08 Feb 2018

Environmental Factors and an Eco-epidemiological Model of Malaria in Indonesia

Ermi M. L. Ndoen
Griffith University

Abstract

Indonesia is one of the countries in Southeast Asia where malaria is a prominent public health concern with an estimated 15 million malaria cases annually and 42,000 deaths. The study explores the environmental risk factors of malaria guided by an eco epidemiological model of malaria transmission. A longitudinal and cross sectional approach has been employed for data gathering of the environmental variables, spatial and temporal patterns of malaria transmission, malaria vectors behaviour and human risk factors of malaria transmission in Indonesia.

Three different regions in Indonesia were used for the study. The first area is West Timor which has the highest malaria incidence in Indonesia. The second location is Sukabumi District of West Java, which had a malaria outbreak in 2003. The final location is Kebumen District of Central Java, which has one of the highest malaria pocket areas in Java. All areas were divided into three different topographical settings – coastal, hilly and highland areas.

In  each  study  areas,  the  environmental  data  were  analysed  using  t-test,  ANOVA,  Pearson Correlation, and General Linear Model Repeated Measures. Further, LISA (Local Indicators of Spatial Association) analysis using GIS was employed to explore local malaria spatial distribution and generate malaria maps for the malaria transmission areas based on the local spatial association.

Adult mosquito (Anopheles spp) surveys were used to explore malaria vectors behaviour in different areas and different topographical settings. Finally, an interview program was used to collect data in order to understand human risk factors in malaria transmission. Human risk factors data were calculated using χ2 and logistic regression.

The results show that 100% of West Timor’s villages are in malaria endemic areas. Villages on the district boundary zones had more malaria than non-boundary villages. The number of rainy days had a significant positive correlation to malaria incidence. Humidity also had a significant positive correlation to malaria incidence. Altitude and maximum temperature had a significant negative correlation with malaria cases.

In Sukabumi, West Java, altitude was not significantly correlated with malaria incidence. The risk of being infected with malaria was similar for respondents in coastal and highland areas. Rainfall, temperature, and wind speed were also not significantly correlated to malaria incidence in Sukabumi.

In Kebumen, Central Java, rainfall patterns did not have a significant correlation with malaria incidence. Altitude, however, showed a significant correlation with malaria incidence, where more cases occurred at an altitude between 60 m and 200 m above sea level. Malaria incidence was higher in village than urban areas in all West Timor, West Java and Central Java. Number of very high-risk malaria villages was higher in dry than wet seasons in all areas.

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