Cattle fever

Texas cattle fever was identified as being caused by a protozoan parasite (just like malaria) and spread by blood-sucking ticks. This discovery provided the first clear evidence that arthropods could transmit diseases.
 Theobald Smith United States 1893 Cattle fever

Texas cattle fever was identified as being caused by a protozoan parasite (just like malaria) and spread by blood-sucking ticks. This discovery provided the first clear evidence that arthropods could transmit diseases.