Disease dynamics and mortality risk in tapirs (Perissodactyla: Tapiridae) through a systematic literature review: Implications for preventive medicine and conservation.

Abstract

The impact of diseases on tapir mortality and potential implications for preventive medicine and conservation remain unclear. A systematic literature review was conducted using seven databases and grey literature to address these gaps. The PRISMA statement was adopted to report results, and boosted regression tree models were employed for data analysis. After screening 5323 records and removing duplicates, the title and abstract of 2484 records were assessed. Out of 502 eligible studies, only 206 met all inclusion criteria. These were published between 1924 and 2023 in ten languages, comprising mainly case reports (45.1 %) and cross-sectional studies (41.3 %). Infectious diseases were found in 72.9 % of the reports, and 27.2 % presented clinical signs. The most affected systems were gastroenteric (22.7 %), integumentary (22.1 %), and respiratory (17.5 %). Respiratory diseases were associated with increased mortality. Factors affecting tapir mortality included species (relative influence 41.5 %), followed by geographic location (23.5 %) and captivity (16.8 %). Clinical signs were the least important variable (4 %). While infectious diseases were associated with higher mortality risk, tapirs were more likely to become ill from non-infectious than infectious diseases. Captive individuals were also more likely to present with illness than their wild counterparts. When considering external causes, vehicle collisions represented the most significant cause of death (52.2 %), followed by hunting (38.2 %). Diseases (8.7 %) were the third most important, with bacterial infections the leading cause of death. This review represents the most comprehensive overview on tapir health to date and provides novel ways to collate epidemiological data from disparate study designs.