Elevated incidence of alveolar echinococcosis in immunocompromised patients

Abstract

Introduction: Recent experimental data has revealed that the course of alveolar echinococcosis (AE) depends on adaptive immunity. For this study, we aimed to analyze the incidence and outcome of AE in immunocompromised humans.

Material and methods: Retrospective analysis of 131 patients with a median age of 54 years treated for AE between 1971 and 2017 at a Swiss tertiary referral Centre. Fifty-two percent were females and 65 patients (50%) were diagnosed incidentally. Fourteen patients (16%) were operated on laparoscopically. Overall, median follow-up was 48 months.

Results: New diagnoses have increased fourfold in immunocompetent and tenfold in immunocompromised patients in the past decade (p ≤ 0.005). Forty-one patients (31.3%) had co-existing or previous immunosuppressive conditions including 16 malignancies (36%), 11 auto-immune diseases or immunosuppressive therapies (31%), 5 infectious diseases (11%), 4 chronic asthma conditions (9%), 2 previous transplantations (4%) and 4 other immunocompromising conditions (9%). Serum levels of anti-Em18, -Em2 and -EgHF antibodies were neither associated with immunocompetence at diagnosis nor during follow-up, but significantly decreased after treatment with benzimidazole (n = 43) or surgery (n = 88) in all patients. Adjuvant therapy for ≥1 year (p = 0.007) with benzimidazole and resection status (R0) (p = 0.002) were both correlated with recurrence-free survival. Survival at 5 and 10 years after surgery was 97% and 94%, respectively, and after conservative treatment 91% and 73%, respectively. Curative surgery (p = 0.014) and immunocompetence (p = 0.048) correlated significantly with overall survival.

Conclusion: The incidence of human AE has increased over the last 2 decades with surgical interventions resulting in excellent outcomes. We have observed an association of immunosuppressive conditions with both incidence and survival of AE eventually justifying the implementation of a screening program for patients at risk in endemic regions.

Keywords: Alveolar echinococcosis, (AE); Benzimidazole; Echinoccocosis; Echinococcus multilocularis; Echinococcus multilocularis, (E. multilocularis); Immunosuppression; alveolar_echinococcosis; benzimidazole, (BZM); immunocompetent, (ICT); immunocompromised, (ICR).

Fig. 1

Distribution of the different immune system compromising conditions of the patients.

Fig. 2

Incidence of new cases of immunocompetent (ICT) and immunocompromised (ICR) patients organized by decades showing a significant increase of new cases over time (p = 0.0273) and from the second last to the last decade for ICT patients (p = 0.0004) and ICR patients (p = 0.005).

Fig. 3

Levels of antibodies against EgHF, Em2 and Em18 at initial diagnosis and 1st follow-up in immunocompetent (ICT) and immunocompromised (ICR) patients. Horizontal bars represent the median. The figure shows a significant decrease of the antibody levels against all 3 antigens after treatment for ICR and for ICT patients (Fig. 3, p ≤ 0.001, Wilcoxon sign-ranktest).

Fig. 4

Recurrence-free survival Kaplan-Meier curves comparing (A) resection status RO with R1 (B) adjuvant treatment with BZM for <1 year with treatment ≥2 years and, (C) adjuvant treatment with BZM <2 years with treatment ≥2 years post resection. Statistical differences were calculated by the log rank test.

Fig. 5

Overall survival Kaplan-Meier curves comparing (A) surgical treatment with conservative treatment with BZM and (B) immunocompetent with IC conditions. Statistical differences were calculated by the log rank test.