circles) and uPCR-detected infections (underlying blue circles). Grey points …
Figure 3
Spatiotemporal distribution of clinical P.falciparum episodes (yellow square points), uPCR-detected P. falciparum infections (blue dots), and a cluster of non-participation in MDA (grey circle/ochre border, detected using SatScan) in TOT village.
Season is indicated by colored squares in the top right corner of each map. A measure of the spread of clinical P. falciparum cases is given by the standard distance deviation (‘SDD’), indicated by …
Figure 4
Cumulative hazard of having a clinical P. falciparum episode by MDA adherence.
Cumulative hazard for clinical P. falciparum episodes in village TOT by (A) neighborhood MDA adherence (‘low non-adhere’ is a neighborhood with a low proportion of non-adherents; ‘high non-adhere’ …
Appendix 1—figure 1
Clinical P.vivax episodes (yellow square points) and uPCR-detected P. vivax infections (blue dots) at house level over time for each of the four study villages.
Statistically significant clusters (detected using SaTScan) are indicated for both clinical episodes (underlying yellow circles) and PCR-detected infections (underlying blue circles). MDA completion …
Appendix 1— figure 2
Spatial clusters (detecting using SatScan) of non-participation in MDA.
https://doi.org/10.7554/eLife.41023.015
Appendix 1— figure 3
Human biting rate (HBR) for primary vectors by study month.
https://doi.org/10.7554/eLife.41023.016
Appendix 1— figure 4
Unspeciated uPCR-detected infection for each village and survey.
https://doi.org/10.7554/eLife.41023.017
Author response image 1
Tables
Table 1
Multivariable mixed effects logistic regression for odds of having a clinical P. falciparum episode (village TOT only).
The model includes a random intercept for individual participants, with repeat observations occurring within individuals over the study period.
| Covariate | AOR | p-Value |
|---|---|---|
| Age 0 to 4 | Comparison | |
| Age 5 to 14 | 3.41 (1.33–8.77) | 0.0104 |
| Age 15 plus | 2.17 (0.86–5.46) | 0.1053 |
| Female | Comparison | |
| Male | 1.19 (0.66–2.11) | 0.5612 |
| Participated in no rounds of MDA | Comparison | |
| Participated in MDA (at least one round) | 1.43 (0.73–2.78) | 0.2994 |
| No house member with clinical episode | comparison | |
| House member with clinical episode | 3.43 (1.52–7.72) | 0.0004 |
| Low neighborhood non-adherence to MDA | comparison | |
| Mid neighborhood non-adherence to MDA | 2.00 (0.87–4.60) | 0.0879 |
| High neighborhood non-adherence to MDA | 2.85 (1.28–6.37) | 0.0098 |
| Mean village HBR | 1.09 (1.05–1.13) | <0.0001 |
| Study month | 1.19 (1.10–1.27) | <0.0001 |
Table 2
Table of predictor variables (covariates) used in regressions.
https://doi.org/10.7554/eLife.41023.007| Covariate | Level | Description |
| Age group | Individual | Ordinal; age groups: 0 to 4; 5 to 14; and 15 and above |
| Gender | Individual | Binary; male or female |
| Individual adherence to MDA | Individual | Binary; whether an individual participated in MDA or not (at least one full round) |
| Household member with clinical episode | Household | Binary; one if another house member had a clinical episode and 0 if not |
| Household member with uPCR-detected infection | Household | Binary; one if another house member had a uPCR-detected infection and 0 if not |
| Neighborhood MDA non-adherence | Household/neighborhood | Ordinal (split into tertiles); proportion of people within 100 m radius who did not complete all three rounds of MDA |
| Human biting rate (HBR) | Village | Continuous; average number of bites per person per night |
| Study month | Village | Continuous; 1–26 (from May 2013 through June 2015); included as a control |
Appendix 1—table 1
Terciles (lower, middle and upper 1/3) of MDA non-adherence (% taking no rounds of MDA) in TOT
https://doi.org/10.7554/eLife.41023.011| High non-adherence | >0.294 |
| Mid non-adherence | >0.20 and <0.294 |
| Low non-adherence | <0.20 |
Appendix 1—table 2
Multivariable mixed effects logistic regression for odds of having a clinical P. falciparum episode.
The model includes a random intercept for individual participants, with repeat observations occurring within individuals over the study period. Unlike the model in the main text (Table 1) …
| Covariate | AOR | p-value |
|---|---|---|
| Age 0 to 4 | comparison | |
| Age 5 to 14 | 3.5 (1.3–9.0) | 0.0112 |
| Age 15 plus | 2.2 (0.9–5.6) | 0.1014 |
| female | comparison | |
| Male | 1.2 (0.7–2.2) | 0.5147 |
| no house member with clinical episode | comparison | |
| house member with clinical episode | 3.8 (1.8–7.7) | 0.0003 |
| proportion of MDA doses complete | 1.0 (1.0–1.1) | 0.4488 |
| proportion of non-adherers in neighborhood | 1.4 (1.0–1.8) | 0.0380 |
| mean village HBR | 1.1 (1.1–1.1) | <0.0001 |
| study month | 1.2 (1.1–1.3) | <0.0001 |
Appendix 1—table 3
Logistic regression for the odds of having a uPCR-detected P. falciparum infection after MDA.
