Life table analysis of Anopheles balabacensis, the primary vector of Plasmodium knowlesi in Sabah, Malaysia

Vector-borne diseases on Borneo island: a scoping review

BACKGROUND

Borneo, the third largest island in the world, is facing a significant burden of emerging and re-emerging vector-borne diseases due to rapid changes in primary tropical rainforests and urban landscapes. These vector-borne diseases include the endemic epidemic cycles that occur in the more populated and urbanized areas, as well as the possible transmission through enzootic and sylvatic transmission cycles that occur mainly in the overlapping landscapes or among the indigenous population in the forest. The island will be changed significantly in the future due to the increase in human activities, especially mega events such as the relocation of the Indonesian capital to Nusantara in East Kalimantan Borneo, increasing urbanization, agriculture, hydropower projects, ecotourism activities in Sabah, North Borneo, and Sarawak, Central and South Borneo. Therefore, an overview of the current situation of vector-borne diseases is crucial for the next possible epidemic preparedness.

METHODS

This study conducted the PRISMA-ScR scoping review and formulated a set of research questions to identify current trends in vector-borne diseases in Borneo. These questions aim to identify which diseases have been studied, what geographical areas have been covered by the research, how the One Health approach-encompassing human, animal and environmental factors-is integrated, and what gaps and challenges exist in addressing these diseases.

RESULTS

A total of 2241 references were screened for eligibility and 117 articles were selected for review. The majority of the materials focused on mosquitoes and malaria, and the One Health elements focused mainly on humans.

CONCLUSIONS

This review has identified the most and least studied vector-borne diseases and highlighted some of the gaps in knowledge and research on vector-borne diseases on the island of Borneo. Future studies should particularly focus on other neglected diseases such as Zika, chikungunya, Japanese encephalitis, filariasis and tick-borne diseases. In addition, advanced surveillance systems will be developed to improve early detection and response specifically for remote regions where vector-borne diseases are endemic or emerging.

Forest Restoration and the Zoonotic Vector Anopheles balabacensis in Sabah, Malaysia

Anthropogenic changes to forest cover have been linked to an increase in zoonotic diseases. In many areas, natural forests are being replaced with monoculture plantations, such as oil palm, which reduce biodiversity and create a mosaic of landscapes with increased forest edge habitat and an altered micro-climate. These altered conditions may be facilitating the spread of the zoonotic malaria parasite Plasmodium knowlesi in Sabah, on the island of Borneo, through changes to mosquito vector habitat. We conducted a study on mosquito abundance and diversity in four different land uses comprising restored native forest, degraded native forest, an oil palm estate and a eucalyptus plantation, these land uses varying in their vegetation types and structure. The main mosquito vector, Anopheles balabacensis, has adapted its habitat preference from closed canopy rainforest to more open logged forest and plantations. The eucalyptus plantations (Eucalyptus pellita) assessed in this study contained significantly higher abundance of many mosquito species compared with the other land uses, whereas the restored dipterocarp forest had a low abundance of all mosquitos, in particular, An. balabacensis. No P. knowlesi was detected by PCR assay in any of the vectors collected during the study; however, P. inui, P. fieldi and P. vivax were detected in An. balabacensis. These findings indicate that restoring degraded natural forests with native species to closed canopy conditions reduces abundance of this zoonotic malarial mosquito vector and therefore should be incorporated into future restoration research and potentially contribute to the control strategies against simian malaria.

Analysis of Malaria Transmission Dynamics at Borobudur Health Center, Magelang Regency (Case Study 2021-2022)

Introduction: Magelang District received a malaria elimination certificate in 2014. No cases found at Borobudur Health Center since 2009 but in October 2021, there was a spike in the number of patients, with 38 instances spread across Giripurno Village, Giritengah Village, and Majaksingi Village. Therefore, it is necessary to study the dynamics of malaria transmission so that the methods of malaria transmission are known to prevent extraordinary malaria cases. Methods: This is qualitative research with a phenomenological approach. This study was conducted in 2023 by reviewing cases from 2021–2022. The respondents in this study included 38 people with malaria. This research uses descriptive analysis assisted by GIS applications to determine the distribution of malaria cases. Results and Discussion: Data processing results for 38 respondents in three villages revealed 23 index cases. Of the 23 cases, nine were within a radius of no more than 400 m and occurred within three days, thus including cluster classification. Theoretically, the same vector transmits it and has a high vectorial capacity. The other 15 patients were suspected to have secondary cases, with two transferred from the first case. The results of the breeding place survey or the potential breeding place after rearing revealed the species Anopheles balabacensis. Other predictors of malaria transmission are optimal temperature and humidity, environment, livestock places to rest mosquitoes, and patient behavior that causes a high frequency of mosquitoes biting humans. Conclusion: In this case, the transmission model was a cluster, and 100% of the cases were indigenous.