Baseline spatial distribution of malaria prior to an elimination programme in Vanuatu

Reid, Heidi, Vallely, Andrew, Taleo, George, Tatem, Andrew J., Kelly, Gerard, Riley, Ian, Harris, Ivor, Henri, Iata, Iamaher, Sam and Clements, Archie C. A . (2010) Baseline spatial distribution of malaria prior to an elimination programme in Vanuatu. Malaria Journal, 9 1: 1-9. doi:10.1186/1475-2875-9-150


Author Reid, Heidi
Vallely, Andrew
Taleo, George
Tatem, Andrew J.
Kelly, Gerard
Riley, Ian
Harris, Ivor
Henri, Iata
Iamaher, Sam
Clements, Archie C. A .
Title Baseline spatial distribution of malaria prior to an elimination programme in Vanuatu
Journal name Malaria Journal   Check publisher's open access policy
ISSN 1475-2875
Publication date 2010
Sub-type Article (original research)
DOI 10.1186/1475-2875-9-150
Open Access Status DOI
Volume 9
Issue 1
Start page 1
End page 9
Total pages 9
Place of publication London, United Kingdom
Publisher BioMed Central
Collection year 2011
Language eng
Formatted abstract
Background

The Ministry of Health in the Republic of Vanuatu has implemented a malaria elimination programme in Tafea Province, the most southern and eastern limit of malaria transmission in the South West Pacific. Tafea Province is comprised of five islands with malaria elimination achieved on one of these islands (Aneityum) in 1998. The current study aimed to establish the baseline distribution of malaria on the most malarious of the province's islands, Tanna Island, to guide the implementation of elimination activities.

Methods

A parasitological survey was conducted in Tafea Province in 2008. On Tanna Island there were 4,716 participants from 220 villages, geo-referenced using a global position system. Spatial autocorrelation in observed prevalence values was assessed using a semivariogram. Backwards step-wise regression analysis was conducted to determine the inclusion of environmental and climatic variables into a prediction model. The Bayesian geostatistical logistic regression model was used to predict malaria risk, and associated uncertainty across the island.

Results

Overall, prevalence on Tanna was 1.0% for Plasmodium falciparum (accounting for 32% of infections) and 2.2% for Plasmodium vivax (accounting for 68% of infections). Regression analysis showed significant association with elevation and distance to coastline for P. vivax and P. falciparum, but no significant association with NDVI or TIR.
Colinearity was observed between elevation and distance to coastline with the later variable included in the final Bayesian geostatistical model for P. vivax and the former included in the final model for P. falciparum. Model validation statistics revealed that the final Bayesian geostatistical model had good predictive ability.

Conclusion

Malaria in Tanna Island, Vanuatu, has a focal and predominantly coastal distribution. As Vanuatu refines its elimination strategy, malaria risk maps represent an invaluable resource in the strategic planning of all levels of malaria interventions for the island.
© 2010 Reid et al; licensee BioMed Central Ltd.

Keyword Plasmodium falciparum
Incidence rates
Bayes theorem
Vanuatu
Malaria falciparum
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes This is an Open Access article: Article number 150, 9 p.

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2011 Collection
School of Public Health Publications
 
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Created: Sun, 18 Jul 2010, 00:03:19 EST