Individuals in the data were coded as having an infection if they were ever determined by uPCR to have an infection through blood screenings in full village blood surveys after MDA. Almost all P. …
| Covariate | AOR | p-value |
|---|---|---|
| 0 to 4 | comparison | |
| five to 14 | 6.1 (1.1–113.9) | 0.0877 |
| 15 plus | 5.5 (1.1–99.3) | 0.1017 |
| female | comparison | |
| male | 1.3 (0.6–2.7) | 0.5217 |
| participated in no rounds of MDA | comparison | |
| participated in MDA (at least one round) | 0.4 (0.2–1.1) | 0.0955 |
| no house member with uPCR infection | comparison | |
| house member with uPCR infection | 1.1 (0.4–2.7) | 0.8039 |
| no house member with clinical episode | comparison | |
| house member with clinical episode | 1.7 (0.7–3.8) | 0.2029 |
| low neighborhood non-adherence to MDA | comparison | |
| mid neighborhood non-adherence to MDA | 1.1 (0.4–3.2) | 0.8743 |
| high neighborhood non-adherence to MDA | 2.6 (1.0–7.1) | 0.0488 |
| number of surveys attended | 1.3 (1.1–1.6) | 0.0075 |
Appendix 1—table 4
Multivariable mixed effects logistic regression for odds of having a clinical P. vivax episode.
The model includes a random intercept for individual participants, with repeat observations occurring within individuals over the study period. Study month was included as a control (a linear …
| Covariate | AOR | p-value |
|---|---|---|
| Age 0 to 4 | comparison | |
| Age 5 to 14 | 1.0 (0.4–2.4) | 0.9945 |
| Age 15 plus | 0.4 (0.2–0.9) | 0.0358 |
| female | comparison | |
| male | 0.8 (0.4–1.5) | 0.4687 |
| participated in no rounds of MDA | comparison | |
| participated in MDA (at least one round) | 1.7 (0.7–4.3) | 0.2678 |
| no house member with clinical episode | comparison | |
| house member with clinical episode | 5.8 (3.4–9.9) | <0.0001 |
| low neighborhood non-adherence to MDA | comparison | |
| mid neighborhood non-adherence to MDA | 1.6 (0.3–7.6) | 0.5546 |
| high neighborhood non-adherence to MDA | 1.8 (0.3–9.8) | 0.5205 |
| mean village HBR | 1.0 (1.0–1.1) | 0.1447 |
| village KNH | comparison | |
| village TPN | 0.6 (0.2–1.8) | 0.3666 |
| village HKT | 0.3 (0.1–1.5) | 0.1329 |
| village TOT | 0.6 (0.1–3.4) | 0.6074 |
| study month | 1.0 (1.0–1.1) | 0.0126 |
Appendix 1—table 5
Multivariable logistic regression for the odds of having a uPCR detected P. vivax infection after MDA.
Individuals in the data were coded as having an infection of either species if they were ever determined by uPCR to have an infection through blood screenings in full village blood surveys after MDA.
| Covariate | AOR | p-value |
|---|---|---|
| 0 to 4 | comparison | |
| five to 14 | 2.6 (1.7–3.9) | <0.0001 |
| 15 plus | 2.1 (1.4–3.2) | 0.0002 |
| female | comparison | |
| male | 1.8 (1.4–2.2) | <0.0001 |
| participated in no rounds of MDA | comparison | |
| participated in MDA (at least one round) | 0.6 (0.4–0.8) | 0.0027 |
| no house member with uPCR infection | comparison | |
| house member with uPCR infection | 1.5 (1.2–1.9) | 0.0022 |
| no house member with clinical episode | comparison | |
| house member with clinical episode | 1.3 (1.0–1.7) | 0.0284 |
| low neighborhood non-adherence to MDA | comparison | |
| mid neighborhood non-adherence to MDA | 0.6 (0.4–1.1) | 0.0994 |
| high neighborhood non-adherence to MDA | 0.6 (0.4–1.1) | 0.0945 |
| KNH | comparison | |
| TPN | 1.0 (0.7–1.5) | 0.8617 |
| HKT | 1.4 (0.8–2.5) | 0.2614 |
| TOT | 5.4 (2.9–9.8) | <0.0001 |
| number of surveys attended | 1.4 (1.3–1.5) | <0.0001 |
Appendix 1—table 6
Household and population counts for study villages
Data used in this analysis are available following the Mahidol-Oxford Tropical Medicine Research Unit data access policy. Both the policy and application form are available at: http://www.tropmedres.…
| Village | Households | Population |
|---|---|---|
| KNH | 86 | 504 |
| TPN | 75 | 468 |
| HKT | 176 | 1338 |
| TOT | 149 | 919 |
| total | 486 | 3229 |
Additional files
-
Transparent reporting form
- https://doi.org/10.7554/eLife.41023.009
