Livestock Diseases and What Carries Them: Ticks, Mosquitoes, Midges, Flies and Soil

Babesiosis is also called tick fever or redwater disease. Babesia parasites destroy red blood cells and cause high fever, anemia and dark red urine, and its page notes that it was eradicated from the United States early in the twentieth century through a coordinated tick control program. It remains endemic wherever its Rhipicephalus tick vectors are established.

Anaplasmosis is the other half of the cattle tick fever complex and is carried by ticks and by biting flies. Its page records that recovered cattle typically remain lifelong carriers able to infect the ticks that feed on them, which is why it is so hard to eliminate once it is established in a herd or region.

Heartwater is spread by Amblyomma ticks and takes its name from the fluid that collects around the heart and lungs of infected animals. Its page notes that it is endemic across sub-Saharan Africa and on several Caribbean islands, and that it is a principal constraint on introducing higher-yielding cattle breeds, because indigenous breeds have usually developed far greater natural resistance.

Rift Valley fever moves from ticks to mosquitoes as the carrier. First identified in Kenya's Rift Valley in the 1930s, it causes abortion storms in pregnant animals and is also a serious zoonotic disease of humans. Its page ties outbreaks to unusually heavy rainfall that floods the breeding sites its mosquito vectors need.

African horse sickness is carried by Culicoides midges, with donkeys and zebras serving as largely symptomless reservoir hosts. Its page records mortality that can exceed 90 percent in susceptible horses, no treatment once clinical signs appear, and periodic spread beyond sub-Saharan Africa into North Africa, the Iberian Peninsula and the Middle East when climate favors the midges.

Nagana is caused by Trypanosoma protozoa transmitted by tsetse flies and produces fever, anemia and progressive wasting. Its page describes it as rendering vast areas of sub-Saharan Africa unsuitable for cattle keeping, and treats the long exclusion of livestock and the plow from the tsetse belt as one of the most significant historical influences on African agricultural development.

Here the carrier is also the pest. The Old World screwworm is a blowfly, Chrysomya bezziana, whose larvae feed on living tissue through open wounds, a condition called myiasis. Its page notes that no region-wide eradication program using sterile insect release has yet succeeded against it, and that countries such as Australia that have kept it out treat it as a standing biosecurity concern.

Anthrax closes the path as the contrast: no tick or fly is needed, because Bacillus anthracis spores persist in soil for decades. Its page describes outbreaks recurring at the same spore-contaminated fields after heavy rain or soil disturbance, with routine vaccination and strict disposal of carcasses without opening them as the primary control, since the disease is also a serious zoonotic threat to anyone handling an infected carcass or hide.