The replication rate of Anaplasma marginale is temperature-mediated in ticks.

<i>Anaplasma marginale</i> , the cause of bovine anaplasmosis, a serious production-limiting disease of cattle found worldwide, is biologically transmitted by adult male <i>Dermacentor</i> spp. ticks in the United States. We tested the impact of 9 temperatures on infected <i>D. andersoni</i> and found that the replication of <i>A. marginale</i> in tick midguts and salivary glands is temperature dependent. There were higher bacterial levels between 32°C and 37°C than between 4°C to 26°C. We observed 100% mortality in ticks at 42°C. Future research should explore the mechanisms of temperature-dependent replication in <i>A. marginale</i> and possible links to transmission rates under climate change.