Malaria early warning tool: linking inter-annual climate and malaria variability in northern Guadalcanal, Solomon Islands
Abstract Background Malaria control remains a significant challenge in the Solomon Islands. Despite progress made by local malaria control agencies over the past decade, case rates remain high in some areas of the country. Studies from around the world have confirmed important links between climate...
| Main Authors: | , , , , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
BMC
2017-11-01
|
| Series: | Malaria Journal |
| Subjects: | |
| Online Access: | http://link.springer.com/article/10.1186/s12936-017-2120-5 |
| _version_ | 1818150091693752320 |
|---|---|
| author | Jason Smith Lloyd Tahani Albino Bobogare Hugo Bugoro Francis Otto George Fafale David Hiriasa Adna Kazazic Grant Beard Amanda Amjadali Isabelle Jeanne |
| author_facet | Jason Smith Lloyd Tahani Albino Bobogare Hugo Bugoro Francis Otto George Fafale David Hiriasa Adna Kazazic Grant Beard Amanda Amjadali Isabelle Jeanne |
| author_sort | Jason Smith |
| collection | DOAJ |
| description | Abstract Background Malaria control remains a significant challenge in the Solomon Islands. Despite progress made by local malaria control agencies over the past decade, case rates remain high in some areas of the country. Studies from around the world have confirmed important links between climate and malaria transmission. This study focuses on understanding the links between malaria and climate in Guadalcanal, Solomon Islands, with a view towards developing a climate-based monitoring and early warning for periods of enhanced malaria transmission. Methods Climate records were sourced from the Solomon Islands meteorological service (SIMS) and historical malaria case records were sourced from the National Vector-Borne Disease Control Programme (NVBDCP). A declining trend in malaria cases over the last decade associated with improved malaria control was adjusted for. A stepwise regression was performed between climate variables and climate-associated malaria transmission (CMT) at different lag intervals to determine where significant relationships existed. The suitability of these results for use in a three-tiered categorical warning system was then assessed using a Mann–Whitney U test. Results Of the climate variables considered, only rainfall had a consistently significant relationship with malaria in North Guadalcanal. Optimal lag intervals were determined for prediction using R2 skill scores. A highly significant negative correlation (R = − 0.86, R2 = 0.74, p < 0.05, n = 14) was found between October and December rainfall at Honiara and CMT in northern Guadalcanal for the subsequent January–June. This indicates that drier October–December periods are followed by higher malaria transmission periods in January–June. Cross-validation emphasized the suitability of this relationship for forecasting purposes $${\text{R}}^{2}{_{\text{LOOCV}}} = 0. 6 3$$ R 2 LOOCV = 0.63 as did Mann–Whitney U test results showing that rainfall below or above specific thresholds was significantly associated with above or below normal malaria transmission, respectively. Conclusion This study demonstrated that rainfall provides the best predictor of malaria transmission in North Guadalcanal. This relationship is thought to be underpinned by the unique hydrological conditions in northern Guadalcanal which allow sandbars to form across the mouths of estuaries which act to develop or increase stagnant brackish marshes in low rainfall periods. These are ideal habitats for the main mosquito vector, Anopheles farauti. High rainfall accumulations result in the flushing of these habitats, reducing their viability. The results of this study are now being used as the basis of a malaria early warning system which has been jointly implemented by the SIMS, NVBDCP and the Australian Bureau of Meteorology. |
| first_indexed | 2024-12-11T13:17:25Z |
| format | Article |
| id | doaj.art-483938ef7a7a4c139a8421490f550872 |
| institution | Directory Open Access Journal |
| issn | 1475-2875 |
| language | English |
| last_indexed | 2024-12-11T13:17:25Z |
| publishDate | 2017-11-01 |
| publisher | BMC |
| record_format | Article |
| series | Malaria Journal |
| spelling | doaj.art-483938ef7a7a4c139a8421490f5508722022-12-22T01:06:00ZengBMCMalaria Journal1475-28752017-11-0116111610.1186/s12936-017-2120-5Malaria early warning tool: linking inter-annual climate and malaria variability in northern Guadalcanal, Solomon IslandsJason Smith0Lloyd Tahani1Albino Bobogare2Hugo Bugoro3Francis Otto4George Fafale5David Hiriasa6Adna Kazazic7Grant Beard8Amanda Amjadali9Isabelle Jeanne10Australian Bureau of MeteorologySolomon Islands Meteorological ServiceNational Vector Borne Disease Control ProgrammeNational Vector Borne Disease Control ProgrammeNational Vector Borne Disease Control ProgrammeNational Vector Borne Disease Control ProgrammeSolomon Islands Meteorological ServiceAustralian Bureau of MeteorologyAustralian Bureau of MeteorologyAustralian Bureau of MeteorologyAustralian Bureau of MeteorologyAbstract Background Malaria control remains a significant challenge in the Solomon Islands. Despite progress made by local malaria control agencies over the past decade, case rates remain high in some areas of the country. Studies from around the world have confirmed important