Here's a breakdown of the contributions:
* Theobald Smith (1889): Smith, working at the U.S. Department of Agriculture, demonstrated that Texas cattle fever was caused by a protozoan parasite (later named *Babesia bigemina*) that lived within the red blood cells of cattle.
* Francis Lowry (1889): Lowry, also working at the U.S. Department of Agriculture, conducted experiments showing that the parasite was transmitted by ticks (primarily the species *Boophilus annulatus*). He demonstrated that ticks could pick up the parasite from infected cattle and then transmit it to healthy cattle.
* Daniel Edward Salmon (1889): Salmon, a veterinarian and colleague of Smith, played a crucial role in establishing the scientific basis for the research and in advocating for control measures to prevent the spread of the disease.
While Smith is often recognized as the primary discoverer, the work of Lowry and Salmon was essential in understanding the mode of transmission.
Therefore, it's more accurate to say that Smith, Lowry, and Salmon together played a vital role in unraveling the etiology and mode of transmission of Texas cattle fever. Their findings revolutionized cattle disease control and laid the foundation for future research on tick-borne diseases.