Ascertainment of Community Exposure Sites to Ross River Virus During the 2020 Outbreak in Brisbane, Australia

TL;DR

During the 2020 lockdown in Brisbane, population movement and area connectivity were key factors in the spread of Ross River virus, with high vegetation density areas showing fewer cases.

Contribution

The study identified how lockdown conditions altered the relationship between vegetation and RRV incidence, emphasizing movement and connectivity as critical risk factors.

Findings

Highly interconnected areas had more RRV cases during lockdown due to population movement.

Areas with high vegetation density had fewer RRV cases during lockdown.

Population movement was a stronger risk factor than environmental conditions in RRV hot spots.

Abstract

This study investigated potential Ross River virus (RRV) exposure sites in Greater Brisbane during the Queensland coronavirus disease 2019 lockdown (January–July 2020). Using RRV notifications, cluster identification techniques, and mobile phone data for movement network analysis, the study examined 993 RRV cases and 9 million movement trajectories from residential RRV cluster areas (hot spots). The findings revealed that population movement was a key risk factor to RRV incidence within hot spots, whereby highly interconnected areas had more RRV cases during lockdown. While environmental conditions within RRV hot spots were less significant compared with their connectivity, areas with higher vegetation density had fewer RRV cases. The study also noted that individuals from RRV hot spots spent less time in green areas before lockdown than during and after lockdown. The results suggest that population movement significantly influenced the 2020 RRV outbreak. These insights can help adapt current vector control and surveillance protocols to target areas identified in this study.

During the coronavirus disease 2019 lockdown, highly connected areas and population movement were risk factors for Ross River virus spread in Brisbane, Australia. Usually, areas with lush vegetation had higher RRV incidence, but during the lockdown we found that this link saturates with very high vegetation cover leadin to less cases, highlighting the importance of connectivity and environmental factors in disease transmission.

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