ABSTRACT
INTRODUCTION Ticks are the natural hosts and vectors of most rickettsias, and domestic and wild animals that ticks feed on are commonly infected with the organisms. Some rickettsias are highly pathogenic in animals with two of the most important diseases of livestock, bovine anaplasmosis and heartwater, being caused by rickettsias. These diseases result in considerable direct and indirect economic losses to the livestock industry worldwide, from morbidity and mortality, decreased productivity, and the development and implementation of control strategies such as disease monitoring, use of acaricides, chemoprophylaxis, and vaccinations. Rickettsias also cause disease in companion animals, dogs, cats, and horses, causing animal suffering and mental and emotional distress to the owners. There are also substantial financial costs to owners, for veterinary treatments and also for tick-prevention programs.
