Neoehrlichiosis in patients with multiple sclerosis in Halmstad, Sweden: A case series

Neoehrlichiosis is an emerging tick-borne infection. The documented cases of human infection demonstrate a varying symptomatology, diagnostic difficulties, a lacking clinical awareness of the condition and a considerable diagnostic delay. A high prevalence of the causative pathogen has been found in ticks in large parts of Europe, and there is believed to be a significant underdiagnosis. B-cell targeting therapy has been found a significant risk factor both for symptomatic and severe infection. However, the number of reports of neoehrlichiosis in multiple sclerosis (MS) patients is scarce, with only four documented cases to date. This case series portrays seven cases of neoehrlichiosis in six MS patients in southern Sweden, yielding a greater understanding of the infection in this patient group. The cases illustrate the elusive symptomatology of neoehrlichiosis, resulting in a diagnostic delay. The findings show that testing for neoehrlichiosis must be considered in patients with B-cell modifying therapy both in the case of fever, but also other suggestive symptoms, and disregarding season and recollection of tick bite. All patients were under active treatment with rituximab, but with significant differences in treatment duration, total accumulated dose and duration since last dose. No correlation was seen to decreased levels of immunoglobulin G (IgG), but rather to B-cell depletion. This illustrates the need to monitor CD19 and CD20 levels when assessing risk for neoehrlichiosis, and to consider screening for infection before onset of B-cell modifying therapy.