Neoeherlichiosis is an emerging tick-borne infection causing disease in individuals with inadequate B-cell responses because of haematologic cancer or treatment with B-cell depletion therapies such as rituximab. The infection has recently been found as a cause of prolonged fever among several patients receiving rituximab in Denmark. This review covers current knowledge on the clinical spectrum among healthy as well as immune compromised individuals, transmission, pathogenesis, diagnosis, and treatment.