Environmental and Breed-Related Determinants of Bovine Ephemeral Fever Outbreaks in Southeastern Türkiye.

Background: Bovine ephemeral fever (BEF) is a biphasic febrile, vector-borne viral disease affecting cattle and buffaloes, leading to significant reductions in milk production and economic losses. BEF's episodic nature often leads to its classification as non-notifiable disease.

Objectives: This study aimed to investigate the environmental and breed-related determinants of BEF in Şanlıurfa, a region in southeastern Türkiye notable for its vulnerability to vector-borne diseases.

Methods: We integrated temperature, precipitation and irrigation data with the occurrence of clinical BEF cases to identify critical environmental conditions associated with outbreaks. Additionally, we conducted an epidemiological analysis focused on a state-owned dairy farm to assess breed-specific morbidity, case fatality and mortality rates. A partial G-gene sequence from a positive sample was phylogenetically analysed to trace its origins.

Results: Temperatures above 15°C, excessive rainfall and increased agricultural irrigation were identified as key factors associated with the emergence and spread of BEF. The cropping pattern, including maize and cotton cultivation, significantly influences irrigation practices and, consequently, vector population dynamics. Holstein-Friesian cattle showed higher morbidity (58.4%), case fatality (12.9%) and mortality (7.5%) rates compared to Simmental cattle, which exhibited lower rates (morbidity 28.1%, case fatality 5.2%, mortality 1.5%). Phylogenetic analysis linked the virus strain to a Middle Eastern clade from the 2018 to 2020 period.

Conclusions: The study highlights the importance of considering environmental conditions, crop patterns, and breed-specific health risks in managing BEF. Tailored intervention strategies are crucial for mitigating the economic and health impacts of BEF on dairy farms.