# Added Value of Sensor-Based Behavioural Monitoring in an Infectious Disease Study with Sheep Infected with Toxoplasma gondii

## TL;DR

This study shows how sensors can continuously and individually track behavior in sheep infected with Toxoplasma gondii, offering more detailed insights than traditional methods.

## Contribution

The study demonstrates the added value of accelerometers and video for individual-level, continuous behavioral monitoring in infectious disease research.

## Key findings

- Sensor technologies provided 24/7 behavioral records, unlike bidaily human observations.
- Each sheep reduced drinking time by 50% after infection, revealed only by sensors.
- Activity levels dropped by 20–40% after infection, with objective daytime activity patterns captured.

## Abstract

The aim of this study was to investigate the added value of two sensor technologies (accelerometers and video) to monitor the activity and drinking behaviour of three sheep infected with the parasite Toxoplasma gondii. We found that the sensor technologies offered additional insights as compared to routine observations. First, they provided 24/7 behavioural records, instead of the bidaily snapshots from human observations. Second, they provided individual data. For example, they showed that each sheep spent 50% less time at the drinker after infection, while the traditional water meter gave only results at the group level. Third, they provided a quantitative measure. For example, they showed that each sheep was from 20% to 40% less active after the infection, while the animal caretakers only scored whether animals were lethargic or not. Last, they provided objective behavioural patterns. For example, they showed that daytime activity was reduced from day 4 to day 10 after infection, while the caretakers only recorded that the sheep were lethargic from day 5 to day 7. While we recognize the challenges and pitfalls of sensor technologies, we recommend wider implementation in animal disease trials to refine experiments and guarantee the quality of their results.

Sensor technologies are increasingly used to monitor laboratory animal behaviour. The aim of this study was to investigate the added value of using accelerometers and video to monitor the activity and drinking behaviour of three rams from 5 days before to 22 days after inoculation with Toxoplasma gondii. We computed the activity from accelerometer data as the vectorial dynamic body acceleration (VDBA). In addition, we assessed individual drinking behaviour from video, using frame differencing above the drinker to identify drinking bouts, and Aruco markers for individual identification. Four days after inoculation, rams developed fever and activity decreased. The daytime VDBA from days 4 to 10 was 60–80% of that before inoculation. Animal caretakers scored rams as lethargic on days 5 and 6 and, for one ram, also on the morning of day 7. Video analysis showed that each ram decreased its number of visits to the drinker, as well as its time spent at the drinker, by up to 50%. The fever and corresponding sickness behaviours lasted until day 10. Overall, while we recognize the limited conclusiveness due to the small number of animals, the sensor technologies provided continuous, individual, detailed, and objective data and offered additional insights as compared to routine observations. We recommend the wider implementation of such technologies in animal disease trials to refine experiments and guarantee the quality of experimental results.