links between climate and malaria transmission. This study focuses on understanding the links between malaria and climate in Guadalcanal, Solomon Islands, with a view towards developing a climate-based monitoring and early warning for periods of enhanced malaria transmission. Methods Climate records were sourced from the Solomon Islands meteorological service (SIMS) and historical malaria case records were sourced from the National Vector-Borne Disease Control Programme (NVBDCP). A declining trend in malaria cases over the last decade associated with improved malaria control was adjusted for. A stepwise regression was performed between climate variables and climate-associated malaria transmission (CMT) at different lag intervals to determine where significant relationships existed. The suitability of these results for use in a three-tiered categorical warning system was then assessed using a Mann–Whitney U test. Results Of the climate variables considered, only rainfall had a consistently significant relationship with malaria in North Guadalcanal. Optimal lag intervals were determined for prediction using R2 skill scores. A highly significant negative correlation (R = − 0.86, R2 = 0.74, p < 0.05, n = 14) was found between October and December rainfall at Honiara and CMT in northern Guadalcanal for the subsequent January–June. This indicates that drier October–December periods are followed by higher malaria transmission periods in January–June. Cross-validation emphasized the suitability of this relationship for forecasting purposes $${\text{R}}^{2}{_{\text{LOOCV}}} = 0. 6 3$$ R 2 LOOCV = 0.63 as did Mann–Whitney U test results showing that rainfall below or above specific thresholds was significantly associated with above or below normal malaria transmission, respectively. Conclusion This study demonstrated that rainfall provides the best predictor of malaria transmission in North Guadalcanal. This relationship is thought to be underpinned by the unique hydrological conditions in northern Guadalcanal which allow sandbars to form across the mouths of estuaries which act to develop or increase stagnant brackish marshes in low rainfall periods. These are ideal habitats for the main mosquito vector, Anopheles farauti. High rainfall accumulations result in the flushing of these habitats, reducing their viability. The results of this study are now being used as the basis of a malaria early warning system which has been jointly implemented by the SIMS, NVBDCP and the Australian Bureau of Meteorology.http://link.springer.com/article/10.1186/s12936-017-2120-5MalariaSolomon IslandsGuadalcanalClimateRainfallEarly warning |
| spellingShingle | Jason Smith Lloyd Tahani Albino Bobogare Hugo Bugoro Francis Otto George Fafale David Hiriasa Adna Kazazic Grant Beard Amanda Amjadali Isabelle Jeanne Malaria early warning tool: linking inter-annual climate and malaria variability in northern Guadalcanal, Solomon Islands Malaria Journal Malaria Solomon Islands Guadalcanal Climate Rainfall Early warning |
| title | Malaria early warning tool: linking inter-annual climate and malaria variability in northern Guadalcanal, Solomon Islands |
| title_full | Malaria early warning tool: linking inter-annual climate and malaria variability in northern Guadalcanal, Solomon Islands |
| title_fullStr | Malaria early warning tool: linking inter-annual climate and malaria variability in northern Guadalcanal, Solomon Islands |
| title_full_unstemmed | Malaria early warning tool: linking inter-annual climate and malaria variability in northern Guadalcanal, Solomon Islands |
| title_short | Malaria early warning tool: linking inter-annual climate and malaria variability in northern Guadalcanal, Solomon Islands |
| title_sort | malaria early warning tool linking inter annual climate and malaria variability in northern guadalcanal solomon islands |
| topic | Malaria Solomon Islands Guadalcanal Climate Rainfall Early warning |
| url | http://link.springer.com/article/10.1186/s12936-017-2120-5 |
| work_keys_str_mv | AT jasonsmith malariaearlywarningtoollinkinginterannualclimateandmalariavariabilityinnorthernguadalcanalsolomonislands AT lloydtahani malariaearlywarningtoollinkinginterannualclimateandmalariavariabilityinnorthernguadalcanalsolomonislands AT albinobobogare malariaearlywarningtoollinkinginterannualclimateandmalariavariabilityinnorthernguadalcanalsolomonislands AT hugobugoro malariaearlywarningtoollinkinginterannualclimateandmalariavariabilityinnorthernguadalcanalsolomonislands AT francisotto malariaearlywarningtoollinkinginterannualclimateandmalariavariabilityinnorthernguadalcanalsolomonislands AT georgefafale malariaearlywarningtoollinkinginterannualclimateandmalariavariabilityinnorthernguadalcanalsolomonislands AT davidhiriasa malariaearlywarningtoollinkinginterannualclimateandmalariavariabilityinnorthernguadalcanalsolomonislands AT adnakazazic malariaearlywarningtoollinkinginterannualclimateandmalariavariabilityinnorthernguadalcanalsolomonislands AT grantbeard malariaearlywarningtoollinkinginterannualclimateandmalariavariabilityinnorthernguadalcanalsolomonislands AT amandaamjadali malariaearlywarningtoollinkinginterannualclimateandmalariavariabilityinnorthernguadalcanalsolomonislands AT isabellejeanne malariaearlywarningtoollinkinginterannualclimateandmalariavariabilityinnorthernguadalcanalsolomonislands |