many countries where vector ticks are found, such as R. e. evertsi, Hy. truncatum, and D. nitens. Dogs are at risk from severe infection with Ba. canis and its subspecies, transmitted by the dog ticks R. sanguineus, D. reticulatus, and Ha. leachi. Domestic cats become infected with Ba. felis and Ba. cati from feeding ticks. Cytauxzoon felis is a protozoan related to Babesia and Theileria. It is transmitted by the American dog tick, Dermacentor variabilis. This microbe circulates between wild bobcats in southern USA, causing little apparent disease. If it infects domestic cats, it causes a cytauxzoonosis that is eventually fatal. Theileria annulata is a protozoan closely related to Babesia. In cattle, it causes the disease tropical theileriosis throughout a long arc of countries from Morocco across to China. Theileria parva is the causative microbe of East Coast fever of cattle in Eastern, Central, and Southern Africa. Theileria species infect monocytic white blood cells of their hosts. The infected cells are induced to divide by the Theileria, which then proliferates within each daughter cell, in a rapidly expanding infection. This causes multiple inflammatory crises, of which pulmonary edema is a predominant cause of death. Theileria annulata is transmitted by Hy. anatolicum, Hy. detritum, and other hyalommas. Theileria parva is transmitted predominantly by Rhipicephalus appendiculatus. Because this is a three-host feeding tick, the opportunities for transmission are from infected cow to feeding larva then through the molt into the nymph which feeds and transmits. Similarly, transmission can also be from feeding nymphs to infected adult. This is known as transstadial transmission, and no transovarian transmission occurs in this case. The development of Theileria in ticks includes sexual reproduction which enables generation of new variants that can evade the immune mechanisms of cattle. Disease control methods Treatment with chemical and botanical pesticides against ticks Synthetic chemical acaricides Ticks infesting sheep and cattle have been controlled with a wide variety of chemicals ranging from coal tar extracts, arsenic salts, and specific pesticidal chemicals such as DDT for many decades. These are now replaced by various synthetic chemicals of high specificity for acarines and ticks, and farmers frequently rely on treating their animals with these materials as their default method. However, the expense of labour, equipment and acaricide can sometimes upset a good balance of cost : benefit with conventional treatment methods. Synthetic chemical pesticides specific for ticks (acaricides) are suspended in water for