Low occurrence of pulmonary lophomoniasis among cigarette smokers: An analysis of risk factors based on registry data.

Background And Objectives: Lophomonas blattarum is an emerging protozoan agent that mainly causes pulmonary lophomoniasis. Given that cigarette smokers are predisposed to various diseases while some conditions are less common among them, the current study aimed to compare the relationship between smoking status and the prevalence of pulmonary lophomoniasis in patients registered at the Iranian National Registry Center for Lophomoniasis (INRCL). Additionally, we examined common risk factors associated with Lophomonas infection among these registered subjects.

Materials And Methods: This descriptive-analytical cross-sectional registry-based study was conducted on 600 registered subjects through microscopic examination (wet mount smears) and conventional polymerase chain reaction assay between 2021 and 2023. We analysed the smoking status and smoking intensity of 135 Lophomonas-positive patients and 465 Lophomonas-negative patients who were referred to the INRCL. Baseline data were collected from participants using a questionnaire.

Results: Our results showed the prevalence of Lophomonas infection among enrolled subjects was estimated to be 22.5% (135/600). Also, we studied 135 Lophomonas positive patients (male = 92, female = 43). Furthermore, most patients testing positive for Lophomonas (74.8%; 101/135) also had at least one comorbidity condition. Our findings showed a statistically significant occurrence of Lophomonas infection among non-smokers (70.4%; n = 95), in contrast to smokers (29.6%; n = 40) (P = 0.001). Correspondingly, among the 40 Lophomonas-positive smokers, the majority (62.5%) were classified as light smokers. Moreover, based on the multiple logistic regressions, Lophomonas infection was 2.123, 3.142, and 2.353 times higher in men compared to women, patients aged 51-70 years compared to other age groups, and non-smokers compared to cigarette smokers, respectively (P = 0.001).

Conclusion: Our findings reveal that Lophomonas infection is significantly lower among cigarette smokers compared to nonsmokers. Our data shed light on a new hypothesis about lophomoniasis among smokers. Further research is needed to assess the role of smoking in the pathophysiology of lophomoniasis.