Zoonotic Malaria and land use in Indonesia

The challenge

An emerging parasite of macaque and human malaria in Southeast Asia

Critical information regarding the transmission dynamics of zoonotic malaria caused by Plasmodium knowlesi, in Southeast Asia, remains unknown. The parasite requires as warm-blooded and affects macaques and then humans.

In this context we are interested in critical linkages between environmental health and human health in Indonesia.

Deforestation and subsequent use of the land for plantations or crops for example can increase macaque-human interactions if occurring near settlements or in areas frequently visited by agricultural workers.

The parasite also affects people engaging in activities associated with palm oil plantations and vegetation clearing and households with higher encounters of macaques.

The new landscape patterns and land use after deforestation can also facilitate increases in mosquito populations near human settlements. 

Our response

Evaluation of agricultural and land use factors associated with zoonotic malaria transmission.

We contribute to a One Health project that evaluates risk factors for zoonotic malaria in humans across Indonesia and agricultural and forestry land use change.

We analyse critical indicators of land use change trends and landscape complexity in two Indonesian provinces: North Sumatra and North Kalimantan.

Our analysis includes: 

• Deforestation rates 1990 to 2015 and 2017 to 2021
• Forest area converted to agricultural land and plantations
• Landscape shape complexity measures
• Percent of oil palm plantations in landscape.

The spatial scale for this analysis ranges from household level to project site and regencies, which are Indonesia’s second level administrative units.

For high spatial resolution we use publicly available land use and cover maps based on 10-m Sentinel-2 satellite imagery, oil palm plantation maps and the national landcover map of Indonesia.

This project is led by the Menzies School of Health Research and funded by the Australian Centre for International Agricultural Research (ACIAR).

Other project partners are the Eijkman Institute for Molecular Biology in the Indonesia University of Sumatera Utara, James Cook University, the University of Melbourne, the University of Western Australia and the Ministry of Health in Indonesia.

The results

Key trends in land use change and deforestation

Each study site differs in landscape composition and deforestation rates. Industrial and smallholder oil palm plantations account for about 10 to 17 per cent of land use in the study sites in North Kalimantan, but for only three to twelve per cent of land use in North Sumatra.

Deforestation rates have been higher in the period 1990 to 2015, than between 2017 and 2021. Deforestation rates between 1990 and 2015 were 3 per cent to 14 per cent in North Kalimantan and up to 14 per cent in North Sumatra except for small areas in the southeast of one study sites where all primary forest area was lost.

Between 2017 and 2021 tree cover has increased in five out of the six study sites, with the strongest increases in North Sumatra.

The project is ongoing and there are opportunities to use the information on land use land cover changes and landscape complexity to provide additional information on environmental and agricultural factors explaining risk exposure to malaria parasites, for example the absence or presence of specific land use classes that are expected to increase exposure.

This can be aggregated to the population level for each study site to compare risk factors.